<p><b>氫氧化鈉</b>（sodium hydroxide）又稱<b>苛性鈉</b>（sodium hydroxide），俗稱<b>鹼液</b>（lye）、<b>火鹼</b>、<b>燒鹼</b>、<b>液鹼</b>等，化學式為NaOH，是一種具有高腐蝕性的強鹼，一般為白色片狀或顆粒，能溶於水生成鹼性溶液，另也能溶解於甲醇及乙醇。此鹼性物具有潮解性，會吸收空氣中的水蒸氣，亦會吸取二氧化碳、二氧化硫等酸性氣體。
</p><p>氫氧化鈉為常用的化學品之一。其應用廣泛，為很多工業過程的必需品：常用於製造木漿紙張、紡織品、肥皂及其他清潔劑等，另也用於家用的水管疏通劑。2004年全球總共製造了六千萬噸的氫氧化鈉，而總消耗量為五千一百萬噸。</p>


<h2><span id=".E5.8C.96.E5.AD.A6.E6.80.A7.E8.B3.AA"></span><span id="化学性質">化學性質</span></h2>
<h3><span id=".E5.92.8C.E9.85.B8.E5.8F.8D.E5.BA.94"></span><span id="和酸反应">和酸反應</span></h3>
<p>氫氧化鈉於水中會完全解離成鈉離子與氫氧根離子，可以和酸進行酸鹼中和反應：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {NaOH+HCl\rightarrow NaCl+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">H</mi>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">l</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">l</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {NaOH+HCl\rightarrow NaCl+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+H_{2}SO_{4}\rightarrow Na_{2}SO_{4}+2H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">S</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>4</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">S</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>4</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mn>2</mn>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+H_{2}SO_{4}\rightarrow Na_{2}SO_{4}+2H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><p>利用這一性質，可以製備一些酸的鈉鹽，如：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {NaOH+C_{6}H_{5}COOH\rightarrow C_{6}H_{5}COONa+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">C</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>6</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>5</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <msub>
              <mi mathvariant="normal">C</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>6</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>5</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {NaOH+C_{6}H_{5}COOH\rightarrow C_{6}H_{5}COONa+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {NaOH+CH_{3}COOH\rightarrow CH_{3}COONa+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {NaOH+CH_{3}COOH\rightarrow CH_{3}COONa+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><p>酸性很弱的苯酚也能與之反應：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {NaOH+C_{6}H_{5}OH\rightarrow C_{6}H_{5}ONa+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">C</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>6</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>5</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <msub>
              <mi mathvariant="normal">C</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>6</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>5</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {NaOH+C_{6}H_{5}OH\rightarrow C_{6}H_{5}ONa+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><h3><span id=".E5.92.8C.E9.85.B8.E6.80.A7.E6.B0.A7.E5.8C.96.E7.89.A9.E5.8F.8D.E5.BA.94"></span><span id="和酸性氧化物反应">和酸性氧化物反應</span></h3>
<p>氫氧化鈉在空氣中容易變質，就是因為和空氣中的二氧化碳發生了反應：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+CO_{2}\rightarrow Na_{2}CO_{3}+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+CO_{2}\rightarrow Na_{2}CO_{3}+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><p>在溶液中發生，過量的二氧化碳會將碳酸鈉轉化為碳酸氫鈉（俗稱小蘇打）：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {Na_{2}CO_{3}+CO_{2}+H_{2}O\rightarrow 2NaHCO_{3}}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">H</mi>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {Na_{2}CO_{3}+CO_{2}+H_{2}O\rightarrow 2NaHCO_{3}}}}</annotation>
  </semantics></math></span></span></dd></dl><p>由於玻璃製品中含有二氧化矽，氫氧化鈉會與之反應生成矽酸鈉，使得玻璃儀器中的活塞黏著於儀器上，無法再次使用。因此，存放氫氧化鈉的細口瓶一般用橡膠塞封口。如果以玻璃容器長時間盛裝熱的氫氧化鈉溶液，會造成玻璃容器損壞，甚至破裂的情況。
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+SiO_{2}\rightarrow Na_{2}SiO_{3}+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">S</mi>
            <mi mathvariant="normal">i</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">S</mi>
            <mi mathvariant="normal">i</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+SiO_{2}\rightarrow Na_{2}SiO_{3}+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><p>同樣地，氫氧化鈉也能和三氧化鉻、五氧化二磷、三氧化二砷、二氧化硫、二氧化硒等其它酸性氧化物反應，生成它們的鹽：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+CrO_{3}\rightarrow Na_{2}CrO_{4}+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">r</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">r</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>4</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+CrO_{3}\rightarrow Na_{2}CrO_{4}+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+2CrO_{3}\rightarrow Na_{2}Cr_{2}O_{7}+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mn>2</mn>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">r</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">r</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>7</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+2CrO_{3}\rightarrow Na_{2}Cr_{2}O_{7}+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><h3><span id=".E5.92.8C.E4.B8.A4.E6.80.A7.E6.B0.A7.E5.8C.96.E7.89.A9.E5.8F.8A.E6.B0.A2.E6.B0.A7.E5.8C.96.E7.89.A9.E7.9A.84.E5.8F.8D.E5.BA.94"></span><span id="和两性氧化物及氢氧化物的反应">和兩性氧化物及氫氧化物的反應</span></h3>
<p>氫氧化鈉可以和兩性氧化物或氫氧化物反應，生成鹽和水，如：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+Al_{2}O_{3}+3H_{2}O\rightarrow 2Na[Al(OH)_{4}]}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">A</mi>
            <msub>
              <mi mathvariant="normal">l</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mn>3</mn>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mo stretchy="false">[</mo>
            <mi mathvariant="normal">A</mi>
            <mi mathvariant="normal">l</mi>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>4</mn>
              </mrow>
            </msub>
            <mo stretchy="false">]</mo>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+Al_{2}O_{3}+3H_{2}O\rightarrow 2Na[Al(OH)_{4}]}}}</annotation>
  </semantics></math></span></span></dd></dl><h3><span id=".E5.92.8C.E5.8D.95.E8.B4.A8.E7.9A.84.E5.8F.8D.E5.BA.94"></span><span id="和单质的反应">和單質的反應</span></h3>
<p>硼、矽和兩性金屬（如鈹、鋁、鋅等）和氫氧化鈉反應，放出氫氣：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {Si+2NaOH+H_{2}O\rightarrow Na_{2}SiO_{3}+2H_{2}\uparrow }}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">S</mi>
            <mi mathvariant="normal">i</mi>
            <mo>+</mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">S</mi>
            <mi mathvariant="normal">i</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mn>2</mn>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">↑<!-- ↑ --></mo>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {Si+2NaOH+H_{2}O\rightarrow Na_{2}SiO_{3}+2H_{2}\uparrow }}}</annotation>
  </semantics></math></span></span></dd></dl><p>英國在1986年有一油罐車誤裝載重量百分率濃度為25%的氫氧化鈉水溶液，氫氧化鈉便與油罐壁上的鋁產生化學變化，導致油罐因內部壓力過載而受損，反應方程式如下所示：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2Al+2NaOH+2H_{2}O\rightarrow 2NaAlO_{2}+3H_{2}\uparrow }}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">A</mi>
            <mi mathvariant="normal">l</mi>
            <mo>+</mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mn>2</mn>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">A</mi>
            <mi mathvariant="normal">l</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mn>3</mn>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">↑<!-- ↑ --></mo>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2Al+2NaOH+2H_{2}O\rightarrow 2NaAlO_{2}+3H_{2}\uparrow }}}</annotation>
  </semantics></math></span></span></dd></dl><p>氯、溴、碘、硫、白磷等單質和氫氧化鈉發生歧化反應：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {Cl_{2}+2NaOH\rightarrow NaCl+NaClO+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">l</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">l</mi>
            <mo>+</mo>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">l</mi>
            <mi mathvariant="normal">O</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {Cl_{2}+2NaOH\rightarrow NaCl+NaClO+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><h3><span id=".E5.92.8C.E7.9B.90.E7.9A.84.E5.8F.8D.E5.BA.94"></span><span id="和盐的反应">和鹽的反應</span></h3>
<p>過渡金屬的鹽類和一些主族金屬的鹽可以和氫氧化鈉反應，生成更難溶的氫氧化物，或轉化為可溶性的羥基配合物再次溶解。
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+CoSO_{4}\rightarrow Na_{2}SO_{4}+Co(OH)_{2}}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">o</mi>
            <mi mathvariant="normal">S</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>4</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">S</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>4</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">o</mi>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+CoSO_{4}\rightarrow Na_{2}SO_{4}+Co(OH)_{2}}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+CuCl_{2}\rightarrow 2NaCl+Cu(OH)_{2}}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">u</mi>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">l</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">l</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">u</mi>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+CuCl_{2}\rightarrow 2NaCl+Cu(OH)_{2}}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {3NaOH+Cr(NO_{3})_{3}\rightarrow 3NaNO_{3}+Cr(OH)_{3}}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>3</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">r</mi>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mn>3</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">r</mi>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {3NaOH+Cr(NO_{3})_{3}\rightarrow 3NaNO_{3}+Cr(OH)_{3}}}}</annotation>
  </semantics></math></span></span>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {NaOH+Cr(OH)_{3}\rightarrow Na[Cr(OH)_{4}]}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">r</mi>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mo stretchy="false">[</mo>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">r</mi>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>4</mn>
              </mrow>
            </msub>
            <mo stretchy="false">]</mo>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {NaOH+Cr(OH)_{3}\rightarrow Na[Cr(OH)_{4}]}}}</annotation>
  </semantics></math></span></span></dd></dl></dd></dl><p>以上反應的產物的顔色、溶解度等可被用來測試某種陽離子。
</p><p>對於汞等氫氧化物不能穩定存在的物質來說，會生產氧化物或氧化物的水合物沉澱：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {2NaOH+HgCl_{2}\rightarrow 2NaCl+HgO+H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mi mathvariant="normal">H</mi>
            <mi mathvariant="normal">g</mi>
            <mi mathvariant="normal">C</mi>
            <msub>
              <mi mathvariant="normal">l</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mn>2</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">C</mi>
            <mi mathvariant="normal">l</mi>
            <mo>+</mo>
            <mi mathvariant="normal">H</mi>
            <mi mathvariant="normal">g</mi>
            <mi mathvariant="normal">O</mi>
            <mo>+</mo>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {2NaOH+HgCl_{2}\rightarrow 2NaCl+HgO+H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><p>氫氧化鈉可以將過渡金屬的醯基離子轉化為陰離子酸根（簡單離子或多聚離子），如VO<sub>2</sub><sup>+</sup>、UO<sub>2</sub><sup>2+</sup>等：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\rm {6NaOH+2UO_{2}(NO_{3})_{2}\rightarrow 4NaNO_{3}+Na_{2}U_{2}O_{7}+3H_{2}O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mrow class="MJX-TeXAtom-ORD">
            <mn>6</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">O</mi>
            <mi mathvariant="normal">H</mi>
            <mo>+</mo>
            <mn>2</mn>
            <mi mathvariant="normal">U</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">(</mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <msub>
              <mo stretchy="false">)</mo>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mo stretchy="false">→<!-- → --></mo>
            <mn>4</mn>
            <mi mathvariant="normal">N</mi>
            <mi mathvariant="normal">a</mi>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>3</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mi mathvariant="normal">N</mi>
            <msub>
              <mi mathvariant="normal">a</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">U</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <msub>
              <mi mathvariant="normal">O</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>7</mn>
              </mrow>
            </msub>
            <mo>+</mo>
            <mn>3</mn>
            <msub>
              <mi mathvariant="normal">H</mi>
              <mrow class="MJX-TeXAtom-ORD">
                <mn>2</mn>
              </mrow>
            </msub>
            <mi mathvariant="normal">O</mi>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\rm {6NaOH+2UO_{2}(NO_{3})_{2}\rightarrow 4NaNO_{3}+Na_{2}U_{2}O_{7}+3H_{2}O}}}</annotation>
  </semantics></math></span></span></dd></dl><p>氫氧化鈉跟銨鹽產生反應，生成氨氣、水和相應的鈉鹽。此為銨離子的檢驗方法。
</p>
<h3><span id=".E5.92.8C.E5.85.B6.E5.AE.83.E6.97.A0.E6.9C.BA.E7.89.A9.E7.9A.84.E5.8F.8D.E5.BA.94"></span><span id="和其它无机物的反应">和其它無機物的反應</span></h3>
<p>二氧化氯、二氧化氮等可以和氫氧化鈉發生反應。
</p><p>高錳酸鈉在氫氧化鈉溶液中煮沸，可以還原為錳酸鈉。
</p>
<h3><span id=".E5.92.8C.E6.9C.89.E6.9C.BA.E7.89.A9.E7.9A.84.E5.8F.8D.E5.BA.94"></span><span id="和有机物的反应">和有機物的反應</span></h3>
<p>氫氧化鈉可以將鹵代烴、酯和醯鹵水解。其醇溶液可以用於鹵代烴的消去。例如：
</p>
<ul><li>氯乙烷的水解， 生成氯化鈉和乙醇： <span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {EtCl + NaOH -&gt; EtOH + NaCl}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mtext>EtCl</mtext>
          <mo>+</mo>
          <mtext>NaOH</mtext>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <mtext>EtOH</mtext>
          <mo>+</mo>
          <mtext>NaCl</mtext>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {EtCl + NaOH -&gt; EtOH + NaCl}}}</annotation>
  </semantics></math></span></span></li>
<li>乙酸乙酯的加鹼水解： <span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {CH3COOC2H5 + OH- -&gt;[H2O] CH3COO- + C2H5OH}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <msubsup>
            <mtext>CH</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>3</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <msubsup>
            <mtext>COOC</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>5</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mo>+</mo>
          <msup>
            <mtext>OH</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mo>−<!-- − --></mo>
            </mrow>
          </msup>
          <mrow class="MJX-TeXAtom-REL">
            <mover>
              <mo>→</mo>
              <mpadded width="+0.611em" lspace="0.278em" voffset=".15em">
                <mi>H</mi>
                <mn>2</mn>
                <mi>O</mi>
              </mpadded>
            </mover>
          </mrow>
          <msubsup>
            <mtext>CH</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>3</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <msup>
            <mtext>COO</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mo>−<!-- − --></mo>
            </mrow>
          </msup>
          <mo>+</mo>
          <msubsup>
            <mtext>C</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>5</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>OH</mtext>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {CH3COOC2H5 + OH- -&gt;[H2O] CH3COO- + C2H5OH}}}</annotation>
  </semantics></math></span></span></li>
<li>如果是高級脂肪酸酯，水解成皂的反應，統一命名為皂化反應。</li></ul><p>另外，氫氧化鈉是一種鹼,可提供氫氧根離子，可催化羥醛縮合反應。首先，氫氧根離子會去質子化醛或酮，生成烯醇負離子和水，該烯醇負離子會進攻令一電中性的醛或酮，生成羥醛加成物負離子。然後，那加成物會質子化，在第一步所生成的水上拿掉質子，在生成最終的羥醛產物後，亦同時再生氫氧根離子（催化劑）。
</p>
<p>由於氫氧化鈉可以提供氫氧根離子，所以亦可催化酮-烯醇互變異構。這叫鹼催化酮-烯醇互變異構：
</p>
<h2><span id=".E5.B7.A5.E4.B8.9A.E5.88.B6.E6.B3.95"></span><span id="工业制法">工業製法</span></h2>
<p>氫氧化鈉為工業中製氯氣過程的副產物，工業上，透過電解大量飽和食鹽水以量產氯氣，然而，當氯離子氧化成氯氣逸出的同時，溶液中也只剩下氫氧化鈉一種溶質，反應方程式如下所示：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {2NaCl + 2H_2O -&gt; 2NaOH + Cl_2 ^ + H_2 ^}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>NaCl</mtext>
          <mo>+</mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>NaOH</mtext>
          <mo>+</mo>
          <msubsup>
            <mtext>Cl</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mrow class="MJX-TeXAtom-ORD">
            <mo stretchy="false">↑<!-- ↑ --></mo>
          </mrow>
          <mo>+</mo>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mrow class="MJX-TeXAtom-ORD">
            <mo stretchy="false">↑<!-- ↑ --></mo>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {2NaCl + 2H_2O -&gt; 2NaOH + Cl_2 ^ + H_2 ^}}}</annotation>
  </semantics></math></span></span></dd></dl><p>19世紀以前，氫氧化鈉的製備通常會先以勒布朗制鹼法生成前驅物碳酸鈉，再通過高溫煅燒，使得碳酸鈉分解為氧化鈉與二氧化碳，最後，將氧化鈉溶於水中，便可製得氫氧化鈉：
</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {Na_2CO_3 -&gt; Na_2O + CO_2 ^}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <msubsup>
            <mtext>Na</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <msubsup>
            <mtext>CO</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>3</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <msubsup>
            <mtext>Na</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
          <mo>+</mo>
          <msubsup>
            <mtext>CO</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mrow class="MJX-TeXAtom-ORD">
            <mo stretchy="false">↑<!-- ↑ --></mo>
          </mrow>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {Na_2CO_3 -&gt; Na_2O + CO_2 ^}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {Na_2O + H_2O -&gt; 2NaOH}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <msubsup>
            <mtext>Na</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
          <mo>+</mo>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>NaOH</mtext>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {Na_2O + H_2O -&gt; 2NaOH}}}</annotation>
  </semantics></math></span></span></dd></dl><p>另外，也可利用複分解制備氫氧化鈉，碳酸鈉（俗稱為蘇打）與氫氧化鈣（俗稱為熟石灰）的反應方程式如下所示：</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {Na_2CO_3 + Ca(OH)_2 -&gt; CaCO_3 v + 2NaOH}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <msubsup>
            <mtext>Na</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <msubsup>
            <mtext>CO</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>3</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mo>+</mo>
          <mtext>Ca</mtext>
          <msubsup>
            <mrow class="MJX-TeXAtom-ORD">
              <mo stretchy="false">(</mo>
              <mtext>OH</mtext>
              <mo stretchy="false">)</mo>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <msubsup>
            <mtext>CaCO</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>3</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mrow class="MJX-TeXAtom-ORD">
            <mo stretchy="false">↓<!-- ↓ --></mo>
          </mrow>
          <mo>+</mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>NaOH</mtext>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {Na_2CO_3 + Ca(OH)_2 -&gt; CaCO_3 v + 2NaOH}}}</annotation>
  </semantics></math></span></span></dd></dl><h2><span id=".E5.AE.89.E5.85.A8.E6.80.A7"></span><span id="安全性">安全性</span></h2>


<p>氫氧化鈉固體或其溶液皆能灼傷皮膚，對無防護措施者可造成永久性傷害（如疤痕）。倘若讓氫氧化鈉直接接觸眼睛的話，嚴重者甚至可造成失明。個人防護措施，諸如橡膠手套、防護衣與護目鏡等便能大大降低接觸氫氧化鈉所帶來的危險。
</p><p>氫氧化鈉溶於水中（如稀釋），抑或是與酸反應，都會放出大量的熱量，可能導致灼傷或點燃易燃物（如有機溶劑）。除此之外，氫氧化鈉能夠腐蝕一些金屬（如鋁）生成易燃的氫氣，還能夠輕度腐蝕玻璃製品，應慎選儲存氫氧化鈉的容器材質。</p>
<dl><dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {2Al + 2NaOH + 2H_2O -&gt; 3H_2 + 2NaAlO_2}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>Al</mtext>
          <mo>+</mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>NaOH</mtext>
          <mo>+</mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <mn>3</mn>
          <mspace width="thinmathspace"></mspace>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mo>+</mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <msubsup>
            <mtext>NaAlO</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {2Al + 2NaOH + 2H_2O -&gt; 3H_2 + 2NaAlO_2}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {2Al + 6NaOH + xH_2O -&gt; 3H_2 + 2 Na_3AlO_3 + x H_2O}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>Al</mtext>
          <mo>+</mo>
          <mn>6</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>NaOH</mtext>
          <mo>+</mo>
          <msubsup>
            <mtext>xH</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <mn>3</mn>
          <mspace width="thinmathspace"></mspace>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mo>+</mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <msubsup>
            <mtext>Na</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>3</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <msubsup>
            <mtext>AlO</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>3</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mo>+</mo>
          <mtext>x</mtext>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
        </mrow>
      </mstyle>
    </mrow>
    <annotation encoding="application/x-tex">{\displaystyle {\ce {2Al + 6NaOH + xH_2O -&gt; 3H_2 + 2 Na_3AlO_3 + x H_2O}}}</annotation>
  </semantics></math></span></span></dd>
<dd><span><span><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle {\ce {2Al + 2NaOH + 6H_2O -&gt; 3H_2 + 2NaAl(OH)_4}}}">
  <semantics>
    <mrow class="MJX-TeXAtom-ORD">
      <mstyle displaystyle="true" scriptlevel="0">
        <mrow class="MJX-TeXAtom-ORD">
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>Al</mtext>
          <mo>+</mo>
          <mn>2</mn>
          <mspace width="thinmathspace"></mspace>
          <mtext>NaOH</mtext>
          <mo>+</mo>
          <mn>6</mn>
          <mspace width="thinmathspace"></mspace>
          <msubsup>
            <mtext>H</mtext>
            <mrow class="MJX-TeXAtom-ORD">
              <mn>2</mn>
            </mrow>
            <mrow class="MJX-TeXAtom-ORD">
              <mspace width="0pt" height="0pt" depth=".2em"></mspace>
            </mrow>
          </msubsup>
          <mtext>O</mtext>
          <mo stretchy="false">⟶<!-- ⟶ --></mo>
          <mn>3</mn>
          <mspace width="thinmathspace"></mspace>
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          <mtext>NaAl</mtext>
          <msubsup>
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              <mo stretchy="false">(</mo>
              <mtext>OH</mtext>
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    <annotation encoding="application/x-tex">{\displaystyle {\ce {2Al + 2NaOH + 6H_2O -&gt; 3H_2 + 2NaAl(OH)_4}}}</annotation>
  </semantics></math></span></span></dd></dl><h2><span id=".E5.8F.82.E7.9C.8B"></span><span id="参看">參看</span></h2>
<ul><li>鹼</li>
<li>氫氧根：氫氧化鉀、氫氧化鈣</li>
<li>皂化反應</li></ul><h2><span id=".E5.8F.83.E8.80.83.E8.B3.87.E6.96.99"></span><span id="參考資料">參考資料</span></h2>

<h2><span id=".E6.B3.A8.E9.87.8A"></span><span id="注释">注釋</span></h2>

<h2><span id=".E5.A4.96.E9.83.A8.E9.93.BE.E6.8E.A5"></span><span id="外部链接">外部連結</span></h2>
<ul><li>Chemistry WebBook上的化學數據</li>
<li>科學空間 （頁面存檔備份，存於網際網路檔案館）</li></ul>
**氫氧化鈉**（sodium hydroxide）又稱**苛性鈉**（sodium hydroxide），俗稱**鹼液**（lye）、**火鹼**、**燒鹼**、**液鹼**等，化學式為 NaOH，是一種具有高腐蝕性的強鹼，一般為白色片狀或顆粒，能溶於水生成鹼性溶液，另也能溶解於甲醇及乙醇。此鹼性物具有潮解性，會吸收空氣中的水蒸氣，亦會吸取二氧化碳、二氧化硫等酸性氣體。

氫氧化鈉為常用的化學品之一。其應用廣泛，為很多工業過程的必需品：常用於製造木漿紙張、紡織品、肥皂及其他清潔劑等，另也用於家用的水管疏通劑。2004 年全球總共製造了六千萬噸的氫氧化鈉，而總消耗量為五千一百萬噸。

## 化學性質

### 和酸反應

氫氧化鈉於水中會完全解離成鈉離子與氫氧根離子，可以和酸進行酸鹼中和反應：

　
: ${\rm {NaOH+HCl\rightarrow NaCl+H_{2}O}}$

　
: ${\rm {2NaOH+H_{2}SO_{4}\rightarrow Na_{2}SO_{4}+2H_{2}O}}$

利用這一性質，可以製備一些酸的鈉鹽，如：

　
: ${\rm {NaOH+C_{6}H_{5}COOH\rightarrow C_{6}H_{5}COONa+H_{2}O}}$

　
: ${\rm {NaOH+CH_{3}COOH\rightarrow CH_{3}COONa+H_{2}O}}$

酸性很弱的苯酚也能與之反應：

　
: ${\rm {NaOH+C_{6}H_{5}OH\rightarrow C_{6}H_{5}ONa+H_{2}O}}$

### 和酸性氧化物反應

氫氧化鈉在空氣中容易變質，就是因為和空氣中的二氧化碳發生了反應：

　
: ${\rm {2NaOH+CO_{2}\rightarrow Na_{2}CO_{3}+H_{2}O}}$

在溶液中發生，過量的二氧化碳會將碳酸鈉轉化為碳酸氫鈉（俗稱小蘇打）：

　
: ${\rm {Na_{2}CO_{3}+CO_{2}+H_{2}O\rightarrow 2NaHCO_{3}}}$

由於玻璃製品中含有二氧化矽，氫氧化鈉會與之反應生成矽酸鈉，使得玻璃儀器中的活塞黏著於儀器上，無法再次使用。因此，存放氫氧化鈉的細口瓶一般用橡膠塞封口。如果以玻璃容器長時間盛裝熱的氫氧化鈉溶液，會造成玻璃容器損壞，甚至破裂的情況。

　
: ${\rm {2NaOH+SiO_{2}\rightarrow Na_{2}SiO_{3}+H_{2}O}}$

同樣地，氫氧化鈉也能和三氧化鉻、五氧化二磷、三氧化二砷、二氧化硫、二氧化硒等其它酸性氧化物反應，生成它們的鹽：

　
: ${\rm {2NaOH+CrO_{3}\rightarrow Na_{2}CrO_{4}+H_{2}O}}$

　
: ${\rm {2NaOH+2CrO_{3}\rightarrow Na_{2}Cr_{2}O_{7}+H_{2}O}}$

### 和兩性氧化物及氫氧化物的反應

氫氧化鈉可以和兩性氧化物或氫氧化物反應，生成鹽和水，如：

　
: ${\rm {2NaOH+Al_{2}O_{3}+3H_{2}O\rightarrow 2Na[Al(OH)_{4}]}}$

### 和單質的反應

硼、矽和兩性金屬（如鈹、鋁、鋅等）和氫氧化鈉反應，放出氫氣：

　
: ${\rm {Si+2NaOH+H_{2}O\rightarrow Na_{2}SiO_{3}+2H_{2}\uparrow }}$

英國在 1986 年有一油罐車誤裝載重量百分率濃度為 25% 的氫氧化鈉水溶液，氫氧化鈉便與油罐壁上的鋁產生化學變化，導致油罐因內部壓力過載而受損，反應方程式如下所示：

　
: ${\rm {2Al+2NaOH+2H_{2}O\rightarrow 2NaAlO_{2}+3H_{2}\uparrow }}$

氯、溴、碘、硫、白磷等單質和氫氧化鈉發生歧化反應：

　
: ${\rm {Cl_{2}+2NaOH\rightarrow NaCl+NaClO+H_{2}O}}$

### 和鹽的反應

過渡金屬的鹽類和一些主族金屬的鹽可以和氫氧化鈉反應，生成更難溶的氫氧化物，或轉化為可溶性的羥基配合物再次溶解。

　
: ${\rm {2NaOH+CoSO_{4}\rightarrow Na_{2}SO_{4}+Co(OH)_{2}}}$

　
: ${\rm {2NaOH+CuCl_{2}\rightarrow 2NaCl+Cu(OH)_{2}}}$

　
: ${\rm {3NaOH+Cr(NO_{3})_{3}\rightarrow 3NaNO_{3}+Cr(OH)_{3}}}$

　
: ${\rm {NaOH+Cr(OH)_{3}\rightarrow Na[Cr(OH)_{4}]}}$

以上反應的產物的顔色、溶解度等可被用來測試某種陽離子。

對於汞等氫氧化物不能穩定存在的物質來說，會生產氧化物或氧化物的水合物沉澱：

　
: ${\rm {2NaOH+HgCl_{2}\rightarrow 2NaCl+HgO+H_{2}O}}$

氫氧化鈉可以將過渡金屬的醯基離子轉化為陰離子酸根（簡單離子或多聚離子），如 VO2+、UO22+ 等：

　
: ${\rm {6NaOH+2UO_{2}(NO_{3})_{2}\rightarrow 4NaNO_{3}+Na_{2}U_{2}O_{7}+3H_{2}O}}$

氫氧化鈉跟銨鹽產生反應，生成氨氣、水和相應的鈉鹽。此為銨離子的檢驗方法。

### 和其它無機物的反應

二氧化氯、二氧化氮等可以和氫氧化鈉發生反應。

高錳酸鈉在氫氧化鈉溶液中煮沸，可以還原為錳酸鈉。

### 和有機物的反應

氫氧化鈉可以將鹵代烴、酯和醯鹵水解。其醇溶液可以用於鹵代烴的消去。例如：

* 氯乙烷的水解， 生成氯化鈉和乙醇： ${\ce {EtCl + NaOH -> EtOH + NaCl}}$
* 乙酸乙酯的加鹼水解： ${\ce {CH3COOC2H5 + OH- ->[H2O] CH3COO- + C2H5OH}}$
* 如果是高級脂肪酸酯，水解成皂的反應，統一命名為皂化反應。

另外，氫氧化鈉是一種鹼，可提供氫氧根離子，可催化羥醛縮合反應。首先，氫氧根離子會去質子化醛或酮，生成烯醇負離子和水，該烯醇負離子會進攻令一電中性的醛或酮，生成羥醛加成物負離子。然後，那加成物會質子化，在第一步所生成的水上拿掉質子，在生成最終的羥醛產物後，亦同時再生氫氧根離子（催化劑）。

由於氫氧化鈉可以提供氫氧根離子，所以亦可催化酮 - 烯醇互變異構。這叫鹼催化酮 - 烯醇互變異構：

## 工業製法

氫氧化鈉為工業中製氯氣過程的副產物，工業上，透過電解大量飽和食鹽水以量產氯氣，然而，當氯離子氧化成氯氣逸出的同時，溶液中也只剩下氫氧化鈉一種溶質，反應方程式如下所示：

　
: ${\ce {2NaCl + 2H_2O -> 2NaOH + Cl_2 ^ + H_2 ^}}$

19 世紀以前，氫氧化鈉的製備通常會先以勒布朗制鹼法生成前驅物碳酸鈉，再通過高溫煅燒，使得碳酸鈉分解為氧化鈉與二氧化碳，最後，將氧化鈉溶於水中，便可製得氫氧化鈉：

　
: ${\ce {Na_2CO_3 -> Na_2O + CO_2 ^}}$

　
: ${\ce {Na_2O + H_2O -> 2NaOH}}$

另外，也可利用複分解制備氫氧化鈉，碳酸鈉（俗稱為蘇打）與氫氧化鈣（俗稱為熟石灰）的反應方程式如下所示：

　
: ${\ce {Na_2CO_3 + Ca(OH)_2 -> CaCO_3 v + 2NaOH}}$

## 安全性

氫氧化鈉固體或其溶液皆能灼傷皮膚，對無防護措施者可造成永久性傷害（如疤痕）。倘若讓氫氧化鈉直接接觸眼睛的話，嚴重者甚至可造成失明。個人防護措施，諸如橡膠手套、防護衣與護目鏡等便能大大降低接觸氫氧化鈉所帶來的危險。

氫氧化鈉溶於水中（如稀釋），抑或是與酸反應，都會放出大量的熱量，可能導致灼傷或點燃易燃物（如有機溶劑）。除此之外，氫氧化鈉能夠腐蝕一些金屬（如鋁）生成易燃的氫氣，還能夠輕度腐蝕玻璃製品，應慎選儲存氫氧化鈉的容器材質。

　
: ${\ce {2Al + 2NaOH + 2H_2O -> 3H_2 + 2NaAlO_2}}$

　
: ${\ce {2Al + 6NaOH + xH_2O -> 3H_2 + 2 Na_3AlO_3 + x H_2O}}$

　
: ${\ce {2Al + 2NaOH + 6H_2O -> 3H_2 + 2NaAl(OH)_4}}$

## 參看

* 鹼
* 氫氧根：氫氧化鉀、氫氧化鈣
* 皂化反應

## 參考資料

## 注釋

## 外部連結

* Chemistry WebBook 上的化學數據
* 科學空間 （頁面存檔備份，存於網際網路檔案館）
1310-73-2