Base (chemistry) Base (chemistry) In chemistry, bases are substances that, in aqueous solution, release hydroxide (OH) ions, are slippery to the touch, can taste bitter if an alkali, change the color of indicators (e.g., turn red litmus paper blue), react with acids to form salts, promote certain chemical reactions (base catalysis), accept protons from any proton donor or contain completely or partially displaceable OH ions. Examples of bases are the hydroxides of the alkali metals and the alkaline earth metals (NaOH, Ca(OH), etc., see alkali hydroxide and alkaline earth hydroxide). These particular substances produce hydroxide ions (OH) in aqueous solutions, and are
Amalgam (chemistry) organic synthesis (e.g., for the Clemmensen reduction). It is the reducing agent in the Jones reductor, used in analytical chemistry. Formerly the zinc plates of dry batteries were amalgamated with a little mercury to prevent deterioration in storage. It is a binary solution (liquid-solid) of mercury and zinc. For the alkali metals, amalgamation is exothermic, and distinct chemical forms can be identified, such as KHg and KHg. KHg is a gold-coloured compound with a melting point of 178 °C, and KHg a silver-coloured compound with a melting point of 278 °C. These amalgams are very sensitive to air and water,