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
Sparging (chemistry) Sparging (chemistry) In chemistry, sparging, also known as gas flushing in metallurgy, is a technique which involves bubbling a chemically inert gas, such as nitrogen, argon, or helium, through a liquid. This can be used to remove dissolved gases (e.g. oxygen) from the liquid. By Henry's law, the amount of dissolved gases in a liquid depend on the partial pressure of the gases exposed to the liquid. Sparging increases the gas-liquid interface. Solvents used in high-performance liquid chromatography (HPLC) are often sparged with helium. In biochemical engineering, sparging can also be a method to remove low-boiling liquids from a solution.