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) The low-boiling components tend to evaporate more rapidly, hence they may be removed from the bulk solution containing higher-boiling components. It is an alternative to distillation, and it does not require heat. This technique is also used in environmental chemistry to extract the volatile organic contaminants from subsoil water and soil. In metallurgy, this process is used to remove dissolved gases from the melt prior to the material being processed. For example, before casting aluminium alloys, argon bubbles are injected into liquid aluminium using a rotary degasser. The resulting argon bubbles will rise to the surface, bringing with them a