Ion exchange using natural or synthetic resins removes calcium, magnesium and carbonate ions from water, replacing them with hydrogen and hydroxyl ions.
Photolysis of water vapor and carbon dioxide produces hydroxyl ions and atomic oxygen, respectively, and these in turn produce oxygen in small concentrations, with hydrogen escaping into space.
The positive hydronium ions that approach the negative cathode mostly combine with negative hydroxyl ions to form water.
Marked increases or decrease in conductance are associated with the changing concentrations of the two most highly conducting ionsthe hydrogen and hydroxyl ions.
In alkaline solutions, nucleophilic hydroxyl ions attack the electrophilic central carbon to produce the colourless triphenylmethanol or carbinol form of the dye.
In an aqueous base, hydroxyl ions are better nucleophiles than polar molecules such as water.
This applies in general: any equilibrium constant is equally valid for a product with an oxide ion as for the product with two hydroxyl ions.
Their hydrolysis occurs when the nucleophile (a nucleus-seeking agent, e.g., water or hydroxyl ion) attacks the carbon of the carbonyl group of the ester or amide.
