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Alkalis are usually defined as a subset of the bases. One of two subsets is commonly chosen. A basic salt of an alkali metal or alkaline earth metal [2] (this includes Mg(OH) 2 (magnesium hydroxide) but excludes NH 3 ). Any base that is soluble in water and forms hydroxide ions [3] [4] or the solution of a base in water. [5]
They consist of hydroxide (OH −) anions and metallic cations, [1] and are often strong bases. Some metal hydroxides, such as alkali metal hydroxides, ionize completely when dissolved . Certain metal hydroxides are weak electrolytes and dissolve only partially in aqueous solution .
An aqueous solution is a solution in which the solvent is water. It is mostly shown in chemical equations by appending (aq) to the relevant chemical formula . For example, a solution of table salt , also known as sodium chloride (NaCl), in water would be represented as Na + (aq) + Cl − (aq) .
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The difference between a basic salt and an alkali is that an alkali is the soluble hydroxide compound of an alkali metal or an alkaline earth metal. A basic salt is any salt that hydrolyzes to form a basic solution. Another definition of a basic salt would be a salt that contains amounts of both hydroxide and other anions. White lead is an ...
When a strong acid is neutralized by a strong base there are no excess hydrogen ions left in the solution. The solution is said to be neutral as it is neither acidic nor alkaline. The pH of such a solution is close to a value of 7; the exact pH value is dependent on the temperature of the solution. Neutralization is an exothermic reaction.
In water, by altering the autoionization equilibrium, bases yield solutions in which the hydrogen ion activity is lower than it is in pure water, i.e., the water has a pH higher than 7.0 at standard conditions. A soluble base is called an alkali if it contains and releases OH − ions quantitatively.
Bases are proton acceptors; a base will receive a hydrogen ion from water, H 2 O, and the remaining H + concentration in the solution determines pH. A weak base will have a higher H + concentration than a stronger base because it is less completely protonated than a stronger base and, therefore, more hydrogen ions remain in its solution.