In neutralization, hydrogen ions and hydroxide ions become water, and the other ions are left behind. These make up a salt, an ionic compound of the cation of the base and the anion of the acid.
Hydrochloric acid and sodium hydroxide give sodium chloride, and sulfuric acid and potassium hydroxide give potassium sulfate: \mathrm{H_2SO_4 + 2KOH \longrightarrow K_2SO_4 + 2H_2O}. The sulfate ion comes from the acid and the potassium ions from the base.
Ammonia also neutralizes acids, although it has no hydroxide ion to give. It takes a hydrogen ion and becomes the ammonium ion, so nitric acid and ammonia give ammonium nitrate, \mathrm{NH_4NO_3}, and no water forms.
Salts are also grouped by their formulas. A salt in which no hydrogen of the acid and no hydroxide of the base remains, such as sodium chloride or sodium sulfate, is a normal salt.
When only one of the two hydrogen ions of sulfuric acid is neutralized by sodium hydroxide, sodium hydrogensulfate, \mathrm{NaHSO_4}, forms. A salt in which hydrogen of the acid remains is an acid salt, and sodium hydrogencarbonate, \mathrm{NaHCO_3}, is another.
In the same way, a salt in which hydroxide of the base remains is a basic salt, such as magnesium chloride hydroxide, \mathrm{MgCl(OH)}. Neutralizing the remaining hydrogen or hydroxide gives the normal salts sodium sulfate and magnesium chloride.
A solution of a salt is not always neutral. Whether it is acidic, neutral or basic depends on the strength of the acid and the base that the salt comes from.
At 25 °C, a 0.1 mol/L solution of sodium chloride, the salt of a strong acid and a strong base, has a pH of 7.0. The salt of a weak acid and a strong base, sodium ethanoate, gives a basic solution of about pH 8.9.
Ammonium chloride, the salt of a strong acid and a weak base, gives an acidic solution of about pH 5.1. When both are weak, as in ammonium ethanoate, the solution is close to neutral, because ethanoic acid and ammonia are about equally weak.
Ethanoic acid is a weak acid, so the ethanoate ion can take a hydrogen ion from a water molecule, which is left as a hydroxide ion. This is why sodium ethanoate solution is basic.
Ammonia is a weak base, so the ammonium ion can give a hydrogen ion to water, forming an oxonium ion and making ammonium chloride solution acidic. Sodium and chloride ions, from a strong base and a strong acid, do not react with water.
Such a reaction between the ions of a salt and water is called hydrolysis. In 0.1 mol/L sodium ethanoate at 25 °C, only about 1 in 13,000 ethanoate ions reacts, yet this is enough to raise the pH from 7 to about 8.9.
The names normal, acid and basic salt describe the formula, not the solution. For 0.1 mol/L solutions at 25 °C, sodium hydrogensulfate, an acid salt, gives about pH 1.5, because the hydrogensulfate ion releases hydrogen ions.
Sodium hydrogencarbonate is an acid salt too, but it gives about pH 8.3, a weakly basic solution. Carbonic acid is weak, so the hydrogencarbonate ion takes hydrogen ions from water more readily than it releases them.
Normal salts also range from acidic to basic: ammonium chloride gives about pH 5.1, sodium chloride 7.0 and sodium carbonate about 11.6. The pH follows from the strength of the parent acid and base, not from the name.