Students, now I want to help you discussing acid and base theories. Here I remind you that the three acid base theories are discovered by the following scientists.
Arrhenius TheoryArrhenius proposed that when ionic compounds are dissolved in water, these dissociate and form cations and anions. These ions are separated one of another in the aqueous solution and they move freely, although there are cations and anions. These evidence is accured as a result of solvation process during the compounds dissociate. Remember your last lesson in the grade X about electrolyte solutions. There are three different electrolyte solutions, i.e. acids, bases, and salts. The solutes of these solutions are ionic compounds and molecular compounds. In water, these molecular compounds ionize and become free ions in the solution. Some of them ionize completely and some of them ionize partly. The first is classified as strong electrolytes (strong acids or strong bases) and the second is grouped as weak electrolytes (weak acids or weak bases).
According to Arrhenius,
An acid is a substance that produce H+ ions in water.
A base is a substance that produce OH- ions in water.
When acid and base are mixed they will produce water, because H+ ion is combined with OH- ion and form H2O molecule. This reaction is classified as a neutralization reaction. When this reaction is heated, water is evaporatedand there is a crystalline of salt.
Examples of acid, base, salt, and their chemical equations.
Acid: HCl(aq) --> H+(aq) + Cl-(aq)
Base: NaOH(aq) --> Na+(aq) + OH-(aq)
Neutralization: Acid + Base --> Salt + Water
Molecular Equation: HCl(aq) + NaOH(aq) --> NaCl(aq) + H2O(l) at room temperature
When it isw heated: HCl(aq) + NaOH(aq) --> NaCl(s) + H2O(g)
Ionic Equation: H+(aq) + OH-(aq) --> H2O(l)
Weak acid: CH3COOH(aq) == CH3COO-(aq) + H+(aq)
Weak base: NH3(aq) + H2O(l) == NH4+(aq) + OH-(aq)
(==) is indicated as a reversible reaction.
When a strong base is added to a weak acid, the reaction is also named as neutralization.
Molecular Equation: CH3COOH(aq) + NaOH(aq) --> CH3COONa(aq) + H2O(l)
Ionic Equation: CH3COOH(aq) + OH-(aq) --> CH3COO-(aq) + H2O(l)
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