Acetic acid (CH3COOH) is a weak acid while methylamine (CH3NH2) is a weak base. During an acid base reaction, an acid tends to lose a proton while a base tends to accept a proton. The reaction at equilibrium is as follows:
↔
Hence the species in equilibrium are:
Acetate anion: CH3COO-
Methyl ammonium cation: CH3NH3+
<u>Answer:</u> The pH of the solution in the beginning is 1.89 and the pH of the solution after the addition of base is
<u>Explanation:</u>
To calculate the pH of the solution, we use the equation:
We are given:
Nitric acid is a monoprotic acid and it dissociates 1 mole of hydrogen ions. So, the concentration of hydrogen ions is 0.013 M
Putting values in above equation, we get:
To calculate the number of moles, we use the equation:
Molarity of nitric acid solution = 0.013 M
Volume of solution = 15 mL
Putting values in above equation, we get:
Molarity of methylamine solution = 0.017 M
Volume of solution = 10 mL
Putting values in above equation, we get:
As, the mole ratio of nitric acid and methyl amine is 1 : 1. So, the limiting reagent will be the reactant whose number of moles are less, which is methyl amine.
By Stoichiometry of the reaction:
1 mole of methyl amine produces 1 mole of
So, of methyl amine will produce =
To calculate the of base, we use the equation:
where,
= base dissociation constant =
Putting values in above equation, we get:
We are given:
Putting values in above equation, we get:
To calculate pH of the solution, we use the equation:
Hence, the pH of the solution is 4.59