HIGHER GRADE CHEMISTRY CALCULATIONS

1
HIGHER GRADE CHEMISTRY CALCULATIONS

• pH and Concentration

pH is related to the concentration of hydrogen
ions. e.g H(aq) 1 x 10-1 mol l -1, pH
1 H(aq) 1 x 10-6 mol l -1, pH
6 Also, in aqueous solution, H(aq) x
OH-(aq) 1 x 10-14 mol2 l-2.
Worked example 1. What is the concentration of
OH-(aq) in a solution with a pH of 5?
pH 5
H(aq) 1 x 10-5 mol l-1.
2
Calculations for you to try. 1. What is the pH
of 0.01 mol l-1 hydrochloric acid?
H(aq) 1 x 10-2 mol l-1.
pH 2
2. The concentration of OH-(aq) is 1 x 10-4
mol l-1. What is the pH of the solution?
OH-(aq) 1 x 10-4 mol l-1.
H(aq) OH-(aq) 1 x 10-14 mol2 l-2.
So H(aq) 1 x 10-10 mol l-1.
pH 10
3. What is the pH of 0.05 mol l-1 sulphuric acid?
H(aq) 2 x 0.05 0.1 mol l-1.
Formula (H)2SO42-
H(aq) 1 x 10-1 mol l-1.
Higher Grade Chemistry
pH 1