Question

Calculate the concentration of H^+ and the pH of: a) 0.0010 M HClO4 b) 0.00000050M HBr c) 0.050 M LiOH d) 0.00000030 M NaOH

Answer 1

a) HClO4 is strong acid so [HClO4] = [H⁺]

[H⁺] = 0.001 M

pH = -log [H⁺]

pH = - log [0.001]

pH = 3.0

b) HBr is strong acid so [HBr] = [H⁺]

[H⁺] = 0.0000005 M

pH = -log [H⁺]

pH = -log [0.0000005]

pH = 6.3

c) LiOH is strong base so [LiOH] = [OH^-]

[OH^-] = 0.05 M

[H⁺] = 1.0 x 10^-14 / 0.05

[H⁺] = 2.0 x 10^-13 M

pH = -log [H⁺]

pH = - log [2.0 x10^-13]

pH = 12.7

d) NaOH is strong base so [NaOH] = [OH^-] = 0.0000003 M

[H⁺] = 1.0 x 10^-14 / 0.0000003

[H⁺] = 3.3 x 10^-8M

pH = - log [H⁺]

pH = -log [3.3 x 10^-8]

pH = 7.48