Ionisation constant of CH3COOH is 1,7×10⁻⁵and concentration of H+ ions is 3,4×10-4. Then find out initial concentration of CH3COOH molecule ?

Ionisation constant of CH3COOH is 1,7×10⁻⁵and concentration of H+  ions is 3,4×10^-4. Then find out initial concentration of CH3COOH molecule ?

SOLUTION

Known:

CH3COOH = 1,7x10^-5

H+ = 3,4×10^-4

Asked: concentration of CH3COOH molecule ?

CH3COOH —> CH3COO⁻ + H⁺

x                   3,4x10^-4         3x10^-4

K = [CH3COO^-] [H+]/[CH3COOH]

1,7x10^-5 = [3,4x10^-4] [3,4x10^-4]/x

x = 6,8x10^-3

so, the concentration of CH3COOH molecule is 6,8x10^-3