Answer to Question #170673 in Chemistry for Hyeri

Question

What is the hydronium ion concentration of 1 g of acetic acid in 200 ml of water?

Answer 1

The molarity of the solution is:

M = n / V = m / (Mr V)

where M - molarity, n - number of moles, m - mass, Mr - molecular weight, V - volume.

From here:

M = 1 g / (60 g/mol × 0.2 L) = 0.83 M

According to the dissociation equation:

Ka = [H₃O⁺] [CH₃COO^-] / [CH₃COOH]

As dissociation constant of acetic acid equals 1.7×10⁻⁵, the hydronium ion concentration is:

[H₃O⁺] × [CH₃COO^-] = Ka × [CH₃COOH]

[H₃O⁺]² = Ka × [CH₃COOH]

[H₃O⁺] = (Ka × [CH₃COOH])^1/2 = (1.7×10⁻⁵ × 0.83 M)^1/2 = 0.00376 M

Answer: 0.00376 M