Glycine, H2NCH2COOH (aq) is a nonessential amino acid, and has a Ka = 4.5 ×10 -7 at 25 degrees Celsius. Calculate the hydronium ion concentration, the pH, and the percent reaction in a 0.058 mol/L aqueous solution of glycine at 25 degree Celsius
To calculate the hydronium ion concentration, we need to first determine the concentration of the hydronium ion formed by the dissociation of glycine.
The dissociation of glycine can be represented as follows:
H2NCH2COOH ⇌ H+ + H2NCH2COO-
The Ka expression for glycine is:
Ka = [H+][H2NCH2COO-]/[H2NCH2COOH]
Since glycine is a monoprotic acid, the concentration of H+ is equal to the concentration of H2NCH2COO-, so we can simplify the expression to:
Ka = [H+]^2/[H2NCH2COOH]
We can rearrange this equation to solve for [H+]:
[H+]^2 = Ka*[H2NCH2COOH]
[H+] = sqrt(Ka*[H2NCH2COOH])
[H+] = sqrt(4.5 × 10^-7 * 0.058)
[H+] = 2.95 × 10^-5 M
To calculate the pH, we can use the formula:
pH = -log[H+]
pH = -log(2.95 × 10^-5)
pH = 4.53
To calculate the percent reaction, we can use the formula:
% reaction = ([H+] / initial concentration of glycine) * 100
% reaction = (2.95 × 10^-5 / 0.058) * 100
% reaction = 5.086 * 10^-4 %
Therefore, the hydronium ion concentration is 2.95 × 10^-5 M, the pH is 4.53, and the percent reaction in the 0.058 mol/L aqueous solution of glycine is 5.086 × 10^-4 %.