In: Chemistry
The Ka of a weak acid is 1.48 x 10-5. Assuming the "x is small" approximation is valid, what is the predicted pH of a 0.05 M solution of the weak acid? Provide your response to two decimal places.
HA ------------> H^+ (aq) + A^- (aq)
I 0.05 0 0
C -x +x +x
E 0.05-x +x +x
Ka = [H+][A-]/[HA]
1.48*10^-5 = x*x/(0.05-x)
1.48*10^-5 *(0.05-x) = x^2
x = 0.000853
[H+] = x = 0.000853M
PH = -log[H+]
= -log0.000853
= 3.069 >>>answer