In: Chemistry
Calculate the pH and concentrations of CH3NH2 and CH3NH3 in a 0.0495 M methylamine (CH3NH2) solution. The Kb of CH3NH2 = 4.47 × 10-4.
CH3NH2 + H2O --------------> CH3NH3+ + OH-
0.0495 0 0
0.0495 - x x x
Kb = x^2 / 0.0495 - x
4.47 × 10^-4 = x^2 / 0.0495 - x
x = 4.48 x 10^-3
[OH-] = 0.00448 M
[CH3NH3+] = 0.00448 M
pOH = -log [OH-] = -log (0.00448)
= 2.35
pH = 11.65