Question

How will the concentration of hydronium ions and the pH be affected by the addiction KF to the following Equilibrium

HF+ H20 <-----> CH3NH2 +H3O ^+

Answer 1

HF+ H2O <------------------> F- +H3O ^+

to this equailibrium on addition of KF

KF ----------------------> K+ + F-

due to common ion F- on the product side the degree of ionisation of weak acid HF decreases.

so H3O + concentration also decreases

if H3O + concentration decreases pH will increases from the formula pH = -log [H3O+]

note : you gave wrong equation in the problem . HF+ H20 <-----> CH3NH2 +H3O ^+ . check once . for the question i wrote correct eqaution