Question #a3dd1

1 Answer
May 29, 2015

Your solution will have a pH equal to 4.0.

Since you're dealing with a weak acid, you can use an ICE table on its dissociation equilibrium to determine the equilibrium concentrations of the species involved in the reaction

HA(aq)+H2O(l)H3O+(aq)+A(aq)
I.......1.........................................0.................0
C....(-x)......................................(+x).............(+x)
E.....1-x........................................x.................x

The acid dissociation constant, Ka, will be equal to

Ka=[H3O+][A][HA]=xx1x=x21x

Since Ka has such a small value, you ca approximate (1-x) to be equal to 1, which would mean that

Ka=x21=x2=108x=108=104

Sincex is equal to the equilibrium concentration of the hydronium ion, you'll have

[H3O+]=104M

Therefore, the pH of the solution will be

pHsol=log([H3O+])

pHsol=log(104)=4.0