Chemical Forums

Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Oxyale on June 08, 2006, 11:08:42 PM

Title: Acids and Bases - pH & acid strength
Post by: Oxyale on June 08, 2006, 11:08:42 PM

Hey, I have a problem. The question is..

N2H4 is a weak base. Would you expect the pH of a 0.15 M solution of N2H4 to be:
(a) greater than 7
(b) less than 7
(c) close to 7

The back of the book says the answer is (a) but I'm not sure why it is. I thought that the weak base would mean the reverse reaction wouldn't be as great as the forward reaction, so the equilibrium would move to the right to minimize the disturbance (more [H+] ions in solution so lower the pH)

Thanks.

Title: Re: Acids and Bases - pH & acid strength
Post by: AWK on June 09, 2006, 01:47:32 AM

H2N-NH2 + H2O = H2N-NH3⁺ + OH^-
During dissociation of base (Bronsted notation) anions OH- are formed, hence solution is basic (ph>7)

Title: Re: Acids and Bases - pH & acid strength
Post by: swati on June 09, 2006, 07:54:49 AM

 :) Hello everyone

Even though it is a weak base but it is a base. And bases have pH >7