[boomvoom4000]

A 5.25 g sample of NH4Br is dissolved in water to make 850 mL of solution. What is the pH of the solution? Kb (NH3) = 1.8 × 10-5. I found molarity initial to be .062

I found Ka of NH4 to be 5.6 x 10^10. I then set up the ICE box from the net reaction 
NH₄⁺ + H₂0  NH₃ + H₃0⁺
 I got pH to be 5.23 but answer says it is 11.02??

[Borek]

5.23 it is, answer key is wrong. They calculated pH for solution of ammonia, not ammonium ion.

For the record: K_a of ammonium ion is 5.6×10^-10. Most likely just a typo on your side.

[boomvoom4000]

Thanks! I've been stuck on this one for soo long!