posted by Calvin .
A solution of volume 0.500 L contains 1.70g NH3 and 4.15g (NH4)2SO4. What is the pH of this solution?
Answer obtained was 9.76, however it states that it is slightly off...
I get 9.76 also using 1.8E-5 for Kb. Use the Kb found in your text or notes. Watch the number of significant figures and rounding.