Question

What is the pH of the solution created by combining 8.00 mL of the 0.10 M NH3 with 8.00 mL of the 0.10 M HCl?
I found their moles= 8*10^(-4)

Answer 1

NH3 + HCl ==> NH4Cl

So you have 8 x 10^-4 moles each. That means the solution is exactly neutralized; therefore, the pH of the solution will be determined by the hydrolysis of NH4Cl.
Write the hydrolysis equation for NH4^+, set up an ICE chart, and solve for H3O^+, then convert to pH.