What is the pH at different points in a titration of CH3NH2 with HNO3?

[_Bd_]

Homework Statement

You are titrating 30.0 mL of .3 M CH₃NH₂ with .15 M HNO₃ K_b = 4.4 x 10^-4. Calculate
pH:
-initially
-after 10.0 mL of acid has been added
at the half equivalence point
at the equivalence point
when 70 mL of acid has been added.

Homework Equations

not sure. . .

The Attempt at a Solution

I was thinking that since Kb is given I can get the pOH using the fact that
[OH] = [tex]\sqrt{K_b x Molarity}[/tex] <- im not sure if this is correct tho.

then do an ICE table for the reaction. . . I am not sure about the reaction tho. . .

HNO3 + CH3NH2 >> CH3NH3⁺ + NO3^- . . .is that it?
the first ICE table should be a limiting reagent problem?

knowing the moles of both after 10 mL yields:

HNO3 + CH3NH2 >> CH3NH3⁺ + NO3^-

.0015 | .009 ...| 0....|0 <<<<<<<<<<Initial
-.0015 |-.0015 ...| +.0015 ...| +.0015 <<<<<<<<Consumed
0 ...|.0075 .....| .0015 ...| .0015 <<<<<<< Final

so I can get K at this point right? (K = products/reactants) but that's K_a or K_b?

 

[Borek]

acid base titration curve calculation