Consider the titration of 50.0 mL of 0.217 M hydrazoic acid (HN3, Ka=2.6 x 10-5) with 0.183 M NaOH. Calculate the pH of the solution after addition of 29.7 mL of the NaOH solution.

please explain. I have an exam on this in 3 hours and need to know how to do it

Question

Consider the titration of 50.0 mL of 0.217 M hydrazoic acid (HN3, Ka=2.6 x 10-5) with 0.183 M NaOH.  Calculate the pH of the solution after addition of 29.7 mL of the NaOH solution.

please explain. I have an exam on this in 3 hours and need to know how to do it

jfraser · Answer

you need to find:

the overall reaction occuring (a neutralization)

the $moles$ of acid to start with

the $moles$ of base added

the stoichiometry ratios (this is a limiting reactant problem)

the $moles$ of acid left over

the $[H^{+1}]$ using the left over acid and the $K_A$ expression