Question

A 26 mal solution containing 2.0 M HClO3 is mixed with a 40mL solution containing 0.5 M NaOH. What is the pH of the resulting mixture ?

Answer 1

Reaction:

$HClO_3$ is a strong aciid

$HClO_3+NaOH=NaClO_3+H_2O$

$$\nu_0(NaOH)=C(NaOH)\cdot V(NaOH)=0.02 mol$$ $$\nu_0(HClO_3)=C(HClO_3)\cdot V(HClO_3)=0.052 mol$$

$\nu(NaOH)=0mol$

$\nu(HClO_3)=(0.052-0.02) mol=0.032 mol$

Total volume:

$V = V_1+V_2=66ml=.066L$

$C(HClO_3)=[H^+]=\nu(HClO_3)/V=0.485M$

$pH=-lg[H^+]=0.314$