Question

14cm^3, each of solutions A and B with pH of 5 and 3 respectively are mixed. Determine the pH of the solution

Answer 1

For solution $A$ ,$[H^+](M_1)=10^{-5} mol/L$

Volume$(V_1) =14\ cm^3=14 \times 10^{-3} dm^3=14 ml$

For solution B,$[H^+]=10^{-3} mol/L$

Volume$(V_2)=14 cm^3=14 \ ml$

After mixing,Volume will be$(V_3)=14+14=28 ml$

Using molarity equation of mixing,

$M_1V_1+M_2V_2=M_3V_3$

$10^{-5}\times 14+10^{-3}\times 14=M_3\times 28$

$M_3=\frac{10^{-3}+10^{-5}}{2}=\frac{101}{200000}$ mol/L

pH of solution$=-log(M_3)=3.30$