Question

A 50 mL solution of strong acid of pH = 1 is mixed with a 50 mL solution of strong acid of pH = 2. The pH of the mixture will be :
$(lo{g}_{10}5.5=0.74)$

• A. 0.74
• B. 1.26
• C. 1.76
• D. 1.5

Answer 1

The correct option is B 1.26

$p{H}_{acid1}=1;M_1=\left[H^{+}\right]={10}^{-1}p{H}_{acid2}=2;M_2=\left[H^{+}\right]={10}^{-2}{M}_3=[H^{+}{]}_{mixture}{V}_1=50mL,V_2=50mL{V}_3=V_1+V_2=100mLApplying:$
$M_1{V}_1+M_2{V}_2=M_3{V}_3{M}_3=\frac{M_1{V}_1+M_2{V}_2}{V_3}=\frac{({10}^{-1}\times 50)+({10}^{-2}\times 50)}{100}{M}_3=\left[H^{+}\right]=5.5\times {10}^{-2}pH=-lo{g}_{10}\left[H^{+}\right]=-lo{g}_{10}(5.5\times {10}^{-2})pH=-(0.74-2)=1.26Ans$