Question

What is the $pH$ of a solution obtained by mixing $10$mL of $0.1$M $HCl$ and $40$ mL of $0.2$M $H_{2}S{O}_4$?

• A. $0.074$
• B. $7.4$
• C. $4.68$
• D. $0.468$

Answer 1

Answer: (D)

$0.468$

$HCl\to H^{+}+C{l}^{-}$

number of millimole of $H^{+}=10\times 0.1=1$

$H_{2}S{O}_4\to 2H^{+}+S{O}_4^{2-}$

number of millimole of $H^{+}-2\times 40\times 0.2=16$

overall $\left[H^{+}\right]$ concentration $=\frac{1+16}{10+40}=0.34M$

$pH=-\log \left[H^{+}\right]$

$=-\log 0.34$

$pH=0.468$