Question

$4 \, \text{ml}$ of $HCl$ solution of $pH=2$ is mixed with $6\,ml$ of $NaOH$ solution of $pH=12$ . What would be the final $pH$ of solution?
$\left[\log 2 = 0.3\right]$

• A. $10.3$
• B. $11.3$
• C. $11$
• D. $4.3$

Answer 1

Answer: (B)

$\left[\right.HCl\left]\right.=0.01\left[\right.NaOH\left]\right.=0.01$
$M_{\text{mixt}}=\frac{6 \times 0.01 - 4 \times 0.01}{10}=\frac{0.02}{10}$
$\left[\right.\overset{\Theta}{O}H\left]\right.=0.002$
$\text{pOH} = - \text{log} \left(\right. 0.002 \left.\right) = 2.7$