Question

$500mL$ of $HCl$ of $pH$ $4.3010$ is allowed to react with $500mL$ of $pH$ $9.6990$ $NaOH$ solution at $300K$. If temperature remains constant, approximate $pH$ of resulting solution is:

Answer 1

For $NaOH$ solution,

$pOH=14-pOH$

$=14-9.6990$

$=4.3010$.
Thus the $pH$ of $HCl$ is equal to $pOH$ of $NaOH$.
Also, the volumes of the two solutions are equal.
Hence, the number of moles of hydrogen ions present in $HCl$ is equal to the number of moles of hydroxide ions present in $NaOH$.
Thus, two solutions will completely neutralize each other. The $pH$ of the resulting solution will be $7$.