Question

calculate pH obtained by mixing equal volumes of 0.1M h2so4 and 0.3M Naoh

Answer 1

First start by writing the correct equation.

$2NaOH+H_2SO_4\longrightarrow Na_2SO_4+2H_2O$

From the equation, 2 moles of sodium hydroxide reacts with a mole of sulphuric acid.

$2\space moles\space NaOH \equiv 1\space mole\space sulphuric\space acid$

Using the above relation we can find the moles of sodium hydroxide that will react as

$\frac{0.1×2}{1}=0.2\space moles.$

The moles of sodium hydroxide are in excess and the remaining amount is

$0.3-0.2=0.1\space moles$

The pH of the resulting solution is

$pOH=(-log\space 0.1)=1\\pH=14-1=13\\pH=13$