Question

$200ml$ of $1M{H}_2{SO}_4$, $300ml$ of $3MHCl$ and $100ml$ of $2MHCl$ are mixed and made up to $1litre$. The proton concentration in the resulting solution is:

• A. $1.25M$
• B. $1.5M$
• C. $2.5M$
• D. $0.75M$

Answer 1

The correct option is C $2.5M$

$H_{2}S{O}_4$ contains two $H^{+}$ ions

So 200 ml of $H_{2}S{O}_4$ contains $0.2l\times 1mol/l\times 2=0.4$ mol $H^{+}$

similarly 300 ml of $HCL$ of 3M contains $0.3l\times 3mol/l\times 1=0.9$ mol $H^{+}$

similarly 100 ml of $HCL$ of 2M contains $0.1l\times 2mol/l\times 1=0.2$ mol $H^{+}$

So Total number of moles $=0.4+0.9+0.2=1.5$ mol

Total volume $=200ml+300ml+100ml=600ml$ or 0.6 l

Concentration of $H^{+}=1.5/0.6mol/l=2.5mol/l$