Question

A solution of $200\, mL$ of $1\, M\, KOH$ is added to $200\, mL$ of $1 \,M \,HCl$ and the mixture is well shaken. This rise in temperature $T_{1}$ is noted. The experiment is repeated by using $100\, mL$ of each solution and increase in temperature $T_{2}$ is again noted. Which of the following is correct?

• A. $T_{1}=T_{2}$
• B. $T_{2}$ is twice as large as $T_{1}$
• C. $T_{1}$ is twice as large as $T_{2}$
• D. $T_{1}$ is four times as large as $T_{2}$

Answer 1

Answer: (A)

$200 \,mL$ of $1 \,M \,KOH +200\, mL$ of $1\, M\, HCl$

Number of milliequivalents $=200$ milliequivalents Total volume $=400\, mL$

Heat produced $=-\frac{13.7 \times 200}{1000} kcal =400 \,T _{1}$

$\Rightarrow T_{1}=-\frac{13.7}{1000 \times 2}$

$100\, mL \,1\, M\, KOH +100\, mL\, 1\, M\, HCl$

Number of milliequivalents $=100$ milliequivalents

Total volume $=200\, mL$ Heat produced

$=-\frac{13.7 \times 100}{1000} kcal =200\, T _{2}$

Evidently $T_{1}=T_{2}$