Question

A current is passed through $500$ mLof an aqueous solution of $Ca{I}_2$. After sometime, it is observed that $50$ millimoles of $I_2$ have been formed.

Which of the following statements is(are) correct?

• A. The number of faradays of charge passed through the solution is $0.10F.$
• B. The volume of dry $H_2$ at $STP$ that has been formed during electrolysis is $1120mL.$
• C. The $pH$ of the solution is nearly $\mathrm{0.7.}$
• D. The mass of calcium produced is $2.0g.$

Answer 1

Answer: (A), (B)

The correct options are
A The number of faradays of charge passed through the solution is $0.10F.$
B The volume of dry $H_2$ at $STP$ that has been formed during electrolysis is $1120mL.$

a.$[Mrnoles{I}_2=50\Rightarrow \underset{(2I^{\ominus }\to I_2+2e^{-})}{100mFpasses=0.1F}]$

b. Also, mmoles of $H_2=\frac{1}{2}\times$ number of mF

$=\frac{1}{2}\times 100-50\Rightarrow V_{H_2}$ at STP

$50\times 22.4ml=1120mL$

c. $100$ mmoles $\stackrel{\oplus }{O}H$ left

$\Rightarrow \left[\stackrel{\oplus }{O}\right]=\frac{100}{500}=0.2$

$\Rightarrow pOH--\log 0.2-0.7$

$\Rightarrow pH-13.3$