MHT CET · Chemistry · Electrochemistry

Two electrolytic cells are connected in series containing $C u S O_{4}$ solution and molten $A l C l_{3} .$ If in electrolysis $0.4$ moles of ‘ $C u$ ’ are deposited on cathode of ﬁrst cell. The number of moles of ‘ $A l$ ’ deposited on cathode of the second cell is

A $0.6$ moles
B $0.27$ moles
C $0.18$ moles
D $0.4$ moles

Verified Solution

Answer & Solution

Correct Answer

(D) $0.4$ moles

Step-by-step Solution

Detailed explanation

According to Faraday’s second law of electrolysis:

\frac{m_{c u}}{m_{A l}} = \frac{E_{c u}}{A_{A l}}

\frac{0.4 \times 63.5}{m_{A l}} = \frac{\frac{63.5}{2}}{\frac{27}{3}}

m_{A l} = 7.2 g

\Rightarrow

No. of moles of

A l = n_{A l} = \frac{7.2}{27} = 0.27

Hint:

E_{c u} = \frac{A t o m i c m a s s o f C u}{2}

and

E_{A l} = \frac{A t o m i c m a s s o f A l}{3}

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

Same subject

Explore more questions on app

From MHT CET

Explore more questions on app

Two electrolytic cells are connected in series containing CuSO4 solution and molten AlCl3. If in electrolysis 0.4 moles of ‘ Cu ’ are deposited on cathode of ﬁrst cell. The number of moles of ‘ Al ’ deposited on cathode of the second cell is

Step-by-step Solution

Two electrolytic cells are connected in series containing $C u S O_{4}$ solution and molten $A l C l_{3} .$ If in electrolysis $0.4$ moles of ‘ $C u$ ’ are deposited on cathode of ﬁrst cell. The number of moles of ‘ $A l$ ’ deposited on cathode of the second cell is