Exams › JEE Advanced › Chemistry
Molten aluminium oxide is electrolysed at 1000 deg C to obtain aluminium metal, the cathode reaction being Al³+ + 3e⁻ -> Al (1 Faraday = 96500 C). How much electric charge is needed to deposit 5.12 kg of aluminium?
- 5.49 * 10⁷ C of electric charge
- 5.49 * 10⁴ C of electric charge
- 5.49 * 10¹ C of electric charge
- 1.83 * 10⁷ C of electric charge
Correct answer: 5.49 * 10⁷ C of electric charge
Solution
Deposition of one mole of Al requires 3 moles of electrons (3 Faradays). Total charge scales with the mass of Al deposited.
Related JEE Advanced Chemistry questions
- During the electrolysis process used to extract aluminium from alumina, what is the primary purpose of adding cryolite?
- In the reaction X → Y, where ΔG° = -193 kJ mol⁻¹, all the energy released is utilized to oxidize M⁺ to M³⁺ according to the equation M⁺ → M³⁺ + 2e⁻, with E° = -0.25 V. Under standard conditions, how many moles of M⁺ are oxidized when one mole of X transforms into Y? [F = 96500 C mol⁻¹]
- In the following electrochemical cell operating at 298 K: Pt(s) | H₂(g, 1 bar) | H⁺(aq, 1 M) || M⁴⁺(aq), M²⁺(aq) | Pt(s), the cell potential is measured to be 0.092 V when the ratio [M²⁺(aq)] / [M⁴⁺(aq)] equals 10^x. If the standard reduction potential of the M⁴⁺/M²⁺ couple is 0.151 V and 2.303 RT/F equals 0.059 V, determine the value of x.
- For the electrochemical cell represented as Zn(s) | ZnSO₄(aq) || CuSO₄(aq) | Cu(s), if the concentration of Zn²⁺ ions is ten times greater than that of Cu²⁺ ions, what is the formula for ΔG (in J mol⁻¹)? (Here, F is the Faraday constant, R is the gas constant, T is the temperature, and the standard cell potential E°(cell) = 1.1 V.)
- When 1/Λm is plotted against cΛm for an aqueous solution of a weak monobasic acid (HX), the graph yields a straight line with an intercept on the y-axis equal to P and a slope equal to S. What is the value of the ratio P/S?
- A conductivity cell filled with 0.05 M oxalic acid solution has a resistance of 200 ohm and a cell constant of 2.0 cm⁻¹. What is the equivalent conductance (in S cm² eq⁻¹) of this oxalic acid solution?
⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →