Faraday's laws Knowledge-Based Practice

Questions

1. 1.

   What constant current, in amperes, must be passed through an electrolytic cell containing an aqueous nickel(II) sulfate ($\text{NiSO}_4$) solution for 1,930 seconds to deposit 1.77 g of nickel metal at the cathode? (Molar mass of $\text{Ni} = 59.0\text{ g/mol}$, Faraday constant = $96,500\text{ C/mol}$)

   • A) 3.00 A
   • B) 1.50 A
   • C) 6.00 A
   • D) 0.75 A
2. 2.

   During the electrolysis of a salt solution containing $M^{n+}$ ions, a constant current of 4.825 A is passed for 3,000 seconds, depositing 0.050 mol of metal $M$ at the cathode. What is the oxidation state $n$ of the metal cation? (Faraday constant = 96,500 C/mol)

   • A) +3
   • B) +2
   • C) +1
   • D) +4
3. 3.

   A steady current of 1.93 A is passed through a dilute sulfuric acid solution for 5,000 seconds. What volume of oxygen gas ($\text{O}_2$), measured at standard temperature and pressure (STP), is liberated at the anode? (Faraday constant = 96,500 C/mol; molar volume of gas at STP = 22.4 L/mol)

   • A) 2.24 L
   • B) 1.12 L
   • C) 0.28 L
   • D) 0.56 L
4. 4.

   Two electrolytic cells containing molten NaCl and molten AlCl3 are connected in series. If 2.70 g of aluminum is deposited at the cathode of the second cell, what mass of sodium is deposited at the cathode of the first cell? (Molar masses: Na = 23.0 g/mol, Al = 27.0 g/mol)

   • A) 6.90 g
   • B) 2.30 g
   • C) 3.45 g
   • D) 0.77 g
5. 5.

   An electric current of 9.65 A is passed through a solution of copper(II) sulfate for 1,000 seconds. What mass of copper is deposited at the cathode? (Molar mass of Cu = 63.5 g/mol, Faraday constant = 96,500 C/mol)

   • A) 12.7 g
   • B) 6.35 g
   • C) 1.59 g
   • D) 3.18 g

Answers and step-by-step solutions appear after you finish the test.