Electrolysis Calculations FARADAYS LAW 2021

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6 Question 5 [MPUMALANGA 2014] The sketch below represents an electro-chemical cell. A suitable light bulb in the external circuit is glowing. The direction of electron flow is indicated.

9 Question 10 EASTERN CAPE 2015

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18 FARADAY’S LAW OF ELECTROLYSIS WORKSHEET Faraday’s Law of Electrolysis : the quantity (moles) of product formed by an electric current is stoichiometrically equivalent to the amount (moles) of electrons supplied It Q (quantity of charge Q=nq e ) N (number of electrons n(e)=N/N A ) n(e) (mole electrons) n (moles) m (mass) 1 If 306C of charge is passed through a solution of Cu(NO 3 ) 2 during an electrolysis experiment, what is the number of moles of copper metal deposited at the cathode? 2 If 612 C of charge is passed through a solution of Cu(NO 3 ) 2(aq) , calculate the number of moles of copper metal deposited. 3 How long will it take to deposit 0.0047 mol of gold by electrolysis of KAuCl 4 using a constant current of 0.214 A? Answer: 106 minutes 4 How much Ca will be produced in an electrolytic cell of molten CaCl 2 if a current of 0.452 A is passed through the cell for 1.5 hours? Answer: 0.5 g Ca 5 An electric current of 100 ampere is passed through a molten liquid of sodium chloride for 5 hours. Calculate the volume of chlorine gas liberated at the electrode at STP. 6 A 40.0 amp current flowed through molten iron(III) chloride for 10.0 hours (36,000 s). Determine the mass of iron and the volume of chlorine gas (measured at 25 o C and 1 atm) that is produced during this time. 7 How long must a 20.0 amp current flow through a solution of ZnSO 4 in order to produce 25.00 g of Zn metal. 8 What current is required to produce 400.0 L of hydrogen gas, measured at STP, from the electrolysis of water in 1 hour (3600 s)? 9 Calculate the mass of zinc plated onto the cathode of an electrolytic cell by a current of 750 mA in 3.25 h. (2.97 g) 10 The nickel anode in an electrolytic cell decreases in mass by 1.20 g in 35.5 minutes. The oxidation half-- ‐ reaction converts nickel atoms to nickel (II) ions. What is the average current? (1.85 A)