Question

A silver voltmeter,copper voltameter and oxygen voltameter are connected in series. Given that 4.32g of silver is deposited during the electrolytic process, determine(I) the mass of copper deposited(ii) the volume of oxygen liberated (Ag=108, Cu=64, O=16, G.M.V=22.4dm³

Answer 1

Additional information: aqueous silver always has a +1 charge aqueous copper has a +2 charge in voltameters solids always have a 0 charge gaseous oxygen is diatomic and will be notated as oxygen2 *since subscript/superscript is not available full names are written out in place of atomic symbols to add clarity. 1) write a balanced equation (numbers in parenthesis indicate charge): total reaction: silver(+1) + copper(0) -> silver(0) + copper(+2) half reaction: silver (+1) + e- -> silver (0) half reaction: copper(0) -> copper (+2) + 2e- need to multiple the silver half reaction by two to balance the number of electrons: half reaction: 2silver (+1) + 2e- -> 2silver (0) half reaction: copper(0) -> copper (+2) + 2e- now the electrons cancel out for a total reaction of: 2silver(+1) + copper(0) -> 2silver(0) + copper(+2) 2) convert the amount of silver to moles using the molar mass of silver (make sure units cancel): 4.32g of silver x (1 mole of silver/108g) = 0.04 moles of silver 3) convert silver to copper using the stoichiometry of the balanced equation (make sure units cancel): 0.04 moles of silver x (1 mole copper / 2 moles of silver) = 0.02 moles of copper 4) cover moles of copper to the mass of copper using the molar mass of copper (make sure units cancel): 0.02 moles of copper (64g / 1 mole of copper) = 1.28 of copper Objects in a series will experience the same current so REPEAT FOR OXYGEN. 1) write a balanced equation total reaction: silver(+1) + oxygen(-2) -> silver(0) + oxygen2(0) balance the molecules in the reaction total reaction: silver(+1) + 2oxygen(-2) -> silver(0) + oxygen2(0) half reaction: silver (I) + e- -> silver (0) half reaction: 2oxygen(-2) -> oxygen2(0) + 4e- need to multiple the silver half reaction by four to balance the number of electrons: half reaction: 4silver (+1) + 4e- -> 4silver (0) half reaction: 2oxygen(-2) -> oxygen2(0) + 4e- now the electrons cancel out for a total reaction of: 4silver(+1) + 2oxygen(-2) -> 4silver(0) + oxygen2(0) 2) convert the amount of silver to moles using the molar mass of silver (make sure units cancel): 4.32g of silver x (1 mole of silver / 108g) = 0.04 moles of silver 3) convert silver to oxygen using the stoichiometry of the balanced equation (make sure units cancel). Remember to compare solid silver to gaseous, diatomic oxygen: 0.04 moles of silver x (1 mole oxygen2 / 4 moles of silver) = 0.01 moles of oxygen2 4) convert moles of oxygen to the liters of oxygen using the G.M.V. (make sure units cancel): 0.01 moles of oxygen x (22.4dm3 / 1 mole of oxygen) = 0.224 dm3 of copper