Question

Electrolysis

Students will employ electrolysis in the oxidation of a neutral metal to determine the molar mass of the metal by measuring current and collecting hydrogen produced in the oxidationreduction reaction. Introduction Oxidation of a neutral metal refers to a chemical process in which the metal takes on a positive charge by losing one or more electrons. In an oxidation-reduction (redox) reaction this is accomplished by an electron transfer from the neutral metal to another reactant. Electrolysis is a technique that uses an external voltage (battery or power supply) to drive a direct electric current (DC) in a direction that would otherwise be non-spontaneous for the redox reaction under the given reaction conditions. In this experiment the positive terminal (anode) of the voltage source will be connected to the reactant metal with a wire and the negative terminal (cathode) will be connected to a conductor with another wire, both immersed in a conducting solution. Thus the two reactants will be physically separated in the electrolytic cell, and the electrons forced to flow from one reactant to the other through the wires of the resulting circuit. The reaction will occur in a slightly acidic solution which provides for the reduction of hydrogen ion to hydrogen gas. Assuming that the metal is one that oxidizes to a +2 cation we can use the following half reactions to show stoichiometric ratios between moles of reactants, products and electrons.

A) What acts as the cathode (negative end) in this experiment?

B) What property of the metal is measured in this experiment?

	Conductivity of the metal
	Gain of mass by the metal
	Loss of mass of the metal
	Resistivity of the metal

C) The purpose of this experiment is to

	find the molar mass of a metal using moles of hydrogen produced when the metal is oxidized.
	find the molar mass of hydrogen using moles of metal lost when the metal is reduced.
	find the molar mass of hydrogen using moles of metal lost when the metal is oxidized.
	find the molar mass of hydrogen using moles of metal gained when the metal is reduced.
	find the molar mass of a metal using moles of hydrogen produced when the metal is reduced.
	find the molar mass of hydrogen using moles of metal gained when the metal is oxidized.

D) The H⁺ in this experiment is

	oxidized to H2 gas.
	reduced to H2 gas.

Answer 1

A) cathode : Hydrogen electrode acts as cathode

anode : metal electrode acts as anode

B).Ans - Loss of mass of the metal

During electrolysis, metal oxidizes by loosing electrons. Hence, metal looses its mass.

C) Ans - Find the molar mass of a metal using moles of hydrogen produced when the metal is oxidized.

D)   The H⁺ in this experiment is - reduced to H₂ gas.