Experiment Plan. Chemistry IA: Electrolysis of Metal Sulphate solutions (NiSO4)

by claudiaxc (student)

Chemistry IA: Electrolysis of Metal Sulphate solutions (NiSO4)

Introduction

Electrolysis is the chemical decomposition of a compound by applying an electric current through a solution containing ions. Electrolytes are required to conduct electricity. They must be dissolved in water or in molten state for the electrolytes to conduct because then, the ions are free to move allowing the solution to be electrolyzed.[1] In electrolysis, reduction happens at the cathode whilst oxidation happens at the anode. Reduction is the loss of electrons and oxidation is the gain of electrons.

Research Question

In this experiment, I will be electrolyzing nickel sulphate (NiSO4) solution. To further explain the aim of this experiment, I have formulated a research question: “How does changing the current affect the mass of nickel deposited at the cathode in the electrolysis of nickel sulphate?”

Hypothesis

I predict that as the electrical charge increases, the mass of nickel deposited at the cathode after electrolysis will also increase. Faraday’s law of electrolysis, which investigates the quantitative relationship on electrochemical, can support this. Faraday’s law states, “The amount of the substance produced by current at an electrode is directly proportional to the quantity of electricity used”.[2]

During this electrolysis experiment, the aqueous solution of Nickel Sulphate will transfer Nickel from the anode to the cathode. Therefore indicating that the nickel sulphate solution is ionised by the electric current and dissociated into nickel ions and sulphate ions. This can be represented in a chemical equation: NiSO4  Ni2+ + SO42-

At the cathode, positively charged nickel ions are formed there and Ni2+ ions are reduced to Ni by gaining two electrons: Ni2+ + 2e  Ni

At the anode, Ni is oxidised into Ni2+ by dissolving and going into the nickel sulphate solution and finally depositing nickel at the cathode: Ni  Ni2+ + 2e

When the electrolysis circuit has electricity flowing, the nickel ions will float towards the electrode. Therefore, when the current is increased, the nickel ions flow faster and reaching the cathode faster. So there will be more nickel deposited as the rate of electrolysis is increased.

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