Electrolysis Using Inert and Reactive Electrodes

Chemistry tuition classes in Miracle Learning Centre is easy to understand and help you in the chemistry tuition application questions. If you do not understand chemistry in school, you must definitely come for chemistry tuition classes at Miracle Learning Centre. Let us learn about the electrolysis using inert electrode in this chemistry tuition lesson.

Graphite and platinum are examples of inert electrodes. Examples of reactive electrodes are copper, silver and gold.

An example of electrolysis using inert electrodes is the electrolysis of dilute sulfuric acid using graphite electrodes for the cathode and anode. At the cathode, hydrogen ions will be discharged, hence hydrogen gas is formed at the cathode. At the anode, hydroxide ions will be discharged, hence oxygen gas is formed at the anode. From the half equation, four moles of electrons are needed to discharge one mole of oxygen. Two moles of electrons are needed to discharge one mole of hydrogen. Hence the ratio of hydrogen to oxygen gas is 2:1.

Another example of electrolysis using inert electrodes is the electrolysis of concentrated aqueous sodium chloride using graphite electrodes for the cathode and anode. At the cathode, hydrogen ions will be discharged, hence hydrogen gas is formed at the cathode. At the anode, chloride ions will be discharged, hence chlorine gas is formed at the anode. This is because chloride ions are present in high concentration, hence it is preferentially discharged. From the half equation, two moles of electrons are needed to discharge one mole of chlorine. Two moles of electrons are needed to discharge one mole of hydrogen. Hence the ratio of hydrogen to chlorine gas is 1:1.

An example of electrolysis using reactive electrode is the electrolysis of copper (II) sulfate using copper electrodes for the cathode and anode. At the cathode, copper(II) ions will be deposited, hence a brown solid is formed at the cathode. This is because copper(II) ions are preferentially discharged as copper is lower than hydrogen in the electrochemical series. At the anode, copper anode dissolves because copper is a reactive electrode. Copper dissolves to form copper(II) ions, this results in a loss of copper metal in the anode. The copper that is deposited in the cathode is replaced by the copper that is dissolved from the anode. Hence the blue color in the solution remains blue. The student in Miracle Learning Centre asks why do we need to learn about electrolysis using inert electrode. Mrs Lew from Miracle Learning Centre replied, “This is useful in the electroplating of ornaments. For example, if we want to electroplate a ring with silver, we put the ring on the cathode. Silver metal is placed at the anode. The electrolyte is aqueous silver nitrate. Silver from the solution is deposited in the cathode where the ring is placed. Silver from the anode dissolves in the solution and replaces the silver which is deposited in the cathode. Electroplating is widely used in many industries.”

Miracle Learning Centre aims to educate students about electrolysis using inert electrode. Do come to Miracle Learning Centre for more chemistry tuition lessons to learn more about electrolysis using inert electrode.

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