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Ch.19 - Electrochemistry
Chapter 19, Problem 132

Magnesium metal is produced by the electrolysis of molten magnesium chloride using inert electrodes. (a) Sketch the cell, label the anode and cathode, indicate the sign of the electrodes, and show the direction of electron and ion flow.

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Start by drawing a simple diagram of an electrolytic cell. This will include a container to hold the molten magnesium chloride (MgCl_2).
Label the two electrodes: the anode and the cathode. In an electrolytic cell, the anode is the positive electrode, and the cathode is the negative electrode.
Indicate the direction of electron flow. In an electrolytic cell, electrons flow from the anode to the cathode through the external circuit.
Show the direction of ion flow in the molten MgCl_2. Magnesium ions (Mg^{2+}) will move towards the cathode to gain electrons and form magnesium metal, while chloride ions (Cl^-) will move towards the anode to lose electrons and form chlorine gas.
Label the products formed at each electrode: magnesium metal (Mg) at the cathode and chlorine gas (Cl_2) at the anode.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Electrolysis

Electrolysis is a chemical process that uses electrical energy to drive a non-spontaneous reaction. In this process, an electric current is passed through an electrolyte, causing the decomposition of the compound. In the case of magnesium chloride, the electrolysis results in the production of magnesium metal at the cathode and chlorine gas at the anode.
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Electrodes and Their Functions

In an electrolysis cell, there are two electrodes: the anode and the cathode. The anode is the positive electrode where oxidation occurs, while the cathode is the negative electrode where reduction takes place. In the electrolysis of magnesium chloride, magnesium ions gain electrons at the cathode to form magnesium metal, while chloride ions lose electrons at the anode to produce chlorine gas.
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Ion and Electron Flow

During electrolysis, ions move towards the electrodes due to the electric field created by the applied voltage. Cations (positively charged ions) migrate towards the cathode, where they gain electrons, while anions (negatively charged ions) move towards the anode, where they lose electrons. Understanding the direction of ion and electron flow is crucial for correctly sketching the electrolysis cell and labeling the electrodes.
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