A simple electrolytic cell

By separating the two parts of the redox reaction, we have caused a current to flow through a wire. We have a simple battery, which we could use to 

What determines the magnitude of this cell voltage, when it is not zero Intuitively, we would suspect that it depends a lot on what metals we use to make the electrodes, and if we thought a bit more, we might think that the concentrations of the ions in solution would have an effect too. This is exactly the case, and we must develop an equation relating the voltage to the activities of the reactants and products in the cell reaction. 

An oxidation reaction cannot take place without an accompanying reduction reaction - the electrons have to go somewhere - but it is convenient to nonetheless split cell reactions into two complementary half-cell reactions. In our copper-iron case, these half-cells are 

We also imagine that each half-cell reaction has a half-cell voltage associated with it, and that the cell voltage is the sum of the two half-cell voltages. If we 

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Electrolysis is the process in which an electric current is used to produce a chemical change. In this MiniLab, you will use the current from a 9-V battery to produce chemical changes in a simple electrolytic cell. 

What happens when an electric current is passed through a solution Let s consider a hydrochloric acid solution in a simple electrolytic cell, as shown in Figure 17.4. The cell consists of a source of direct current (a battery) coimected to two electrodes that are immersed in a solution of hydrochloric acid. The negative electrode is called the cathode because cations are attracted to it. The positive electrode is called the anode because anions are attracted to it. The cathode is attached to the negative pole and the anode to the positive pole of the battery. The battery supplies electrons to the cathode. 

Figure 20.19 shows a simple electrolytic cell. IMres from a battery are connected to electrodes that dip into molten sodium chloride. (NaCl melts at 801°C.) At the electrode connected to the negative pole of the battery, globules of sodium metal form chlorine gas evolves from the other electrode. The half-reactions are... 

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