1. What is the electrolyte?
2. What are negatively charged ions called and which electrode are they attracted to?
3. What are the electrodes normally made of and why?
5. What happens if you electrolyse a solution of ions in water?
6. What element is given off at the anode for each of these negative ions: Chloride, Iodide, Bromide, Sulfate?
1. The electrolyte is the molten ionic solid or solution of ions. Electrolysis is only used on ionic compounds.
2. Anions and they are attracted to the positive electrode - the anode. Cations are positively charged and attracted to the negative electrode - the cathode.
3. Graphite or platinum - because they are unreactive substances.
4. Oxidation Is Loss (of electrons). Reduction Is Gain.
5. Hydrogen may be produced at the cathode if the other positive ions are of metals more reactive than hydrogen. Essentially, if two elements can be produced at an electrode, the less reactive element will be formed.
6. Chlorine, Iodine, Bromine, Oxygen
1. What is brine?
2. When brine is electrolysed, what is produced where and how is it used?
3. Why do we purify copper after it is extracted from its ore?
4. Explain the purification of copper.
1. Brine is sodium chloride in water.
2. Hydrogen is produced at the cathode from hydrogen ions in the water. Chlorine is produced at the anode from the chloride ions. Sodium ions and hydroxide ions are left in the solution. Sodium hydroxide is used for making soap, bleach and paper. Chlorine is used to kill bacteria in drinking water an swimming pools. Hydrogen is used to make margarine and hydrochloric acid.
3. Because it is only 99% pure and this affects its conductivity.
4. Impure copper is used as the anode and the cathode is a thin sheet of pure copper. Copper atoms on the anode are oxidised, forming copper ions that go into the solution. These ions are attracted to the cathode where they are reduced, forming copper. The copper is deposited on the cathode increasing its thickness. This happens until all the copper from the anode is dissolves. The impurities include precious metals like gold, silver and platinum. These are extracted from the sludge.