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ELECTROCHEMISTRY A - LEVEL CHEMISTRY QUESTIONS AND ANSWERS WITH SOLUTIONS 2024
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ELECTROCHEMISTRY A - LEVEL CHEMISTRY QUESTIONS AND ANSWERS WITH SOLUTIONS 2024
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ELECTROCHEMISTRY A - LEVEL CHEMISTRY QUESTIONS AND ANSWERS WITH SOLUTIONS 2024 Why must a high resistance voltmeter used in electrochemical cells to measure the potential difference? - ANSWER The voltmeter needs to be of very high resistance to stop the current from flowing in the circuit. In this state it is possible to measure the maximum possible potential difference (E). The reactions will not be occurring because the high resistance voltmeter stops the current from flowing. Oxidising agent - ANSWER Accepts electrons and gets reduced. Reducing agent - ANSWER Donates electrons and becomes oxidized. Disproportionation - ANSWER A redox reaction in which the same species is both oxidized and reduced. Why do electrochemical cells require a salt bridge? - ANSWER The salt bridge allows ions to flow between the solutions to complete the circuit, keeping the balance of positive and negative ions in each half cell without them mixing together. The salt bridge is often a piece of filter paper or agar gel soaked in potassium nitrate which is will not react with either of the solutions in the half cells). What is electromotive force? - ANSWER There is a potential difference between the two electrodes. If there was a bulb in the circuit instead of a high resistance voltmeter a current would flow as because of the potential difference chemical energy is converted to electrical energy. The voltmeter takes measurements when there is zero -current which means the measurements is the maximum possible potential difference between the two half cells and this is called the e.m.f. Electrode potential depends on? - ANSWER 1. Nature of ions in the solution 2. Conc. of ions in the solution 3. Type of electrode 4. Temperature What happens if the oxidising agent > 1M - ANSWER Favours reduction, more positive E What happens if the oxidising agent < IM - ANSWER Favours oxidation, more negative E What happens if 2 gases are want to measured. - ANSWER They are bubbled through the solution so it it in contact with the electrode What happens if the current is allowed to flow between the two half cells - ANSWER If there was a bulb in the circuit instead of a high resistance voltmeter a current would flow as because of the potential difference chemical energy is converted to electrical energy. The reactions will then occur separately at each electrode. The voltage will fall to zero as the reactants are used up. What do electrochemical cells consist of? - ANSWER Two half -cells that have to be connected with a salt bridge and which have electrodes that can conduct electricity when connected by wires.The benefits of buying summaries with Stuvia:
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