7. (a) Define (i) oxidation, (ii) reduction, in terms of electron transfer - Leaving Cert Chemistry - Question 7 - 2016
Question 7
7. (a) Define (i) oxidation, (ii) reduction, in terms of electron transfer.
(b) When a piece of zinc is left in a solution of copper sulfate, the zinc becomes coa... show full transcript
Worked Solution & Example Answer:7. (a) Define (i) oxidation, (ii) reduction, in terms of electron transfer - Leaving Cert Chemistry - Question 7 - 2016
Step 1
Define (i) oxidation
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Answer
Oxidation is defined as the loss of electrons by a substance, which results in an increase in its oxidation number.
Step 2
Define (ii) reduction
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Reduction is defined as the gain of electrons by a substance, causing a decrease in its oxidation number.
Step 3
(i) Which species is oxidised?
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The species that is oxidised is zinc (Zn).
Step 4
(ii) How many electrons are transferred when one zinc atom reacts according to the equation above?
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One zinc atom loses two electrons during the reaction.
Step 5
(iii) Identify the oxidising agent and the reducing agent.
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The oxidising agent is copper sulfate (CuSO₄), and the reducing agent is zinc (Zn).
Step 6
(i) Why must sodium never be held with the fingers?
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Sodium is highly reactive and may tarnish upon contact with moisture. Holding sodium with fingers could cause a dangerous and exothermic reaction due to the sweat on the skin.
Step 7
(ii) What is observed when the sodium reacts with the water?
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When sodium reacts with water, it fizzes and produces a vigorous reaction, resulting in the formation of sodium hydroxide and hydrogen gas.
Step 8
(iii) Name the gas produced when sodium reacts with water.
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The gas produced when sodium reacts with water is hydrogen.
Step 9
(iv) What difference would you observe if potassium were used instead of sodium?
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When potassium is used instead of sodium, the reaction is more vigorous, producing a larger flame and resulting in a more intense reaction due to its higher reactivity.
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