Reactions of metals with dilute acids
3 marks · EasyA student adds a piece of zinc to dilute hydrochloric acid. State one observation she might make.
What test could be used to confirm the identity of the gas produced? State the result.
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(a) Fizzing (bubbles); temperature rise; colourless solution forms · must show Fizzing/gas bubbles OR test-tube gets warmer
(b) Test with a lighted splint; a squeaky pop confirms hydrogen gas. · must show Lighted splint AND squeaky pop
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Marking points
B1 (a) · 1 mark · States an acceptable observation (e.g. fizzing/bubbling, solution forms, temperature rise).
B2 (b) · 1 mark · Mentions use of a lighted splint or burning splint as the test for hydrogen.
B3 (b) · 1 mark · States correct result (squeaky pop) for a positive test.
Worked solution
(a) When zinc is added to dilute hydrochloric acid, fizzing (bubbles of gas) are seen, and the test-tube gets warmer.
(b) The gas can be tested with a lighted splint. If it is hydrogen, the gas burns with a squeaky pop.