Reactions of metals with dilute acids
4 marks · NormalAn experiment was carried out to compare the reactivity of metals with dilute hydrochloric acid. The results are:
| Metal | Observation |
|---|---|
| Magnesium | Rapid fizzing, test-tube gets hot, gas burns with a squeaky pop |
| Zinc | Steady fizzing, test-tube gets warm, gas burns with a squeaky pop |
| Copper | No reaction, no temperature change, no gas produced |
Arrange the metals in order of decreasing reactivity according to the observations.
Write a word equation for the reaction between magnesium and hydrochloric acid.
State the name of the gas produced in these reactions and describe how it is tested.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Magnesium, zinc, copper
(b) Magnesium + hydrochloric acid → magnesium chloride + hydrogen
(c) Hydrogen. It is tested by applying a lighted splint to the gas, which produces a squeaky pop. · must show hydrogen gas, squeaky pop with lighted splint
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Correct order: magnesium, zinc, copper (in decreasing reactivity).
B2 (b) · 1 mark · Correct word equation for reaction of magnesium with hydrochloric acid.
B3 (c) · 1 mark · Identifies hydrogen as the gas produced.
B4 (c) · 1 mark · Describes the test: lighted splint gives a squeaky pop.
Worked solution
a. The order, from most to least reactive, is magnesium, zinc, copper.
b. Magnesium + hydrochloric acid → magnesium chloride + hydrogen
c. The gas produced is hydrogen. It is tested by holding a lighted splint to the gas; a squeaky pop indicates hydrogen.