Reactions of metals with dilute acids
4 marks · NormalThe results of an experiment measuring the temperature rise when four metals react with excess hydrochloric acid are shown in the bar chart below.
Which metal is the most reactive according to the results? Give evidence from the chart.
Which metal does not react at all with hydrochloric acid?
Describe the trend in reactivity shown by these four metals.
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(a) Barium; it shows the highest temperature rise (24°C).
(b) Copper
(c) Reactivity decreases from barium to copper; the temperature change gets smaller as you go from barium down to copper, which shows less heat released and lower reactivity.
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Marking points
B1 (a) · 1 mark · Identifies barium as most reactive and refers to temperature change as evidence.
B2 (b) · 1 mark · Correctly identifies copper as not reacting.
B3 (c) · 1 mark · States reactivity decreases from barium to copper (or similar trend).
B4 (c) · 1 mark · Explains that temperature change falls, meaning less reactivity or heat produced with each metal.
Worked solution
a. Barium is the most reactive metal, as it gives the biggest temperature rise (24°C) on the bar chart.
b. Copper does not react; the temperature change is 0°C.
c. The trend is that reactivity decreases as you go from barium to copper—the temperature rise gets smaller, so each metal reacts less strongly with hydrochloric acid.