Reactions of metals with dilute acids
4 marks · NormalA student observes the reaction between four different metals and dilute hydrochloric acid. She records the following results:
| Metal | Observation |
|---|---|
| Calcium | Rapid bubbling; white suspension forms; test-tube gets hot |
| Iron | Slow fizzing; pale green solution; little heat noticed |
| Zinc | Steady bubbles; colourless solution; test-tube gets warm |
| Gold | No reaction; no observable change |
Which metal, from the table, is the most reactive? Explain your answer.
Explain why gold does not react with dilute hydrochloric acid.
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.
Show answer
(a) Calcium; it reacts rapidly, forms lots of bubbles, and produces a lot of heat, showing it is most reactive.
(b) Gold is below hydrogen in the reactivity series, so it does not react with dilute hydrochloric acid as it cannot displace hydrogen.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies calcium as the most reactive metal.
B2 (a) · 1 mark · Explains that this is due to rapid bubbling, lots of heat, and observable reaction.
B3 (b) · 1 mark · States that gold does not react because it is below hydrogen in the reactivity series (or cannot displace hydrogen).
B4 (b) · 1 mark · Links non-reactivity to gold being unable to react with dilute acids for this reason.
Worked solution
a. Calcium is the most reactive because it reacts very rapidly, produces many bubbles, and the test-tube gets hot, all showing strong reactivity.
b. Gold does not react because it is below hydrogen in the reactivity series, so it cannot displace hydrogen from acid and therefore shows no reaction.