Reactivity Series
6 marks · NormalSome metals react with dilute hydrochloric acid at different rates. The reactivity series can be used to predict how metals behave in these reactions.
A student adds small pieces of magnesium, iron, and copper to separate test tubes containing dilute hydrochloric acid. State the trend in reactivity observed for these three metals with dilute acids.
Give one observation the student would make when magnesium reacts with dilute hydrochloric acid.
| Metal | Temperature change / °C |
|---|---|
| Magnesium | 21 |
| Zinc | 7 |
| Iron | 4 |
| Copper | 0 |
Using the data in the table, identify the most reactive and the least reactive metal.
A new, unfamiliar metal 9 is found to react with dilute hydrochloric acid and produces a temperature change greater than zinc but less than magnesium. Predict, using the reactivity series, where 9 would be placed relative to magnesium and zinc. Explain your answer.
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) Magnesium > Iron > Copper · must show Magnesium most reactive, Iron less reactive, Copper least/no reaction
(b) Fizzing/effervescence (or temperature increase, or squeaky pop with a lighted splint) · must show Fizzing/effervescence (hydrogen gas produced)
(c) Most reactive: Magnesium; Least reactive: Copper · must show Magnesium most reactive, Copper least reactive
(d) 9 would be placed between magnesium and zinc in the reactivity series, since its temperature change is greater than zinc but less than magnesium. · must show Placed between magnesium and zinc, Reason: temperature change is between those of magnesium and zinc
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States correct reactivity trend: magnesium most reactive, then iron, then copper (or correctly compares them).
B1 (b) · 1 mark · Describes a correct observation for the reaction of magnesium with acid (e.g. fizzing, temperature increase, squeaky pop).
B1 (c) · 1 mark · Identifies magnesium as the most reactive using the data.
B2 (c) · 1 mark · Identifies copper as the least reactive using the data.
M1 (d) · 1 mark · Uses the reactivity series and links observed temperature change to position in series.
A1 (d) · 1 mark · Correctly places 9 between magnesium and zinc and gives suitable reason.
Worked solution
a) The trend is: magnesium reacts most strongly with dilute acids, iron reacts less strongly, and copper does not react.
b) The student would see fizzing due to hydrogen gas, the test-tube gets hot, or a squeaky pop is heard when testing the gas.
c) Magnesium shows the largest temperature change (21°C), so it is the most reactive. Copper shows 0°C temperature change, so it is the least reactive.
d) 9 should be placed between magnesium and zinc in the reactivity series. This is because its temperature change in the reaction is greater than zinc but less than magnesium, indicating it is more reactive than zinc but less reactive than magnesium.