Reactivity Series
6 marks · NormalA student investigates the reaction between metals and dilute hydrochloric acid. She uses 0.010 mol of each metal and measures the temperature change during the reaction. Her results are shown below:
| Metal | Initial temperature / C | Maximum temperature / C |
|---|---|---|
| Magnesium | 20 | 42 |
| Zinc | 20 | 28 |
| Iron | 20 | 24 |
| Copper | 20 | 20 |
Another metal, chromium, is placed between iron and zinc in the reactivity series.
Calculate the temperature rise for each metal. Complete the table below.
| Metal | Temperature rise / C |
|---|---|
| Magnesium | |
| Zinc | |
| Iron | |
| Copper |
Based on your answers to part a, describe and explain the trend in reactivity of these metals with dilute hydrochloric acid.
Predict the temperature rise the student would expect if she repeated the experiment using 0.010 mol of chromium. 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) — · must show Magnesium: 22, Zinc: 8, Iron: 4, Copper: 0
(b) — · must show Ranking Mg > Zn > Fe > Cu, Higher temperature rise = greater reactivity, Explanation: magnesium gives out most heat, so is most reactive, copper least
(c) — · must show Prediction: value between 4 and 8 (e.g., 6), Justification: chromium placed between iron and zinc, its reactivity is intermediate, so temperature rise should be between their values.
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Correct calculation of temperature rise for any two metals.
A1 (a) · 1 mark · All four temperature rises correct and placed in the table.
B1 (b) · 1 mark · Correct description of the trend: magnesium > zinc > iron > copper.
B2 (b) · 1 mark · Explanation linking temperature rise to reactivity.
B3 (c) · 1 mark · Prediction: temperature rise for chromium falls between zinc and iron values (e.g., 6).
B4 (c) · 1 mark · Justification based on position of chromium in the reactivity series and data given.
Worked solution
a) Calculate the temperature rise for each metal:
| Metal | Temperature rise / C |
|---|---|
| Magnesium | 42 - 20 = 22 |
| Zinc | 28 - 20 = 8 |
| Iron | 24 - 20 = 4 |
| Copper | 20 - 20 = 0 |
b) The temperature rise decreases from magnesium to copper: magnesium (22) has the highest, then zinc (8), iron (4), and copper (0). This means magnesium is the most reactive, followed by zinc, then iron, and copper is the least.
Higher temperature rise means a more vigorous reaction and higher reactivity with the acid.
c) Chromium is between zinc and iron in the reactivity series, so its temperature rise would be between 8 and 4. A reasonable prediction is about 6 C. This prediction is based on the pattern that metals higher in the series give greater temperature rises.