Year 10 Science · Unit 2 · Lesson 7
Challenge Worksheet
Learning Goals
Design a mini-experiment
A scientist wants to investigate: "How does the reactivity of magnesium, zinc, iron, and copper compare when each is added to hydrochloric acid?" Plan the full investigation below.
| What I will change (independent variable) | |
| What I will keep the same (controlled variables, list 4) | |
| What I will measure / observe (dependent variable, be specific) | |
| Safety: two specific risks and how to manage them | |
| My prediction (rank the metals from most to least reactive with HCl) | |
| How I would know if my prediction is wrong | |
| One limitation of using HCl as the test acid (why might results differ with other acids?) |
1. Design a data table to record your observations for all four metals reacting with HCl. Your table should have columns for: metal name, observations (rate of bubbling, colour change, temperature change), and a reactivity ranking (1 = most reactive). Fill in the expected results based on the reactivity series.
2. In Australian hydrometallurgy, iron scrap is used to displace copper from solution. A student suggests that aluminium would be a better choice than iron for this purpose because aluminium is higher in the reactivity series. Evaluate this suggestion: would aluminium work, and what are the practical advantages and disadvantages of using aluminium versus iron for this industrial process?
3. The zinc coating on galvanised steel acts as a "sacrificial anode." Explain what this term means, using the reactivity series to justify why zinc sacrifices itself to protect iron. Then explain what would eventually happen to galvanised iron once all the zinc has been consumed.
Wrap Up
In one sentence, what was the main idea of this lesson?