9.4 Acid Reactions & Reactivity
Topic: Metal Reactivity with Dilute Acids | Reactivity Series | The Hydrogen Rule
Observations
Zinc and copper are added to separate test tubes of dilute hydrochloric acid. Describe the difference in observations between the two test tubes.
Think about where each metal sits relative to hydrogen in the reactivity series.
Magnesium ribbon is added to dilute sulfuric acid. State TWO observations you would make.
What happens to the solid? What gas is produced?
Iron filings and magnesium powder are added to separate beakers of dilute hydrochloric acid. Compare the rates of reaction and describe the observations for each metal.
Check the reactivity series: Mg > Fe > H.
A student adds gold to dilute nitric acid and observes no reaction. Explain this observation.
Where is gold in the reactivity series?
Dilute hydrochloric acid is added to copper(II) oxide powder. Describe what you observe and write a word equation for the reaction.
Metal OXIDES are bases — they react with acids in a neutralisation reaction, not a displacement.
Reactivity Ranking
Rank the following metals in order of the RATE at which they produce hydrogen gas with dilute hydrochloric acid, fastest first: Zinc, Magnesium, Iron.
Higher in the reactivity series = faster reaction with acid.
Calcium, tin, and lead are reacted with dilute sulfuric acid. Rank them in order of reactivity, most reactive first, and predict which ONE would produce the most vigorous reaction.
Calcium is a Group 2 metal — very reactive!
Four metals W, X, Y, and Z are tested with dilute hydrochloric acid. W reacts vigorously, X reacts slowly, Y shows no reaction, and Z reacts moderately. Place them in order of reactivity, most reactive first.
Rate of reaction with acid directly mirrors position in the reactivity series.
Sodium, potassium, and lithium are Group 1 metals. Rank them in order of reactivity with dilute hydrochloric acid. Explain the trend using atomic structure.
As you go DOWN Group 1, what happens to the outer electron's distance from the nucleus?
A student claims that aluminium should react faster with dilute acid than zinc because aluminium is higher in the reactivity series. However, in an experiment, zinc reacted faster. Suggest why.
Aluminium has a special protective layer...
The Hydrogen Rule
Explain, with reference to the reactivity series, why silver does not react with dilute sulfuric acid.
Metals BELOW hydrogen in the reactivity series cannot displace it.
State the general rule for predicting whether a metal will react with a dilute acid to produce hydrogen gas. Apply this rule to predict whether platinum will react with dilute hydrochloric acid.
It's all about position in the reactivity series relative to hydrogen.
Write a balanced symbol equation, including state symbols, for the reaction between zinc and dilute sulfuric acid. Identify what is oxidised and what is reduced.
Zinc displaces hydrogen. Check oxidation numbers: Zn goes from 0 to +2, H goes from +1 to 0.
A student tests four unknown metals (A, B, C, D) with dilute hydrochloric acid. Metal A and C react, B and D do not. Explain what this tells you about the positions of A, B, C, and D relative to hydrogen in the reactivity series. Can you determine the order of A and C from this experiment alone?
Reacting = above hydrogen. Not reacting = below hydrogen. But can you rank within each group?
Extended Question: A student has three white powders: magnesium carbonate, calcium carbonate, and copper(II) carbonate. They add dilute hydrochloric acid to each. (a) State the observation for each powder. (b) Write a general equation for the reaction. (c) Explain why this is NOT a test based on the hydrogen rule.
Metal carbonates + acid → salt + water + CO₂. This is neutralisation, not displacement!
Cambridge IGCSE Chemistry 0620
Topic 9.4 — Acid Reactions & Reactivity Series
Limitless Chemistry Professor • Standard Design Protocol
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