- Define and explain The Reactivity Series in your own words
- Use key terms such as reactivity series accurately
- Apply what you have learned to new examples and questions
- Avoid the common mistakes learners make with this topic
This lesson focuses on The Reactivity Series: use the series to predict displacement and extraction reactions.
Use the series to predict displacement and extraction reactions.
Key ideas
The reactivity series predicts displacement
A more reactive metal displaces a less reactive one from its compound: iron displaces copper from copper sulfate solution, but copper cannot displace iron. The series also explains extraction — very reactive metals like aluminium need electrolysis, while iron can be extracted by reduction with carbon. Carbon sits in the series as a reference point for these decisions.
Acids react in predictable patterns
Acids react with metals to give a salt plus hydrogen: for example, magnesium + hydrochloric acid → magnesium chloride + hydrogen. With carbonates they give a salt plus water plus carbon dioxide: calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide. Learn these two patterns and you can write the equation for any acid–metal or acid–carbonate reaction.
Key term — reactivity series: Metals listed in order of reactivity, from potassium (most reactive) to gold (least).
You add dilute hydrochloric acid to an unknown white powder and a gas is produced that turns limewater milky. Identify the gas, name the type of reaction, and write the word equation if the powder is calcium carbonate.
A gas that turns limewater milky is carbon dioxide. Acid + carbonate → salt + water + carbon dioxide, so the powder contains a carbonate. With calcium carbonate: calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide. Check: the gas matches the limewater test, and the equation follows the acid–carbonate pattern.
Answer: The gas is carbon dioxide; the powder is a carbonate. Word equation: calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide.
- Saying exothermic reactions make energy Energy cannot be created: in an exothermic reaction, chemical energy stored in bonds is transferred to the surroundings as heat. The total energy stays the same.
- Writing hydrogen as a product of acid + carbonate Acids reacting with carbonates produce carbon dioxide, not hydrogen — hydrogen comes from acids reacting with metals. Mixing these patterns is one of the most common exam errors.
Practice
Endothermic (thermal decomposition): calcium carbonate → calcium oxide + carbon dioxide needs continuous heat input, taking energy from the surroundings.
Zinc + sulfuric acid → zinc sulfate + hydrogen.
Iron is more reactive than copper, so it displaces copper from the solution: iron + copper sulfate → iron sulfate + copper. The blue colour fades as brown copper appears.
Yes. Magnesium is more reactive than zinc, so it can take the oxygen from zinc oxide: magnesium + zinc oxide → magnesium oxide + zinc.
Quick check
Which of these best defines "reactivity series"?
How would you make pure crystals of copper sulfate from copper oxide and dilute sulfuric acid?
Burning methane warms the room. Is this exothermic or endothermic? Explain in terms of bonds.
- The Reactivity Series: use the series to predict displacement and extraction reactions.
- The reactivity series predicts displacement: A more reactive metal displaces a less reactive one from its compound: iron displaces copper from copper sulfate solution, but copper cannot displace iron.
- exothermic: A reaction that releases energy to the surroundings, usually as heat — the surroundings warm up.
- Watch out for: saying exothermic reactions make energy