2.1.1Inorganic Chemistry: Part 1
Metals Reacting with Water and Acids — Edexcel International GCSE Science Double Award (Modular) - Chemistry Unit 1 Revision Notes & Topical Questions
5 min read 6 parts Lesson 2 of 15
Part 1 of 4Reactions with water
| Metal | Behaviour with water | Reactivity |
|---|---|---|
| Potassium | Reacts violently with cold water | Very high |
| Sodium | Reacts quickly, fizzing and moving across the surface | High |
| Lithium | Reacts less strongly, steady fizzing | High |
| Calcium | Reacts less strongly, gradually dissolving | Fairly high |
| Magnesium | Very slow with cold water but burns brightly in steam | Medium |
| Zinc and iron | Only react slowly with steam | Lower |
| Copper | No reaction | Very low |
Part 2 of 4Equations for metals and water
Cold water
- Cold water A reactive metal and water form a metal hydroxide and hydrogen.
- For calciumCa(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g).
Steam
- Steam Less reactive metals such as magnesium, zinc and iron form a metal oxide and hydrogen instead.
- The hydrogen can be collected and tested with a lighted splint, which gives a squeaky pop.
Part 3 of 4Reactions with dilute acids
metal + acid → salt + hydrogen
Which metals react
- Which metals react Only metals above hydrogen in the reactivity series react with dilute hydrochloric or sulfuric acid.
- Copper, silver and gold are below hydrogen and show no reaction.
Vigour of reaction
- Vigour of reaction The higher the metal is in the series, the faster the bubbling.
- Potassium and sodium are so reactive that they react explosively with acids and must never be tried.
Salt formed
- Salt formed Hydrochloric acid makes chlorides and sulfuric acid makes sulfates.
- Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
- Zn(s) + H2SO4(aq) → ZnSO4(aq) + H2(g)
- Fe(s) + 2HCl(aq) → FeCl2(aq) + H2(g)
Part 4 of 4Using observations to rank metals
1
React equal-sized pieces of each metal with the same volume and concentration of acid at the same temperature.
2
Note the speed of bubbling, any temperature rise and how fast the metal disappears.
3
Rank the metals from the fastest to the slowest reaction.
4
Place any metal that does not react at all, such as copper, at the bottom, below hydrogen.
Key terms
| Term | Meaning |
|---|---|
| Reactivity series | A list of metals arranged from the most to the least reactive. |
| Salt | A compound formed when the hydrogen of an acid is replaced by a metal. |
| Hydroxide | A compound containing the OH− ion; metal hydroxides form with cold water. |
| Squeaky pop | The sound made by hydrogen burning with a lighted splint, used as its test. |
| Steam | Water in its gaseous state, which can react with metals that do not react with liquid water. |
Avoid these mistakes
1
Writing that copper reacts slowly with dilute acid. It does not react because it is below hydrogen in the series.
2
Forgetting that metals with steam give an oxide, not a hydroxide.
3
Leaving hydrogen out of the products or writing it as H instead of H2.
4
Judging reactivity from a single fast reaction without keeping the acid concentration, temperature and metal size the same.
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