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Reactions of Acids (Edexcel IGCSE Chemistry: Double Science)
Revision Note
Reactions of Acids
Reactions of acids with metals
- Only metals above hydrogen in the reactivity series will react with dilute acids
- The more reactive the metal then the more vigorous the reaction will be
- Metals that are placed high on the reactivity series such as potassium and sodium are very dangerous and react explosively with acids
- When acids react with metals they form a salt and hydrogen gas
- The general equation is:
metal + acid ⟶ salt + hydrogen
- Some examples of metal-acid reactions and their equations are given below:
Table of acid-metal reactions
Metal | Sulfuric acid | Hydrochloric acid |
Magnesium | Mg (s) + H2SO4 (aq) → MgSO4 (aq) + H2 (g) | Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g) |
Zinc | Zn (s) + H2SO4 (aq) → ZnSO4 (aq) + H2 (g) | Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2 (g) |
Iron | Fe (s) + H2SO4 (aq) → FeSO4 (aq) + H2 (g) | Fe (s) + 2HCl (aq) → FeCl2 (aq) + H2 (g) |
- In general, we can summarise the reaction of a metal that forms a +2 ion as follows:
Acids-Metals Summary Table
Acid | Name of products | Equation for reaction |
Hydrochloric acid | Metal chloride and hydrogen | M + 2HCl → MCl2 + H2 |
Sulfuric acid | Metal sulfate and hydrogen | M + H2SO4 → MCl2 + H2 |
Reaction of acids with bases
- When an acid reacts with a base, a neutralisation reaction occurs
- In all acid-base neutralisation reactions, a salt and water are produced:
acid + base ⟶ salt + water
- The identity of the salt produced depends on the acid used and the positive ions in the base
- Hydrochloric acid produces chlorides, sulfuric acid produces sulfate salts and nitric acid produces nitrates
- Metal oxides and metal hydroxides act as bases
- The following are some specific examples of reactions between acids and metal oxides / hydroxides:
2HCl + CuO ⟶ CuCl2 + H2O
H2SO4 + 2NaOH ⟶ Na2SO4 + 2H2O
HNO3 + KOH ⟶ KNO3 + H2O
- In general, we can summarise the reaction of metals and bases as follows:
Acids and Metals Oxides or Hydroxides Summary Table
Acid | Name of products | Equation for reaction |
Hydrochloric acid | Metal chloride and water | MOH + HCl ⟶ MCl + H2O |
Sulfuric acid | Metal sulfate and water | MO + H2SO4 ⟶ MSO4 + H2O |
Nitric acid | Metal nitrate and water | MO + HNO3 ⟶ MNO3 + H2O |
Reactions of Acids with Metal Carbonates
- Acids will react with metal carbonates to form the corresponding metal salt, carbon dioxide and water
- These reactions are easily distinguishable from acid – metal oxide/hydroxide reactions due to the presence of effervescence caused by the carbon dioxide gas
Acids & Metal Carbonates Reactions Table
Acid | Name of Products | Equation for Reaction |
Hydrochloric acid | Metal chloride, carbon dioxide and water | MCO3 + 2HCl ⟶ MCl2 + CO2 + H2O |
Sulfuric acid | Metal sulfate, carbon dioxide and water | MCO3 + 2H2SO4 ⟶ MSO4 + CO2 + H2O |
Nitric acid | Metal nitrate, carbon dioxide and water | MCO3 + HNO3 ⟶ M(NO3)2 + CO2 + H2O |
- The following are some specific examples of reactions between acids and metal carbonates:
2HCl + Na2CO3 ⟶ 2NaCl + H2O + CO2
H2SO4 + CaCO3⟶ CaSO4 + H2O + CO2
Examiner Tip
If in an acid-base reaction there is effervescence produced then the base must be a metal carbonate which produces carbon dioxide gas.
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