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Reactions of acids
This topic connects acids to hydrogen ions, salt formation, practical preparation of soluble salts, pH measurement and neutralisation calculations.
42
Objectives
210
Flashcards
210
Questions
90 min
Study time
AQAGCSEChemistryChemical changes
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42 objective pages available
Reactions of acids with metals8 objectives
- State that acids react with some metals to produce salts and hydrogen.
- Predict the salt produced when hydrochloric acid reacts with a metal.
- Predict the salt produced when sulfuric acid reacts with a metal.
- Predict the salt produced when nitric acid reacts with a metal.
- Write word equations for reactions between acids and metals.
- Write balanced symbol equations for acid-metal reactions when formulae are supplied.
- Describe the test for hydrogen gas using a lighted splint.
- Explain why less reactive metals may not react readily with dilute acids.
Neutralisation of acids and salt production8 objectives
- Describe neutralisation as the reaction between an acid and a base or alkali.
- State that acids react with alkalis to produce salts and water.
- State that acids react with bases to produce salts and water.
- State that acids react with carbonates to produce salts, water and carbon dioxide.
- Predict the name of a salt from the acid and the positive ion in the base, alkali or carbonate.
- Write word equations for acid-base, acid-alkali and acid-carbonate reactions.
- Write balanced symbol equations for neutralisation reactions when formulae are supplied.
- Describe the test for carbon dioxide using limewater.
Soluble salts9 objectives
- Describe how to prepare a soluble salt from an acid and an insoluble reactant.
- Explain why the insoluble solid is added in excess when preparing a soluble salt.
- Explain why filtration is used after reacting an acid with an excess insoluble solid.
- Describe how evaporation and crystallisation produce a pure dry salt sample.
- Identify suitable apparatus for preparing, filtering and crystallising a soluble salt. (AT 2, AT 3, AT 4, AT 6)
- Write word equations for soluble salt preparation reactions.
- Write balanced symbol equations for soluble salt preparation when formulae are supplied.
- Explain how to obtain a pure dry sample of a named soluble salt in the required practical.
- Describe safety precautions when using acids and heating solutions during salt preparation.
The pH scale and neutralisation9 objectives
- Use the pH scale to classify solutions as acidic, neutral or alkaline.
- Describe universal indicator and pH meters as methods for measuring pH.
- Explain that acids produce hydrogen ions, H+, in aqueous solution.
- Explain that alkalis produce hydroxide ions, OH-, in aqueous solution.
- Describe neutralisation in terms of hydrogen ions reacting with hydroxide ions to produce water.
- Write the ionic equation H+ + OH- -> H2O for neutralisation.
- Explain why pH increases when an acid is neutralised by an alkali.
- Explain why pH decreases when an alkali is neutralised by an acid.
- Use pH data to identify whether a solution is acidic, neutral or alkaline.
Strong and weak acids (HT only)8 objectives
- (HT only) Describe a strong acid as completely ionised in aqueous solution.
- (HT only) Describe a weak acid as only partially ionised in aqueous solution.
- (HT only) Explain that acids of the same concentration can have different pH values because of different degrees of ionisation.
- (HT only) Explain that a lower pH means a higher hydrogen ion concentration.
- (HT only) Explain that decreasing pH by one unit means the hydrogen ion concentration increases by a factor of ten.
- (HT only) Distinguish acid strength from acid concentration.
- (HT only) Compare pH changes when strong and weak acids are diluted.
- (HT only) Use powers of ten to compare hydrogen ion concentrations from pH values. (MS 1b, MS 2h)
Key terms
AcidSalthydrochloric acidmetal saltSulfuric acidMetal sulfate saltNitric acidMetalacid-metal reactionbalanced symbol equationhydrogen gas testlighted splint
Exam tips
- Remember the “Metal‑Acid” Rule: Link the chemical change carefully by when you see an acid and a metal, write the metal’s ion and the acid’s anion to form the salt, then add H₂ gas. Link your answer to Reactions of acids with metals in Reactions of acids, and name the acid-base term, ion, electrode, reaction type, product, observation, or salt-preparation step where relevant.
- Know Your Salts: Link the chemical change carefully by memorize the common salts produced from hydrochloric acid reactions, such as sodium chloride from sodium and hydrochloric acid. Link your answer to Reactions of acids with metals in Reactions of acids, and name the acid-base term, ion, electrode, reaction type, product, observation, or salt-preparation step where relevant.
Common mistakes
- Misunderstanding Acid Reactions: Focus on learning which specific metals react with acids and remember that metals like copper do not react with dilute acids.
- Common Mistake in Predicting Salts: To fix this, remember that the salt produced from hydrochloric acid will always be named after the metal and will be a chloride. For example, if zinc reacts with hydrochloric acid, the salt produced is zinc chloride.
Practice preview
- For Reactions of acids with metals, which reaction focus answer best supports this Unit 4.4 objective: State that acids react with some metals to produce salts and hydrogen?
- When hydrochloric acid reacts with zinc, what salt is produced?
- Which of the following is a product of the reaction between sulfuric acid and a metal?
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