OCR GCSE Chemistry Acids and alkalis
This page covers the following topics:
3. Reactions of acids with metals
Acids are ionic compounds that form positive hydrogen ions when dissolved in water. Acids have a pH lower than 7, can conduct electricity when dissolved in water and they react with metals to produce hydrogen gas. When soluble non-metal oxides are dissolved in water, acidic solutions are formed. Common acids include: hydrochloric acid (HCl), nitric acid (HNO₃), sulfuric acid (H₂SO₄), carbonic acid (H₂CO₃), acetic acid (CH₃COOH) and phosphoric acid (H₃PO₄).
Alkalis are ionic compounds that form hydroxide ions when dissolved in water. Alkalis have pH higher than 7, can conduct electricity when dissolved in water and can be produced by dissolving metal oxides in water. Common bases include: potassium hydroxide (KOH), sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)₂) and ammonia (NH₃).
Acids react with metals to form salts and hydrogen gas. The higher up the metal is on the reactivity scale, the faster the reaction. Acid-metal reactions are redox reactions. This is a type of chemical reaction that involves a transfer of electrons between two species. The electron donor is called the reducing agent, and the electron acceptor is the oxidising agent.
Magnesium reacts with hydrochloric acid to form magnesium chloride. Write the reduction half-equation for the reaction described.
If carbon monoxide is dissolved in water, will it form an acid? Explain your answer.
Write a balanced equation for the reaction of magnesium with hydrochloric acid.
Write a balanced equation for the reaction that produces potassium hydroxide using water.
Sulfur dioxide (SO₂) is a colourless, poisonous gas. Does it form an alkaline when dissolved in water?
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