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AQA GCSE Chemistry Acids and alkalis

Acids and alkalis

This page covers the following topics:

1. Acids
2. Alkalis
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 (Hβ‚‚SOβ‚„), carbonic acid (Hβ‚‚CO₃), acetic acid (CH₃COOH) and phosphoric acid (H₃POβ‚„).

Acids

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)β‚‚) and ammonia (NH₃).

Alkalis

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.

Reactions of acids with metals

1

Magnesium reacts with hydrochloric acid to form magnesium chloride. Write the reduction half-equation for the reaction described.

Magnesium reacts with hydrochloric acid to form magnesium chloride. Write the reduction half-equation for the reaction described.

2

If carbon monoxide is dissolved in water, will it form an acid? Explain your answer.

If carbon monoxide is dissolved in water, will it form an acid? Explain your answer.

3

Write a balanced equation for the reaction of magnesium with hydrochloric acid.

Write a balanced equation for the reaction of magnesium with hydrochloric acid.

4

Write a balanced equation for the reaction that produces potassium hydroxide using water.

Write a balanced equation for the reaction that produces potassium hydroxide using water.

5

Sulfur dioxide (SOβ‚‚) is a colourless, poisonous gas. Does it form an alkaline when dissolved in water?

Sulfur dioxide (SOβ‚‚) is a colourless, poisonous gas. Does it form an alkaline when dissolved in water?

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