Study Notes
In chemistry, changes to materials involve chemical reactions that create new substances and are not easily reversible. Writing word equations helps represent these reactions, and neutralisation reactions occur when acids react with alkalis to form water and salts.
- Chemical Reaction — A process where substances change to form new substances. Example: Combustion of methane produces carbon dioxide and water.
- Word Equation — A representation of a chemical reaction using the names of the substances involved. Example: Calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide.
- Neutralisation Reaction — A reaction between an acid and an alkali producing water and a salt. Example: Hydrochloric acid + sodium hydroxide → sodium chloride + water.
Exam Tips
Key Definitions to Remember
- Chemical Reaction: A process that changes substances into new substances.
- Word Equation: A way to represent a chemical reaction using words.
- Neutralisation Reaction: A reaction between an acid and an alkali forming water and a salt.
Common Confusions
- Thinking all reactions are reversible.
- Confusing chemical symbols with word equations.
Typical Exam Questions
- What is a chemical reaction? A process where substances change to form new substances.
- How do you write a word equation for a reaction? Use the names of reactants and products separated by an arrow.
- What happens in a neutralisation reaction? An acid reacts with an alkali to form water and a salt.
What Examiners Usually Test
- Understanding of chemical reactions and their characteristics.
- Ability to write and interpret word equations.
- Knowledge of neutralisation reactions and their applications.