Study Notes
Changes to materials involve various chemical reactions that create new substances and are not easily reversible. These reactions can be represented by word equations and involve different interactions such as acids with metals or carbonates, and displacement reactions.
- Chemical Reaction — A process where substances change to form new substances. Example: Burning wood results in ash and smoke.
- Word Equation — A representation of a chemical reaction using words instead of symbols. Example: Calcium carbonate + hydrochloric acid → calcium chloride + water + carbon dioxide.
- Displacement Reaction — A reaction where a more reactive metal displaces a less reactive metal from its compound. Example: Magnesium + copper sulfate → copper + magnesium sulfate.
- Rate of Reaction — The speed at which reactants are converted to products. Example: Rusting is a slow reaction, while an explosion is fast.
- Factors Affecting Rate of Reaction — Conditions that influence how fast a reaction occurs, such as temperature, concentration, surface area, and catalysts. Example: Increasing temperature generally increases the reaction rate.
Exam Tips
Key Definitions to Remember
- Chemical Reaction: A process that results in the formation of new substances.
- Word Equation: A way to describe a chemical reaction using the names of the reactants and products.
- Displacement Reaction: A reaction where a more reactive metal replaces a less reactive metal in a compound.
Common Confusions
- Confusing word equations with chemical formulas.
- Misunderstanding that not all reactions are reversible.
Typical Exam Questions
- What are the indicators of a chemical reaction? Color change, effervescence, precipitation, temperature change, smell, and sound.
- How do you write a word equation for a reaction? Use the format: reactants → products.
- What factors affect the rate of reaction? Concentration, temperature, surface area, and catalysts.
What Examiners Usually Test
- Ability to identify reactants and products in a reaction.
- Understanding of how different factors affect reaction rates.
- Knowledge of the reactivity series and displacement reactions.