Topic C3: Chemical reactions – GCSE OCR Foundation Combined Science Chemistry revision notes

Topic C3: Chemical reactions covers Introducing chemical reactions, Energetics, Types of chemical reactions, and Electrolysis in GCSE OCR Foundation Combined Science Chemistry. 28 lessons in 4 subtopics.

The law of conservation of mass states that no atoms are lost or made during a chemical reaction, so the mass of the products equals the mass of the reactants. The The Law of Conservation of Mass notes cover this in full.

A base is a substance that neutralises acids by accepting hydrogen ions. The Neutralisation Reactions and Salt Formulae notes cover this in full.

Electrolysis is using an electric current to break down an ionic compound that is molten or dissolved. The Understanding Electrolytes and Ion Movement notes cover this in full.

Percentage uncertainty = uncertainty ÷ measured value × 100. The Understanding Uncertainty in Chemical Measurements notes cover this in full.

The metal reactivity series, from most reactive to least reactive, is potassium, sodium, lithium, calcium, magnesium, aluminium, zinc, iron, copper. The Metal Reactions and the Reactivity Series notes cover this in full.

The test for hydrogen is to hold a burning splint at the mouth of the test tube: if hydrogen is present, it burns rapidly with a pop sound. The Testing for hydrogen gas notes cover this in full.

Examples of endothermic reactions include thermal decomposition, such as calcium carbonate breaking down into calcium oxide and carbon dioxide, and citric acid reacting with sodium hydrogencarbonate. The Examples and Applications of Energy Transfer Reactions notes cover this in full.

In an exothermic reaction profile, the products are at a lower energy level than the reactants, because energy is released to the surroundings. The Drawing and Understanding Reaction Profiles notes cover this in full.