GCSE Chemistry Paper 2: Questions with Complete Solutions, Latest Edition

Activation emnergy - Ans .minimum amount of energy needed for a reaction to occur why does increasing the temperature increase the rate of reaction? - Ans .particles have more kinetic energy more frequent collisions collisions are harder and more successful concentration? - Ans .more particles in same volume increases frequency of collisions surface area? - Ans .more frequent collisions what is a catalyst? - Ans .speeds up the rate of reaction without being used up itself provides an alternative pathway with lower activation energy what is a reversible reaction - Ans .products can react again to form the original reactants what is dynamic equilibrium? - Ans .concentrations of reactants and products don't change forward and reverse reactions are happening at the same rate. what is the general formula for alkanes? - Ans .CnH2n+2 What are the first four alkanes? - Ans .methane, ethane, propane, butane hydrocarbon? - Ans .compound contain hydrogen and carbon atoms only general formula for alkenes? - Ans .ethene, propene, butene, pentene what does saturated mean? - Ans .carbon bonds are single C-C what does unsaturated mean? - Ans .a double carbon bond C=C how do you carry out fractional distillation? - Ans .crude oil is heated until it evaporates it rises, cools and condenses different fractions have different boiling points and so condense at different points in the fractionating tower order of fraction (from top) - Ans .refinery gases petroleum kerosene diesel fuel oil bitumen properties of short chain hydrocarbons - Ans .low viscosity high volatility high flammability lighter in colour lower boiling point properties of long chain hydrocarbons? - Ans .high viscosity low volatility low flammability darker in colour higher boiling point what is a fuel - Ans .substance that releases energy when burnt complete combustion - Ans .carbon dioxide and water