GCSE Chemistry REVISION QUESTIONS WITH VERIFIED SOLUTIONS
LATEST 2025 UPDATE.
Temperatures effect on the rate of reaction - ANSWER- Increasing the temperature will cause
particles to move faster and with more energy, they will therefore collide more often and with
greater energy
-More collisions
-More energy
Concentrations effect on the rate of reaction - ANSWER- Increasing the concentration
increases the amount of reactant particles which may collide and so react
-More collisions
Surface areas effect on the rate of reaction - ANSWER- A higher surface area means a greater
area of reactant is exposed and available for collision
-More collision
A catalysts effect on the rate of reaction - ANSWER- Presence of a catalyst reduces the amount
of activation energy needed for a reaction to take palce
-Less energy needed
How to measure the speed of reaction - ANSWER- You can measure
-Speed at which reactants are being used up
-Speed at which products are being formed
How to measure the speed of reaction when a gas is produced - ANSWER- Gas syringe
Explosions in a chemical reaction - ANSWER- Explosions occurs when a chemical reaction
suddenly accelerates and goes at an extremely fast rate
-Reaction gives of a lot of heat which heats up the reactants making the reaction go even faster
,-No opportunity for the heat of reaction to escape or for the reactants to move away
-Occurs if the gas/powder is flammable
Oxidation - ANSWER- -Gain of oxygen by an atom, molecule or ion
-Loss of electron from an atom, molecule or ion
What do oxidising agents do - ANSWER- -Give oxygen
-Remove electron
Reduction - ANSWER- -Removal of oxygen in a compound
-Gain of electrons from an atom molecule or ion
What do reducing agents do - ANSWER- -Remove oxygen
-Donate electrons
Redox reaction - ANSWER- Reaction which involves both oxidation and reduction
-Oil rig happen simultaneously
eg. When a metal oxide is being displaced
-Electrolysis
Atom - ANSWER- The smallest part of an element that can take place in a chemical reaction
Molecule - ANSWER- a group of atoms held together by covalent bonds
e.g H2 (2 hydrogen atoms bonded together)
What is the molecular structure of an element based on - ANSWER- The amount of electrons
in its outer shell
,Chromatography - ANSWER- Method used to separate and distinguishes the different
substances within a mixture
Describe the process of chromatography - ANSWER- 1) Mixture is placed at the end of a strip
of a paper
2) The strip of water is dipped in water
3)As water level rises it takes different dye molecules with it
4) If the ink is a mixture of 2 or more inks different colours will move at different rates allowing
us to identify all the different colours
-Based on how strong the attraction is between the dye molecules and the water
Filtration - ANSWER- Method used to remove undissolved solids from liquids
Describe the process of filtration - ANSWER- 1) Filter paper is folded and put into a funnel
2) Filter allows liquid to flow through but not the solids
3) Results with the solid in the filter paper and the liquid in another container
Crystillization - ANSWER- Method used to separate dissolved solids from liquids
Describe the process of crystillization - ANSWER- 1)Solution is heated in an open container
2) Solvent evaporates leaving a saturated solution
3) Saturated solution is left to cool where crystals of solid will grow in the solution
, 4) When the solution has completely evaporated crystallised solids are left
Distillation - ANSWER- Method used to separate a pure liquid from a mixture
Describe the process of distillation - ANSWER- 1) Mixture is heated in a flask
2) At a specific temperature the substance with a lower boiling point will evaporate into vapour
3) The vapour will travel down a condenser filled with cool running water cooling it back down a
liquid
4) As it travels down the condensor it will be collected in a separate container leaving the other
liquid in the flask
Fractional distillation - ANSWER- Method to separate a liquid mixture into its individual
components
Describe the process of fractional distillation - ANSWER- 1) Mixture is heated and different
substances evaporate at different time based on their boiling point
2)Different substance condense at different portions of the fractionating column (The higher up,
the lower the temperature)
3)Each substance will travel down a different condensor and get collected in different containers
Describe the importance of purity in substances - ANSWER- Impurities in drugs or foods can
be hazardous and detrimental to our health
LATEST 2025 UPDATE.
Temperatures effect on the rate of reaction - ANSWER- Increasing the temperature will cause
particles to move faster and with more energy, they will therefore collide more often and with
greater energy
-More collisions
-More energy
Concentrations effect on the rate of reaction - ANSWER- Increasing the concentration
increases the amount of reactant particles which may collide and so react
-More collisions
Surface areas effect on the rate of reaction - ANSWER- A higher surface area means a greater
area of reactant is exposed and available for collision
-More collision
A catalysts effect on the rate of reaction - ANSWER- Presence of a catalyst reduces the amount
of activation energy needed for a reaction to take palce
-Less energy needed
How to measure the speed of reaction - ANSWER- You can measure
-Speed at which reactants are being used up
-Speed at which products are being formed
How to measure the speed of reaction when a gas is produced - ANSWER- Gas syringe
Explosions in a chemical reaction - ANSWER- Explosions occurs when a chemical reaction
suddenly accelerates and goes at an extremely fast rate
-Reaction gives of a lot of heat which heats up the reactants making the reaction go even faster
,-No opportunity for the heat of reaction to escape or for the reactants to move away
-Occurs if the gas/powder is flammable
Oxidation - ANSWER- -Gain of oxygen by an atom, molecule or ion
-Loss of electron from an atom, molecule or ion
What do oxidising agents do - ANSWER- -Give oxygen
-Remove electron
Reduction - ANSWER- -Removal of oxygen in a compound
-Gain of electrons from an atom molecule or ion
What do reducing agents do - ANSWER- -Remove oxygen
-Donate electrons
Redox reaction - ANSWER- Reaction which involves both oxidation and reduction
-Oil rig happen simultaneously
eg. When a metal oxide is being displaced
-Electrolysis
Atom - ANSWER- The smallest part of an element that can take place in a chemical reaction
Molecule - ANSWER- a group of atoms held together by covalent bonds
e.g H2 (2 hydrogen atoms bonded together)
What is the molecular structure of an element based on - ANSWER- The amount of electrons
in its outer shell
,Chromatography - ANSWER- Method used to separate and distinguishes the different
substances within a mixture
Describe the process of chromatography - ANSWER- 1) Mixture is placed at the end of a strip
of a paper
2) The strip of water is dipped in water
3)As water level rises it takes different dye molecules with it
4) If the ink is a mixture of 2 or more inks different colours will move at different rates allowing
us to identify all the different colours
-Based on how strong the attraction is between the dye molecules and the water
Filtration - ANSWER- Method used to remove undissolved solids from liquids
Describe the process of filtration - ANSWER- 1) Filter paper is folded and put into a funnel
2) Filter allows liquid to flow through but not the solids
3) Results with the solid in the filter paper and the liquid in another container
Crystillization - ANSWER- Method used to separate dissolved solids from liquids
Describe the process of crystillization - ANSWER- 1)Solution is heated in an open container
2) Solvent evaporates leaving a saturated solution
3) Saturated solution is left to cool where crystals of solid will grow in the solution
, 4) When the solution has completely evaporated crystallised solids are left
Distillation - ANSWER- Method used to separate a pure liquid from a mixture
Describe the process of distillation - ANSWER- 1) Mixture is heated in a flask
2) At a specific temperature the substance with a lower boiling point will evaporate into vapour
3) The vapour will travel down a condenser filled with cool running water cooling it back down a
liquid
4) As it travels down the condensor it will be collected in a separate container leaving the other
liquid in the flask
Fractional distillation - ANSWER- Method to separate a liquid mixture into its individual
components
Describe the process of fractional distillation - ANSWER- 1) Mixture is heated and different
substances evaporate at different time based on their boiling point
2)Different substance condense at different portions of the fractionating column (The higher up,
the lower the temperature)
3)Each substance will travel down a different condensor and get collected in different containers
Describe the importance of purity in substances - ANSWER- Impurities in drugs or foods can
be hazardous and detrimental to our health
