gcse chemistry
Required Practicals
There are a number of Required Practicals you will carry out in GCSE Chemistry, and you should familiarise yourself with them. You can find videos of all of them, and lots of other information here:
PAPER 1:
RP1: making salts
Making soluble salts: preparation of pure, dry copper sulfate crystals.
Chemical Equations:
Copper Oxide + Sulfuric Acid → Copper Sulfate + Water
CuO (s) + H2SO4 (aq) → CuSO4 (aq) + H2O (l)
RP2: titration
Determination of the reacting volumes of solutions of a strong acid and a strong alkali by titration.
Calculations: Concentration = moles ÷ volume
RP3: electrolysis
Investigating what happens when two different aqueous solutions are electrolysed using inert electrodes.
Anode (Positive Electrode): Hydrogen gas will always be observed, unless there is an element less reactive than hydrogen (e.g. copper, silver, gold).
Cathode (Negative Electrode): Oxygen gas will always be observed, unless the solution contains halide ions (fluoride, chloride, bromide, iodide).
RP4: temperature changes
Investigate the variables that affect temperature change in chemical reactions, e.g. acid plus alkali.
Independent Variable: Volume of alkali
Dependent Variable: Change in temperature
Control Variables: Room temperature
Volume of acid
Concentration of acid/alkali
PAPER 2:
RP5: rates of reaction
Investigate how changing the concentration of a reactant changes the rate of reaction by measuring the decrease in transparency of solution.
Independent Variable: Concentration of sodium thiosulfate
Dependent Variable: Time taken for cross to disappear
Control Variables: Temperature
Volume of sodium thiosulfate
Volume/concentration of hydrochloric acid
RP5: rates of reaction 2
Investigate how changing the concentration of a reactant changes the rate of reaction by measuring the volume of gas produced.
Independent Variable: Mass of marble chips
Dependent Variable: Volume of gas produced
Control Variables: Volume of hydrochloric acid
Calculations: Rate of reaction = change in reactants or products
÷ time taken
RP6: chromatography
Investigate how paper chromatography can be used to separate and identify a mixture of food colourings.
Independent Variable: Ink
Dependent Variable: Distance moved by spot
Control Variables: Solvent used
Calculations: Rf = Distance moved by solute ÷
Distance moved by solvent
RP7: identifying ions
Use of chemical tests to identify the ions in unknown single ionic compounds.
Flame Tests: Sodium Hydroxide Tests: Halide Tests:
Copper = Green Copper = Blue Chloride = White
Sodium = Yellow Iron (II) = Green Bromide = Cream
Lithium = Crimson Iron (III) = Brown Iodide = Yellow
Calcium = Brick red Magnesium = White
Potassium = Lilac Calcium = White
Aluminium = White (disappears in excess)
RP8: water purification
Analysing and purifying a sample of water and making it safe to drink.
Independent Variable: Water sample
Dependent Variable: Mass of dissolved solids
Control Variables: Volume of water