Starter quiz
- How can you increase the concentration of a solution?
- by adding solvent
- by diluting the solution
- by adding solute ✓
- by decreasing the temperature
- by removing solvent ✓
-
- What is the purpose of filtration?
- to dissolve solids in a liquid
- to separate insoluble solids from a liquid ✓
- to change the chemical composition of a mixture
- to increase the temperature of a mixture
- to mix two liquids together
-
- Which of the following equations represent neutralisation reactions used for making salts?
- metal + acid → salt + hydrogen ✓
- metal hydroxide + acid → salt + water ✓
- metal oxide + acid → salt + water ✓
- metal carbonate + acid → salt + water + carbon dioxide ✓
- metal + water → metal hydroxide + hydrogen
-
- Match each salt with the reactants that can be used to make it.
- magnesium chloride⇔magnesium and hydrochloric acid ✓
- copper sulfate⇔copper oxide and sulfuric acid ✓
- copper nitrate⇔copper oxide and nitric acid ✓
- What is a saturated solution?
- a solution that can dissolve more solute
- a solution where no more solute can dissolve ✓
- a solution that has evaporated completely
- a solution mixed with an insoluble solid
- a solution that changes colour with more solute
-
- What happens during crystallisation?
- the solute evaporates leaving the solvent
- the solvent dissolves more solute to form crystals
- solid crystals form by removing the solvent ✓
- the temperature of the solution decreases
- the solvent turns into a solid
-
Exit quiz
- Reactions between an acid and a metal, or between an acid and certain metal compounds (like hydroxide, oxide or carbonate), are all types of ______ reactions.
- 'neutralisation' ✓
- An insoluble metal oxide reacts with an acid to make a soluble salt. What are the main steps, in any order, needed to make pure crystals of the soluble salt.
- crystallising the soluble salt from a solution ✓
- dissolving the metal oxide in water
- filtering to remove any excess insoluble metal oxide ✓
- neutralising the acid with the insoluble metal oxide ✓
- reducing the temperature of the reactant mixture
-
An insoluble metal oxide reacts with an acid to make a soluble salt. Put each step in the correct order to describe how a metal oxide is reacted with an acid, making sure all the acid has reacted.- 1⇔add one spatula at a time of powdered metal oxide to the acid and stir
- 2⇔stop when some of the metal oxide does not react
- 3⇔gently heat the mixture to allow more metal oxide to react with the acid
- 4⇔if needed, add more spatulas of metal oxide until it does not react again
- 5⇔use pH paper to check that the solution is neutral
The undissolved impurity in a salt solution that remains in filter paper after filtration is called the ______.- 'residue' ✓
Put each step in the correct order to describe how to obtain crystals of salt from a pure salt solution.- 1⇔light a Bunsen burner and turn the gas tap down to give a small yellow flame
- 2⇔open the air hole to get a small blue flame
- 3⇔use it to gently heat the solution in a evaporating dish over a water bath
- 4⇔remove the Bunsen burner each time the solution bubbles vigorously
- 5⇔replace the Bunsen burner, as necessary, to evaporate more water
- 6⇔stop heating when there is still a little water left
- 7⇔the rest of the water should evaporate as the evaporating dish cools down
- Match these key terms to the correct definitions.
- soluble⇔the property of a substance that dissolves in a liquid ✓
- excess reactant⇔the reactant left over after a reaction is complete ✓
- filtration⇔a technique for separating insoluble solids from a liquid ✓
- crystallisation⇔forming solid crystals from a saturated solution by evaporation ✓
- limiting reactant⇔the reactant that is fully used up during a reaction ✓
Worksheet
Loading worksheet ...
Presentation
Loading presentation ...
Video
Lesson Details
Key learning points
- Reacting a metal oxide with an appropriate acid can form a desired salt and water.
- Adding metal oxide to excess ensures that the acid fully reacts to form salt and water.
- Excess metal oxide can be removed by filtration so that the filtrate contains only salt and water.
- Water can be removed from the salt by evaporation.
Common misconception
Pupils often do not understand that observing excess metal oxide in the reaction mixture means that the acid has fully reacted.
Emphasise how to observe the end of the reaction and what these observations mean, i.e. excess metal oxide in the reaction mixture or using pH paper to indicate the solution is neutral. Both are evidence of the acid having fully reacted.
Keywords
Soluble - When a substance dissolves in a liquid, it is described as soluble in that liquid.
Excess reactant - any reactant present in a greater amount than is necessary to completely react with the limiting reactant
Filtration - a technique to separate insoluble solids from a liquid by passing the mixture it is in through a filter
Crystallisation - a process that forms solid crystals from a saturated solution by evaporating the solvent
+