Separating pure salt from dirty rock salt | Science | Quizalize & Oak National Academy

Starter quiz

True or false? If a substance is described as 'soluble', then it means it can be dissolved in a solvent.
- True ✓
- False
Which of the following can filtration be used for in the context of separating mixtures?
- To dissolve all components.
- To separate insoluble substances from soluble substances. ✓
- To change the colour of the mixture.
- To increase the temperature of the mixture.
Which of the following properties is not a physical property?
- colour
- boiling point
- shiny or dull
- flammability ✓
Which property is most important when choosing a solvent to dissolve a substance?
- The colour of the solvent.
- The boiling point of the solvent.
- The solubility of the substance in the solvent. ✓
- The smell of the solvent.
Substances that do not dissolve in a liquid are described as ...
- 'insoluble' ✓
True or false? Crystallisation is a process that only occurs at high temperatures.
- True, as crystallisation requires high temperatures to form crystals.
- True, because it only happens when a solution is boiled.
- False, as crystallisation can occur at many temperatures, even during cooling. ✓
- False, because crystallisation does not involve temperature changes.

Put the following steps in the correct order to separate salt from rock salt.
- 1
  
  ⇔
  
  Crush the rock salt into smaller pieces.
- 2
  
  ⇔
  
  Add water to the rock salt to dissolve the salt.
- 3
  
  ⇔
  
  Filter the rock salt and water mixture to remove insoluble substances.
- 4
  
  ⇔
  
  Collect the filtrate (water and salt solution).
- 5
  
  ⇔
  
  Evaporate the water to leave salt crystals.
The process of producing solid crystals by evaporating the solvent from a saturated solution is called ...
- 'crystallisation' ✓
When a substance dissolves in a liquid it is described as ______ in that liquid.
- 'soluble' ✓
Which of these statements best describes the purpose of creating a solution in the separation process of pure salt from rock salt?
- To make the process longer.
- To dissolve the soluble component for easier separation. ✓
- To change the chemical properties of the components.
- To make filtration unnecessary.
True or false? Sand, being insoluble in water, can be completely removed from rock salt using crystallisation.
- True
- False ✓
When dissolving salt into water, the solution will reach a point where no more salt can be dissolved at a given temperature. When no more solute can be dissolved we have made a ______ solution.
- 'saturated' ✓

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The properties of the substances in a mixture help to determine the technique best suited to separate them.
When mixtures contain more than two components, multiple techniques may be needed to separate them.
Creating a solution of an existing mixture can allow a specific technique to be used for separation.
Separating salt from rock salt requires: making a solution, filtration, and crystallisation.

Filtration alone can separate salt from rock salt - idea that only one technique is needed.

Highlight that each separation technique (so far) creates two products; one of them may still be a mixture that requires further separation.

Separation technique - A process or method used to isolate a substance from a mixture, usually to obtain a pure sample of it.
Property - A property is a feature or characteristic of a substance that can be used to classify it, or describe how it behaves.
Soluble - When a substance dissolves in a liquid it is described as soluble in that liquid.
Insoluble - An insoluble substance is one that will not dissolve in a particular solvent.