Mixtures and separation — final check

1. Identify / Explain / Describe

Read this preparation record: a little solid Z dissolves completely in liquid propanone, making a uniform liquid. No other substance is present. Identify the solvent and solute, explaining each role. Describe everything included in the solution. No formulas or practical tests are needed.

2. Explain

A sample contains only water and a little fully dissolved salt. Its label says: ‘Pure water: no solid can be seen.’ Choose the supported statements, then explain how you would correct the label.

Tick every correct statement.

• Dissolved salt is still present.
• No visible crystals proves that only water remains.
• The sample contains two substances.
• The salt has become water.

Explain why the label is incorrect and give the correct description of the sample.

3. Describe / Explain

A written sample contains water, fully dissolved L and insoluble powder M. Intact ordinary paper retains every stated M grain. L neither reacts nor becomes retained. Describe residue and filtrate, naming each component and explaining its destination.

Residue — components and explanation

Filtrate — components and explanation

4. Suggest / Explain / Describe

You want to separate dry W and Z by dissolving and filtering. Both liquids are teacher-approved and react with neither solid. W dissolves in A and B. Z dissolves in A but not B; paper retains undissolved Z. Choose and justify a liquid. Describe residue and filtrate. Don't propose heating: recovery conditions weren't supplied.

Circle one answer.

• Candidate A
• Candidate B

Justify the choice and describe residue and filtrate. Explain why the supplied facts do not justify heating.

5. Explain

Feed A contains a solid fully dissolved in water. Feed B contains water and insoluble grains that ordinary paper retains. You want solid on the paper. Predict and explain the outcome for each feed.

Write the number of the matching option.

1. Solid is collected as residue
2. Solution passes; the wanted solid is not collected

• Feed A: ______
• Feed B: ______

Explain why ordinary filtration achieves the goal for one feed but not the other.

6. Suggest / Describe / Explain

An already-wet sample contains water, dissolved T and undissolved U retained by paper. Neither solid reacts with water. T stays stable and non-volatile during the approved water-removal method. You want both solids separately, not water. Describe and explain a sequence. Name every component in the first receiver. Assess a colleague's suggestion to evaporate the whole sample first.

Write the number of each step in order.

1. Remove water from the separate filtrate by the approved procedure.
2. Filter the existing wet sample.

• First: ______
• Second: ______

Explain both solids’ destinations and name every component in the first receiver. Assess evaporating the whole starting sample first.