Which method fits this mixture? — questions

1. identify

Match each sample and product goal to a suitable method. Use the component properties, rather than the liquid's appearance.

Write the number of the matching option.

1. Filtration
2. Simple distillation
3. Fractional distillation

• Insoluble sand in water; keep sand: ______
• Nonvolatile dissolved salt; keep water: ______
• Two miscible volatile liquids; compare enriched fractions: ______

Nudge (only if you are stuck): Is the solid insoluble or dissolved? Is one liquid volatile, or are there two volatile liquids to separate?

2. explain

P and Q are miscible. Their pure boiling points are 78°C and 83°C at the same pressure. P is more volatile over the relevant range. Choose apparatus for improved separation and explain why it helps.

Circle one answer.

• Filter funnel
• Simple distillation without a column
• Fractional distillation with a column

Use the supplied properties.

Nudge (only if you are stuck): How close are their boiling points? Which apparatus repeats condensation and vaporisation?

3. explain

A clear liquid has passed through ordinary filter paper. Does that establish purity? Use dissolved salt to explain your answer.

Nudge (only if you are stuck): Can dissolved salt pass with water without making the filtrate cloudy?

4. explain

Use the temperature table to suggest when to stop collecting the early fraction. Explain what the readings suggest and what they cannot prove.

Suggested change and evidence

Limit of the evidence

Nudge (only if you are stuck): Where does head-vapour temperature begin to change? Does that identify the substance uniquely?

5. explain

Water contains insoluble grit and dissolved nonvolatile salt. You want collected water. Describe a suitable sequence and account for grit and salt. Keep the distillation flask from becoming dry.

Sequence and reasons

Where each substance ends up

Nudge (only if you are stuck): What can filtration remove first? Which substance will remain when water then vaporises?