Year 7 Science · Unit 2 · Lesson 9
Foundation Worksheet
Learning Goals
Fill the gap
Choose the correct word from the word bank to complete each sentence. Two words will not be used.
Distillation separates liquids that have different points. As the mixture is heated, the liquid with the lower boiling point vaporises first and travels into a cool tube called a , where it turns back into a liquid and is collected. This process is called . To separate dissolved substances that travel at different speeds through paper, scientists use . The moving liquid in this technique is called the , and the distance each substance travels is used to calculate its value.
Match each term to its definition
Write the matching letter next to each separation technique on the left to show which mixture type it best separates.
| Separation technique | Your answer | Best used for this type of mixture |
|---|---|---|
| Filtration | A. Two liquids with different boiling points (e.g. ethanol and water) | |
| Evaporation | B. A dissolved solid in a solution (e.g. saltwater), to identify each component by how far it travels | |
| Distillation | C. One part is magnetic, the other is not (e.g. iron filings and sulfur) | |
| Chromatography | D. An insoluble solid mixed with a liquid (e.g. sand in water) | |
| Using a magnet | E. A dissolved solid in solution where you want to recover the solid (e.g. salt from saltwater) | |
| Dissolving + filtering | F. A mixture of a soluble and an insoluble solid (e.g. salt + sand — dissolve the salt, then filter off the sand) |
1. A scientist heats a mixture of ethanol (boiling point 78 °C) and water (boiling point 100 °C) in a distillation flask. Predict which liquid will collect in Flask B first, and explain why.
2. A dye spot travels 4.8 cm up the chromatography paper, and the solvent front travels 8.0 cm. Calculate the Rf value for this dye. Show your working.
Wrap Up
In one sentence, what was the main idea of this lesson?