Separating mixtures

Author: Pamela Burt

This resource was developed as a result of participation 
in CSIRO’s teacher professional learning program, 
Teacher Researcher in Partnership Program.

© Separating Mixtures (created by Pamela Burt) (2019). 
Copyright owned by West Moreton Anglican College. 
Except as otherwise noted, this work is licenced under 
the Creative Commons Attribution 4.0 International 
Licence. To view a copy of this licence, visit
http://creativecommons.org/licenses/by/4.0/

CSIRO Australia’s National Science Agency

Separating mixtures practical

Station 1 – Centrifugation

Materials

Benchtop manual centrifuge and tubes

Calcium hydroxide 

Vegetable oil

Method

1. Add a small amount of calcium hydroxide powder to a centrifuge tube. Add water until approx. 2cm from the 
top. Cap and shake until fully mixed.

2. Place the tube in the centrifuge.

3. Add equal amounts of oil and water to the second tube. Cap and shake until fully mixed.

4. Place the tube in the centrifuge opposite to the calcium hydroxide tube. This will keep the 
apparatus balanced.

5. Turn the handle gently and spin the samples for a few minutes.

6. Carefully remove the tubes and observe.

7. When finished leave the filled tubes for the next group.

Questions

1. What physical property does centrifugation use to separate mixtures?

2. Which substances were pulled to the bottom of the centrifuge tubes? 

3. What does this tell you about them?

4. What type of mixture can be separated using centrifugation? Homogenous/Heterogenous?



Separating mixtures practical

Station 2 – Distillation

Materials

Distillation apparatus

Coloured water

This is a demonstration only station. Do not touch the equipment. Observe what is happening 
and answer the questions below. If the amount of impure liquid is getting low, tell your teacher.

Questions

1. What physical property does distillation use to separate mixtures?

2. Where does evaporation take place? 

3. Where does condensation take place?

4. Which component of the mixture (dye or water) is the distilled liquid? 

5. What does this suggest about it compared to the other component?

6. What type of mixture can be separated using distillation? Homogenous/Heterogenous



Separating mixtures practical

Station 3 – Stacked sieving

Materials

6 disposable cups

Hole poking tools (5 sizes)

Rock mixture

Method

1. Using the tools provided, poke holes (from the inside to outside) in the cup in 5 different sizes. Don’t put 
holes in the 6th cup.

2. Stack the cups so that the largest holes are on the top, decreasing in size to the smallest holes and then the 
cup with no holes.

3. Pour a sample of the rock mixture into the top cup.

4. Lift the first cup slightly and shake it so the rocks that can fit through the holes will move into the cup below. 
When only the largest rocks remain, take the cup out and put it to the side.

5. Repeat the process with each cup in turn.

6. At the end you should hopefully have 6 cups with particles of different sizes in them.

7. Tip the rock sample back into the original container and mix well. Leave the setup for the next group.

Questions

1. What physical property does stacked sieving use to separate mixtures?

2. Why must the cups be stacked in this order? What would happen if they weren’t?

3. Were all of the rocks in each layer of a similar size? If they weren’t, how could you modify the design to make 
this happen?

4. What type of mixture can be separated using stacked sieving? Homogenous/Heterogenous



Student worksheet

Paper chromatography lab

Learning objectives 

• To use paper chromatography to separate the components of a mixture. 
• To calculate the retention factor (Rf) for each component.
• To interpret the Rf values and compare the solubility of the components. 
• To compare paper chromatography with gas chromatography.


Safety

Wear safety googles at all times during the experiment.

Materials

Beaker or similar container

Pencil

Ruler

Sticky tape

Strip of filter paper 5cm wide

Water

Water soluble marker (black works well)

Method

1. Add 1cm of water to the beaker.

2. Rule a straight line with the pencil across the strip of paper about 1cm from the bottom.

3. Draw a spot with the marker on the ruler line. 

4. Tape the top of the strip of paper to a pencil so that the end 

of the paper hangs touches the water but the spot is not submerged.

5. Let sit until the component colours have travelled up the paper approximately 2/3 of the way. 

6. Remove from the cup, mark the solvent front in pencil immediately and leave to dry.



Analysis

1. Measure the distance from the pencil line to the centre of each band of colour.

2. Measure the distance from the pencil line to the solvent front.

3. Use the formula below to calculate the retention factor for each component.

Rf =

distance from baseline to component

distance from baseline to solvent front

Band colour

Distance travelled

Solvent front

Retention factor





Questions

1. Which component was the most soluble in water? How do you know?

2. Which component was the least soluble in water? How do you know? 

3. What is the relationship between retention factor and solubility?