A
The solid that dissolves
Solute
The liquid that does the dissolving
Solvent
Insoluble solid trapped on the filter paper
Residue
The pure liquid that is collected after distillation
Distillate
The liquid that passes through the filter paper
Filtrate
How would you separate nickel from a mixture of zinc, salt and nickel?
Magnet
Filtration is used to separate __________ from a liquid.
an insoluble solid
How would you separate sugar from sugar solution?
Crystallisation
True or false: For fractional distillation, we add a fractional column to the distillation set-up.
False. We add a fractionating column to the set-up.
A mixture of acetone and ethanol is heated in a fractional distillation set-up. Acetone has a boiling point of 56°C while ethanol has a boiling point of 78°C. Which substance is distilled out last?
Ethanol
What is a saturated solution?
A saturated solution contains the maximum mass of solute in a given volume of solvent at a given temperature.
Before starting a chromatography experiment, the student draws the start line of the chromatogram in pencil. Why?
Pencil lead is not soluble in water and would not travel up the chromatogram and interfere with the results.
What is a concentrated solution?
A concentrated solution contains a large mass of solute dissolved in a small volume of solvent.
Give an example of filtration in our daily lives
- nose hair used to filter dirt and dust
- filtration units in air-conditioners to filter dirt and dust
- water treatment
- filtration in fish tanks to remove solid waster
- filtering tea leaves/coffee grounds
Give an example of chromatography in our daily lives.
- Identify dyes in ink used in check forgery
- Identify drugs used by athletes in sport competitions
- Identify strands of DNA in blood samples
- Identify food colourings in food products
True or false: The further the dye spot from the start line in a chromatogram, the less soluble the dye is.
False. The most soluble substance will travel the furthest distance from the start line.
Explain the principle behind filtration
The filter paper has pores which allow the smaller particles to pass through; but not the larger, insoluble particles.
Why are boiling chips added to the distilling flask during distillation?
To ensure smooth boiling
A student wants to obtain copper(II) sulfate crystals from copper(II) sulfate solution. He suggests heating the solution to evaporate all of the water. Do you agree? Why or why not?
No, if we evaporate all of the water, the copper sulfate will decompose.
A student sets up a condenser by running the water in from the bottom of the condenser and lets it exit from the top of the condenser. What is the purpose of this?
To ensure efficient cooling and condensation of the vapour.
How would you separate salt from a mixture of salt, water and ethanol?
1. Fractional distillation to separate ethanol out
2. Evaporate to dryness the remaining salt solution until only salt is left behind.
What two physical processes (changes in state) are involved in distillation?
Boiling and condensation.
How would you separate copper(II) sulfate from a mixture of copper(II) sulfate, sand and water?
1. Filter the mixture to remove the sand. The filtrate will contain copper(II) sulfate solution.
2. Use crystallisation to obtain copper(II) sulfate from the solution.
True or false: Crystallisation can be used to collect salt from salt water.
True. Crystallisation can technically be used. However, evaporation to dryness is a more efficient method.
How do we test if a solution is saturated?
Method 1: A solution is saturated when the added solute can no longer be dissolved in the solution.
OR
Method 2: Heat the solution to evaporate most of the solvent. Dip a glass rod into the heated solution and lift it. The solution is saturated when small crystals start to form on the cool glass rod when it is lifted.