Pure Substances and Mixtures
This type of matter contains only one kind of particle.
What is a pure substance?
A solution is made from a solute and this substance.
What is a solvent?
This property describes how much mass is packed into a volume.
What is density?
Used to separate an insoluble solid from a liquid.
What is filtration?
This technique separates dyes in ink.
What is chromatography?
A pure substance made from only one type of atom.
What is an element?
A substance that dissolves in water is called this.
What is soluble?
This force allows some insects to walk on water.
What is surface tension?
Used to separate magnetic materials from a mixture.
What is magnetic separation?
How to separate red blood cells from plasma.
What is centrifuge
A pure substance made from two or more types of atoms chemically bonded together.
What is a compound?
A solution that cannot dissolve any more solute.
What is a saturated solution?
If an object is less dense than water, it will do this.
What is float?
Used to separate a dissolved solid from a solution by removing the liquid.
What is evaporation?
A student wants to separate sand, salt and iron filings. What should be removed first?
What are iron filings (using magnetic separation)?
A mixture that looks the same throughout.
What is a homogeneous mixture?
Which type of solution contains the greatest amount of dissolved solute: dilute, concentrated or saturated?
What is a saturated solution?
Name the formula used to calculate density.
What is Density = Mass ÷ Volume?
Used to separate liquids based on different boiling points.
What is distillation?
A scientist measures how much sugar dissolves at different temperatures. What variable is being investigated?
What is temperature?
Explain the difference between a homogeneous and heterogeneous mixture and provide one example of each.
Homogeneous mixtures have a uniform composition (e.g. salt water). Heterogeneous mixtures have visible different parts (e.g. sand and water).
Using particle theory, explain why heating water often increases the solubility of solids.
Heating gives particles more energy and movement, allowing more solute particles to spread between water particles and dissolve.
Explain how density differences can be used to separate a mixture.
More dense substances sink while less dense substances float, allowing separation using decanting or skimming.
Compare filtration and centrifuging. Which property do both techniques rely on?
Both separate substances based on differences in particle properties. Filtration uses particle size, while centrifuging uses density.
Design a method to separate muddy salt water into clean water and dry salt. Name the techniques in order
Filtration → Distillation (or evaporation then condensation) → Crystallisation/Evaporation to recover the salt.