Most elements are rarely found in their pure form. They are found chemically combined with other elements in compounds. Compounds are often found mixed with other compounds. Mixtures may be separated and analysed.
Which of the following is not true of a pure substance?
A pure substance is a single element or compound.
A pure substance contains only one type of atom.
A pure substance is not mixed with any other substance.
Which method could be used to separate a mixture of ethanol and water?
What is the definition of ‘solution’?
The liquid in which a solute is dissolved.
A solute dissolved in a solvent.
The substance that dissolves in a liquid.
Distillation involves which physical processes?
Evaporation and condensation.
Melting and freezing.
Dissolving and sublimation.
In chromatography, what can be used to identify an unknown substance?
What chemical compound is used to test for the presence of water?
Anhydrous copper(II) sulfate.
Hydrated copper(II) sulfate.
Copper (II) carbonate.
What colour flame would a compound containing calcium ions give in a flame test?