Purity and Formulations
This lesson covers:
- What the field of chemical analysis is
- What a 'pure' substance is
- How pure substances can be identified by their melting and boiling points
- What a 'formulation' is
Chemical analysis (also known as analytical chemistry) is about:
The study of carbon-containing compounds
The application of quantum mechanics to chemical systems
The instruments and methods we use to separate, identify, and quantify different substances.
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In chemistry, a pure substance is a:
Single element or compound that hasn't been mixed with any other substances
Single element that hasn't been mixed with any other substances
Substance that has had nothing added to it
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Which of the following is an example of a pure substance?
Fruit juice
Distilled water
Clay
Milk
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True or false? Pure substances always melt and boil at specific temperatures.
True
False
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Pure water boils at 100°C, and freezes at 0°C.
A student is given an unknown, transparent, colourless liquid. What test could be done to see if the liquid is pure water?
(Select all that apply)
See if the liquid evaporates
See if the liquid can be burned
Freeze it, and see if the freezing point is 0°C
Boil it, and see if the boiling point is 100°C
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A student tests the melting point of a sample of salol. The sample starts melting at 36°C, but it doesn't melt completely until the temperature is 48°C. Is the sample chemically pure, or impure?
Pure
Impure
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molecules / elements / mixtures / formula / beaker
Formulations are that have been prepared using a specific .
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components / function / large / precise
Formulations are made from amounts of different , and each component has a particular .
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Which of the following would require a formulation?
(Select all that apply)
Medicines
Distilled water
Paints
Cleaning agents
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Which of the following techniques can be used to separate substances?
(Select all that apply)
Filtration
Distillation
Chromatography
Dissolving
Flame tests
Crystallisation
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If we test a substance for purity by measuring its boiling point, is that a physical test or a chemical test?
Physical
Chemical
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