Pure and impure substances

Pure and impure substances

Pure and impure substances

Pure and impure substances

What is meant by (pure orange juice) or (pure mineral water) ?

– This means that nothing else was added to the orange juice or mineral water during manufacture.

– However, these substances are not pure to a scientist.

– In science, a pure substance contains only one element or compound.

– Pure substances: substances that are made of only one type of atom or only one type of molecule
What are types of pure substances ?

1.Elements (one type of atoms) EX. pure iron, pure gold

2.Compounds (one type of particles) Ex. table salt , distilled water

 

 

 

– A pure substances cannot be separated by physical means:

filtration /evaporation/distillation/chromatography

– A pure substance is one which contains only a single substance and no impurities.

– A pure substances has an exact melting point while an impure substance melts over a range of temperature.

– The pure substances cost more than impure ones( bec, the costs of purification must be considered).


Impure substances are commonly termed as mixtures.”
– Impurities are substances which make something less pure (are chemical substances inside a confined amount of liquid, gas, or solid)

 

– Mineral water is mostly water, but there are other substances mixed with it.

– These are the ingredients that you see listed on the bottle’s label.

 

– Impure substances can be separated by physical means

Ex. filtration /evaporation/distillation/chromatography


 Making pure salt from rock salt
– Rock salt is a mixture of salt and other rocks(sandstone).
Purifying rock salt:

– Carry out the following experiment to make some

pure salt from some crushed rock salt:

1. Adding crushed rock salt to water and stirring.

2. Filtering the mixture.

3. Heating the solution to form solid salt.

 

– In hot countries salt is produced by evaporation of sea water.

– The sun provides the energy to evaporate the water.

– Large , shallow pans are used when evaporating sea water.

Residue : the material left over at the end of a process, often the material that is removed during purification of a substance.
Filtration : the process of passing a mixture through a device “soluble substances pass through the filter as a ‘filtrate’ but insoluble substances or unwanted material will stay in the filter as a ‘residue”.

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Pure and impure substances

Pure and Impure Substances ( PDF )

 

Pure and Impure Substances ( sheet answers) ( PDF )

Pure and impure substances

Pure and impure substances

Pure and impure substances

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