Elements compounds and mixtures

Question 1

Pure substance melting point

Answer 1

Fixed

Question 2

Mixture melting point

Answer 2

May melt or boil over a range of temperatures

Question 3

Element

Answer 3

Made up of only one kind of atom.

Question 4

Compounds

Answer 4

Made up of different elements that are chemically joined/ bonded together.

Question 5

Mixture

Answer 5

Made up of elements , compounds or both that are mixed and can be separated as the different elements and compounds are not joined/ bonded to each other.

Question 6

Simple distillation

Answer 6

Can be used to separate the components of a solution.Although we can use crystallisation to separate sodium chloride from a sodium chloride solution , we can also collect water if we use simple distillation

Question 7

Fractional distillation

Answer 7

Used to separate a mixture of liquids such as ethanol (alcohol) and water. Both liquids boil, but by carful heating you can control the temp of the column so that all the water condenses in the column and trickles back into the flask.

Question 8

Filtration

Answer 8

Can be used to separate a solid from a liquid. The substance left in the filter paper is called the residue and the liquid that comes through is called the filtrate.

Question 9

Crystallisation

Answer 9

Can be used to separate a solution. It could me used to separate sodium chloride from a sodium chloride solution. Using a rod

Question 10

paper chromatography

Answer 10

Can be used to separate a variety of mixtures. Usually it is used to separate mixtures of coloured inks or food colourings.

Question 11

Rf value calculation

Answer 11

distance moved by substance/ distance moved by solvent