chemical analysis

Question 1

pure substances

Answer 1

a single element or compound not mixed with any other substance

Question 2

pure substances

Answer 2

diamond, pure water and gold

Question 3

mixtures

Answer 3

crude oil, air and sea water

Question 4

melting point

Answer 4

when a solid changes into a liquid

Question 5

boiling point

Answer 5

temperature at which a liquid changes into a gas

Question 6

formulation

Answer 6

mixture that has been designed as a useful product
formed by mixing together several different substances in carefully measured quantities to ensure product has required properties

Question 7

alloy

Answer 7

mixture of two or more elements where at least one is a metal resulting mixture has metallic properties
formulation made my mixing measured quantities to ensure the alloy has specific properties required for its use

Question 8

medicine

Answer 8

tablets are formulations of the active drug along with ingredients such as corn starch to bind the tablet together and a lubricant to make it easier to swallow

Question 9

fertilisers

Answer 9

contains mixtures of nitrogen, phosphorus and potassium compounds. Different formulations are suitable for different plants

Question 10

mixture

Answer 10

two or more substances mixed together

Question 11

solute

Answer 11

the substance which dissolve in the solvent

Question 12

solvent

Answer 12

the liquid in which the solute dissolves

Question 13

solution

Answer 13

a solute dissolved in a solvent

Question 14

soluble substances

Answer 14

one which will dissolve in a solvent

Question 15

filtration

Answer 15

used to separate an insoluble solid from a liquid

Question 16

filtrate

Answer 16

the liquid which passes through the filter during filtration

Question 17

residue

Answer 17

the solid that remains on the filter paper after filtration

Question 18

evaporation

Answer 18

change of state from liquid to gas

to remove soluble substance from a solution( remove salt from salt water)

Question 19

saturated solution

Answer 19

one in which no more solid can dissolve at that particular temperature

Question 20

crystallisation

Answer 20

involves heating the solution to boil off some solvent, creating a saturated solution
this saturated solution is the cooled.

The dissolved solid becomes less soluble and cannot remain dissolved. it crystallises out of solution. The crystals may then be separated from saturated solution by filtrate

Question 21

simple distillation

Answer 21

used to separate a solvent from a solution

Question 22

condensation

Answer 22

the change of state from gas to liquid when cooled

Question 23

anti bumping granules

Answer 23

added to promote smooth boiling

Question 24

distillate

Answer 24

the liquid that is cooled from vapour and is collected during distillation

Question 25

fractional distillation

Answer 25

used to separate miscible liquids which have different boiling points

Question 26

immiscible liquids

Answer 26

liquids that do not mix well together by from two distinct layers e.g. oil and water

Question 27

miscible liquids

Answer 27

liquids that mix together like ethanol and water

Question 28

how fractional distillation works

Answer 28

mixture of miscible liquids is heated liquid boil one by one as temperature rises each vapour rises up and condenses in the fractionating column, falling back down to the mixture in the flask only the vapour from the liquid with the lowest boiling point passes into the condenser, condenses into a liquid , and is collected as a fraction

Question 29

how does fractional distillation provide better separation

Answer 29

the evaporated liquids below their melting points do not reach condenser- they condense on the glass beads in the fractioning column and return to the flask

Question 30

chromatography

Answer 30

used to separate mixtures of soluble substances in a solution, e.g. inks and dyes

Question 31

chromatography method

Answer 31

using a pencil, draw a base line on chromatography paper, around 1 to 2cm from the bottom use pencil as it will not dissolve in solvent and interfere with results using a capillary place a spot of substance to be analysed on base line. . when dry add another spot on top to make it concentrated place paper in beaker with solvent at bottom the pencil line and spots must be above level of solvent so that the spots do not dissolve into the solvent in the beaker solvent travels up paper by when solvent has reached the top, take paper out of solvent and mark level solvent has reached, known as solvent front leave paper to dry mixtures should have separated into different components, seen as spots on the paper

Question 32

mobile phase stationary phase

Answer 32

water paper

Question 33

relative attraction

Answer 33

substances with a stronger attraction to the solvent and are more soluble in it, move quickly and travel a long way up the paper substances with a stronger attraction to the paper move slowly and only travel a short distance up the paper

Question 34

Rf values

Answer 34

Rf= distance moved by substance ____________________________________ distance moved by solvent