S1.1

Question 1

4 main properties of matter

Answer 1

mass, volume, motion, particles

Question 2

what can all matter be split up into?

Answer 2

pure or a mixture

Question 3

what can pure substances be split into?

Answer 3

either elements or compounds

Question 4

what can a mixture be split into?

Answer 4

heterogenous (non-uniform composition) or homogeneous(uniform composition)

Question 5

define an atom

Answer 5

smallest particle of an element to show the characteristic properties of that element

Question 6

define an element

Answer 6

a pure chemical substance composed of atoms with the same number of protons in the atomic nucleus

Question 7

define a compound

Answer 7

substance made by chemically combining 2 or more elements in a fixed ratio of atoms

Question 8

define a mixture

Answer 8

components aren’t chemically bonded and not in a fixed ratio so components retain their individual properties

Question 9

homogeneous

Answer 9

components are in the same state

Question 10

heterogeneous

Answer 10

components are in different states of matter

Question 11

what is STP?

Answer 11

273K and 100kPa/1ATM

Question 12

what is the relative atomic mass?

Answer 12

a weighted average of an element’s isotopes(thats why they’re decimals)

Question 13

what is filtration used for?

Answer 13

to separate an insoluble solid from a liquid

Question 14

what can you do if the solid particles are very small for filtration?

Answer 14

process can be done under reduced pressure in a Buchner flask using a vacuum pump

Question 15

when can evaporation/recrystallisation be used?

Answer 15

if only 1 of the components of the mixture is soluble in a solvent like water/ethanol or in a non-polar solvent like hexane

Question 16

describe the process of evaporation/recrystallization

Answer 16

1) mixture can be warmed with the solvent to dissolve the soluble component
2) solution is filtered to remove undissolved solid particles and solvent is evaporated to leave solute behind
3) solid can be purified by dissolving in a heated solvent and leaving solution to stand so crystals are formed
4) impurities remain in solution
5) after filtering, crystals can be washed with small amount of cold solvent and dried

Question 17

what is a separatory funnel used for?

Answer 17

to separate 2 immiscible liquids

Question 18

how does using a separatory funnel work?

Answer 18

1) mixture is shaken with stopper on and allowed to stand
2) when 2 layers have formed, stopper is removed
3) more dense lower layer run off by opening the tap

Question 19

what is distillation used for?

Answer 19

to obtain a pure solvent from a mixture(eg seawater)

Question 20

how does distillation work?

Answer 20

the volatile solvent boils to form a gas which is condensed and collected

Question 21

what can the distillation apparatus be rearranged for?

Answer 21

for reflux apparatus which is used to allow volatile compounds to react together when heated for a period of time, with no loss of compounds through evaporation or voiling

Question 22

how to check the m.p. of a substance to see if it is pure or impure?

Answer 22

1) sample placed in a small m.p. tube
2) either use a commercial m.p. apparatus
3)or attach it to a thermometer in an oil bath that is gradually heated

Question 23

what is paper made of?

Answer 23

mainly cellulose fibres which contains lots of hydroxyl groups making the paper polar and water molecules hydrogen bond to these groups so ‘dry’ paper has 10% water which acts as the stationary phase

Question 24

how does thin-layer chromatography work?

Answer 24

uses a thin layer of solid egg alumina Al2O3 or silica SiO2 on an inert support like glass; works by adsorption but alumina and silica have a high affinity for water so separation happens by partition with water as the stationary phase

Question 25

what is one advantage of thin-layer chromatography over paper?

Answer 25

each of the separated components can be recovered pure

Question 26

when does a solid melt?

Answer 26

when the vibration is sufficient to overcome the forces holding the lattice together

Question 27

when does a liquid boil?

Answer 27

when the pressure of the vapour is equal to the pressure above the liquid