sc1 - 2, states of matter (paper 1)

Question 1

define compound

Answer 1

two or more different elements held together by different bonds (always found in the same proportions)

Question 2

define mixture

Answer 2

two or more substances not chemically bonded together (as they haven’t reacted)

Question 3

what is filtration used for

Answer 3

to separate an insoluble solid from a liquid

Question 4

what is crystallisation for

Answer 4

to seperate a soluble solid from a liquid

Question 5

what is a solvent

Answer 5

a liquid that dissolves substances

Question 6

steps of chomotography paper practical

Answer 6

• chomotography paper with pencil lines on the bottom and put dotted lines of the pen we want to use
• lower it into a solvent which makes it way up the paper and dissolves ink in the two coloured dots which are carried up

Question 7

what is the stationary phase in the chomotography paper practical

Answer 7

paper as it doesn’t move

Question 8

what is the mobile phase in the chomotography paper practical

Answer 8

solvent as it moves

Question 9

why does chomotography paper practical work

Answer 9

because each chemical mixture will be attracted to the stationary phase to a different extent

Question 10

what is simple distillation used for

Answer 10

• separate a solvent from a solution
• if we want to keep the liquid

Question 11

what is fractional distillation used for

Answer 11

• separate a mixture of miscible liquids

Question 12

how to calculate the Rf

Answer 12

distance by spot / distance by solvent

Question 13

what happens in paper chomotography

Answer 13

• each soluble substance in the mixture forms bonds with the two phases
• substances that form stronger attractive forces with the stationary or mobile phase move different lengths

Question 14

in paper chomotography:
if the subtance moves further, is it more attracted to the mobile or stationary phase?

Answer 14

mobile phase

Question 15

in paper chomotography:
if the subtance moves less, is it more attracted to the mobile or stationary phase?

Answer 15

stationary phase

Question 16

how can we make the Rf more accurate

Answer 16

using a longer or different paper

Question 17

what can a chromatogram be used for

Answer 17

• distinguish pure and impure inks
• identify a substance by comparing

Question 18

what does a pure ink produce in paper chromatography

Answer 18

only one spot

Question 19

what does an impure ink produce in paper chromatography

Answer 19

multiple spots

Question 20

steps in simple distillation

Answer 20

• solution is heated and the solvent boils
• solvent va[our passes into the condenser
• vapour cools and condenses back to the liquid state in a seperate beaker/flask

Question 21

steps in fractional distillation

Answer 21

• the mixture is heated and hot vapour rises up the fractionating column
• the liquid with the higher boiling point condenses when it hits the cools urface and drips back
• the liquid with the lowest boiling point has it’s vapour reach the condenser first

Question 22

how does a condenser keep cool

Answer 22

it has two tubes keeping cold water running in and out

Question 23

describe the tempurature gradient in a fractionating column

Answer 23

hottest at the bottom, coldest at the top

Question 24

define molecule

Answer 24

two or more atoms, held together by chemical bonds, which can contain different elements

Question 25

steps in crystallisation

Answer 25

• place the solution in an evaporating dish and slowly heat
• once some of the solvent has evaporated and crystals start forming, stop heating it
• leave it to cool
• more crystals start to form, as solids are less soluble at colder tempuratures
• filter them
• dry them in an air oven or warm place

Question 26

steps in evaporation

Answer 26

• heat solution in an evaporating dish
• solvent starts evaporating and the remaining solution becomes more concentrated, forming crystals

Question 27

con of evaporation

Answer 27

it may be quick and easy but some solids may decompose when heated (thermal decomposition)

Question 28

steps in filtration

Answer 28

• use a filter paper and funnel
• filter paper has small holes that allow the liquid to pass through, but not the solid

Question 29

what is filtration used for

Answer 29

to seperate an insoluble salt from a liquid

Question 30

what happens in sublimation

Answer 30

solid to gas

Question 31

what happens in deposition

Answer 31

gas to solid

Question 32

what happens during a state change

Answer 32

• energy is transferred to or from the particles
• the arrangement of particles change
• the movement of particles change

Question 33

what is the order of different states in increasing energy stores

Answer 33

solid, liquid, gas

Question 34

what is the order of different states in decreasing energy stores

Answer 34

gas, liquid, solid

Question 35

true or false: mixtures have a more varied melting/boiling point than a single element, which is more sharp

Answer 35

true

Question 36

what are the stages of making water potable

Answer 36

sedimentation, filtration, chlorination

Question 37

define potable

Answer 37

safe to drink

Question 38

what must potable water have

Answer 38

low levels of contaminating substabces and microbes

Question 39

explain why tapn water is potable but not pure

Answer 39

it contains dissolved salts and chlorine which is more than one element

Question 40

why is using distillation by boiling and condensing for sea water hard

Answer 40

it’s expensive

Question 41

what is sedimentation

Answer 41

large insoluble particles sink to the bottom of a tank

Question 42

what is filtration

Answer 42

small insoluble particles are removed by filtering through beds of sand

Question 43

what is chlorination

Answer 43

chlorine gas is bubbles from the water to kill microbes