Summer assessment 1

Question 1

solid to liquid?

Answer 1

melting

Question 2

liquid to solid?

Answer 2

freezing

Question 3

liquid to gas?

Answer 3

evapourating

Question 4

gas to liquid?

Answer 4

condensing

Question 5

solid to gas?

Answer 5

subliming

Question 6

What are elements?

Answer 6

consist of only one type of atom only

Question 7

What is a compound?

Answer 7

a substance that is made of two or more differant elements which are chemically joined together

Question 8

What is a mixture?

Answer 8

no chemical bonds between different parts of a mixture – can be seperated out by physical methods

Question 9

What is a pure substance?

Answer 9

• if it is completely made up of a single element or compound

Question 10

What does every pure substance have?

Answer 10

a specific melting and boiling point

Question 11

What is an impure substance?

Answer 11

it will melt or boil gradually over a range of temperatures

Question 12

When is filtration used?

Answer 12

to separate an insoluble solid from a liquid,

purification

Question 13

Explain process of filtration?

Answer 13

put filter paper into a funnel and pour your mixture into it

- liquid runs through and solid residue is left behind

Question 14

What is crystallisation?

Answer 14

seperates a soluble solid from a solution

Question 15

Explain crystallisation?

Answer 15

• pour solution into an evapourating dish and gently heat solution. some water will evaporated and solution becomes more concentrated
• once some water has evaporared crystals start to form, remove from heat and leave to cool
• salt should start to form crystals as it becomes insoluble
• filter crystals out of the solution and leave in warm place to dry
• can use drying oven or a desiccator

Question 16

What can you use to separate rock salt?

Answer 16

filtration and crystallisation

Question 17

Explain rock salt?

Answer 17

simply a mixture of salt and sand - compounds but salt dissolves in water and sand doesnt

Question 18

Process of seperating rock salt?

Answer 18

• grind with pestle and mortar
• dissolve in beaker
• filter through filter paper in funnel
• crystallise in evaporating dish

Question 19

What is chromatography used for?

Answer 19

separate out mixtures

Question 20

How does cromatography work?

Answer 20

• different dyes move at different rates
• some stick to paper and others will dissolve more readily
• distance dyes travel up paper depends on solvent and paper

Question 21

How do you calculate RF?

Answer 21

distance travelled by solute/ distance travelled by solvent

Question 22

What is Rf?

Answer 22

ratio between distance travelled by dissolved substance and the distance travelled by solvent

Question 23

Why is chromatography used>

Answer 23

to see if a certain substance is present in a mixture

Question 24

What are samples of pure substances called?

Answer 24

standard reference materials

Question 25

What is distillation?

Answer 25

seperate mixtures that contain liquids

Question 26

What are the two types of distillation?

Answer 26

simple and fractional

Question 27

Explain process of simple distillation?

Answer 27

- solution heated, lowest boiling point part evaporated - vapour is cooled and condenses and is collected - rest of solution left in flask

Question 28

Why is fractional distillation used?

Answer 28

if you have a mixture of liquids with similar boiling points

Question 29

Explain process of fractional distillation?

Answer 29

- put mixture in flask and add fractioning column on top and heat it - different boiling points mean will separate at different temps - lowest boiling point seperatas first - column is coolest at the top - when first liquid has been collected, rise temp and wait until next one reaches top q

Question 30

What are group 0 elements called?

Answer 30

noble gases

Question 31

What are noble gases?

Answer 31

inert - dont react with much at all

Question 32

What colour are noble gases?

Answer 32

colourless

Question 33

Litmus paper colours?

Answer 33

red in acid purple in neutral blue in alkaline

Question 34

Phenolphalein colours/

Answer 34

colourless in acid | bright pink in alkaline

Question 35

Methyl orange colours?

Answer 35

red in acid, yellow in alkaline

Question 36

Acid definition?

Answer 36

source of hydrogen ions, proton donors

Question 37

Base definition?

Answer 37

substance that can neutralise an acid, proton accepters

Question 38

Alkali definition?

Answer 38

soluble bases, source of hydroxide ions

Question 39

What is neutralissation?

Answer 39

reaction between acid and base or alkali

Question 40

Neutralistaion equation?

Answer 40

H+. +. OH- = H20

Question 41

What four things does rate of reaction depend on?

Answer 41

- temperature - surface area - concentration - catalyst

Question 42

Explain increasing temperature?

Answer 42

- particles move faster, more collisions - increases energy of collisions - more successful collisions increasing rate

Question 43

Explain increasing concentration?

Answer 43

- more liekly for collisions to take place as frequency increases

Question 44

Explain surface area and rate?

Answer 44

- increase surface area to volume ratio | - more area to work on so frequency increases

Question 45

What are theoretical yields?

Answer 45

calculated yield

Question 46

What is actual yeild?

Answer 46

yield from experiment

Question 47

How do you work out % yield?

Answer 47

actual yield / theoretical. x100

Question 48

How do you make soluble salt?

Answer 48

using an acid that contains one of the ions you want in the salt and an insoluble base containing other ion

Question 49

Describe steps in making a soluble salt?

Answer 49

- heat acid in water bath, in fume cupboard - ad base to acid, produce soluble salt - filter off excess to only get salt and water - heat slightly to evaporate some water. leave to cool and crystallise - filter off solid salt and leave to dry

Question 50

What are the two ways of finding empirical formula?

Answer 50

combustion reaction and reduction reaction

Question 51

How does combustion work?

Answer 51

- when substance reacts with oxygen

Question 52

Explain how to find empirical formula with combustion?

Answer 52

- heat crucible till red hot - ensures clean - leave to cool and weigh it - add clean magnesium ribbon and reweigh - heat crucible with lid on to stop parts escaping but with small gap fo oxygen - heat around 10 mins or till magnesium white - cool and reweigh - mass of magnesium oxide is latest reading - initial reading

Question 53

What is reduction?

Answer 53

loss of oxygen from substance

Question 54

Explain how to do the reduction reaction?

Answer 54

- put rubber bung on test tube and weigh them - then put small amount of copper oxide in middle of tube - put bung in and reweigh - place test tube sideways with bunsen underneath copper oxide and tube facing downwards - expel air by turning on gas for 5 seconds - light bunsen for about 10 mins or solid changes from black to brown- pink - leave to cool - weigh test tube

Question 55

Explain an experiment for how temp effects rate of reaction?

Answer 55

- sodium thiosulfate and hydrochloric acid are both clear - find rate by watching black cross disappear in cloudy sulfur - repeat for differant temps by heating solution in water bath

Question 56

Which experiment alows you to see the affect of catalysts on rate?

Answer 56

decomposition of hydrogen peroxide

Question 57

Which catalysts are used in experiment of decomposition?

Answer 57

- manganese oxide - copper oxide - zinc oxide

Question 58

WHat is given off in decompostion to tell us the rate?

Answer 58

oxygen gas

Question 59

Describe steps in catalyst rate experiment?

Answer 59

- Set up conical flask filled with catalyst and hydrogen peroxide with bung and tube leading to syringe filled with oxygen - measure volume at regular intervals in syringe - repeat with same concentration and volume but differant catalyst