Summer assessment 1 Flashcards

1
Q

solid to liquid?

A

melting

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2
Q

liquid to solid?

A

freezing

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3
Q

liquid to gas?

A

evapourating

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4
Q

gas to liquid?

A

condensing

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5
Q

solid to gas?

A

subliming

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6
Q

What are elements?

A

consist of only one type of atom only

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7
Q

What is a compound?

A

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

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8
Q

What is a mixture?

A

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

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9
Q

What is a pure substance?

A
  • if it is completely made up of a single element or compound
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10
Q

What does every pure substance have?

A

a specific melting and boiling point

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11
Q

What is an impure substance?

A

it will melt or boil gradually over a range of temperatures

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12
Q

When is filtration used?

A

to separate an insoluble solid from a liquid,

purification

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13
Q

Explain process of filtration?

A

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

- liquid runs through and solid residue is left behind

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14
Q

What is crystallisation?

A

seperates a soluble solid from a solution

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15
Q

Explain crystallisation?

A
  • 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
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16
Q

What can you use to separate rock salt?

A

filtration and crystallisation

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17
Q

Explain rock salt?

A

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

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18
Q

Process of seperating rock salt?

A
  • grind with pestle and mortar
  • dissolve in beaker
  • filter through filter paper in funnel
  • crystallise in evaporating dish
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19
Q

What is chromatography used for?

A

separate out mixtures

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20
Q

How does cromatography work?

A
  • 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
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21
Q

How do you calculate RF?

A

distance travelled by solute/ distance travelled by solvent

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22
Q

What is Rf?

A

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

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23
Q

Why is chromatography used>

A

to see if a certain substance is present in a mixture

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24
Q

What are samples of pure substances called?

A

standard reference materials

25
Q

What is distillation?

A

seperate mixtures that contain liquids

26
Q

What are the two types of distillation?

A

simple and fractional

27
Q

Explain process of simple distillation?

A
  • solution heated, lowest boiling point part evaporated
  • vapour is cooled and condenses and is collected
  • rest of solution left in flask
28
Q

Why is fractional distillation used?

A

if you have a mixture of liquids with similar boiling points

29
Q

Explain process of fractional distillation?

A
  • 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
30
Q

What are group 0 elements called?

A

noble gases

31
Q

What are noble gases?

A

inert - dont react with much at all

32
Q

What colour are noble gases?

A

colourless

33
Q

Litmus paper colours?

A

red in acid
purple in neutral
blue in alkaline

34
Q

Phenolphalein colours/

A

colourless in acid

bright pink in alkaline

35
Q

Methyl orange colours?

A

red in acid, yellow in alkaline

36
Q

Acid definition?

A

source of hydrogen ions, proton donors

37
Q

Base definition?

A

substance that can neutralise an acid, proton accepters

38
Q

Alkali definition?

A

soluble bases, source of hydroxide ions

39
Q

What is neutralissation?

A

reaction between acid and base or alkali

40
Q

Neutralistaion equation?

A

H+. +. OH- = H20

41
Q

What four things does rate of reaction depend on?

A
  • temperature
  • surface area
  • concentration
  • catalyst
42
Q

Explain increasing temperature?

A
  • particles move faster, more collisions
  • increases energy of collisions
  • more successful collisions increasing rate
43
Q

Explain increasing concentration?

A
  • more liekly for collisions to take place as frequency increases
44
Q

Explain surface area and rate?

A
  • increase surface area to volume ratio

- more area to work on so frequency increases

45
Q

What are theoretical yields?

A

calculated yield

46
Q

What is actual yeild?

A

yield from experiment

47
Q

How do you work out % yield?

A

actual yield / theoretical. x100

48
Q

How do you make soluble salt?

A

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

49
Q

Describe steps in making a soluble salt?

A
  • 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
50
Q

What are the two ways of finding empirical formula?

A

combustion reaction and reduction reaction

51
Q

How does combustion work?

A
  • when substance reacts with oxygen
52
Q

Explain how to find empirical formula with combustion?

A
  • 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
53
Q

What is reduction?

A

loss of oxygen from substance

54
Q

Explain how to do the reduction reaction?

A
  • 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
55
Q

Explain an experiment for how temp effects rate of reaction?

A
  • 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
56
Q

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

A

decomposition of hydrogen peroxide

57
Q

Which catalysts are used in experiment of decomposition?

A
  • manganese oxide
  • copper oxide
  • zinc oxide
58
Q

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

A

oxygen gas

59
Q

Describe steps in catalyst rate experiment?

A
  • 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