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Chemistry > Paper 2 > Flashcards

Paper 2 Flashcards

1
Q

How do you find the empirical formula from the mass of each element combined in a compound?

A

Write out each symbol in a seperate column
Underneath each write mass
Divide the mass by the Ar
Divide that by the smallest answer to get ratio
Write out formula

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1
Q

How do you find the mass of reactants/products?

A

Underline the substance you have been given mass of and the one you’re trying to find. Write the masses above them
Find the Mr for each
Divide Mr of chemical ? by the Mr of the known chemical
Multiply that by the known mass

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2
Q

How do you find the limiting reactant?

A

Work out the number of moles of the first recatant
Look at the ratio and see how much moles of the second reactant there should be
Calculate the number of moles of the second reactant
Compare

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3
Q

What is Avogadro’s Constant?

A

6.02 * 10²³

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4
Q

What are the properties of alkali metals? (6)

A

Malleable
Low melting points
Conduct electricity
Soft and easy to cut
Shiny when freshly cut
Very reactive with non metals

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5
Q

What is the equation for potassium reacting with air?

A

4K (s) + O₂ (g) –> 2K₂O (s)

(Same for any other element, just change the K for whatever else)

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6
Q

What is the equation for lithium reacting with water?

A

2Li (s) + 2H₂O (l) –> 2LiOH (aq) + H₂ (g)

(Same for any other element, just change the Li for whatever else.

Also, the aqueous thing splits into ions e.g.

2LiOH (aq) ===== 2Li+ + 2OH-

)

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7
Q

What are the properties of halogens?

A

Toxic
Corrosive
Non-metals
Poor conductors of heat and electricity
Diatomic

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8
Q

What does chlorine look like at room temperature?

A

Green gas

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9
Q

What does bromine look like at room temperature?

A

Brown liquid

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10
Q

What does iodine look like at room temperature?

A

Purple/black solid

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11
Q

As you go down the group, what happens to halogens?

A

Melting + boiling points increase
Density increases

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12
Q

What are the uses of halogens?

A

Disinfectants and bleaches

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13
Q

What is the use of sodium chloride?

A

Table salt

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14
Q

What is the use of sodium fluoride?

A

Toothpaste

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15
Q

How does the reactivity change as you go down the alkali metals?

A

Goes up

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16
Q

What are the properties of noble gases?

A

Inert
All exist as single atoms
Colourless
Low melting and boiling points
Poor conductors of heat and electricity

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17
Q

How do you calculate the average rate of reaction?

A

Volume of gas / time taken

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18
Q

What is activation energy?

A

Minimum energy for a successful collision

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19
Q

How do catalysts work?

A

Lower the activation energy

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20
Q

What can catalysts help with?

A

Existing bonds to break
Molecules to collide in such a way that they can react and form bonds

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21
Q

How can catalysts be used?

A

Catalytic converters
Enzyme

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22
Q

How do catalytic converters work?

A

Platinum or palladium is used in cars to speed up the reaction of harmful gases (e.g. carbon monoxide) into harmless gases (e.g. nitrogen)

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23
Q

What happens to potassium when it reacts with water?

A

Burns with a lilac flame

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24
Q

What happens to sodium when it reacts with water?

A

Effervesces rapidly and releases enough energy to melt itself. It then floats on the surface of the water

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25
Q

What happens to lithium when it reacts with water?

A

Fizzes steadily and gets smaller until it disappears

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26
Q

What are some examples of endothermic reactions?

A

Photosynthesis
Cracking
Thermal decomposition
Nuclear fusion

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27
Q

What are some examples of exothermic reactions?

A

Neutralisation
Displacement
Combustion
Nuclear fission

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28
Q

What is bond energy?

A

Energy needed to break one mole of a particular covalent bond

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29
Q

What is bond energy measured in?

A

Kj/mol

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30
Q

How is crude oil formed?

A

From ancient remains of microscopic animals and plants that lived in the sea

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31
Q

What is a hydrocarbon?

A

Molecule made of hydrogen and carbon only

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32
Q

What are the layers of fractional distillation of crude oil?

A

Gases
Petrol
Kerosene
Diesel
Fuel oil
Bitumen

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33
Q

What are gases used for (in terms of crude oil)?

A

LPG

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34
Q

What is petrol used for?

A

Fuelling cars

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35
Q

What is kerosene used for?

A

Fuelling planes

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36
Q

What is diesel used for?

A

Fuelling cars/lorries

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37
Q

What is fuel oil used for?

A

Fuelling trains

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38
Q

What is bitumen used for?

A

Paving roads

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39
Q

What is the general formula of alkanes?

A

CₙH₂ₙ₊₂

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40
Q

What is the general formula of alkenes?

A

CₙH₂ₙ

41
Q

What are molecules called that have the same molecular formula but different arrangements?

A

Isomers

42
Q

What is used to test alkanes and alkenes?

A

Bromine water

43
Q

What colour does bromine water turn in an alkane?

A

Stays orange/brown

44
Q

What colour does bromine water turn in an alkene?

A

Orange/brown to colourless

45
Q

What is the equation for complete combustion of hydrocarbons?

A

Hydrocarbon + oxygen -> carbon dioxide + water

46
Q

What is the equation for incomplete combustion of hydrocarbons?

A

Hydrocarbon + oxygen -> carbon + carbon monoxide + water

47
Q

What are the 2 tests for water?

A

White anhydrous copper sulphate turns blue
Cobalt chloride paper goes pink -> blue

48
Q

What is acid rain?

A

Rain with pH lower than 5.2 due to sulphur dioxide

49
Q

How is acid rain formed?

A

Sulphur dioxide dissolves in water in clouds to form sulphurous acid
Some of the sulphurous acid is oxidised to form sulfuric acid

50
Q

What is cracking?

A

Breaking down long-chain, low demand molecules into short-chain, high demand molecules

51
Q

What are the conditions of cracking?

A

650c
Aluminium oxide catalyst

52
Q

What does cracking form?

A

An alkane and an alkene

53
Q

How did the atmosphere evolve?

A

Earth began to cool forming crust and lots of volcanoes
About 4 billion years ago, the Earth cooled down and the water vapour in the air condensed, forming oceans which trapped carbon dioxide
Carbon dioxide levels fall even more once first plants grow and photosynthesise

54
Q

What evidence is there that there was no oxygen in the early atmosphere?

A

Volcanoes do not produce oxygen
Presence of iron pyrite which only forms when there is no oxygen present

55
Q

What are stromatolites?

A

Some of the earliest photosynthetic organisms forming sticky mucus which trapped sand and other sediments

56
Q

What are the commonly used plants used to make alcohols?

A

Beer - barley seeds
Wine - grapes
Whiskey - barley seeds
Vodka - wheat seeds

57
Q

What is the process of fermentation?

A

Seeds are germinated so that enzymes break down starch into glucose
Sugar is dissolved in water and mixed with yeast to form ethanol and carbon dioxide

58
Q

What conditions are needed for fermentation?

A

Temperature between 20c and 40c
Neutral pH
Airlock

59
Q

What are the properties of alcohols?

A

Can be oxidised to make carboxylic acids
React with reactive metals and give hydrogen as a product

60
Q

What are some uses of alcohols?

A

Solvents in cosmetics, medicine, varnishes
Fuels (e.g. methanol, ethanol)

61
Q

What is the process of obtaining ethanol throught hydration and what are the conditions?

A

Ethene mixed with steam and passed over a catalyst of silicon dioxide coated with phosphoric acid
300c temperature
60-70 atmoshperes of pressure

62
Q

How are carboxylic acids made?

A

Via oxidising alcohols

63
Q

What are the properties of carboxylic acids?

A

Form solutions of weak acids
React with metals to form salt + hydrogen
React with bases to form salt + water
React with carbonates to form salt, water and carbon dioxide

64
Q

What is a polymer?

A

Long molecules made from lots of repeating units (monomers) e.g. plastics, protein, starch

65
Q

What are the properties of polythene?

A

Flexible
Cheap
Good insulator

66
Q

What are the properties of polypropylene?

A

Flexible
Does not shatter

67
Q

What are the properties of PVC?

A

Tough
Good insulator
Can be flexible

68
Q

What is a condensation reaction?

A

When organic molecules form and sometimes form a small molecule (usually water) alongside the polymer

69
Q

What are the problems with making polymers?

A

Made from crude oil - finite, non-renewable, bad for wildlife
Non-biodegradable
Take up space in landfills
Produce toxic gases when burned

70
Q

What are the steps of recycling plastics?

A
  1. Collect waste
  2. Sort waste into different polymers
  3. Dispose of waste that can’t be recycled
  4. Clean polymers and grind into chips
  5. Purify chips
  6. Melt chips and form into a new product
71
Q

How do you perform a flame test?

A
  1. Light bunsen burner and open air hole
  2. Clean wire loop in hydrochloric acid
  3. Use wire loop to pick up some of the substance that will be tested
  4. Hold the sample in flame and observe colour
72
Q

What colour does lithium go in a flame?

A

Red

73
Q

What colour does sodium go in a flame?

A

Yellow

74
Q

What colour does potassium go in a flame?

A

Lilac

75
Q

What colour does calcium go in a flame?

A

Orange

76
Q

What colour does copper go in a flame?

A

Blue-green

77
Q

Why is flame photometry used?

A

Faster and more accurate + sensitive

78
Q

When added to NaOH what colour precipitate does iron(II) form?

A

Green

79
Q

When added to NaOH what colour precipitate does iron(III) form?

A

Brown

80
Q

When added to NaOH what colour precipitate does copper form?

A

Blue

81
Q

When added to NaOH what colour precipitate does calcium form?

A

White

82
Q

When added to NaOH what colour precipitate does aluminium form?

A

White

83
Q

How do you tell the difference between calcium and aluminium ions when testing using NaOH?

A

Add NaOH in excess, white precipitate will go colourless if it’s aluminium

84
Q

What is the test for an ammonium cation?

A

When added to sodium hydroxide and warmed, NH₃ will be produced

85
Q

What is the test for a carbonate ion?

A

Gives off carbon dioxide when added to HCl

86
Q

What is the test for a sulfate ion?

A

Do carbonate test
Add a few drops of barium chloride which will form a white precipitate

87
Q

What are the tests for halide ions?

A

Add nitric acid then add a few drops of silver nitrate

88
Q

When testing for halide ions, what colour does chloride go?

A

White

89
Q

When testing for halide ions, what colour does bromide go?

A

Cream

90
Q

When testing for halide ions, what colour does iodide go?

A

Yellow

91
Q

What are the properties of ceramics?

A

Unreactive
Hard and stiff
Brittle
Poor electrical + thermal conductors
High melting points
Opaque

92
Q

What are the properties of polymers?

A

Strong
Poor electrical and thermal conductors
Chemically unreactive

93
Q

What is concrete made of?

A

Mix of cement, sand, aggregate and water

94
Q

What is a laminate?

A

Layering wood to make it strong in all directions

95
Q

What are nanoparticles?

A

Tiny particles consisting of only a few hundred atoms

96
Q

How big are nanoparticles?

A

Between 1nm and 100nm

97
Q

What are the uses of nanoparticles?

A

Socks - silver nanoparticles good at killing bacteria
Sunscreen - titanium dioxide nanoparticles absorb harmful UV rays
Stain resistant clothing - nanoparticles catalyse breakdown of dirt

98
Q

What are the risks of nanoparticles?

A

May pose hazard to human health and environment
Can be breathed in or pass through skin
High SA:V may allow them to catalyse harmful reactions

99
Q

What are the 3 most reactive metals in the reactivity series? (From most reactive)

A

Potassium
Sodium
Lithium

100
Q

What are the 3 least reactive metals in the reactivity series? (From least reactive)

A

Gold
Copper
Iron

Chemistry (2 decks)

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