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GCSE Chemistry > 5) Separate Chemistry > Flashcards

5) Separate Chemistry Flashcards

1
Q

Where are transition metals found?

A

In the middle of the periodic table

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2
Q

How does transition metal melting point compare to alkali metals?

A

Higher melting point

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3
Q

How does transition metal strength compare to alkali metals?

A

Stronger and harder

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4
Q

How does transition metal density compare to alkali metals?

A

Higher density

More mass for the same volume

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5
Q

How does transition metal reactivity compare to alkali metals?

A

Less reactive

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6
Q

What are special properties of transition metals?

A

Can form ions with diofferent positive charges
Can form different coloured compounds
Often used as catalysts

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7
Q

What transition metals are used at catalytic converters in cars?

A

Platinum

Rhodium

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8
Q

What is corrosion?

A

The gradual destruction of metals because of reactons with oxygen and water

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9
Q

What is the reaction of rusting?

A

Iron + oxygen + water –> hydrated

iron (III) oxide

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10
Q

What is the rusting experiment?

A

Place iron nail in boiling tube under conditions:
Only water - no rust
Only air - no rust
Air and water - rust

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11
Q

What are the 3 main ways of preventing corrosion?

A

Coatings
Galvanising
Sacrificial method

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12
Q

What is galvanising?

A

A hybrid of coatings and sacrifical method
Protected metal is sprayed with more reactive metal (coating)
If more reactive metal is damaged it protects as sacrifical metal

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13
Q

What are corrosion coatings?

A

Applying a barrier such as greasing, painting or electroplating

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14
Q

What is a disadvantge of coatings?

A

Any damage leads to metal becoming exposed

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15
Q

What is the sacrifical method of corrosion?

A

Metal requiring protection has more reactive metal atatched to it
Water and oxygen will stop reacting with protected metal

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16
Q

What process is used to electroplate objects?

A

Electrolysis

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17
Q

What is the process of electroplating?

A

Metal to be electroplated placed at cathode and coating metal at anode

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18
Q

Why do we electroplate?

A

To coat a cheaper metal with a more expensive one (jewellery)

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19
Q

What are alloys?

A

A combination of 2+ elements with at least 1 metal

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20
Q

Why are alloys stronger than pure metals?

A

Ions of different sizes cannot slide across each other easily

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21
Q

What are uses of aluminium alloys?

A

Armour plating

Manufacturing planes

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22
Q

What is bronze an alloy of?

A

Copper

Tin

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23
Q

What is bronze used for?

A

Making coins
Electrical hardware
Statues

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24
Q

How many carats is pure gold?

A

24 carats

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25
Q

Why does gold often become an alloy?

A

Pure gold is soft

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26
Q

What is brass an alloy of?

A

Copper

Zinc

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27
Q

What is brass used for?

A

Hinges
Locks
Instruments

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28
Q

What is steel an alloy of?

A

Iron

Other metals

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29
Q

How do stainless steels react with oxygen and water?

A

They are strong and resistant to corrosion

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30
Q

What can the concentration of a solution be measured in?

A

Moles (mol/dm^3)

Mass (g/dm^3)

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31
Q

What do we need to know to calculate the amount of solute in a solution?

A

Concentration of solution

Volume of solution

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32
Q

What do we need to know to calculate the concentration of a solution?

A

Volumes of 2 solutions that react completely

Concentration of 1 of these solutions

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33
Q

What is a solute?

A

A dissolved substance

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34
Q

How is the concentration of a solution calculated?

A

Concentration of solution = amount of solute / volume

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35
Q

How many dm^3 does any 1 mole of gas take up in a room at room temperature and normal pressure?

A

24 dm^3

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36
Q

What 4 factors ensure percentage yield stays below 100%?

A

Incomplete reactions
Waste
Extraction
Side reactions

37
Q

How can an incomplete reaction happen?

A

Slow reaction isn’t given enough time to happen

Reversible reaction has some products converted back to reactants

38
Q

How can waste occur in reactions?

A

Some chemicals will remain stuck on apparatus

39
Q

How can extraction reduce percentage yield?

A

Difficult to fully separate product from reaction mixture

40
Q

How do side reactions reduce percentage yield?

A

Intended product is not created

41
Q

What is the equation for percentage yield?

A

Percentage yield = real yield / theoretical yield x 100

42
Q

What is the actual yield?

A

The mass of a desired product obtained from a reaction

43
Q

What is the theoretical yield?

A

The maximum mass of a product that could possibly be created from a reaction

44
Q

What can theoretical yield be calculated from?

A

Balanced equations if mass of reactants is known

45
Q

What is percentage yield?

A

A comparison of the actual and theoretical yields of a reaction

46
Q

What is the equation for atom economy?

A

atom economy (%) = relative molecular mass of desired products / total relative molecular mass of all reactants x 100

47
Q

What is atom economy?

A

The amount of reactants that end up as useful products

48
Q

Why are reaction pathways with high atom economies good?

A

Cost-effective

Low waste

49
Q

What is the equation for moles?

A

Moles = mass / Mr

50
Q

What is reacted in the Haber process?

A

Nitrogen

Hydrogen

51
Q

What are the stages of the Haber process?

A

1) Collect and purify nitrogen and hydrogen gases
2) Pass over iron catalyst
3) Condensation
4) Recycling

52
Q

What temperature and pressure are nitrogen and hydrogen passed over an iron catalyst in the Haber process?

A

450°C

200 atm

53
Q

What is the chemical symbol for ammonia?

54
Q

What is the chemical equation for the Haber process?

A

N2 + 3H2 2NH3 (+heat)

55
Q

How is the hydrogen used in the Haber process obtained?

A

Reacting methane in natural gas with steam

56
Q

Is the forward reaction of the Haber process endothermic or exothermic?

A

Exothermic

57
Q

How does increasing temperature affect the Haber process?

A

Increased rate of reaction

Decreased yield

58
Q

Why is a catalyst used in the Haber process?

A

To establish equilibrium faster

59
Q

How does increasing the pressure affect the equilibrium position of the Haber process?

A

Equilibrium moves towards products

60
Q

What do fertilisers increase the number of?

A

Essential nutrients

61
Q

What do fertilisers contain?

62
Q

What 3 essential elements are added to soils in fertilisers?

A

Nitrogen
Phosphorus
Potassium

63
Q

How is ammonium nitrate produced?

A

Reacting nitric acid and ammonia

64
Q

What is the chemical equation for ammonium nitrate?

A

NH3 + HNO3 —> NH4NO3

65
Q

Why is ammonium nitrate ideal in fertilisers?

A

It contains two sources of nitrogen

66
Q

When are industrial reactions only possible?

A

If cost of making chemical needed is suitable

67
Q

What must be considered in making chemical manufacturing feasible?

A 
Catalyst use
Cost of raw materials
Danger of explosion
Danger of fire
Energy requirements
68
Q

How is ammonium sulfate made?

A 
Sulfuric acid (H2SO4)
Ammonia (NH3)
69
Q

How is ammonium sulfate produced through titration (laboratory method)?

A

1) Add drops of methyl orange to ammonia (turns yellow)
2) Slwoly add dilute sulfuric acid to ammonia until red (swirl flask)
3) Colour change (red) means you have ammonium sulfate

70
Q

How do you purify the ammonium sulfate solution?

A

1) Repeat titration without using indicator using exact same volume of acid
2) Evaporate solution until only a small amount is left to get ammonium sulfate crystals
3) Once solution has crystallised, filter out crystals

71
Q

Why does the industrial production of ammonium sulfate have several stages?

A

Ammonium and sulfuric acid must be made from their raw materials

72
Q

What is one industrial method of producing ammonium sulfate?

A

Spray sulfuric acid into gas chamber where it reacts with ammonia to form ammonium sulfate powder

73
Q

How can we make a simple cell?

A

Connect 2 different electrodes and put them in an electrolyte

74
Q

What produces a voltage in a simple cell?

A

The difference in reactivity of the metals

75
Q

How long does a chemical cell produce potential difference for?

A

Until the reactants are used up

76
Q

What are advantages of fuel cells?

A

Reliable
Compact and lightweight
High efficiency
Low pollution

77
Q

How do fuel cells produce electrical energy?

A

Using a reaction between an external fuel source (hydrogen) and oxygen

78
Q

What generates a voltage in hydrogen fuel cells?

A

The oxidation of hydrogen

79
Q

What is the only waste product of hydrogen fuel cells?

80
Q

What is pumped in at the anode of hydrogen fuel cells?

81
Q

What is pumped in at the cathode of hydrogen fuel cells?

82
Q

What is the anode half equation of hydrogen fuel cells?

A

2H2 —> 4H+ + 4e-

83
Q

What forms at the cathode of hydrogen fuel cells?

84
Q

What is the cathode half equation of hydrogen fuel cells?

A

O2 + 4H+ + 4e- —> 2H2O

85
Q

What is the overall equation of hydrogen fuel cells?

A

2H2 + O2 —> 2H2O

86
Q

What is produced by hydrogen fuel cells?

A

Voltage

Water

87
Q

Why are fuel cells better than rechargeable batteries?

A

Less toxic
Indefinite lifetime
Higher capacity
Higher risks

88
Q

Why are hydrogen fuel cells a safety risk?

A

Hydrogen and to be stored at high pressures

Hydrogen is explosive

GCSE Chemistry (10 decks)

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