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GCSE Chem > Topic 5 > Flashcards

Topic 5 Flashcards

Done except for a few specpoints

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1
Q

5.1
Where are transition metals found in the periodic table?

A

In the middle

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2
Q

5.1
What are the properties of transition metals?

A

-↑ densities
-↑ mp & bp
-Good electrical conductors
-Form coloured compounds
-Have variable oxidation states (lose diff no. of e⁻)

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3
Q

5.1
Explain why transition metals typically have high melting and boiling points

A

-Strong electrostatic forces of attraction between oppositely charged cations & e⁻
-Lot of energy needed to overcome these forces

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4
Q

5.1
Explain why transition metals typically have high densities

A

Cations closely packed together

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5
Q

5.1
Explain why transition metals are good electrical conductors

A

-Release outer shell e⁻ to form metal ions in sea of delocalised e⁻
-e⁻ free to move + carry charge

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6
Q

5.2
Define the term corrosion

A

Oxidation of metal

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7
Q

5.2
Why do objects made of aluminium not corrode as much as expected?

A

-Al reacts rapidly w/ O₂ bc very reactive -> forms aluminium oxide layer
-Layer is unreactive -> will no longer react -> resistant to further corrosion

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8
Q

5.3
How can rusting of iron be prevented?

A

-Exclusion of oxygen
-Exclusion of water
-Sacrificial protection (galvanising)

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9
Q

5.3
3 nails are left in contact with air and water for a few days. The nail wrapped in magnesium does not rust. The nail alone rusts but the nail wrapped in copper rusts more. Explain these observations.

A

-Mg more reactive than Fe
-Mg oxidises more readily
-Nail doesn’t rust

-Fe more reactive than Cu
-Fe oxidises more readily
-So Cu rusts faster than nail alone

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10
Q

5.4
What is electroplating?

A

Coating 1 metal object with another

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11
Q

5.4
How does electroplating work?

A

-Electric current passed through solution
-Cathode = iron/steel object
-Anode = plating material
-Electrolyte = contains ions of plating material

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12
Q

5.4
How would you electroplate silver onto copper?

A

-Ag atoms lose e^- -> Ag+ ions
-Ag+ ions go into electrolyte -> migrate to negative Cu ring
-Ag+ ions gain e^- -> Ag atoms

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13
Q

5.4
What is the purpose of electroplating?

A

-Improve aesthetic
-Improve resistance to corrosion of metal objects

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14
Q

5.5
Define the term alloy

A

Mixture of metals

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15
Q

5.5
Explain why alloying increases the strength of the pure metal [3 marks]

A

-Pure metal: atoms = same size
-So atoms can move/slide easily within LAYERS
-Alloy: atoms = diff sizes
-Prevents layers from sliding

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16
Q

5.7
State 2 uses of aluminium and the properties that make it suitable for that use

A

Aeroplanes + cars
-Low density
Drink cans
-Resistant to corrosion

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17
Q

5.7
State 2 uses of copper and the properties that make it suitable for that use

A

Electrical cables
-Good electrical conductor
Water pipes
-Resistant to corrosion

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18
Q

5.7
State 2 uses of gold and the properties that make it suitable for that use

A

Jewellery
-Unreactive -> doesn’t corrode
-Attractive
Circuit boards in phones
-Good electrical conductor

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19
Q

5.8
Convert 1dm³ into cm³

A

1000cm³

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20
Q

5.8
State 2 equations to calculate concentration in mol dm³

A

=amount of solute in mol/v of solution in dm³
(c=n/v)

=concentration in gdm³/ Mr of solute

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21
Q

5.8
Calculate the volume of solution, in cm³, containing 0.005 mol of potassium chloride that will have a concentration of 5.0 mol dm³

A

v=n/c
=0.005/5
=0.001dm³
=1cm³

1cm³

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22
Q

5.10
See freescience lessons vid on titration calculations

A

-

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23
Q

5.11
State the equation for percentage yield

A

-Percentage yield = actual yield/theoretical yield x100
(%y = acc/theo x 100)

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24
Q

5.12
Define the term theoretical yield

A

Max mass of product that can be formed from given amount of reactant

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25
Q

5.12
Define the term actual yield

A

Actual m of product formed

26
Q

5.12
The percentage yield of a reaction is usually less than 100% because the actual yield tends to be less than the theoretical yield. Explain why this is

A

-Incomplete reactions
-Practical losses during experiment
-Competing side reactions

27
Q

5.13
Define the term atom economy

A

Shows %, by mass, of useful products formed in reaction

28
Q

5.14
State the equation for atom economy

A

Mᵣ of useful product/Mᵣ of all reactants
x100

29
Q

5.14
In what situation can an atom economy of 100% be obtained?

A

-If only 1 product formed & it = useful
-e.g. 2H₂ + O₂ -> 2H₂

30
Q

5.14
Explain a reason for why a low atom economy is a disadvantage in a manufacturing process

A

-Produce waste products
-May be toxic/corrosive-> difficult/expensive to dispose of

31
Q

5.14
State how the atom economy can be improved

A

Find uses for waste products

32
Q

5.16
State the equation used to work out the amount of gas (mol)

A

=volume of gas (dm³)/molar volume (dm³)
(n=v/V little m)
Assume Vm = 24dm³ unless stated otherwise

33
Q

5.16
What is the molar volume of any gas at room temperature?

A

24dm^3

34
Q

5.19
What is the Haber Process?

A

Reversible reaction between nitrogen & hydrogen to form ammonia

35
Q

5.19
What does the rate of reaction mean?

A

How fast/slow reaction occurs

36
Q

5.19
See book for rate graphs

A

-

37
Q

5.20
State 5 factors affecting the rate of reaction

A

-Concentration
-Temperature
-Pressure (of gases)
-Catalysts
-SA of one of reactants

38
Q

5.20
Explain how increasing the temperature affects the rate of reaction [3 marks]

A

-Hotter particles-> gain more KE -> faster
-More frequent, successful collisions between particles in given t
-Increases

39
Q

5.20
Explain how increasing the pressure affects the rate of reaction [3 marks]

A

-As pressure increases, space in which gas particles move in becomes smaller
-More frequent, successful collisions between particles in given time
-Increases

40
Q

5.20
Explain how increasing the concentration affects the rate of reaction [2 marks]

A

-More particles in same VOLUME
-More frequent, successful collisions between particles in given time
-Increases

41
Q

5.20
Describe the effect of increasing the pressure on the movement of particles and the time taken for equilibrium to be reached

A

-Equilibrium position moves in direc that produces less gas (fewest molecules)
-Time decreases

42
Q

5.20
Describe the effect of increasing the concentration on the movement of particles and the time taken for equilibrium to be reached

A

-Equilibrium position shifts AWAY from that reactant
-Time decreases

43
Q

5.20
Describe the effect of increasing the temperature on the movement of particles and the time taken for equilibrium to be reached

A

-Equilibrium position shifts in direc of endo reaction
-Time decreases

44
Q

5.20
Describe the effect of adding a catalyst on the equilibrium and the time taken for equilibrium to be reached

A

-Increases r. reaction
-But no change in equilibrium position
-Time decreases

45
Q

5.21
In industrial reactions e.g. the Haber process, what is considered when choosing the conditions?

A

The availability & cost of:
-Raw materials
-Energy
-Supplies

46
Q

5.22
What are fertilisers?

A

-Replace mineral ions
-Promote plant growth

47
Q

5.22
State the 3 main elements found in fertilisers

A

-Nitrogen
-Phosphorus
-Potassium
(N,P,K)

48
Q

5.22
State the formula for
a) Ammonia
b) Ammonium

A

a) NH₃
b)NH₄

49
Q

5.23
What fertiliser is produced in the reaction between ammonia and nitric acid?
Then give the balanced chemical equation for this reaction

A

-Ammonium nitrate
-NH₃ (aq) + HNO₃ (aq) -> NH₄NO₃ (aq)

50
Q

5.23
Work out the formula for the fertiliser ammonium phosphate

A

(NH₄)₃PO₄

Help: (NH₄^+ PO₄^3-
1 3)

51
Q

5.24a
Describe the laboratory preparation of producing the fertiliser ammonium sulfate

A

-Small scale
-Starting materials: Ammonia solution & dilute sulfuric acid
-Stages: Titration then crystallisation
-Type of process: Batch

52
Q

5.24b
Describe the industrial production of producing the fertiliser ammonium sulfate

A

-Large scale
-Starting materials: Raw materials for making ammonia & sulfuric acid
-Stages: Several
-Type of process: Continuous

53
Q

5.25
What is a battery?

A

2/more electrical cells joined together

54
Q

5.25
Name the 2 types of electrical cells

A

-Chemical cells
-Fuel cells

55
Q

5.25
What are chemical/electrical cells?

A

Use chemical reaction to produce electricity

56
Q

5.25
Explain which cell, made from the following combinations of metals and their salt solutions, will produce the greatest voltage:
-Magnesium & zinc
-Magnesium & copper
-Zinc & copper

A

-Mg & Cu
-The further away the metals are from each other in the reactivity series, the greater the voltage

57
Q

5.26
Describe and explain what happens (the reaction) in a hydrogen-oxygen fuel cell. Give the balanced chemical equation

A

-Hydrogen + Oxygen react to produce VOLTAGE

-Anode: oxidation
-H₂ atoms lose e^- -> H₂ ions
-2H₂ (g) -> 4H^+ (aq) + 4e

-Cathode: reduction
-H₂ ions & e^- react w/ O₂ to form water
-4H^+ (aq) + 4e + O₂ (g) -> 2H₂O (l)

-Water = only product
-2H₂ (g) + O₂ (g) -> 2H₂O (l)

58
Q

5.27
Discuss the advantages and disadvantages of using hydrogen rather than diesel as a fuel for vehicles

A

Adv
-Only water produced (harmless/no GHG)
-Raw material for production of H₂ is water -> renewable/plentiful supply

Dis
-H₂ difficult to store bc needs to be under pressure
-Difficult to transport bc gas leaks (flammable)
-CO₂ produced in manufacture & storage & transport
-Few H₂ refuelling stations
-More expensive

59
Q

5.27
What are 3 advantages of using fuel cells in spacecraft?

A

-Lightweight
-Small for amount of electricity they produce
-No harmful emissions

60
Q

5.27
Why do spacecrafts have 2 sources of energy they interchange between and what are they?

A

-Hydrogen & solar
-Hydrogen fuel cells supplied w/ H₂ & O₂
-Could be problem when leave Earth
-So have solar cells
-Convert light -> electricity
-But only works when in light
-Ensures reliable power supply

61
Q

eDescribe how you could prepare a pure solution of ammonium chloride in the laboratory

A

-Ammonia solution in beaker
-Add indicator (e.g. universal indicator)
-Add HCl until solution just changes colour

62
Q

Iron fences can be galvanised with a layer of zinc. When this layer is scratched, exposing the iron, the iron does not rust. Explain why

A

-Zn corrodes instead
-Bc it is more reactive

GCSE Chem (13 decks)

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