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Flashcards in C2 - Chemical Resources Deck (53)
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31

Why doesn't aluminium corrode (rust) when wet?

Aluminium doesn't corrode when wet because it's much more reactive than iron, meaning it reacts quickly with the oxygen in the air to form aluminium oxide. This aluminium oxide works as a protective layer than sticks to the material and stops the rusting reaction from occurring.

32

What factors effect the rate of rusting?

Salt water or acid rain will speed up the rusting process.

33

Describe advantages and disadvantages of using aluminium rather than steel to manufacture a car.

Advantages:
- Car body of same size will be lighter with aluminium.
- Car body with aluminium will corrode less.
- Aluminium is more expensive.

34

Describe an advantage and disadvantage of recycling materials used to make cars?

- Helps save limited natural resources.
- Non-metal materials need to be separated before they can be recycled. This costs money.

35

What is the word equation for neutralisation?

acid + base --> salt + water

36

What is the ionic half equation for neutralisation?

H+ + OH-⇌ H2O

37

Why do all metal oxides and metal hydroxides react with water?

They are bases, so when dissolved in water, are alkalis.

Therefore, they react with acids to form a salt and water.

38

What is the symbol equation for the neutralisation reaction between hydrochloric acid and copper oxide?

HCl + CuO ---> CuCl2 + H2O

39

What is the symbol equation for the neutralisation reaction between nitric acid and sodium hydroxide?

HNO3 + NaOH --> NaNO3 + H2O

40

What is the symbol equation for the neutralisation reaction between sulphuric acid and calcium carbonate?

H2SO4 + CaCO3 ---> H2O + CO2 + CaSO4

41

What is the symbol equation for the neutralisation reaction between nitric acid and ammonia?

HNO3 + NH3 ---> NH4O3

42

What is the general word equation for a reaction between an acid and ammonia?

Acid + Ammonia --> Ammonium salt

43

Why do fertilisers need to be dissolved in water?

So that they can be absorbed by the plants' roots.

44

How do fertilisers increase crop yield?

- Replaces elements needed by plant that have been used up by previous crops.
- More nitrogen available means that plants can build more proteins and therefore grow larger.

45

Explain the process of eutrophication?

- Leaching/run-off of fertiliser into streams.
- Increased nitrate or phosphate in river.
- Algal bloom as they have more nitrogen, so can grow/reproduce more.
- Growth of algae blocks off sunlight to plants underwater.
- Aerobic bacteria reproduce rapidly as they feed on the dying plants. The growing population of aerobic bacteria means that oxygen is used up in the water.
- As a result, other living organisms start dying.

46

How can you prepare ammonium nitrate in the lab?

Solution of ammonium and an indicator are kept in a flask. Above the flask, is a burette containing a nitric acid solution.

Slowly, drops of nitric acid are added to the ammonium solution. As soon as the indicator changes colour, stop adding the the nitric acid - the neutralisation reaction ahs finished.

To obtain a solid fertiliser product, the solution must slowly evaporate and then be left to crystalise. To get pure ammonium nitrate crystals without the indicator, the titration must be repeated with that exact volume of acid.

47

What is the symbol equation for reaction in the Haber Process?

N2 + 3H2 ⇌ 2NH3

48

How does pressure affect the percentage yield of the Haber Process?

Pressure favours the forward reaction, so the higher the pressure - the greater the percentage yield.

49

How does temperature affect of the percentage yield of the Haber Process?

Temperature favours the reverse reaction, so the higher the temperature - the smaller the percentage yield.

50

What is the optimum temperature used in the Haber Process? Why is that temperature the optimum one?

450 degrees Celsius:
- Fast rate of reaction
- Reasonable percentage yield
- It's a compromise

51

What catalyst is used in the Haber Process? How does this catalyst affect the reaction?

Iron catalyst:
- Speeds up rate of reaction
- Therefore, temperatue does not need to be raised as high (which is good, as higher temperature decreases percentage yield).

52

How is solution mining used to extract salt?

Hot water is pumped underground, dissolving the salt. The salt solution is then forced to the surface via the pressure of the water.

53

Describe the electrolysis of brine (sodium chloride solution).

The sodium chloride solution contains four different ions, Na+, OH-, Cl- and H+. At the cathode, H+ ions gain electrons to produce hydrogen gas. At the anode, Cl- ions lose electrons to form chlorine gas.