Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Chemistry Edexcel > Topic 5 - Separate Chemistry > Flashcards

Topic 5 - Separate Chemistry Flashcards

1
Q

What are the typical properties of transition metals?

A
  • High melting point.
  • High density.
  • Form coloured compounds.
  • Transition metals and their compounds can be used as catalysts
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which transition metal is used as a catalyst in the Haber process?

A

Iron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What causes metals to corrode

A

Oxygen reacts with the metal to form a metal oxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is corrosion of a metal a redox reaction?

A

The metals loses electrons so is oxidised.
Oxygen gains electrons so is reduced.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is rusting?

A

Rusting is the name specifically given to the corrosion of iron when it reacts to oxygen and water in the air.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What two substances need to be excluded to prevent rusting?

A

Oxygen (O2)
Water (H2O)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How can oxygen and water be excluded to prevent
iron rusting?

A

Paint the metal.
Coat the metal in oil/grease.
Cover the metal in plastic.
Keep the metal in a vacuum container.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is sacrificial protection? How does it prevent
corrosion?

A

Sacrificial protection is when the metal being
protected from rusting is galvanized with a
more reactive metal.
The outer metal will corrode first and will
prevent the corrosion of the inner metal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which metal is used to in the sacrificial protection of
iron?

A

Zinc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is electroplating?

A

A process in which a metal is coated with
a layer of another metal.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are two reasons for using electroplating?

A
  • To make a metal more resistant to
    corrosion.
  • To improve the appearance of a metal
    (e.g. silver plated cutlery).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Explain how the process of electroplating works

A

Similar setup to electrolysis:
The metal being coated is the cathode. The
metal that will form the exterior layer is the
anode. The electrolyte solution must contain ions
of the metal which will form the outer coating. A
power supply is connected to both electrodes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why are pure metals generally very malleable?

A

The atoms lie in uniform rows which are
able to slide over one another.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is an alloy?

A

An alloy is a mixture of two or more
metals or a metal and another element.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

A pure metal can be converted into an alloy. How
does this increase the strength of the product?

A

Alloys contain several metals which will have
different sized atoms. This distorts the regular
arrangement of the atoms so the layers are
unable to slide over one another very easily.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why is iron alloyed with other metals to produce
alloy steels?

A

Iron is relatively brittle so it is combined with other elements
such as carbon produces a material with more desirable
qualities.
● Low carbon steel: Malleable so used for sheeting.
● High carbon steel: Hard so used for cutting tools.
● Stainless steel: Corrosion resistant so used for cutlery.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What property of copper makes it suitable to be used
in electrical cables?

A

Very good electrical conductor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What property of aluminium makes it suitable for use
in aircrafts?

A

Low density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is a key property of gold that makes it suitable
for use in jewellery?

A

Very unreactive so resist to corrosion.
Jewellery appearance will not be
affected over time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is magnalium? What is it used for?

A

Magnalium is an alloy of magnesium and
aluminium.
It is lighter and stronger than aluminium and
more resistant to corrosion. It is used for car and
aircrafts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is brass? What is it used for?

A

Brass is an alloy of copper and zinc.
Brass is hard and resistant to corrosion.
It is used for decorative hardware such
as plumbing fittings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How do you calculate the concentration of a solution
in mol dm-3?

A

Concentration (mol dm-3) = moles ÷ volume (dm3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How can you convert concentration in g dm-3 to mol
dm-3?

A

Concentration(mol dm-3) = concentration(g dm-3) ÷Mr

Mr - molecular mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Describe how to carry out an acid-alkali titration to
find the concentration of alkali

A
  1. Rinse the pipette with the solution of unknown concentration (alkali). Use
    this pipette to add a known volume of alkali to a conical flask.
  2. Add a few drops of indicator.
  3. Rinse and fill the burette with acid.
  4. Gradually add the acid to the conical flask.
  5. Record the volume in the burette when the indicator changes colour.
  6. Repeat the experiment until you have concordant results.
  7. Use results to calculate a mean titre and the concentration of alkali.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
If you know the volume of acid required to neutralise an alkali, how could you calculate the concentration of the acid, given the alkali concentration and volume?
- Calculate the number of moles of the alkali using the known volume and concentration (moles = concentration x volume). - Use the chemical equation to work out the ratio of acid and alkali that react and hence work out how many mole of acid have reacted. - Divide the moles of acid by the volume used in neutralisation to find concentration.
26
What is meant by the term theoretical yield?
The amount of product that would be collected under perfect reaction conditions.
27
How do you calculate percentage yield?
Percentage yield = (Actual yield ÷ Theoretical yield) x 100
28
What is the percentage yield of NH3 if 40.5 g of NH3 is produced from 20.0 mol H2 and excess N2?
1. Equation: N2 + 3H2 → 2NH3 2. Moles of ammonia = 20/1.5 = 13.3 moles 3. Mass of ammonia = 13.3 x (14+1+1+1) = 227 g 4. Percentage yield = (40.5/227) x 100 = 17.8%
29
Why could the actual yield of product be less than expected?
- Incomplete reaction. - Competing, unwanted side reactions. - Practical losses, for example some solid may get lost when being transferred between beakers.
30
What is the atom economy of a reaction?
Atom economy is a measure of the efficiency of the reaction. It looks at the amount of reactants that get turned into useful products.
31
How can atom economy be calculated?
Atom economy = (Mr of desired product ÷ Mr of reactants) x 100 Mr - molecular mass
32
Fill in the gap: ‘The _____ the atom economy, the more sustainable and efficient the process’
Higher
33
Why might one reaction pathway be chosen over another?
Higher atom economy. Higher yield. Faster rate. Equilibrium position favours products more. By-products are more useful / less harmful.
34
What does Avogadro’s Law state about gas volumes?
At the same temperature and pressure, equal amounts of gas will occupy the same volume.
35
What is the molar volume of a gas?
The volume occupied by one mole of molecules of any gas at room temperature and pressure.
36
What is RTP?
Room temperature and pressure: - 20 degrees C - 1 atmosphere
37
How can the molar volume of a gas be calculated? What are the units?
Molar volume = volume (dm3) ÷ moles of gas Units: dm3 mol-1
38
What is the Haber process?
A reversible reaction that forms ammonia from nitrogen and hydrogen.
39
Describe the steps that are carried out during the Haber process
1. Reactants are obtained (hydrogen from natural gas, nitrogen from air). 2. The gases are compressed to 200 atm and heated to 450oC before being pumped into a tank containing layers of catalytic iron beads. 3. Ammonia forms. 4. Ammonia and unreacted hydrogen and nitrogen pass into a cooling tank where the ammonia is collected as a liquid. 5. The unreacted hydrogen and nitrogen are recycled back into the tank.
40
What is meant by the term dynamic equilibrium?
The rate of the forward reaction equals the rate of the backwards reaction. The concentration of reactants and products are constant.
41
What is the chemical equation for the formation of ammonia from hydrogen and nitrogen?
N2 + 3H2 ⇌ 2NH3
42
What are the ideal conditions for the Haber process?
- 450 C temperature - 200 atm pressure - Iron catalyst
43
How is the rate of attainment of equilibrium affected by temperature?
A higher temperature means equilibrium is reached quicker. This is because the reacting particles have more kinetic energy so there are more frequent successful collisions.
44
How is the rate of attainment of equilibrium affected by a catalyst?
Equilibrium is reached faster when a catalyst is used because the catalyst provides an alternative reaction pathway with a lower activation energy.
45
How is the rate of attainment of equilibrium affected by pressure?
Equilibrium is reached faster with a higher pressure. This is because there are more particles in the same volume (or the same number of particles in a smaller volume) so more collisions between reacting particles.
46
How is the rate of attainment of equilibrium affected by concentration?
Equilibrium is reached faster at a higher concentration. This is because there are more particles in the same volume so more collisions between the reacting particles.
47
Why are the conditions used in the Haber process a compromise?
- A high temperature increases the rate of reaction however, it will favour the reverse reaction, decreasing the yield. A compromise of 450 degrees C is used to obtain a sufficient rate and yield. - A high pressure speeds up the rate and favours the forward reaction (increasing the yield). High pressures can be dangerous and require expensive machinery so a compromise of 200 atm is used.
48
Why is a catalyst used in the Haber process?
To increase the rate of reaction so more product is produced within the same time frame.
49
What factors should be considered before deciding the conditions for an industrial reaction?
- Availability and cost of raw materials. - Energy requirements. - Optimum temperature and pressure for high yield and fast rate of reaction. - Need for a catalyst.
50
What is the purpose of fertilisers?
To promote plant growth.
51
What chemical compounds might fertilisers contain?
Nitrogen, phosphorus and potassium compounds.
52
What compounds are found in NPK fertilisers?
A combination of all three fertiliser compounds: nitrogen, phosphorus and potassium compounds.
53
Which parts of plant growth do the compounds nitrogen, potassium and phosphorus help with?
Nitrogen: Healthy leaves. Phosphorus: Healthy roots. Potassium: Growth and healthy fruit / flowers.
54
Which ammonium salt is most commonly used in fertilisers?
Ammonium nitrate
55
How is the salt ammonium nitrate formed? Write a chemical equation for the reaction taking place
React ammonia with nitric acid NH3 + HNO3 → NH4NO3
56
What is the chemical equation for the formation of ammonium sulfate from ammonia and sulfuric acid?
2NH3 + H2SO4 → (NH4)2SO4
57
How can ammonium sulfate be prepared in a laboratory?
Titration between ammonia and sulfuric acid: - Exact volume of NH3 added to a conical flask using a pipette. - Add a few drops of indicator. - Add H2SO4 from the burette drop by drop. Stop when the indicator changes colour. - Repeat, adding the exact volumes of reactants without the indicator (as it is an impurity). - Remove the water by evaporation and crystallisation, leaving pure crystals.
58
How can ammonium sulfate be produced on an industrial scale?
Raw materials obtained from the Haber process (ammonia) and the contact process (sulfuric acid). A large reactor chamber is filled with ammonia gas. Sulfuric acid is sprayed into the chamber from above. Ammonium sulfate crystals are produced.
59
Compare the laboratory method of producing ammonium sulfate with the industrial process
Laboratory method: Faster rate of reaction. Small reactant quantities can easily be bought. Room temperature and pressure Simple equipment required. Very small yield. Industrial process: Very expensive and complex. Continuous process so continuous yield. Large volumes of product. Slow rate of reaction. High energy requirement. Other industrial processes required to obtain the reactants.
60
Describe how to set up a chemical cell. How is a voltage produced from a chemical cell?
Two metals of different reactivities are placed in an electrolyte. The more reactive metal releases electrons, becoming positively charged. The electrons flow to the other electrode which becomes negatively charged. The difference in the ability of each electrode to release electrons causes a voltage to be produced.
61
When will a chemical cell stop producing a voltage?
When one of the reactants has been used up.
62
What is a fuel cell?
A cell that continually produces a voltage as long as it is supplied with oxygen and a fuel (like hydrogen).
63
What is the only product of a hydrogen-oxygen fuel cell?
Water
64
How does a hydrogen-oxygen fuel cell work?
Hydrogen and oxygen are pumped through porous electrodes. The electrolyte is often an acid such as phosphoric acid. Hydrogen and oxygen react, producing electricity and water.
65
Write an equation for the overall reaction that takes place in a hydrogen-oxygen fuel cell
2H2 + O2 → 2H2O
66
What are the advantages of using fuel cells?
- No pollution produced. - Produce more energy than an alternative fuel like petrol. - Continuous process as long as fuel is supplied.
67
What are the disadvantages of using fuel cells?
- Materials used to make them are expensive. - High pressure tanks required to store oxygen and fuels like hydrogen. - Hydrogen is expensive and hard to store. - Efficiency is affected by temperature.

Chemistry Edexcel (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions