Combined Chemistry - C4 Chemical Changes Flashcards Preview

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Flashcards in Combined Chemistry - C4 Chemical Changes Deck (45)
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1
Q

What two non-metals are often included in the reactivity series?

A

Hydrogen and Carbon

2
Q

What is the name for the reaction that involves the gaining of oxygen?

A

Oxidation

3
Q

If an atom is very reactive, is it more or less likely to turn into an ion?

A

More likely

4
Q

What type of reaction is shown by the equation below?

magnesium + oxygen → magnesium oxide

A

Oxidation

5
Q

What is that name for the reaction that involves the removal of oxygen?

A

Reduction

6
Q

Put the following elements in order of reactivity from least to most reactive:

iron / lithium / zinc / copper / potassium / calcium / sodium / magnesium

A

(least reactive) copper – iron – zinc – magnesium – calcium – lithium – sodium – potassium (most reactive)

7
Q

Why can’t aluminium be extracted by reduction with carbon?

A

Aluminium is more reactive than carbon

8
Q

What chemical reaction is shown by the equation below to extract iron from iron oxide?

Iron oxide + carbon → iron + carbon dioxide

A

Reduction (with carbon)

9
Q

Q. Complete the general equation:

Metal + Acid →

Q. Complete the general equation:

Metal + Water →

A
  • Metal + Acid → Salt + Hydrogen
  • Metal + Water → Metal hydroxide + Hydrogen
10
Q

Q. Complete the general equation:

Acid + Metal Carbonate →

Q. Complete the general equation:

Acid + Metal oxide →

A

Acid + Metal carbonate → Salt + Water + Carbon dioxide

Acid + Metal oxide → Salt + Water

11
Q

What type of separation process would you use to separate a soluble salt?

A

Crystallisation

12
Q

What type of separation process would you use to separate an insoluble salt?

A

Filtration

13
Q

Why is gold found naturally in the Earth, but other metals are locked up in compounds?

A

Gold is unreactive

14
Q

Name the ‘salt’ produced when the following chemicals react:

a) Sodium carbonate + nitric acid
b) Magnesium oxide + sulfuric acid
c) Iron hydroxide + hydrochloric acid

*these are just examples, you need to be able to do this for any base reacting with hydrochloric, sulfuric and nitric acid.

A

a) Sodium nitrate
b) Magnesium sulfate
c) Iron chloride

15
Q

Write the formulae of the following salts using the formulae of ions provided below.

Formulae of common ions: Na+, Cl-, Mg2+

a) Sodium Chloride
b) Magnesium Chloride

*these are just examples, you need to be able to do this for any salt when given the formulae of common ions

A

a) NaCl
b) MgCl2

16
Q

Describe how you would make a pure, dry sample of a soluble salt using an insoluble base and an acid.

A
  • Add base in excess to acid.
  • Filter excess base.
  • Crystallisation – to separate salt from its solution.
17
Q

a) What is the pH range of acids?
b) What is the pH range of alkalis?
c) What is the pH of a neutral solution?

A

a) 0-6
b) 8-14
c) 7

18
Q

Name the ion found in alkaline solutions

A

Hydroxide ion, OH-

19
Q

Write an ionic equation for neutralisation

A

H+ (aq) + OH- (aq) → H2O (l)

20
Q

What is the name for the separation process shown in the diagram?

A

Electrolysis

21
Q

Name the ion found in acidic solutions

A

Hydrogen ion, H+

22
Q

What is the name for the reaction when an acid reacts with an alkali to make a salt + water?

A

Neutralisation reaction

23
Q

When there are several ions in solution, which ion will collect:

a) At the anode?
b) At the cathode?

A

a) At the cathode: Hydrogen is produced if the metal is more reactive than Hydrogen
b) At the anode: Oxygen is produced unless the solution contains halide ions, then the halogen is produced.

24
Q

What is the name for the liquid that contains the ions in the electrolysis process?

A

Electrolyte

25
Q

In electrolysis, what is the positive electrode called?

A

Anode

26
Q

To which electrode are positive ions attracted to?

A

Negative electrode (opposites attract)

27
Q

In the electrolysis of lead bromide, what collects at:

a) The positive electrode (the anode)?
b) The negative electrode (the cathode)?

A
  • Bromine (at the anode)
  • Lead (at the cathode)
28
Q

Why must aluminium be extracted by electrolysis?

A

It is more reactive than carbon (and therefore can’t be extracted by reduction with carbon)

29
Q

In electrolysis, what is the negative electrode called?

A

Cathode

30
Q

To which electrode are negative ions attracted to?

A

Positive electrode (opposites attract)

31
Q

Why does a metal compound have to be molten or dissolved for electrolysis to work?

A

Because the ions need to be free to flow

32
Q

Why is cryolite used in the electrolysis of aluminium oxide?

A

To lower the melting point of aluminium oxide (to save energy and costs)

33
Q

Why does the positive electrode have to be regularly replaced in the extraction of aluminium oxide?

A
  • Because oxide ions react with the carbon electrode…
  • …Releasing CO2
  • …Meaning the electrodes gradually degrade
34
Q

Higher Q. Fill in the blanks:

Oxidation is the _____ of electrons.

Reduction is the _____ of electrons.

A
  • Oxidation is the loss of electrons
  • Reduction is the gain of electrons
35
Q

Higher Q. In the following equation, state which species are oxidised and which are reduced?

2Fe2O3 + 3C → 4Fe + 3CO2

*this is just an example, you need to be able to do this for any given reaction.

A
  • 2Fe2O3 (Iron oxide) is reduced
  • 3C (carbon) is oxidised
36
Q

Higher Q. Explain why the reaction below is a redox reaction.

Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2 (g)

A
  • Zinc atoms are oxidised.
  • Hydrogen atoms are reduced.
  • Hence reduction and oxidation happen at the same time so it’s called a redox reaction.
37
Q

Higher Q. Write an ionic equation for each of the displacement reactions below:

a) Mg + CuSO4 → Cu + MgSO4
b) Fe + CuCl2 → Cu + FeCl2

*these are just examples, you need to be able to do this for any displacement reaction.

A

a) Mg(s) + Cu2+(aq)→ Cu(s) + Mg2+(aq)
b) Fe(s) + Cu2+(aq) → Cu(s) + Fe2+ (aq)

38
Q

Higher Q. In the following equation, state which species are oxidised and which are reduced?

a) Mg (s) + 2HCl (aq) → MgCl2 (aq) + H2 (g)

*this is just an example, you need to be able to do this for reactions between the following metals (magnesium, zinc, iron) and the following acids (hydrochloric and sulfuric)

A
  • Magnesium atoms (Mg) are oxidised.
  • Hydrogen ions (H+) are reduced.
39
Q

Higher Q. During electrolysis, what happens to ions at the:

a) Cathode?
b) Anode?

A
  • At the Cathode: Ions gain electrons and turn into atoms (Reduction)
  • At the Anode: Ions lose electrons and turn into atoms (Oxidation)
40
Q

Higher Q. Write half equations at the anode and cathode for the electrolysis of water.

A

Anode: 4OH- - 4e- → O2 + 2H2O

or 4OH- → O2 + 2H2O + 4e-

Cathode: 2H+ + 2e- → H2

41
Q

Higher Q. Give two examples of strong acids and two examples of weak acids.

A
  • Strong acids include: Hydrochloric, Nitric and Sulfuric
  • Weak acids include: Carbonic, Ethanoic and Citric
42
Q

Higher Q. What is a ‘weak’ acid?

A

An acid that is only partially ionised in water

43
Q

Higher Q. If you compared the pH of a 1M Strong Acid and a 1M Weak acid, which would have the higher pH and why?

A

The weaker acid will have the higher pH because it only partially ionises in water (or vice versa).

44
Q

Higher Q. As the hydrogen ion concentration of a solution increases by a factor of 10, what happens to the pH of the solution?

A

The pH decreases by 1 unit

45
Q

Higher Q. Write the half equations at the anode and cathode for the electrolysis of lead bromide.

*this is just an example, you need to be able to do this for any given electrolysis example.

A

Anode: 2Br- - 2e- → Br2 or 2Br- → Br2 + 2e-

Cathode: Pb2+ + 2e- → Pb