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Aqa Gcse Chemistry > Paper 1 - Topic 4, Chemical Changes > Flashcards

Paper 1 - Topic 4, Chemical Changes Flashcards

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1
Q

What do acids produce in aqueous solutions

A

Hydrogen ions (H+)

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2
Q

What’s the pH range for an acid

A

0-6

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3
Q

What do alkalis produce in aqueous solutions

A

Hydroxide ions (OH-)

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4
Q

What is the pH range for alkalis

A

8-14

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5
Q

What is crystallisation

A

A separation technique used to produce solid crystals from a solution by evaporating the solvent

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6
Q

What is displacement

A

A chemical reaction in which more reactive element displaces a less reactive element from its compound

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7
Q

What is electrolysis

A

The splitting up of an ionic compound using electricity, the electric current is passed through a substance causing chemical reactions at the electrodes and the decomposition of the materials

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8
Q

What is an electrolyte

A

A solution containing free ions from the molten or dissolved ionic substance, the ions are free to move to carry charge

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9
Q

What are extraction techniques used for

A

Extraction techniques are used to separate a desired substance when it is mixed with others

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10
Q

What is filtration

A

A separation technique used to separate solids from liquids

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11
Q

What happens at the negative electrode (cathode)

A

Hydrogen is produced if the metal in the electrolyte is more reactive than hydrogen and positively charged ions gain electrons, this is a reduction reaction

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12
Q

What is neutralisation

A

The reaction when an acid and a base react to form water and a salt

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13
Q

What is oxidation

A

A reaction involving gaining oxygen, oxidation is the loss of electrons

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14
Q

What is the pH scale used for

A

To measure the acidity or alkalinity of a solution and can be measure using a universal indicator or a pH probe

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15
Q

What happens at the positive electrode (anode)

A

Oxygen is produced at the anode unless the solution contains halide ions then the halogen is produced, it is where negatively charged ions lose electrons, this is an oxidation reaction

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16
Q

What is a redox reaction

A

A reaction in which both oxidation and reduction occurs simultaneously

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17
Q

What is reduction

A

A reaction invoking the loss of oxygen, reduction is the gain of electrons

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18
Q

What is reduction with carbon

A

Where metals less reactive than carbon can be extracted from their oxides by reduction with carbon

19
Q

What is a strong acid

A

A strong acid is completely ionised in aqueous solution, examples are hydrochloric acid and sulphuric acids

20
Q

What is the reactivity series

A

Metals arranged in order of their reactivity, this can be used to predict products from reactions

21
Q

What is titration

A

A technique used where a solution of known concentration is used to determine the concentration of an unknown solution

22
Q

What is a Universal indicator

A

A mixture of dyes that changes colour gradually over a range of pH and is used for testing for acids and alkalis

23
Q

What is a weak acid

A

A weak acid is only partially ionised in aqueous solution, examples are acid ethanoic and carbonic acids

24
Q

How are unreactive metals found in Earth

A

In their natural state

25
Q

How are metals more reactive than carbon extracted

A

By electrolysis

26
Q

What is the general equation for a reaction between metals and acids

A

Metal + acid —> salt + hydrogen
This is a redox reaction and a displacement reaction

27
Q

Which metals in the reactivity series will react with acid

A

Those above hydrogen

28
Q

What is the general equation for a neutralisation reaction

A

Base + acid —> salt + water

29
Q

What is the general reaction between metal carbonate and acid

A

Metal carbonate + acid —> salt+ water + carbon dioxide

30
Q

What is the general reaction between metal oxides and acids

A

Metal oxide + acid —> a salt + water

31
Q

What are bases

A

Compounds that neutralise acids

32
Q

General equation for a neutralisation reaction in short, ionic form

A

H+ + OH- —> H 2O

33
Q

What happens to the pH as concentration of H + increases

A

The pH decreases

34
Q

What is a concentrated acid

A

Has more moles of acid per unit volume than dilute

35
Q

What does the ‘strength’ of an acid refer to

A

Refers to whether the acid is completely ionised in water or only partially

36
Q

What is a cathode

A

Negative elctrode

37
Q

What is an anode

A

Positive electrode

38
Q

How is aluminium manufactured and why is it so expensive

A

Aluminium made through electrolysis of aluminium oxide and cryolite
Lots of energy is needed to produce the current in electrolysis which makes this process expensive

39
Q

What are the half equations in the extraction of aluminium

A

Al 3+ + 3e - —> Al (cathode)
2O 2- —> O 2 + 4e - (anode)

40
Q

Why is cryolite used in manufacturing of aluminium

A

It lowers the melting point of aluminium oxide, reducing energy costs

41
Q

What is the order of the reactivity series from most reactive to least reactive

A
  • potassium
  • sodium
  • lithium
  • calcium
  • magnesium
  • carbon
  • zinc
  • iron
  • hydrogen
  • copper
42
Q

Describe potassium, sodium, lithium and calcium’s reaction with water

A
  • potassium = violent
  • sodium = very quick
  • lithium = quick
  • calcium = more slow
43
Q

Describe calcium, magnesium, zinc, iron and copper’s reaction with dilute acid

A
  • calcium = very quick
  • magnesium = quick
  • zinc = fairly slow
  • iron = more slow
  • copper = very slow

Aqa Gcse Chemistry (10 decks)

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