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Chemistry C1-C6 revision > Chemical changes > Flashcards

Chemical changes Flashcards

1
Q

What is a pH scale?

A

measures how acidic or alkaline a solution is.

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2
Q

The lower the pH means what?

A

The more acidic

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3
Q

The higher the pH means what?

A

The more alkaline

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4
Q

What pH does a Neutral substance have?

A

pH7

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5
Q

How can you measure the pH of a solution?

A

Universal indicator

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6
Q

How can you measure the pH electronically?

A

pH probe which is more accurate than an indicator

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7
Q

What ions do Acids produce in aqueous solutions?

A

Hydrogen ions (H+)

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8
Q

H+ + CL- form what?

A

HCI

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9
Q

What are bases?

A

They are chemicals with a pH greater than 7 which can neutralise acids and produce salt and water

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10
Q

What is a alkali?

A

It is a base that dissolves in water to forma solution greater than 7.

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11
Q

Name an example of bases.

A

sodium hydroxide

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12
Q

What ions do Alkali’s from in water?

A

OH- ions

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13
Q

What does a green colour show on a pH scale

A

Neutral

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14
Q

What do colours towards red show on a pH scale?

A

Show acidic solutions

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15
Q

What do colours towards Purple show on a pH scale?

A

Alkaline solutions

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16
Q

What do acids have a pH of?

A

Less than 7

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17
Q

What are solutions with a pH of 7 show?

A

It is Neutral

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18
Q

What do Alkaline’s have a pH of?

A

8-14

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19
Q

What is the Neutralization equation?

A

Acid + base - Salt + water

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20
Q

What is the symbol equation for Neutralization?

A

H+ + OH- - H2O

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21
Q

In aqueous solutions what do acid molecules do?

A

They ionize (split) and release H+

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22
Q

What are strong acids?

A

They fully ionize in aqueous solutions.

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23
Q

Name 3 strong acids?

A

Sulfuric acid
Hydrochloric acid
Nitric acid

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24
Q

How can you tell a reaction is fully ionized (strong acid)

A

Arrow goes in one direction

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25
Q

What are weak acids?

A

They do not fully ionize in solution

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26
Q

How can you tell a reaction has not fully ionized(Weak acid)?

A

Reversible arrow showing it is a reversible reaction.

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27
Q

Name 3 weak acids

A

Ethanoic acid
Citric acid
Carbonic acid

28
Q

What does pH measure?

A

The concentration of Hydrogen Ions.

29
Q

Which has a Bigger pH weak acids or Strong acids?

A

Weak acids

30
Q

As the pH scale decreases by one unit, the concentration of hydrogen ions increase by how much?

31
Q

What does the concentration of an acid tell you?

A

The amount of acid molecules in a given volume of solution.

32
Q

Hydrochloric acid + Copper oxide react together to from what?

A

Copper chloride and Water

33
Q

What do Hydrocholric acid produce ?

34
Q

What do Sulfuric acid produce ?

35
Q

What do Nitric acid produce?

36
Q

An acid + Metal react together to form what?

A

Salt + water + Carbon dioxide

37
Q

Hydrochloric acid + Copper carbonate reacts together to form what?

A

Copper chloride + water + carbon dioxide

38
Q

Acid + Metal oxide react together to form what?

A

Salt + Water

39
Q

Acid + Metal hydroxide react together to form what?

A

Salt + water

40
Q

What do metals react with water to produce?

A

Metal hydroxide + Hydrogen

41
Q

When metals react what happens?

A

they lose electrons and form a positive ion

42
Q

Sodium + water reacts together to form what?

A

Sodium hydroxide and Hydrogen

43
Q

What are ores?

A

Metal compounds

44
Q

If a metal is less reactive than carbon what reaction can you carry out

A

Reduction of Carbon removing the compound from the metal leaving pure metals behind and give carbon dioxide.

45
Q

Why can’t you use a metal more reactive than carbon when carrying out reduction?

A

Because carbon can only take oxygen away from metals which are less reactive than carbon

46
Q

What is Oil rig in terms of Electrons?

A

Oxidation is loss Reduction is gain

47
Q

What does Oxidation mean?

A

A gain of Oxygen e.g Magnesium is Oxidized to make magnesium oxide.

48
Q

What does Reduction mean?

A

A loss of Oxygen e.g. Copper oxide is reduced to copper

49
Q

What process does very reactive metals take?

A

Electrolysis

50
Q

What process does less reactive metals take?

51
Q

What is a displacement reaction?

A

When a more reactive element takes the place of a less reactive element from its compound.

52
Q

In a displacement reaction the metal ion gains electrons meaning what?

53
Q

In a displacement reaction if the metal ion loses electrons what does it mean?

A

It is Oxidized

54
Q

What is Electrolysis?

A

Splitting up with electricity

55
Q

What does Electrolysis work on?

A

A molten(Melted) ionic compound

56
Q

What is the negative electrode called?

57
Q

What is the Positive Electrode called

58
Q

When the Positive ion moves to the electrolyte it moves to the negative electrode what happens to the electrons.

A

Gains electrons meaning it is reduced

59
Q

When the negative ion in the electrolyte moves to the positive electrode what happens to electrons.

A

Loses electrons meaning is Oxidised

60
Q

Why can molten ionic compounds be electrolysed?

A

because the ions can move freely and conduct electricity

61
Q

Why is the anode regularly replaced?

A

Made from carbon and the oxygen molecules produced at the anode reacts with carbon to make carbon dioxide gas.

62
Q

Why is electrolysis expensive?

A

Melting the compounds such as aluminium oxide requires a great deal of energy
A lot of energy is required to produce the electric current.

63
Q

Water molecules ionize to form what?

A

Hydrogen and hydroxide

64
Q

When is Hydrogen produced at the cathode in aqueous solutions?

A

If the metal is more reactive than Hydrogen.

65
Q

At the anode what is usually produced?

66
Q

In electrolysis of sodium chloride produces chlorine gas why?

A

Because the chlorine ions are present in the solution

Chemistry C1-C6 revision (14 decks)

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