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Flashcards in C6 - Chemistry Out There Deck (182):
1

What is reduction?

Gain of electrons

2

What does an oxidising agent do?

Accept electrons and gets reduced

3

What does a reducing agent do?

Donate electrons and get oxidised

4

What does displacement reactions involve?

One metal kicking another one out of a compound

5

What is the rule for displacement reactions?

A more reactive metal will displace a less reactive metal from its compound

6

Why do some iron and steels rust?

When they come into contact with air and water

7

When does rusting of iron only occur?

When iron is in contact with both water and oxygen

8

What is rust a form of?

Hydrated iron (III) oxide

9

What is the equation for rusting?

Iron + oxygen + water -> hydrated iron (III) oxide

10

What type of reaction is rusting of iron?

Redox

11

What happens to iron when it reacts with oxygen?

Loses electrons - oxidised. Each Fe atom loses 3 electrons to become Fe3+.

12

What happens to oxygen when it reacts with iron?

Reduced. Each O atom gains 2 electrons to become O2-.

13

What are the 4 ways to prevent rusting?

Make alloys. Barrier. Tin coating/plating. More reactive metals (galvanising)

14

What are steels alloys of?

Iron with carbon and small quantities of other metals

15

What is stainless steel?

One of most common steels - rustproof alloy of iron, carbon and chromium.

16

How does a barrier prevent rusting?

Keeps out water, oxygen or both.

17

How is painting ideal to prevent rusting?

Ideal for large and small structures. Nice and colourful.

18

How is oiling or greasing used to prevent rusting?

Has to be used when moving parts are involved e.g. Bike chains

19

What is tin plating?

A coat of tin is applied to the object e.g. Food cans.

20

How does tin plating prevent rusting?

Acts as a barrier, stopping water and oxygen from reaching iron surface.

21

Tin plating only as long as...

Tin remains intact. If scratched, iron will lose electrons and rust even faster.

22

Why is it not always a good idea to buy reduced bashed tins?

They could be starting to rust.

23

How does the sacrificial method work?

Place a more reactive metal with the iron. Water and oxygen react with the sacrificial metal instead of iron.

24

What is galvanising?

A coat of zinc put on object. Zinc is sacrificial protection - more reactive - loses electrons in preference to iron.

25

What sort of items are galvanised?

Steel buckets and corrugated iron roofing

26

How can blocks of metal prevent rusting?

E.g. Magnesium can be bolted onto iron. Magnesium loses electrons in preference to iron.

27

When are block of metal used on items?

Hulls of ships and underground iron pipes.

28

What is oxidation?

Loss of electrons

29

What does electrolysis mean?

Breaking down a substance with electricity

30

How does electrolysis work?

Electric current passed through a molten or dissolved ionic compound, causing it to decompose. This creates a flow of charge through the electrolyte.

31

What happens to the positive ions in electrolysis?

Move towards the cathode (-ve) and gain electrons.

32

What happens to negative ions in electrolysis?

Move towards anode (+ve) and lose electrons

33

What happens in electrolysis when ions lose or gain electrons?

They become atoms or molecules and are discharged from the solution at the electrodes.

34

What is the ionic equation at the anode during electrolysis of copper (II) sulfate?

4OH- - 4e- → O2 + 2H2O

35

What is the ionic equation at the cathode during electrolysis of copper (II) sulfate?

Cu2+ + 2e- → Cu

36

What are ions are there in aqueous solutions?

Hydrogen ions (H+), hydroxide ions (OH-) and ions from the solute (ionic compounds)

37

What is it sometimes easier to do in electrolysis?

Discharge ions from the water instead of from the solute

38

What does discharging ions from the water instead of the solute do in electrolysis?

Produce hydrogen at the cathode and oxygen at the anode.

39

What ions does a solution of aqueous sulfuric acid contain?

SO42- , H+ , OH-

40

What is the equation at the cathode for electrolysis with sulfuric acid?

2H+ + 2e- → H2

41

What is the equation at the anode for electrolysis with sulfuric acid?

4OH- - 4e- → O2 + 2H2O

42

What reaction takes place at the anode?

Oxidation

43

What reaction takes place at the cathode?

Reduction

44

Where is hydrogen produced in electrolysis?

Cathode

45

Where is oxygen produced in electrolysis?

Anode

46

What is the reaction at the cathode for the electrolysis of copper(II) sulfate solution?

Cu2+ + 2e- → Cu

47

What is the reaction at the anode for the electrolysis of copper(II) sulfate solution?

4OH- - 4e- -> O2 + 2H2O

48

What charge does the cathode have?

Negative

49

What charge does the anode have?

Positive

50

What happens when chlorine gas is passed through a solution of iron(II) salt?

Solution turns from green to yellow

51

Why does the solution change colour when chlorine gas is passed through a solution of iron(II) salt?

Iron (II) ion is oxidised to iron (III). Fe2+ ion loses an electron to form Fe3+

52

What causes the reaction to oxidise and turn a different colour when chlorine gas is passed through a solution of iron(II) salt?

Oxidising agent - chlorine gas

53

What must be the reducing agent when chlorine gas is passed through a solution of iron(II) salt?

Iron (II) ion

54

What happens to the chlorine when chlorine gas is passed through a solution of iron(II) salt?

Chlorine gains the electron Fe2+ lost. Chlorine reduced.

55

When iron atoms are reacted with dilute acid how are iron (II) ions formed?

When iron atoms are oxidised.

56

When iron atoms are reacted with dilute acid what happens to the iron atoms?

Lose electrons - oxidised by hydrogen ions

57

When iron atoms are reacted with dilute acid what happens to the hydrogen atoms?

Gain electrons - reduced by iron atoms.

58

What is the order of reactivity for zinc, iron, magnesium and tin/copper from most reactive to least reactive?

Magnesium, zinc, iron, tin/copper.

59

What happens to metal ions in displacement reactions?

Gain electrons - are reduced

60

What happens to the metal atoms in displacement reactions?

Loses electrons - are oxidised

61

What happens between hard water and soap?

Doesn't lather. Makes scum

62

What do you need to do to get a good lather with hard water?

Add more soap, use softer water.

63

What does hard water form on pipes/kettles/boilers?

Limescale (calcium carbonate)

64

What does limescale act as?

Thermal insulator

65

How is a kettle with limescale different to a clean kettle?

Kettle with limescale in heating element will take longer to boil.

66

What can limescale eventually do to pipes?

Block them

67

What does hard water contain?

Calcium ions (Ca2+), magnesium ions (Mg2+), or both.

68

What happens as water flows over rocks and through soil?

The soils/rocks contain Ca and Mg compounds - these ions dissolve in the water.

69

What does magnesium sulfate dissolve in?

Water

70

What does calcium carbonate commonly exist as?

Chalk, limestone and marble.

71

Does calcium carbonate dissolve in water?

No but reacts with acids.

72

How do we know rainwater is slightly acidic?

Carbon dioxide from air dissolves in rainwater forming carbonic acid.

73

What is the word equation when rainwater reacts with carbon dioxide?

Carbon dioxide + water → carbonic acid

74

What is the symbol equation when rainwater reacts with carbon dioxide?

CO2 + H2O -> H2CO3

75

What is the molecular formula of carbonic acid?

H2CO3

76

What can rainwater react with to form calcium hydrogencarbonate?

Calcium carbonate

77

What is the word equation for producing calcium hydrogencarbonate?

Carbon dioxide + water + calcium carbonate → calcium hydrogencarbonate

78

What is the symbol equation for producing calcium hydrogencarbonate?

H2CO3 + CaCO3 → Ca(HCO3)2

79

What are the two types of hardness?

Temporary and permanent

80

What is temporary hardness caused by?

Hydrogencarbonate ion (HCO3-) in Ca(HCO3)2

81

What is permanent hardness caused by?

Dissolved calcium sulfate (amongst other things)

82

How is temporary hardness removed?

By boiling

83

What does boiling do to temporary hardness?

Calcium hydrogencarbonate decomposes to form insoluble calcium carbonate.

84

Why doesn't boiling remove permanent hardness?

Calcium carbonate precipitate (limescale) is insoluble

85

What is the word equation for removing temporary hardness?

Calcium hydrogencarbonate → calcium carbonate + water + carbon dioxide

86

What is the symbol equation for removing temporary hardness?

Ca(HCO3)2 (aq) → CaCO3 (s) + H2O (l) + CO2 (g)

87

How can bot types of hardness be removed?

Using washing soda (sodium carbonate, NaCO3) or by 'ion exchange resin'.

88

How does NaCO3 remove both types of hardness?

Carbonate ions join to calcium ions to make insoluble precipitate of calcium carbonate. Works whether hardness is due to calcium sulfate or calcium hydrogencarbonate.

89

What is the ionic equation for removing hardness with sodium carbonate?

Ca2+ (aq) + CO32- (aq) → CaCO3 (s)

90

How does 'ion exchange resin work'?

Lots of sodium ions (or hydrogen ions) and these are exchanged for calcium or magnesium ions.

91

What is the method for comparing the hardness of water samples?

  1. 100cm3 of water - conical flask
  2. Add 1cm3 of soap solution. Bung in and shake.
  3. Repeat until lasting lather formed (bubbles cover surface for at least 30 secs)
  4. Record amount of soap needed.

92

Gain of electrons

What is reduction?

93

Accept electrons and gets reduced

What does an oxidising agent do?

94

Donate electrons and get oxidised

What does a reducing agent do?

95

One metal kicking another one out of a compound

What does displacement reactions involve?

96

A more reactive metal will displace a less reactive metal from its compound

What is the rule for displacement reactions?

97

When they come into contact with air and water

Why do some iron and steels rust?

98

When iron is in contact with both water and oxygen

When does rusting of iron only occur?

99

Hydrated iron (III) oxide

What is rust a form of?

100

Iron + oxygen + water -> hydrated iron (III) oxide

What is the equation for rusting?

101

Redox

What type of reaction is rusting of iron?

102

Loses electrons - oxidised. Each Fe atom loses 3 electrons to become Fe3+.

What happens to iron when it reacts with oxygen?

103

Reduced. Each O atom gains 2 electrons to become O2-.

What happens to oxygen when it reacts with iron?

104

Make alloys. Barrier. Tin coating/plating. More reactive metals (galvanising)

What are the 4 ways to prevent rusting?

105

Iron with carbon and small quantities of other metals

What are steels alloys of?

106

One of most common steels - rustproof alloy of iron, carbon and chromium.

What is stainless steel?

107

Keeps out water, oxygen or both.

How does a barrier prevent rusting?

108

Ideal for large and small structures. Nice and colourful.

How is painting ideal to prevent rusting?

109

Has to be used when moving parts are involved e.g. Bike chains

How is oiling or greasing used to prevent rusting?

110

A coat of tin is applied to the object e.g. Food cans.

What is tin plating?

111

Acts as a barrier, stopping water and oxygen from reaching iron surface.

How does tin plating prevent rusting?

112

Tin remains intact. If scratched, iron will lose electrons and rust even faster.

Tin plating only as long as...

113

They could be starting to rust.

Why is it not always a good idea to buy reduced bashed tins?

114

Place a more reactive metal with the iron. Water and oxygen react with the sacrificial metal instead of iron.

How does the sacrificial method work?

115

A coat of zinc put on object. Zinc is sacrificial protection - more reactive - loses electrons in preference to iron.

What is galvanising?

116

Steel buckets and corrugated iron roofing

What sort of items are galvanised?

117

E.g. Magnesium can be bolted onto iron. Magnesium loses electrons in preference to iron.

How can blocks of metal prevent rusting?

118

Hulls of ships and underground iron pipes.

When are block of metal used on items?

119

Loss of electrons

What is oxidation?

120

Breaking down a substance with electricity

What does electrolysis mean?

121

Electric current passed through a molten or dissolved ionic compound, causing it to decompose. This creates a flow of charge through the electrolyte.

How does electrolysis work?

122

Move towards the cathode (-ve) and gain electrons.

What happens to the positive ions in electrolysis?

123

Move towards anode (+ve) and lose electrons

What happens to negative ions in electrolysis?

124

They become atoms or molecules and are discharged from the solution at the electrodes.

What happens in electrolysis when ions lose or gain electrons?

125

4OH- - 4e- → O2 + 2H2O

What is the ionic equation at the anode during electrolysis of copper (II) sulfate?

126

Cu2+ + 2e- → Cu

What is the ionic equation at the cathode during electrolysis of copper (II) sulfate?

127

Hydrogen ions (H+), hydroxide ions (OH-) and ions from the solute (ionic compounds)

What are ions are there in aqueous solutions?

128

Discharge ions from the water instead of from the solute

What is it sometimes easier to do in electrolysis?

129

Produce hydrogen at the cathode and oxygen at the anode.

What does discharging ions from the water instead of the solute do in electrolysis?

130

SO42- , H+ , OH-

What ions does a solution of aqueous sulfuric acid contain?

131

2H+ + 2e- → H2

What is the equation at the cathode for electrolysis with sulfuric acid?

132

4OH- - 4e- → O2 + 2H2O

What is the equation at the anode for electrolysis with sulfuric acid?

133

Oxidation

What reaction takes place at the anode?

134

Reduction

What reaction takes place at the cathode?

135

Cathode

Where is hydrogen produced in electrolysis?

136

Anode

Where is oxygen produced in electrolysis?

137

Cu2+ + 2e- → Cu

What is the reaction at the cathode for the electrolysis of copper(II) sulfate solution?

138

4OH- - 4e- -> O2 + 2H2O

What is the reaction at the anode for the electrolysis of copper(II) sulfate solution?

139

Negative

What charge does the cathode have?

140

Positive

What charge does the anode have?

141

Solution turns from green to yellow

What happens when chlorine gas is passed through a solution of iron(II) salt?

142

Iron (II) ion is oxidised to iron (III). Fe2+ ion loses an electron to form Fe3+

Why does the solution change colour when chlorine gas is passed through a solution of iron(II) salt?

143

Oxidising agent - chlorine gas

What causes the reaction to oxidise and turn a different colour when chlorine gas is passed through a solution of iron(II) salt?

144

Iron (II) ion

What must be the reducing agent when chlorine gas is passed through a solution of iron(II) salt?

145

Chlorine gains the electron Fe2+ lost. Chlorine reduced.

What happens to the chlorine when chlorine gas is passed through a solution of iron(II) salt?

146

When iron atoms are oxidised.

When iron atoms are reacted with dilute acid how are iron (II) ions formed?

147

Lose electrons - oxidised by hydrogen ions

When iron atoms are reacted with dilute acid what happens to the iron atoms?

148

Gain electrons - reduced by iron atoms.

When iron atoms are reacted with dilute acid what happens to the hydrogen atoms?

149

Magnesium, zinc, iron, tin/copper.

What is the order of reactivity for zinc, iron, magnesium and tin/copper from most reactive to least reactive?

150

Gain electrons - are reduced

What happens to metal ions in displacement reactions?

151

Loses electrons - are oxidised

What happens to the metal atoms in displacement reactions?

152

Doesn't lather. Makes scum

What happens between hard water and soap?

153

Add more soap, use softer water.

What do you need to do to get a good lather with hard water?

154

Limescale (calcium carbonate)

What does hard water form on pipes/kettles/boilers?

155

Thermal insulator

What does limescale act as?

156

Kettle with limescale in heating element will take longer to boil.

How is a kettle with limescale different to a clean kettle?

157

Block them

What can limescale eventually do to pipes?

158

Calcium ions (Ca2+), magnesium ions (Mg2+), or both.

What does hard water contain?

159

The soils/rocks contain Ca and Mg compounds - these ions dissolve in the water.

What happens as water flows over rocks and through soil?

160

Water

What does magnesium sulfate dissolve in?

161

Chalk, limestone and marble.

What does calcium carbonate commonly exist as?

162

No but reacts with acids.

Does calcium carbonate dissolve in water?

163

Carbon dioxide from air dissolves in rainwater forming carbonic acid.

How do we know rainwater is slightly acidic?

164

Carbon dioxide + water → carbonic acid

What is the word equation when rainwater reacts with carbon dioxide?

165

CO2 + H2O -> H2CO3

What is the symbol equation when rainwater reacts with carbon dioxide?

166

H2CO3

What is the molecular formula of carbonic acid?

167

Calcium carbonate

What can rainwater react with to form calcium hydrogencarbonate?

168

Carbon dioxide + water + calcium carbonate → calcium hydrogencarbonate

What is the word equation for producing calcium hydrogencarbonate?

169

H2CO3 + CaCO3 → Ca(HCO3)2

What is the symbol equation for producing calcium hydrogencarbonate?

170

Temporary and permanent

What are the two types of hardness?

171

Hydrogencarbonate ion (HCO3-) in Ca(HCO3)2

What is temporary hardness caused by?

172

Dissolved calcium sulfate (amongst other things)

What is permanent hardness caused by?

173

By boiling

How is temporary hardness removed?

174

Calcium hydrogencarbonate decomposes to form insoluble calcium carbonate.

What does boiling do to temporary hardness?

175

Calcium carbonate precipitate (limescale) is insoluble

Why doesn't boiling remove permanent hardness?

176

Calcium hydrogencarbonate → calcium carbonate + water + carbon dioxide

What is the word equation for removing temporary hardness?

177

Ca(HCO3)2 (aq) → CaCO3 (s) + H2O (l) + CO2 (g)

What is the symbol equation for removing temporary hardness?

178

Using washing soda (sodium carbonate, NaCO3) or by 'ion exchange resin'.

How can bot types of hardness be removed?

179

Carbonate ions join to calcium ions to make insoluble precipitate of calcium carbonate. Works whether hardness is due to calcium sulfate or calcium hydrogencarbonate.

How does NaCO3 remove both types of hardness?

180

Ca2+ (aq) + CO32- (aq) → CaCO3 (s)

What is the ionic equation for removing hardness with sodium carbonate?

181

Lots of sodium ions (or hydrogen ions) and these are exchanged for calcium or magnesium ions.

How does 'ion exchange resin work'?

182

  1. 100cm3 of water - conical flask
  2. Add 1cm3 of soap solution. Bung in and shake.
  3. Repeat until lasting lather formed (bubbles cover surface for at least 30 secs)
  4. Record amount of soap needed.

What is the method for comparing the hardness of water samples?