C6 - Chemistry Out There

Question 1

C6 - Chemistry Out There

What is reduction?

Answer 1

Gain of electrons

Question 2

C6 - Chemistry Out There

What does an oxidising agent do?

Answer 2

Accept electrons and gets reduced

Question 3

C6 - Chemistry Out There

What does a reducing agent do?

Answer 3

Donate electrons and get oxidised

Question 4

C6 - Chemistry Out There

What does displacement reactions involve?

Answer 4

One metal kicking another one out of a compound

Question 5

C6 - Chemistry Out There

What is the rule for displacement reactions?

Answer 5

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

Question 6

C6 - Chemistry Out There

Why do some iron and steels rust?

Answer 6

When they come into contact with air and water

Question 7

C6 - Chemistry Out There

When does rusting of iron only occur?

Answer 7

When iron is in contact with both water and oxygen

Question 8

C6 - Chemistry Out There

What is rust a form of?

Answer 8

Hydrated iron (III) oxide

Question 9

C6 - Chemistry Out There

What is the equation for rusting?

Answer 9

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

Question 10

C6 - Chemistry Out There

What type of reaction is rusting of iron?

Answer 10

Redox

Question 11

C6 - Chemistry Out There

What happens to iron when it reacts with oxygen?

Answer 11

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

Question 12

C6 - Chemistry Out There

What happens to oxygen when it reacts with iron?

Answer 12

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

Question 13

C6 - Chemistry Out There

What are the 4 ways to prevent rusting?

Answer 13

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

Question 14

C6 - Chemistry Out There

What are steels alloys of?

Answer 14

Iron with carbon and small quantities of other metals

Question 15

C6 - Chemistry Out There

What is stainless steel?

Answer 15

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

Question 16

C6 - Chemistry Out There

How does a barrier prevent rusting?

Answer 16

Keeps out water, oxygen or both.

Question 17

C6 - Chemistry Out There

How is painting ideal to prevent rusting?

Answer 17

Ideal for large and small structures. Nice and colourful.

Question 18

C6 - Chemistry Out There

How is oiling or greasing used to prevent rusting?

Answer 18

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

Question 19

C6 - Chemistry Out There

What is tin plating?

Answer 19

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

Question 20

C6 - Chemistry Out There

How does tin plating prevent rusting?

Answer 20

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

Question 21

C6 - Chemistry Out There

Tin plating only as long as…

Answer 21

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

Question 22

C6 - Chemistry Out There

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

Answer 22

They could be starting to rust.

Question 23

C6 - Chemistry Out There

How does the sacrificial method work?

Answer 23

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

Question 24

C6 - Chemistry Out There

What is galvanising?

Answer 24

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

Question 25

# C6 - Chemistry Out There What sort of items are galvanised?

Answer 25

Steel buckets and corrugated iron roofing

Question 26

# C6 - Chemistry Out There How can blocks of metal prevent rusting?

Answer 26

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

Question 27

# C6 - Chemistry Out There When are block of metal used on items?

Answer 27

Hulls of ships and underground iron pipes.

Question 28

# C6 - Chemistry Out There What is oxidation?

Answer 28

Loss of electrons

Question 29

# C6 - Chemistry Out There What does electrolysis mean?

Answer 29

Breaking down a substance with electricity

Question 30

# C6 - Chemistry Out There How does electrolysis work?

Answer 30

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

Question 31

# C6 - Chemistry Out There What happens to the positive ions in electrolysis?

Answer 31

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

Question 32

# C6 - Chemistry Out There What happens to negative ions in electrolysis?

Answer 32

Move towards anode (+ve) and lose electrons

Question 33

# C6 - Chemistry Out There What happens in electrolysis when ions lose or gain electrons?

Answer 33

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

Question 34

# C6 - Chemistry Out There What is the ionic equation at the anode during electrolysis of copper (II) sulfate?

Answer 34

4OH^- - 4e^- → O₂ + 2H₂O

Question 35

# C6 - Chemistry Out There What is the ionic equation at the cathode during electrolysis of copper (II) sulfate?

Answer 35

Cu²⁺ + 2e^- → Cu

Question 36

# C6 - Chemistry Out There What are ions are there in aqueous solutions?

Answer 36

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

Question 37

# C6 - Chemistry Out There What is it sometimes easier to do in electrolysis?

Answer 37

Discharge ions from the water instead of from the solute

Question 38

# C6 - Chemistry Out There What does discharging ions from the water instead of the solute do in electrolysis?

Answer 38

Produce hydrogen at the cathode and oxygen at the anode.

Question 39

# C6 - Chemistry Out There What ions does a solution of aqueous sulfuric acid contain?

Answer 39

SO₄^2- , H⁺ , OH^-

Question 40

# C6 - Chemistry Out There What is the equation at the cathode for electrolysis with sulfuric acid?

Answer 40

2H⁺ + 2e^- → H₂

Question 41

# C6 - Chemistry Out There What is the equation at the anode for electrolysis with sulfuric acid?

Answer 41

4OH^- - 4e^- → O₂ + 2H₂O

Question 42

# C6 - Chemistry Out There What reaction takes place at the anode?

Answer 42

Oxidation

Question 43

# C6 - Chemistry Out There What reaction takes place at the cathode?

Answer 43

Reduction

Question 44

# C6 - Chemistry Out There Where is hydrogen produced in electrolysis?

Answer 44

Cathode

Question 45

# C6 - Chemistry Out There Where is oxygen produced in electrolysis?

Answer 45

Anode

Question 46

# C6 - Chemistry Out There What is the reaction at the cathode for the electrolysis of copper(II) sulfate solution?

Answer 46

Cu²⁺ + 2e^- → Cu

Question 47

# C6 - Chemistry Out There What is the reaction at the anode for the electrolysis of copper(II) sulfate solution?

Answer 47

4OH^- - 4e^- -\> O₂ + 2H₂O

Question 48

# C6 - Chemistry Out There What charge does the cathode have?

Answer 48

Negative

Question 49

# C6 - Chemistry Out There What charge does the anode have?

Answer 49

Positive

Question 50

# C6 - Chemistry Out There What happens when chlorine gas is passed through a solution of iron(II) salt?

Answer 50

Solution turns from green to yellow

Question 51

# C6 - Chemistry Out There Why does the solution change colour when chlorine gas is passed through a solution of iron(II) salt?

Answer 51

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

Question 52

# C6 - Chemistry Out There What causes the reaction to oxidise and turn a different colour when chlorine gas is passed through a solution of iron(II) salt?

Answer 52

Oxidising agent - chlorine gas

Question 53

# C6 - Chemistry Out There What must be the reducing agent when chlorine gas is passed through a solution of iron(II) salt?

Answer 53

Iron (II) ion

Question 54

# C6 - Chemistry Out There What happens to the chlorine when chlorine gas is passed through a solution of iron(II) salt?

Answer 54

Chlorine gains the electron Fe²⁺ lost. Chlorine reduced.

Question 55

# C6 - Chemistry Out There When iron atoms are reacted with dilute acid how are iron (II) ions formed?

Answer 55

When iron atoms are oxidised.

Question 56

# C6 - Chemistry Out There When iron atoms are reacted with dilute acid what happens to the iron atoms?

Answer 56

Lose electrons - oxidised by hydrogen ions

Question 57

# C6 - Chemistry Out There When iron atoms are reacted with dilute acid what happens to the hydrogen atoms?

Answer 57

Gain electrons - reduced by iron atoms.

Question 58

# C6 - Chemistry Out There What is the order of reactivity for zinc, iron, magnesium and tin/copper from most reactive to least reactive?

Answer 58

Magnesium, zinc, iron, tin/copper.

Question 59

# C6 - Chemistry Out There What happens to metal ions in displacement reactions?

Answer 59

Gain electrons - are reduced

Question 60

# C6 - Chemistry Out There What happens to the metal atoms in displacement reactions?

Answer 60

Loses electrons - are oxidised

Question 61

# C6 - Chemistry Out There What happens between hard water and soap?

Answer 61

Doesn't lather. Makes scum

Question 62

# C6 - Chemistry Out There What do you need to do to get a good lather with hard water?

Answer 62

Add more soap, use softer water.

Question 63

# C6 - Chemistry Out There What does hard water form on pipes/kettles/boilers?

Answer 63

Limescale (calcium carbonate)

Question 64

# C6 - Chemistry Out There What does limescale act as?

Answer 64

Thermal insulator

Question 65

# C6 - Chemistry Out There How is a kettle with limescale different to a clean kettle?

Answer 65

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

Question 66

# C6 - Chemistry Out There What can limescale eventually do to pipes?

Answer 66

Block them

Question 67

# C6 - Chemistry Out There What does hard water contain?

Answer 67

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

Question 68

# C6 - Chemistry Out There What happens as water flows over rocks and through soil?

Answer 68

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

Question 69

# C6 - Chemistry Out There What does magnesium sulfate dissolve in?

Answer 69

Water

Question 70

# C6 - Chemistry Out There What does calcium carbonate commonly exist as?

Answer 70

Chalk, limestone and marble.

Question 71

# C6 - Chemistry Out There Does calcium carbonate dissolve in water?

Answer 71

No but reacts with acids.

Question 72

# C6 - Chemistry Out There How do we know rainwater is slightly acidic?

Answer 72

Carbon dioxide from air dissolves in rainwater forming carbonic acid.

Question 73

# C6 - Chemistry Out There What is the word equation when rainwater reacts with carbon dioxide?

Answer 73

Carbon dioxide + water → carbonic acid

Question 74

# C6 - Chemistry Out There What is the symbol equation when rainwater reacts with carbon dioxide?

Answer 74

CO₂ + H₂O -\> H₂CO₃

Question 75

# C6 - Chemistry Out There What is the molecular formula of carbonic acid?

Answer 75

H₂CO₃

Question 76

# C6 - Chemistry Out There What can rainwater react with to form calcium hydrogencarbonate?

Answer 76

Calcium carbonate

Question 77

# C6 - Chemistry Out There What is the word equation for producing calcium hydrogencarbonate?

Answer 77

Carbon dioxide + water + calcium carbonate → calcium hydrogencarbonate

Question 78

# C6 - Chemistry Out There What is the symbol equation for producing calcium hydrogencarbonate?

Answer 78

H₂CO₃ + CaCO₃ → Ca(HCO₃)₂

Question 79

# C6 - Chemistry Out There What are the two types of hardness?

Answer 79

Temporary and permanent

Question 80

# C6 - Chemistry Out There What is temporary hardness caused by?

Answer 80

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

Question 81

# C6 - Chemistry Out There What is permanent hardness caused by?

Answer 81

Dissolved calcium sulfate (amongst other things)

Question 82

# C6 - Chemistry Out There How is temporary hardness removed?

Answer 82

By boiling

Question 83

# C6 - Chemistry Out There What does boiling do to temporary hardness?

Answer 83

Calcium hydrogencarbonate decomposes to form insoluble calcium carbonate.

Question 84

# C6 - Chemistry Out There Why doesn't boiling remove permanent hardness?

Answer 84

Calcium carbonate precipitate (limescale) is insoluble

Question 85

# C6 - Chemistry Out There What is the word equation for removing temporary hardness?

Answer 85

Calcium hydrogencarbonate → calcium carbonate + water + carbon dioxide

Question 86

# C6 - Chemistry Out There What is the symbol equation for removing temporary hardness?

Answer 86

Ca(HCO₃)_{2 (aq)} → CaCO_{3 (s)} + H₂O _(l) + CO_{2 (g)}

Question 87

# C6 - Chemistry Out There How can bot types of hardness be removed?

Answer 87

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

Question 88

# C6 - Chemistry Out There How does NaCO₃ remove both types of hardness?

Answer 88

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

Question 89

# C6 - Chemistry Out There What is the ionic equation for removing hardness with sodium carbonate?

Answer 89

Ca²⁺ _(aq) + CO₃^2- _(aq) → CaCO_{3 (s)}

Question 90

# C6 - Chemistry Out There How does 'ion exchange resin work'?

Answer 90

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

Question 91

# C6 - Chemistry Out There What is the method for comparing the hardness of water samples?

Answer 91

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.

Question 92

# C6 - Chemistry Out There Gain of electrons

Answer 92

What is reduction?

Question 93

# C6 - Chemistry Out There Accept electrons and gets reduced

Answer 93

What does an oxidising agent do?

Question 94

# C6 - Chemistry Out There Donate electrons and get oxidised

Answer 94

What does a reducing agent do?

Question 95

# C6 - Chemistry Out There One metal kicking another one out of a compound

Answer 95

What does displacement reactions involve?

Question 96

# C6 - Chemistry Out There A more reactive metal will displace a less reactive metal from its compound

Answer 96

What is the rule for displacement reactions?

Question 97

# C6 - Chemistry Out There When they come into contact with air and water

Answer 97

Why do some iron and steels rust?

Question 98

# C6 - Chemistry Out There When iron is in contact with both water and oxygen

Answer 98

When does rusting of iron only occur?

Question 99

# C6 - Chemistry Out There Hydrated iron (III) oxide

Answer 99

What is rust a form of?

Question 100

# C6 - Chemistry Out There Iron + oxygen + water -\> hydrated iron (III) oxide

Answer 100

What is the equation for rusting?

Question 101

# C6 - Chemistry Out There Redox

Answer 101

What type of reaction is rusting of iron?

Question 102

# C6 - Chemistry Out There Loses electrons - oxidised. Each Fe atom loses 3 electrons to become Fe³⁺.

Answer 102

What happens to iron when it reacts with oxygen?

Question 103

# C6 - Chemistry Out There Reduced. Each O atom gains 2 electrons to become O^2-.

Answer 103

What happens to oxygen when it reacts with iron?

Question 104

# C6 - Chemistry Out There Make alloys. Barrier. Tin coating/plating. More reactive metals (galvanising)

Answer 104

What are the 4 ways to prevent rusting?

Question 105

# C6 - Chemistry Out There Iron with carbon and small quantities of other metals

Answer 105

What are steels alloys of?

Question 106

# C6 - Chemistry Out There One of most common steels - rustproof alloy of iron, carbon and chromium.

Answer 106

What is stainless steel?

Question 107

# C6 - Chemistry Out There Keeps out water, oxygen or both.

Answer 107

How does a barrier prevent rusting?

Question 108

# C6 - Chemistry Out There Ideal for large and small structures. Nice and colourful.

Answer 108

How is painting ideal to prevent rusting?

Question 109

# C6 - Chemistry Out There Has to be used when moving parts are involved e.g. Bike chains

Answer 109

How is oiling or greasing used to prevent rusting?

Question 110

# C6 - Chemistry Out There A coat of tin is applied to the object e.g. Food cans.

Answer 110

What is tin plating?

Question 111

# C6 - Chemistry Out There Acts as a barrier, stopping water and oxygen from reaching iron surface.

Answer 111

How does tin plating prevent rusting?

Question 112

# C6 - Chemistry Out There Tin remains intact. If scratched, iron will lose electrons and rust even faster.

Answer 112

Tin plating only as long as...

Question 113

# C6 - Chemistry Out There They could be starting to rust.

Answer 113

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

Question 114

# C6 - Chemistry Out There Place a more reactive metal with the iron. Water and oxygen react with the sacrificial metal instead of iron.

Answer 114

How does the sacrificial method work?

Question 115

# C6 - Chemistry Out There A coat of zinc put on object. Zinc is sacrificial protection - more reactive - loses electrons in preference to iron.

Answer 115

What is galvanising?

Question 116

# C6 - Chemistry Out There Steel buckets and corrugated iron roofing

Answer 116

What sort of items are galvanised?

Question 117

# C6 - Chemistry Out There E.g. Magnesium can be bolted onto iron. Magnesium loses electrons in preference to iron.

Answer 117

How can blocks of metal prevent rusting?

Question 118

# C6 - Chemistry Out There Hulls of ships and underground iron pipes.

Answer 118

When are block of metal used on items?

Question 119

# C6 - Chemistry Out There Loss of electrons

Answer 119

What is oxidation?

Question 120

# C6 - Chemistry Out There Breaking down a substance with electricity

Answer 120

What does electrolysis mean?

Question 121

# C6 - Chemistry Out There Electric current passed through a molten or dissolved ionic compound, causing it to decompose. This creates a flow of charge through the electrolyte.

Answer 121

How does electrolysis work?

Question 122

# C6 - Chemistry Out There Move towards the cathode (-ve) and gain electrons.

Answer 122

What happens to the positive ions in electrolysis?

Question 123

# C6 - Chemistry Out There Move towards anode (+ve) and lose electrons

Answer 123

What happens to negative ions in electrolysis?

Question 124

# C6 - Chemistry Out There They become atoms or molecules and are discharged from the solution at the electrodes.

Answer 124

What happens in electrolysis when ions lose or gain electrons?

Question 125

# C6 - Chemistry Out There 4OH^- - 4e^- → O₂ + 2H₂O

Answer 125

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

Question 126

# C6 - Chemistry Out There Cu²⁺ + 2e^- → Cu

Answer 126

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

Question 127

# C6 - Chemistry Out There Hydrogen ions (H⁺), hydroxide ions (OH^-) and ions from the solute (ionic compounds)

Answer 127

What are ions are there in aqueous solutions?

Question 128

# C6 - Chemistry Out There Discharge ions from the water instead of from the solute

Answer 128

What is it sometimes easier to do in electrolysis?

Question 129

# C6 - Chemistry Out There Produce hydrogen at the cathode and oxygen at the anode.

Answer 129

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

Question 130

# C6 - Chemistry Out There SO₄^2- , H⁺ , OH^-

Answer 130

What ions does a solution of aqueous sulfuric acid contain?

Question 131

# C6 - Chemistry Out There 2H⁺ + 2e^- → H₂

Answer 131

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

Question 132

# C6 - Chemistry Out There 4OH^- - 4e^- → O₂ + 2H₂O

Answer 132

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

Question 133

# C6 - Chemistry Out There Oxidation

Answer 133

What reaction takes place at the anode?

Question 134

# C6 - Chemistry Out There Reduction

Answer 134

What reaction takes place at the cathode?

Question 135

# C6 - Chemistry Out There Cathode

Answer 135

Where is hydrogen produced in electrolysis?

Question 136

# C6 - Chemistry Out There Anode

Answer 136

Where is oxygen produced in electrolysis?

Question 137

# C6 - Chemistry Out There Cu²⁺ + 2e^- → Cu

Answer 137

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

Question 138

# C6 - Chemistry Out There 4OH^- - 4e^- -\> O₂ + 2H₂O

Answer 138

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

Question 139

# C6 - Chemistry Out There Negative

Answer 139

What charge does the cathode have?

Question 140

# C6 - Chemistry Out There Positive

Answer 140

What charge does the anode have?

Question 141

# C6 - Chemistry Out There Solution turns from green to yellow

Answer 141

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

Question 142

# C6 - Chemistry Out There Iron (II) ion is oxidised to iron (III). Fe²⁺ ion loses an electron to form Fe³⁺

Answer 142

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

Question 143

# C6 - Chemistry Out There Oxidising agent - chlorine gas

Answer 143

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

Question 144

# C6 - Chemistry Out There Iron (II) ion

Answer 144

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

Question 145

# C6 - Chemistry Out There Chlorine gains the electron Fe²⁺ lost. Chlorine reduced.

Answer 145

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

Question 146

# C6 - Chemistry Out There When iron atoms are oxidised.

Answer 146

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

Question 147

# C6 - Chemistry Out There Lose electrons - oxidised by hydrogen ions

Answer 147

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

Question 148

# C6 - Chemistry Out There Gain electrons - reduced by iron atoms.

Answer 148

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

Question 149

# C6 - Chemistry Out There Magnesium, zinc, iron, tin/copper.

Answer 149

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

Question 150

# C6 - Chemistry Out There Gain electrons - are reduced

Answer 150

What happens to metal ions in displacement reactions?

Question 151

# C6 - Chemistry Out There Loses electrons - are oxidised

Answer 151

What happens to the metal atoms in displacement reactions?

Question 152

# C6 - Chemistry Out There Doesn't lather. Makes scum

Answer 152

What happens between hard water and soap?

Question 153

# C6 - Chemistry Out There Add more soap, use softer water.

Answer 153

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

Question 154

# C6 - Chemistry Out There Limescale (calcium carbonate)

Answer 154

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

Question 155

# C6 - Chemistry Out There Thermal insulator

Answer 155

What does limescale act as?

Question 156

# C6 - Chemistry Out There Kettle with limescale in heating element will take longer to boil.

Answer 156

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

Question 157

# C6 - Chemistry Out There Block them

Answer 157

What can limescale eventually do to pipes?

Question 158

# C6 - Chemistry Out There Calcium ions (Ca²⁺), magnesium ions (Mg²⁺), or both.

Answer 158

What does hard water contain?

Question 159

# C6 - Chemistry Out There The soils/rocks contain Ca and Mg compounds - these ions dissolve in the water.

Answer 159

What happens as water flows over rocks and through soil?

Question 160

# C6 - Chemistry Out There Water

Answer 160

What does magnesium sulfate dissolve in?

Question 161

# C6 - Chemistry Out There Chalk, limestone and marble.

Answer 161

What does calcium carbonate commonly exist as?

Question 162

# C6 - Chemistry Out There No but reacts with acids.

Answer 162

Does calcium carbonate dissolve in water?

Question 163

# C6 - Chemistry Out There Carbon dioxide from air dissolves in rainwater forming carbonic acid.

Answer 163

How do we know rainwater is slightly acidic?

Question 164

# C6 - Chemistry Out There Carbon dioxide + water → carbonic acid

Answer 164

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

Question 165

# C6 - Chemistry Out There CO₂ + H₂O -\> H₂CO₃

Answer 165

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

Question 166

# C6 - Chemistry Out There H₂CO₃

Answer 166

What is the molecular formula of carbonic acid?

Question 167

# C6 - Chemistry Out There Calcium carbonate

Answer 167

What can rainwater react with to form calcium hydrogencarbonate?

Question 168

# C6 - Chemistry Out There Carbon dioxide + water + calcium carbonate → calcium hydrogencarbonate

Answer 168

What is the word equation for producing calcium hydrogencarbonate?

Question 169

# C6 - Chemistry Out There H₂CO₃ + CaCO₃ → Ca(HCO₃)₂

Answer 169

What is the symbol equation for producing calcium hydrogencarbonate?

Question 170

# C6 - Chemistry Out There Temporary and permanent

Answer 170

What are the two types of hardness?

Question 171

# C6 - Chemistry Out There Hydrogencarbonate ion (HCO₃^-) in Ca(HCO₃)₂

Answer 171

What is temporary hardness caused by?

Question 172

# C6 - Chemistry Out There Dissolved calcium sulfate (amongst other things)

Answer 172

What is permanent hardness caused by?

Question 173

# C6 - Chemistry Out There By boiling

Answer 173

How is temporary hardness removed?

Question 174

# C6 - Chemistry Out There Calcium hydrogencarbonate decomposes to form insoluble calcium carbonate.

Answer 174

What does boiling do to temporary hardness?

Question 175

# C6 - Chemistry Out There Calcium carbonate precipitate (limescale) is insoluble

Answer 175

Why doesn't boiling remove permanent hardness?

Question 176

# C6 - Chemistry Out There Calcium hydrogencarbonate → calcium carbonate + water + carbon dioxide

Answer 176

What is the word equation for removing temporary hardness?

Question 177

# C6 - Chemistry Out There Ca(HCO₃)_{2 (aq)} → CaCO_{3 (s)} + H₂O _(l) + CO_{2 (g)}

Answer 177

What is the symbol equation for removing temporary hardness?

Question 178

# C6 - Chemistry Out There Using washing soda (sodium carbonate, NaCO₃) or by 'ion exchange resin'.

Answer 178

How can bot types of hardness be removed?

Question 179

# C6 - Chemistry Out There Carbonate ions join to calcium ions to make insoluble precipitate of calcium carbonate. Works whether hardness is due to calcium sulfate or calcium hydrogencarbonate.

Answer 179

How does NaCO₃ remove both types of hardness?

Question 180

# C6 - Chemistry Out There Ca²⁺ _(aq) + CO₃^2- _(aq) → CaCO_{3 (s)}

Answer 180

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

Question 181

# C6 - Chemistry Out There Lots of sodium ions (or hydrogen ions) and these are exchanged for calcium or magnesium ions.

Answer 181

How does 'ion exchange resin work'?

Question 182

# C6 - Chemistry Out There 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.

Answer 182

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