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Flashcards in C5 - How Much? Deck (196):
1

What catalyst is used in the contact process?

Vanadium Pentoxide catalyst (V₂O₅) is used. This does not change the position of equilibrium.

2

What type of reaction is stage 2 of the contact process?

Exothermic (and reversible)

3

What happens if the temperature is reduced (in the contact process)?

More product but an extremely slow reaction. A compromise of 450°C is used to get a high yield quickly.

4

What pressure is used in the contact process?

Atmospheric pressure (1 atm) because increasing it would make it expensive and shifting equilibrium to right is not necessary as it is already at the right.

5

What happens to equilibrium when the concentration of reactants is increased (in ammonia equation)?

Adding more Nitrogen or hydrogen means the equilibrium tries to decrease it by shifting to the right, making more NH3.

6

What process is used to make sulphuric acid?

The contact process

7

What happens to equilibrium when the temperature is increased?

It moves to try and decrease it. Moves in the endothermic direction.

8

What is the first stage of the contact process?

To make sulfur dioxide (SO₂) sulfur + oxygen → sulfur dioxide S (s) + O₂ (g) → SO₂ (g) Usually by burning sulfur in the air

9

What happens to the equilibrium when the concentration of product is increased?

By adding more NH3, the equilibrium tries to reduce it again. By shifting to the left making more nitrogen and hydrogen.

10

What 3 things can change the position of equilibrium?

Temperature, pressure and concentration.

11

What is the second stage of the contact process?

Sulfur dioxide is oxidised with help of a catalyst to make sulfur trioxide sulfur dioxide + oxygen ⇌ sulfur trioxide 2SO₂ (g) + O₂ (g) ⇌ 2SO₂ (g)

12

What happens to equilibrium when the pressure is increased?

The equilibrium moves to try and reduce it. It moves in the direction where there are fewer moles of gas.

13

When does equilibrium only take place?

If the reversible reaction takes place in a closed system meaning none of the reactants or products can escape.

14

What is the third stage of the contact process?

Sulfur trioxide is used to make sulfuric acid sulfur trioxide + water → sulfuric acid SO₂ (g) + H₂O (l) → H₂SO₄ (aq)

15

What happens to equilibrium when the pressure is decreased?

The equilibrium tries to increase it. It overs in. The direction where there are more moles of gas.

16

What does it mean if the equilibrium lies to the left?

Lots of the reactants but not much of the products. The concentration of reactants is greater than the concentration of the products.

17

What happens to equilibrium when adding a catalyst?

It won't change the position, it speeds up both the forward and backward reactions by the same amount, adding a catalyst means the reaction reaches equilibrium quicker, but you end up with the same amount of products as you would without the catalyst.

18

What does it mean if the equilibrium lies to the right?

Lots of the products and not much of the reactants. The concentration of product is greater than concentration of the reactant.

19

What happens to equilibrium when the temperature is decreased?

It moves to try and increase the temperature. Moves in the exothermic direction to produce more heat.

20

What is relationship between product formed and limiting reactants?

The amount of Podunk formed is directly proporation all to the amount of limiting reactant. E.g halving the amount of limiting reactant will halve the gas produced.

21

What is a reversible reaction?

One where the products of the reactions can themselves react to produce the original reactants.

22

What is equilibrium?

When the forward reaction is going at exactly the same rate as the backward one. Meaning the concentrations of reactants and products have reached a balance and won't change.

23

Describe measuring the mass of gas produced...

Can be measured by carrying out the experiment on a mass balance. As gas is released, the mass disappearing is easily measured on the balance. Most accurate because the mass balance is very accurate. But the gas is released straight out into the room.

24

What does one mole of any gas always occupy?

24dm cubed at RTP.

25

What is RTP?

Room temperature and pressure (25 degrees C and 1 atmosphere)

26

Describe using a gas syringe...

Can be used to collect pretty much any gas. Usually gives volumes accurate to nearest cm squared. However, if reaction is too vigorous, the plunger may blow out.

27

What should the first titration be?

A rough titration to get an idea of approximately where the end point/colour change is.

28

What 3 ways can gas volume be collected?

Gas syringe, upturned measuring cylinder or but pretty, and measuring the mass of gas produced.

29

Describe using an upturned burette or measuring cylinder...

Use a delivery tube to bubble gas into an upturned cylinder or gas jar filled with water. Method is no good for collecting things like hydrogen chloride or ammonia because they dissolve in water. Using a burette is more accurate as you can measure to the nearest 0.1cm cubed.

30

What are the repeats for a titration for?

To make sure you get the same answer or within 0.2cm³ of each other.

31

What equipment is used in a titration?

Pipette and pipette filler, alkali, conical flask, indicator and burette.

32

What is universal indicator used for?

To estimate the pH of a solution because it can turn a variety of colours. Each colour indicates a narrow range of pH values.

33

What colour is phenolphthalein in acids and alkalis?

Pink in alkalis and colourless in acids

34

How do you estimate sodium content?

Sodium chloride's Mr (58.5) to sodium's (23) are divided to give 2.543… Multiply this by the amount of sodium in the food.

35

What colour is litmus in acids and alkalis?

Red in acids and blue in alkalis

36

Why won't all the sodium present come from sodium chloride?

There might be other sodium compounds like sodium nitrate (used as a preservative). Estimate is probably an overestimate.

37

What do titrations allow you to find?

Exactly how much acid is needed to neutralise a quantity of alkali (or vice versa).

38

What is concentration a measure of?

How many moles of acid there are in a litre (dm³)

39

How do you calculate concentration?

number of moles ÷ volume (dm³)

40

Why might GDA numbers not be the amount consumed?

Amounts are given per 100g (or 100ml). The amount per serving is also sometimes listed. Other things may be added, like milk to cereals.

41

What is relative atomic mass a measure of?

It is the average mass of an atom of the element compared to the mass of 1/12 th of an atom of carbon-12.

42

How are the number of moles calculated?

Mass (g) ÷ Mr of element/compound

43

What is a mole?

One mole of atoms or molecules of any substance will have a mass in grams equal to the relative formula mass (Ar or Mr) for that substance.

44

What do acids produce in water?

Protons - acids ionise and produce hydrogen ions, H⁺.

45

What examples are there of a strong acid?

Sulfuric, hydrochloric and nitric

46

What do strong acids do in water?

They ionise completely in water, meaning loads of H⁺ ions are released.

47

What examples are there of a weak acid?

ethanoic, citric and carbonic

48

What do weak acids do in water?

They do not fully ionise, so only a small number of H⁺ ions are released.

49

What symbol is used in the equation for a weak acid?

Reversible reaction arrow.

50

What happens to equilibrium in the ionisation of a weak acid?

The reversible reaction sets up an equilibrium mixture and since only a few H⁺ ions are released, the equilibrium lies well to the left.

51

What is pH a measure of?

The concentration of H⁺ ions in the solution. Can be measured with a pH meter or with universal indicator.

52

What does acid strength tell you?

What proportion of the acid molecules ionise in water.

53

What does concentration of an acid tell you?

It measures how many moles of acid there are in a litre (1dm³) of water. It describes the total number of dissolved acid molecules. The more moles of acid per dm³, the more concentrated the acid is.

54

What is ethanoic acid's electrical conductivity?

It has a much lower conductivity than the same concentration of hydrochloric acid.

55

Why are stronger acids better electrical conductors?

The ions carry charge through the acid solutions as they move. The lower the concentration of ions, the less charge can be carried.

56

What does electrolysis of hydrochloric acid or ethanoic acid produce?

Hydrogen because they both produce H+ ions

57

What is the difference between the reactions with HCl and Ethanoic acid?

Reaction rates. Ethanoic is much slower than HCl of the same concentration.

58

What is the slower reaction rate of ethanoic acid to do with?

Equilibrium in weak acid reaction

59

What happens when you put a weak acid in water?

It releases a few H+ ions but the concentration of H+ ions is low compared to a strong acid.

60

What happens when you add magnesium or calcium carbonate to a weak acid?

The collision frequency between the reactants is low.

61

What happens to equilibrium when H+ ions react?

Concentration of H+ falls , so equilibrium shifts to compensate - meaning more H+ are released. These ions react, so equilibrium shifts again. As ions are removed, more are supplied - drip-feed.

62

What happens to H+ ions in a strong acid?

All acid molecules are ionised and lots of H+ ions are sitting  there waiting to go.

63

What happens when magnesium or calcium carbonate is added to a strong acid?

Collision frequency between the reactants is really high.

64

What will the difference in product be in a weak acid compared to a strong acid?

The same amount - produced at different rates.

65

Why is the amount of product the same for weak and strong acids?

Because if the concentrations are the same, the number of molecules in a litre will be the same.

66

Both HCl and Ethanoic can let go of one H+ ion but...

HCl lets go all at once. Ethanoic lets them go gradually.

67

What do precipitation reactions usually involve?

2 solutions reacting together to make an insoluble substance. Involve ions reacting with each other.

68

What is an insoluble substance called?

Precipitate - makes solution cloudy

69

What do ions have to be able to do to react?

Move

70

What do ions have to be in to be able to move?

Solution or molten

71

Why are precipitation reactions with ions usually extremely quick?

Because there is a high collision frequency between the ions.

72

What is the word equation for a precipitation reaction with barium chloride and sodium sulfate?

barium chloride + sodium sulfate → barium sulfate + sodium chloride

73

What is the symbol equation for a precipitation reaction between barium chloride and sodium sulfate?

BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)

74

What is the symbol equation for ethanoic acid and magnesium?

2CH3COOH + Mg → Mg(CH3COO)2 + H2

75

What is the symbol equation for hydrochloric acid and magnesium?

2HCl + Mg → MgCl2 + H2

76

What is the symbol equation for ethanoic acid and calcium carbonate?

2CH3COOH + CaCO3 → Ca(CH3COO)2 + H2O + CO2

77

What is the symbol equation for hydrochloric acid and calcium carbonate?

2HCl + CaCO3 → CaCl2 + H2O + CO2

78

What is the ionic equation for the precipitate reaction between barium chloride and sodium sulfate?

Ba2+ (aq) + SO42+ (aq) → BaSO4 (s)

79

How can you tell a reaction is a precipitate?

State symbols - two solutions (aq) become a solid (s).

80

What are spectator ions?

Don't change in reaction. e.g. sodium and chloride ions already dissolved before reaction - still dissolved afterwards.

81

What is the test for sulfate ions?

Add dilute HCl, followed by barium chloride.

82

What does a white precipitate of barium sulfate mean?

The original compound was a sulfate.

83

What colour precipitate shows sulfate ions are present?

White

84

 What is the test for chloride, bromide or iodide ions?

Add diluted nitric acid, followed by lead nitrate.

85

What is the precipitate if chloride ions are present?

White precipitate - of lead chloride.

86

What is the precipitate if bromide ions are present?

Cream precipitate - of lead bromide.

87

What is the precipitate if iodide ions are present?

Yellow - of lead iodide.

88

What does there need to be to make an insoluble salt?

Ions in a solution - free to move about.

89

How do you get the nitrates and lead ions in a salt?

Nitrates are soluble - use a solution of lead nitrate for supply of lead ions.

90

What is the word equation for an insoluble salt?

lead nitrate + potassium iodide → lead iodide + potassium nitrate

91

What is the symbol equation for an insoluble salt?

Pb(NO3)2 (aq) + 2KI (aq) → PbI2 (s) + 2KNO3 (aq)

92

What is the ionic equation for an insoluble salt?

Pb2+ (aq) + 2I- (aq) → PbI2 (s)

93

If you only mix lead nitrate with potassium iodide what will happen to the salt?

It will be wet and mixed in with other stuff

94

What are the stages of preparing an insoluble salt?

Precipitate, filter, dry

95

What is involved in Stage 1 when preparing an insoluble salt?

1 spatula of lead nitrate in a test tube filled with distilled water. Shake thoroughly - lead dissolved. Same with potassium iodide. Tip 2 solutions into small beaker and stir - precipitate out.

96

Why is distilled water used when making an insoluble salt?

Make sure there are no other ions in it.

97

What is involved in Stage 2 when preparing an insoluble salt?

Folded filter paper in filter funnel - funnel in conical flask. Pour beaker contents into filter paper. Swill out beaker with distilled water - make sure to get all product from beaker.

98

What is involved in Stage 3 when preparing an insoluble salt?

Rinse contents of filter paper with distilled water - make sure all soluble salts washed away. Scrape lead iodide on to fresh filter paper and leave to dry.

99

Vanadium Pentoxide catalyst (V₂O₅) is used. This does not change the position of equilibrium.

What catalyst is used in the contact process?

100

Exothermic (and reversible)

What type of reaction is stage 2 of the contact process?

101

More product but an extremely slow reaction. A compromise of 450°C is used to get a high yield quickly.

What happens if the temperature is reduced (in the contact process)?

102

Atmospheric pressure (1 atm) because increasing it would make it expensive and shifting equilibrium to right is not necessary as it is already at the right.

What pressure is used in the contact process?

103

Adding more Nitrogen or hydrogen means the equilibrium tries to decrease it by shifting to the right, making more NH3.

What happens to equilibrium when the concentration of reactants is increased (in ammonia equation)?

104

The contact process

What process is used to make sulphuric acid?

105

It moves to try and decrease it. Moves in the endothermic direction.

What happens to equilibrium when the temperature is increased?

106

To make sulfur dioxide (SO₂) sulfur + oxygen → sulfur dioxide S (s) + O₂ (g) → SO₂ (g) Usually by burning sulfur in the air

What is the first stage of the contact process?

107

By adding more NH3, the equilibrium tries to reduce it again. By shifting to the left making more nitrogen and hydrogen.

What happens to the equilibrium when the concentration of product is increased?

108

Temperature, pressure and concentration.

What 3 things can change the position of equilibrium?

109

Sulfur dioxide is oxidised with help of a catalyst to make sulfur trioxide sulfur dioxide + oxygen ⇌ sulfur trioxide 2SO₂ (g) + O₂ (g) ⇌ 2SO₂ (g)

What is the second stage of the contact process?

110

The equilibrium moves to try and reduce it. It moves in the direction where there are fewer moles of gas.

What happens to equilibrium when the pressure is increased?

111

If the reversible reaction takes place in a closed system meaning none of the reactants or products can escape.

When does equilibrium only take place?

112

Sulfur trioxide is used to make sulfuric acid sulfur trioxide + water → sulfuric acid SO₂ (g) + H₂O (l) → H₂SO₄ (aq)

What is the third stage of the contact process?

113

The equilibrium tries to increase it. It overs in. The direction where there are more moles of gas.

What happens to equilibrium when the pressure is decreased?

114

Lots of the reactants but not much of the products. The concentration of reactants is greater than the concentration of the products.

What does it mean if the equilibrium lies to the left?

115

It won't change the position, it speeds up both the forward and backward reactions by the same amount, adding a catalyst means the reaction reaches equilibrium quicker, but you end up with the same amount of products as you would without the catalyst.

What happens to equilibrium when adding a catalyst?

116

Lots of the products and not much of the reactants. The concentration of product is greater than concentration of the reactant.

What does it mean if the equilibrium lies to the right?

117

It moves to try and increase the temperature. Moves in the exothermic direction to produce more heat.

What happens to equilibrium when the temperature is decreased?

118

The amount of Podunk formed is directly proporation all to the amount of limiting reactant. E.g halving the amount of limiting reactant will halve the gas produced.

What is relationship between product formed and limiting reactants?

119

One where the products of the reactions can themselves react to produce the original reactants.

What is a reversible reaction?

120

When the forward reaction is going at exactly the same rate as the backward one. Meaning the concentrations of reactants and products have reached a balance and won't change.

What is equilibrium?

121

Can be measured by carrying out the experiment on a mass balance. As gas is released, the mass disappearing is easily measured on the balance. Most accurate because the mass balance is very accurate. But the gas is released straight out into the room.

Describe measuring the mass of gas produced...

122

24dm cubed at RTP.

What does one mole of any gas always occupy?

123

Room temperature and pressure (25 degrees C and 1 atmosphere)

What is RTP?

124

Can be used to collect pretty much any gas. Usually gives volumes accurate to nearest cm squared. However, if reaction is too vigorous, the plunger may blow out.

Describe using a gas syringe...

125

A rough titration to get an idea of approximately where the end point/colour change is.

What should the first titration be?

126

Gas syringe, upturned measuring cylinder or but pretty, and measuring the mass of gas produced.

What 3 ways can gas volume be collected?

127

Use a delivery tube to bubble gas into an upturned cylinder or gas jar filled with water. Method is no good for collecting things like hydrogen chloride or ammonia because they dissolve in water. Using a burette is more accurate as you can measure to the nearest 0.1cm cubed.

Describe using an upturned burette or measuring cylinder...

128

To make sure you get the same answer or within 0.2cm³ of each other.

What are the repeats for a titration for?

129

Pipette and pipette filler, alkali, conical flask, indicator and burette.

What equipment is used in a titration?

130

To estimate the pH of a solution because it can turn a variety of colours. Each colour indicates a narrow range of pH values.

What is universal indicator used for?

131

Pink in alkalis and colourless in acids

What colour is phenolphthalein in acids and alkalis?

132

Sodium chloride's Mr (58.5) to sodium's (23) are divided to give 2.543… Multiply this by the amount of sodium in the food.

How do you estimate sodium content?

133

Red in acids and blue in alkalis

What colour is litmus in acids and alkalis?

134

There might be other sodium compounds like sodium nitrate (used as a preservative). Estimate is probably an overestimate.

Why won't all the sodium present come from sodium chloride?

135

Exactly how much acid is needed to neutralise a quantity of alkali (or vice versa).

What do titrations allow you to find?

136

How many moles of acid there are in a litre (dm³)

What is concentration a measure of?

137

number of moles ÷ volume (dm³)

How do you calculate concentration?

138

Amounts are given per 100g (or 100ml). The amount per serving is also sometimes listed. Other things may be added, like milk to cereals.

Why might GDA numbers not be the amount consumed?

139

It is the average mass of an atom of the element compared to the mass of 1/12 th of an atom of carbon-12.

What is relative atomic mass a measure of?

140

Mass (g) ÷ Mr of element/compound

How are the number of moles calculated?

141

One mole of atoms or molecules of any substance will have a mass in grams equal to the relative formula mass (Ar or Mr) for that substance.

What is a mole?

142

Protons - acids ionise and produce hydrogen ions, H⁺.

What do acids produce in water?

143

Sulfuric, hydrochloric and nitric

What examples are there of a strong acid?

144

They ionise completely in water, meaning loads of H⁺ ions are released.

What do strong acids do in water?

145

ethanoic, citric and carbonic

What examples are there of a weak acid?

146

They do not fully ionise, so only a small number of H⁺ ions are released.

What do weak acids do in water?

147

Reversible reaction arrow.

What symbol is used in the equation for a weak acid?

148

The reversible reaction sets up an equilibrium mixture and since only a few H⁺ ions are released, the equilibrium lies well to the left.

What happens to equilibrium in the ionisation of a weak acid?

149

The concentration of H⁺ ions in the solution. Can be measured with a pH meter or with universal indicator.

What is pH a measure of?

150

What proportion of the acid molecules ionise in water.

What does acid strength tell you?

151

It measures how many moles of acid there are in a litre (1dm³) of water. It describes the total number of dissolved acid molecules. The more moles of acid per dm³, the more concentrated the acid is.

What does concentration of an acid tell you?

152

It has a much lower conductivity than the same concentration of hydrochloric acid.

What is ethanoic acid's electrical conductivity?

153

The ions carry charge through the acid solutions as they move. The lower the concentration of ions, the less charge can be carried.

Why are stronger acids better electrical conductors?

154

Hydrogen because they both produce H+ ions

What does electrolysis of hydrochloric acid or ethanoic acid produce?

155

Reaction rates. Ethanoic is much slower than HCl of the same concentration.

What is the difference between the reactions with HCl and Ethanoic acid?

156

Equilibrium in weak acid reaction

What is the slower reaction rate of ethanoic acid to do with?

157

It releases a few H+ ions but the concentration of H+ ions is low compared to a strong acid.

What happens when you put a weak acid in water?

158

The collision frequency between the reactants is low.

What happens when you add magnesium or calcium carbonate to a weak acid?

159

Concentration of H+ falls , so equilibrium shifts to compensate - meaning more H+ are released. These ions react, so equilibrium shifts again. As ions are removed, more are supplied - drip-feed.

What happens to equilibrium when H+ ions react?

160

All acid molecules are ionised and lots of H+ ions are sitting  there waiting to go.

What happens to H+ ions in a strong acid?

161

Collision frequency between the reactants is really high.

What happens when magnesium or calcium carbonate is added to a strong acid?

162

The same amount - produced at different rates.

What will the difference in product be in a weak acid compared to a strong acid?

163

Because if the concentrations are the same, the number of molecules in a litre will be the same.

Why is the amount of product the same for weak and strong acids?

164

HCl lets go all at once. Ethanoic lets them go gradually.

Both HCl and Ethanoic can let go of one H+ ion but...

165

2 solutions reacting together to make an insoluble substance. Involve ions reacting with each other.

What do precipitation reactions usually involve?

166

Precipitate - makes solution cloudy

What is an insoluble substance called?

167

Move

What do ions have to be able to do to react?

168

Solution or molten

What do ions have to be in to be able to move?

169

Because there is a high collision frequency between the ions.

Why are precipitation reactions with ions usually extremely quick?

170

barium chloride + sodium sulfate → barium sulfate + sodium chloride

What is the word equation for a precipitation reaction with barium chloride and sodium sulfate?

171

BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)

What is the symbol equation for a precipitation reaction between barium chloride and sodium sulfate?

172

2CH3COOH + Mg → Mg(CH3COO)2 + H2

What is the symbol equation for ethanoic acid and magnesium?

173

2HCl + Mg → MgCl2 + H2

What is the symbol equation for hydrochloric acid and magnesium?

174

2CH3COOH + CaCO3 → Ca(CH3COO)2 + H2O + CO2

What is the symbol equation for ethanoic acid and calcium carbonate?

175

2HCl + CaCO3 → CaCl2 + H2O + CO2

What is the symbol equation for hydrochloric acid and calcium carbonate?

176

Ba2+ (aq) + SO42+ (aq) → BaSO4 (s)

What is the ionic equation for the precipitate reaction between barium chloride and sodium sulfate?

177

State symbols - two solutions (aq) become a solid (s).

How can you tell a reaction is a precipitate?

178

Don't change in reaction. e.g. sodium and chloride ions already dissolved before reaction - still dissolved afterwards.

What are spectator ions?

179

Add dilute HCl, followed by barium chloride.

What is the test for sulfate ions?

180

The original compound was a sulfate.

What does a white precipitate of barium sulfate mean?

181

White

What colour precipitate shows sulfate ions are present?

182

Add diluted nitric acid, followed by lead nitrate.

 What is the test for chloride, bromide or iodide ions?

183

White precipitate - of lead chloride.

What is the precipitate if chloride ions are present?

184

Cream precipitate - of lead bromide.

What is the precipitate if bromide ions are present?

185

Yellow - of lead iodide.

What is the precipitate if iodide ions are present?

186

Ions in a solution - free to move about.

What does there need to be to make an insoluble salt?

187

Nitrates are soluble - use a solution of lead nitrate for supply of lead ions.

How do you get the nitrates and lead ions in a salt?

188

lead nitrate + potassium iodide → lead iodide + potassium nitrate

What is the word equation for an insoluble salt?

189

Pb(NO3)2 (aq) + 2KI (aq) → PbI2 (s) + 2KNO3 (aq)

What is the symbol equation for an insoluble salt?

190

Pb2+ (aq) + 2I- (aq) → PbI2 (s)

What is the ionic equation for an insoluble salt?

191

It will be wet and mixed in with other stuff

If you only mix lead nitrate with potassium iodide what will happen to the salt?

192

Precipitate, filter, dry

What are the stages of preparing an insoluble salt?

193

1 spatula of lead nitrate in a test tube filled with distilled water. Shake thoroughly - lead dissolved. Same with potassium iodide. Tip 2 solutions into small beaker and stir - precipitate out.

What is involved in Stage 1 when preparing an insoluble salt?

194

Make sure there are no other ions in it.

Why is distilled water used when making an insoluble salt?

195

Folded filter paper in filter funnel - funnel in conical flask. Pour beaker contents into filter paper. Swill out beaker with distilled water - make sure to get all product from beaker.

What is involved in Stage 2 when preparing an insoluble salt?

196

Rinse contents of filter paper with distilled water - make sure all soluble salts washed away. Scrape lead iodide on to fresh filter paper and leave to dry.

What is involved in Stage 3 when preparing an insoluble salt?