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Chemistry GCSE OCR Gateway B > C5 - How Much? > Flashcards

C5 - How Much? Flashcards

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1
Q

C5 - How Much?

What catalyst is used in the contact process?

A

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

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2
Q

C5 - How Much?

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

A

Exothermic (and reversible)

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3
Q

C5 - How Much?

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

A

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

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4
Q

C5 - How Much?

What pressure is used in the contact process?

A

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.

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5
Q

C5 - How Much?

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

A

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

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6
Q

C5 - How Much?

What process is used to make sulphuric acid?

A

The contact process

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7
Q

C5 - How Much?

What happens to equilibrium when the temperature is increased?

A

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

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8
Q

C5 - How Much?

What is the first stage of the contact process?

A

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

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9
Q

C5 - How Much?

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

A

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

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10
Q

C5 - How Much?

What 3 things can change the position of equilibrium?

A

Temperature, pressure and concentration.

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11
Q

C5 - How Much?

What is the second stage of the contact process?

A

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

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12
Q

C5 - How Much?

What happens to equilibrium when the pressure is increased?

A

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

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13
Q

C5 - How Much?

When does equilibrium only take place?

A

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

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14
Q

C5 - How Much?

What is the third stage of the contact process?

A

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

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15
Q

C5 - How Much?

What happens to equilibrium when the pressure is decreased?

A

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

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16
Q

C5 - How Much?

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

A

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

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17
Q

C5 - How Much?

What happens to equilibrium when adding a catalyst?

A

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.

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18
Q

C5 - How Much?

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

A

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

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19
Q

C5 - How Much?

What happens to equilibrium when the temperature is decreased?

A

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

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20
Q

C5 - How Much?

What is relationship between product formed and limiting reactants?

A

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.

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21
Q

C5 - How Much?

What is a reversible reaction?

A

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

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22
Q

C5 - How Much?

What is equilibrium?

A

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.

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23
Q

C5 - How Much?

Describe measuring the mass of gas produced…

A

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.

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24
Q

C5 - How Much?

What does one mole of any gas always occupy?

A

24dm cubed at RTP.

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25
Q

C5 - How Much?

What is RTP?

A

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

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26
Q

C5 - How Much?

Describe using a gas syringe…

A

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.

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27
Q

C5 - How Much?

What should the first titration be?

A

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

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28
Q

C5 - How Much?

What 3 ways can gas volume be collected?

A

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

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29
Q

C5 - How Much?

Describe using an upturned burette or measuring cylinder…

A

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.

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30
Q

C5 - How Much?

What are the repeats for a titration for?

A

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

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31
Q

C5 - How Much?

What equipment is used in a titration?

A

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

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32
Q

C5 - How Much?

What is universal indicator used for?

A

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

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33
Q

C5 - How Much?

What colour is phenolphthalein in acids and alkalis?

A

Pink in alkalis and colourless in acids

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34
Q

C5 - How Much?

How do you estimate sodium content?

A

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.

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35
Q

C5 - How Much?

What colour is litmus in acids and alkalis?

A

Red in acids and blue in alkalis

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36
Q

C5 - How Much?

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

A

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

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37
Q

C5 - How Much?

What do titrations allow you to find?

A

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

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38
Q

C5 - How Much?

What is concentration a measure of?

A

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

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39
Q

C5 - How Much?

How do you calculate concentration?

A

number of moles ÷ volume (dm³)

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40
Q

C5 - How Much?

Why might GDA numbers not be the amount consumed?

A

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

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41
Q

C5 - How Much?

What is relative atomic mass a measure of?

A

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.

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42
Q

C5 - How Much?

How are the number of moles calculated?

A

Mass (g) ÷ Mr of element/compound

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43
Q

C5 - How Much?

What is a mole?

A

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.

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44
Q

C5 - How Much?

What do acids produce in water?

A

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

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45
Q

C5 - How Much?

What examples are there of a strong acid?

A

Sulfuric, hydrochloric and nitric

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46
Q

C5 - How Much?

What do strong acids do in water?

A

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

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47
Q

C5 - How Much?

What examples are there of a weak acid?

A

ethanoic, citric and carbonic

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48
Q

C5 - How Much?

What do weak acids do in water?

A

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

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49
Q

C5 - How Much?

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

A

Reversible reaction arrow.

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50
Q

C5 - How Much?

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

A

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

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51
Q

C5 - How Much?

What is pH a measure of?

A

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

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52
Q

C5 - How Much?

What does acid strength tell you?

A

What proportion of the acid molecules ionise in water.

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53
Q

C5 - How Much?

What does concentration of an acid tell you?

A

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.

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54
Q

C5 - How Much?

What is ethanoic acid’s electrical conductivity?

A

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

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55
Q

C5 - How Much?

Why are stronger acids better electrical conductors?

A

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

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56
Q

C5 - How Much?

What does electrolysis of hydrochloric acid or ethanoic acid produce?

A

Hydrogen because they both produce H+ ions

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57
Q

C5 - How Much?

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

A

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

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58
Q

C5 - How Much?

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

A

Equilibrium in weak acid reaction

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59
Q

C5 - How Much?

What happens when you put a weak acid in water?

A

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

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60
Q

C5 - How Much?

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

A

The collision frequency between the reactants is low.

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61
Q

C5 - How Much?

What happens to equilibrium when H+ ions react?

A

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.

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62
Q

C5 - How Much?

What happens to H+ ions in a strong acid?

A

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

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63
Q

C5 - How Much?

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

A

Collision frequency between the reactants is really high.

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64
Q

C5 - How Much?

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

A

The same amount - produced at different rates.

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65
Q

C5 - How Much?

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

A

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

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66
Q

C5 - How Much?

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

A

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

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67
Q

C5 - How Much?

What do precipitation reactions usually involve?

A

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

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68
Q

C5 - How Much?

What is an insoluble substance called?

A

Precipitate - makes solution cloudy

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69
Q

C5 - How Much?

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

A

Move

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70
Q

C5 - How Much?

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

A

Solution or molten

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71
Q

C5 - How Much?

Why are precipitation reactions with ions usually extremely quick?

A

Because there is a high collision frequency between the ions.

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72
Q

C5 - How Much?

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

A

barium chloride + sodium sulfate → barium sulfate + sodium chloride

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73
Q

C5 - How Much?

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

A

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

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74
Q

C5 - How Much?

What is the symbol equation for ethanoic acid and magnesium?

A

2CH3COOH + Mg → Mg(CH3COO)2 + H2

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75
Q

C5 - How Much?

What is the symbol equation for hydrochloric acid and magnesium?

A

2HCl + Mg → MgCl2 + H2

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76
Q

C5 - How Much?

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

A

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

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77
Q

C5 - How Much?

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

A

2HCl + CaCO3 → CaCl2 + H2O + CO2

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78
Q

C5 - How Much?

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

A

Ba2+ (aq) + SO42+ (aq) → BaSO4 (s)

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79
Q

C5 - How Much?

How can you tell a reaction is a precipitate?

A

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

80
Q

C5 - How Much?

What are spectator ions?

A

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

81
Q

C5 - How Much?

What is the test for sulfate ions?

A

Add dilute HCl, followed by barium chloride.

82
Q

C5 - How Much?

What does a white precipitate of barium sulfate mean?

A

The original compound was a sulfate.

83
Q

C5 - How Much?

What colour precipitate shows sulfate ions are present?

A

White

84
Q

C5 - How Much?

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

A

Add diluted nitric acid, followed by lead nitrate.

85
Q

C5 - How Much?

What is the precipitate if chloride ions are present?

A

White precipitate - of lead chloride.

86
Q

C5 - How Much?

What is the precipitate if bromide ions are present?

A

Cream precipitate - of lead bromide.

87
Q

C5 - How Much?

What is the precipitate if iodide ions are present?

A

Yellow - of lead iodide.

88
Q

C5 - How Much?

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

A

Ions in a solution - free to move about.

89
Q

C5 - How Much?

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

A

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

90
Q

C5 - How Much?

What is the word equation for an insoluble salt?

A

lead nitrate + potassium iodide → lead iodide + potassium nitrate

91
Q

C5 - How Much?

What is the symbol equation for an insoluble salt?

A

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

92
Q

C5 - How Much?

What is the ionic equation for an insoluble salt?

A

Pb2+ (aq) + 2I- (aq) → PbI2 (s)

93
Q

C5 - How Much?

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

A

It will be wet and mixed in with other stuff

94
Q

C5 - How Much?

What are the stages of preparing an insoluble salt?

A

Precipitate, filter, dry

95
Q

C5 - How Much?

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

A

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
Q

C5 - How Much?

Why is distilled water used when making an insoluble salt?

A

Make sure there are no other ions in it.

97
Q

C5 - How Much?

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

A

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
Q

C5 - How Much?

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

A

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
Q

C5 - How Much?

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

A

What catalyst is used in the contact process?

100
Q

C5 - How Much?

Exothermic (and reversible)

A

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

101
Q

C5 - How Much?

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

A

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

102
Q

C5 - How Much?

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.

A

What pressure is used in the contact process?

103
Q

C5 - How Much?

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

A

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

104
Q

C5 - How Much?

The contact process

A

What process is used to make sulphuric acid?

105
Q

C5 - How Much?

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

A

What happens to equilibrium when the temperature is increased?

106
Q

C5 - How Much?

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

A

What is the first stage of the contact process?

107
Q

C5 - How Much?

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

A

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

108
Q

C5 - How Much?

Temperature, pressure and concentration.

A

What 3 things can change the position of equilibrium?

109
Q

C5 - How Much?

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

A

What is the second stage of the contact process?

110
Q

C5 - How Much?

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

A

What happens to equilibrium when the pressure is increased?

111
Q

C5 - How Much?

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

A

When does equilibrium only take place?

112
Q

C5 - How Much?

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

A

What is the third stage of the contact process?

113
Q

C5 - How Much?

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

A

What happens to equilibrium when the pressure is decreased?

114
Q

C5 - How Much?

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

A

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

115
Q

C5 - How Much?

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.

A

What happens to equilibrium when adding a catalyst?

116
Q

C5 - How Much?

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

A

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

117
Q

C5 - How Much?

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

A

What happens to equilibrium when the temperature is decreased?

118
Q

C5 - How Much?

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.

A

What is relationship between product formed and limiting reactants?

119
Q

C5 - How Much?

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

A

What is a reversible reaction?

120
Q

C5 - How Much?

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.

A

What is equilibrium?

121
Q

C5 - How Much?

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.

A

Describe measuring the mass of gas produced…

122
Q

C5 - How Much?

24dm cubed at RTP.

A

What does one mole of any gas always occupy?

123
Q

C5 - How Much?

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

A

What is RTP?

124
Q

C5 - How Much?

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.

A

Describe using a gas syringe…

125
Q

C5 - How Much?

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

A

What should the first titration be?

126
Q

C5 - How Much?

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

A

What 3 ways can gas volume be collected?

127
Q

C5 - How Much?

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.

A

Describe using an upturned burette or measuring cylinder…

128
Q

C5 - How Much?

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

A

What are the repeats for a titration for?

129
Q

C5 - How Much?

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

A

What equipment is used in a titration?

130
Q

C5 - How Much?

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

A

What is universal indicator used for?

131
Q

C5 - How Much?

Pink in alkalis and colourless in acids

A

What colour is phenolphthalein in acids and alkalis?

132
Q

C5 - How Much?

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.

A

How do you estimate sodium content?

133
Q

C5 - How Much?

Red in acids and blue in alkalis

A

What colour is litmus in acids and alkalis?

134
Q

C5 - How Much?

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

A

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

135
Q

C5 - How Much?

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

A

What do titrations allow you to find?

136
Q

C5 - How Much?

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

A

What is concentration a measure of?

137
Q

C5 - How Much?

number of moles ÷ volume (dm³)

A

How do you calculate concentration?

138
Q

C5 - How Much?

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

A

Why might GDA numbers not be the amount consumed?

139
Q

C5 - How Much?

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.

A

What is relative atomic mass a measure of?

140
Q

C5 - How Much?

Mass (g) ÷ Mr of element/compound

A

How are the number of moles calculated?

141
Q

C5 - How Much?

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.

A

What is a mole?

142
Q

C5 - How Much?

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

A

What do acids produce in water?

143
Q

C5 - How Much?

Sulfuric, hydrochloric and nitric

A

What examples are there of a strong acid?

144
Q

C5 - How Much?

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

A

What do strong acids do in water?

145
Q

C5 - How Much?

ethanoic, citric and carbonic

A

What examples are there of a weak acid?

146
Q

C5 - How Much?

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

A

What do weak acids do in water?

147
Q

C5 - How Much?

Reversible reaction arrow.

A

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

148
Q

C5 - How Much?

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

A

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

149
Q

C5 - How Much?

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

A

What is pH a measure of?

150
Q

C5 - How Much?

What proportion of the acid molecules ionise in water.

A

What does acid strength tell you?

151
Q

C5 - How Much?

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.

A

What does concentration of an acid tell you?

152
Q

C5 - How Much?

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

A

What is ethanoic acid’s electrical conductivity?

153
Q

C5 - How Much?

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

A

Why are stronger acids better electrical conductors?

154
Q

C5 - How Much?

Hydrogen because they both produce H+ ions

A

What does electrolysis of hydrochloric acid or ethanoic acid produce?

155
Q

C5 - How Much?

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

A

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

156
Q

C5 - How Much?

Equilibrium in weak acid reaction

A

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

157
Q

C5 - How Much?

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

A

What happens when you put a weak acid in water?

158
Q

C5 - How Much?

The collision frequency between the reactants is low.

A

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

159
Q

C5 - How Much?

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.

A

What happens to equilibrium when H+ ions react?

160
Q

C5 - How Much?

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

A

What happens to H+ ions in a strong acid?

161
Q

C5 - How Much?

Collision frequency between the reactants is really high.

A

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

162
Q

C5 - How Much?

The same amount - produced at different rates.

A

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

163
Q

C5 - How Much?

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

A

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

164
Q

C5 - How Much?

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

A

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

165
Q

C5 - How Much?

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

A

What do precipitation reactions usually involve?

166
Q

C5 - How Much?

Precipitate - makes solution cloudy

A

What is an insoluble substance called?

167
Q

C5 - How Much?

Move

A

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

168
Q

C5 - How Much?

Solution or molten

A

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

169
Q

C5 - How Much?

Because there is a high collision frequency between the ions.

A

Why are precipitation reactions with ions usually extremely quick?

170
Q

C5 - How Much?

barium chloride + sodium sulfate → barium sulfate + sodium chloride

A

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

171
Q

C5 - How Much?

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

A

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

172
Q

C5 - How Much?

2CH3COOH + Mg → Mg(CH3COO)2 + H2

A

What is the symbol equation for ethanoic acid and magnesium?

173
Q

C5 - How Much?

2HCl + Mg → MgCl2 + H2

A

What is the symbol equation for hydrochloric acid and magnesium?

174
Q

C5 - How Much?

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

A

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

175
Q

C5 - How Much?

2HCl + CaCO3 → CaCl2 + H2O + CO2

A

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

176
Q

C5 - How Much?

Ba2+ (aq) + SO42+ (aq) → BaSO4 (s)

A

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

177
Q

C5 - How Much?

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

A

How can you tell a reaction is a precipitate?

178
Q

C5 - How Much?

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

A

What are spectator ions?

179
Q

C5 - How Much?

Add dilute HCl, followed by barium chloride.

A

What is the test for sulfate ions?

180
Q

C5 - How Much?

The original compound was a sulfate.

A

What does a white precipitate of barium sulfate mean?

181
Q

C5 - How Much?

White

A

What colour precipitate shows sulfate ions are present?

182
Q

C5 - How Much?

Add diluted nitric acid, followed by lead nitrate.

A

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

183
Q

C5 - How Much?

White precipitate - of lead chloride.

A

What is the precipitate if chloride ions are present?

184
Q

C5 - How Much?

Cream precipitate - of lead bromide.

A

What is the precipitate if bromide ions are present?

185
Q

C5 - How Much?

Yellow - of lead iodide.

A

What is the precipitate if iodide ions are present?

186
Q

C5 - How Much?

Ions in a solution - free to move about.

A

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

187
Q

C5 - How Much?

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

A

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

188
Q

C5 - How Much?

lead nitrate + potassium iodide → lead iodide + potassium nitrate

A

What is the word equation for an insoluble salt?

189
Q

C5 - How Much?

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

A

What is the symbol equation for an insoluble salt?

190
Q

C5 - How Much?

Pb2+ (aq) + 2I- (aq) → PbI2 (s)

A

What is the ionic equation for an insoluble salt?

191
Q

C5 - How Much?

It will be wet and mixed in with other stuff

A

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

192
Q

C5 - How Much?

Precipitate, filter, dry

A

What are the stages of preparing an insoluble salt?

193
Q

C5 - How Much?

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.

A

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

194
Q

C5 - How Much?

Make sure there are no other ions in it.

A

Why is distilled water used when making an insoluble salt?

195
Q

C5 - How Much?

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.

A

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

196
Q

C5 - How Much?

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.

A

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

Chemistry GCSE OCR Gateway B (6 decks)

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