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Chemistry > 3a.3 - Reversible Reactions, The Haber Process, Alcohols, Carboxylic Acids and Esters > Flashcards

3a.3 - Reversible Reactions, The Haber Process, Alcohols, Carboxylic Acids and Esters Flashcards

1
Q

What is a reversible reaction?

A

A reaction where the products of the reaction can themselves react to produce the original reactants

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2
Q

What will reversible reactions eventually reach?

A

Equilibrium

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3
Q

What does a reversible reaction take place in?

A

A closed system

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4
Q

What is equilibrium?

A

The amounts of reactants and products will reach a certain balance and stay there

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5
Q

What will happen in terms of yield if the forward reaction is exothermic and the temperature is raised? (3)

A
  • The equilibrium will shift to the left
  • Because increasing the temperature will favour the endothermic reaction
  • So yield will decrease
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6
Q

What will happen in terms of yield if the forward reaction is endothermic and the temperature is raised? (3)

A
  • Equilibrium shifts to the right
  • Favours endothermic reaction
  • Yield increases
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7
Q

What will happen in terms of yield if the forward reaction is exothermic and the temperature is reduced? (3)

A
  • Equilibrium shifts to right
  • Favours exothermic reaction
  • Yield decreases
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8
Q

What will happen in terms of yield if the forward reaction is endothermic and the temperature is reduced? (3)

A
  • Equilibrium shifts to left
  • Favours exothermic reaction
  • Yield decreases
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9
Q

Why will the yield increase as the temperature is raised in an endothermic reaction?

A

To take in and use up the extra heat

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10
Q

Why will the yield increase as the temperature is reduced in an exothermic reaction?

A

To give out more heat

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11
Q

What will happen in terms of yield if the forward reaction has more molecules and the pressure is raised? (3)

A
  • Equilibrium shifts left
  • Favours side with least molecules
  • Yield decreases
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12
Q

What will happen in terms of yield if the forward reaction has less molecules and the pressure is raised? (3)

A
  • Equilibrium shifts right
  • Favours side with least molecules
  • Yield increases
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13
Q

What will happen in terms of yield if the forward reaction has more molecules and the pressure is reduced? (3)

A
  • Equilibrium shifts right
  • Favours side with most molecules
  • Yield increases
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14
Q

What will happen in terms of yield if the forward reaction has less molecules and the pressure is reduced? (3)

A
  • Equilibrium shifts left
  • Favours side with most molecules
  • Yield decreases
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15
Q

What does a catalyst do? (2)

A
  • Speeds up both forward and backwards reaction by the same amount
  • Reaches equilibrium quicker
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16
Q

Where does the nitrogen come from for the Haber process?

A

From the air

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17
Q

Where does the hydrogen come from for the Haber process?

A

Natural gas or crude oil

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18
Q

What are the uses of ammonia? (3)

A
  • Fertilisers
  • Textiles
  • Explosives
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19
Q

What is the pressure used in the Haber process?

A

200 atmospheres

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20
Q

What is the temperature used in the Haber process?

A

450C

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21
Q

What is the catalyst used in the Haber process?

A

Iron

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22
Q

Why is a compromise made with the pressure? (5)

A
  • High pressure favours forward reaction
  • So pressure needs to be high
  • Expensive to have a plant operating at high pressures
  • Cheaper to have low pressures
  • Compromise is made
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23
Q

Why is a compromise made with the temperature? (5)

A
  • Low temperatures favour exothermic reactions
  • So temperature needs to be low
  • Rate of reaction is lower at lower temperatures
  • Make more money faster with higher temperature
  • Compromise is made
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24
Q

Describe the Haber process (4)

A
  • H2 and N2 mixed in 3:1 ratio
  • Goes through cylinder with trays of iron catalyst
  • Unused H2 and N2 is recycled so nothing is wasted
  • Cools in condenser
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25
Q

Why is a catalyst important in the Haber process? (2)

A
  • Reaction is faster so reaches equilibrium proportions faster
  • Keeps costs down
26
Q

Why is iron used as a catalyst?

A

Because it is in abundance

27
Q

What is the general formula of an alcohol?

A

CnH2n+1OH

28
Q

What are the first three alcohols?

A
  • Methanol
  • Ethanol
  • Propanol
29
Q

What is the formula of methanol?

A

CH3OH

30
Q

What is the formula of ethanol?

A

C2H5OH

31
Q

What is the formula of propanol?

A

C3H7OH

32
Q

What are the similar properties of the first three alcohols? (3)

A
  • They are flammable
  • Dissolve in water to form neutral solutions
  • React with sodium to give hydrogen and alkoxides
33
Q

Why are alcohols used as solvents?

A

They can dissolve substances water cannot dissolve

34
Q

Why can ethanol be used as fuel for cars?

A

It is clean burning so the more added, the less pollution

35
Q

What is the functional group of carboxylic acids?

A

-COOH

36
Q

What are the first three carboxylic acids?

A
  • Methanoic acid
  • Ethanoic acid
  • Propanoic acid
37
Q

What is the formula for methanoic acid?

A

HCCOH

38
Q

What is the formula for ethanoic acid?

A

CH3COOH

39
Q

What is the formula for propanoic acid?

A

C2H5COOH

40
Q

How do you draw the structure of carboxylic acids?

A 
O
     //
--C                (added onto the end)
     \
       OH
41
Q

How do you draw ethanoic acid?

A 
H        O
        |        //
H -- C -- C
        |       \
       H       OH
42
Q

What is produced when you react carboxylic acids with carbonates?

A

Carbon dioxide, water and (carbonate used + the first part of the acid)anoate

43
Q

What is produced when ethonoic acid reacts with sodium carbonate?

A

Carbon dioxide, water and sodium ethanoate

44
Q

Why does carboxylic acids make a solution acidic when it is dissolved in it?

A

They ionise and release H+ ions

45
Q

Why do carboxylic acids only form weak solutions?

A

They don’t ionise completely

46
Q

How can ethanoic acid be made?

A

Oxidising ethanol

47
Q

What is the word equation for the oxidation of ethanol?

A

ethanol + oxygen -> athanoic acid + water

48
Q

What can be made from ethanoic acid?

A

Vinegar

49
Q

What are the main uses of carboxylic acids?

A
  • Soaps and detergents
  • Preparation of esters
  • Good solvent for many organic molecules
50
Q

What are esters formed from?

A

Alcohol and carboxylic acids

51
Q

What type of catalyst is usually used in making esters?

A

An acid catalyst

52
Q

What is the word equation for the formation of esters?

A

alcohol + carboxylic acid -> ester + water

53
Q

How are esters names formed? (3)

A
  • The alcohol forms the first part (e.g. eth)
  • The acid forms the second (e.g. propan)
  • The name ends in ‘-oate’
    (e. g. ethanol + propanoic acid -> ethyl propanoate + water)
54
Q

What does volatile mean?

A

Low boiling point

55
Q

Why does the volatility of an ester make them dangerous?

A

They are also flammable

56
Q

What don’t esters mix well with?

A

Water

57
Q

What do esters mix well with? (2)

A
  • Alcohols

- Organic solvents

58
Q

Why are esters used in perfumes?

A

Smell nice

59
Q

What are the disadvantages of esters? (3)

A
  • Fumes irritate mucous membranes in nose and mouth
  • Heavier than air and flammable
  • Some are toxic
60
Q

What are the advantages of esters?

A

Aren’t as volatile or toxic as some other organic solvents

Chemistry (13 decks)

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