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Chemistry - IGCSE > Ch - 9 (Reversible Reactions) > Flashcards

Ch - 9 (Reversible Reactions) Flashcards

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1
Q

What happens in a reversible reaction?

A

Reaction can go in both directions.

To the right (forms the products)
To the left (forms the reactants)

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2
Q

What does the Haber process help in the production of?

A

Ammonia, hydrogen and nitrogen

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3
Q

What colour do anhydrous blue cobalt (II) chloride crystals turn into when water is added.

A

pink

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4
Q

What colour do cobalt crystals turn into when heated?

A

Blue (water of crystallisation is lost)

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5
Q

What are the chemical tests commonly used to detect the presence of water?

A

CoCl2 (Copper chloride)
CuSO4 (Copper sulfate)

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6
Q

What happens in the concept of equilibrium?

A

The rate of forward reaction equals the rate of the reverse reaction.

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7
Q

How is the molecules affecting the concept of equilibrium?

A

Dynamic, molecules are changing into each other by chemical reactions constantly changing

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8
Q

What happens to the concentration in equilibrium?

A

Remains constant in a closed system

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9
Q

What happens to the position of equilibrium when concentration of reactant increases?

A

Shifts to the left

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10
Q

What happens to the position of equilibrium when concentration of product increases?

A

Shifts to the right

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11
Q

What does the Le Chatelier principle state?

A

When a change is made to the conditions of a system at equilibrium, the system automatically moves to oppose the change.

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12
Q

What is the Le Chatelier Principle used to predict?

A

Predicts the chances to the position of equilibrium when there ate changes in temperature, pressure and concentration.

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13
Q

What is the effect on equilibrium when temperature is increased?

A

Moves in the endothermic direction to reverse the change.

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14
Q

What is the effect on equilibrium when temperature is decreased?

A

Equilibrium moves in the exothermic direction to reverse the change.

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15
Q

What is the effect of an increase in pressure on equilibrium?

A

shifts in the direction that produces the smaller number of molecules of gas to decrease the pressure again.

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16
Q

What is the effect of an decrease in pressure on equilibrium?

A

equilibrium shifts in the direction that produces large number of molecules of gas to increase the pressure.

17
Q

What is the effect of an increase in concentration on Equilibrium?

A

Shifts to the right to reduce the effcf of increase in conc. of a reactant

18
Q

What is the effect of a decrease in concentration on Equilibrium?

A

equilibrium shifts to the left to reduce the effect of a decrease in reactant

19
Q

What is the effect of a catalyst on Equilibrium?

A

it does not affect the position of equilibrium but it does increase the rate at which equilibrium is reached.

20
Q

Why does a catalyst not have an effect on equilibrium?

A
  • Catalyst increases the rate of both forward and backward reactions by the same amount.
  • Concentration of reactant and products is the same.
21
Q

Define Haber process.

A

The manufacturing of ammonia in an exothermic reaction.

22
Q

What are the stages of Haber process?

A

Stage 1: H2 and N2 are obtained from natural gas and the air respectively and are pumped into the compressor through pipe.

Stage 2: Gasses are compressed to about 200 atmospheres inside the compressor.

Stage 3: Pressurized gases are pumped into a tank

Stage 4: Unreacted H2 & N2 and the product ammonia pass through the cooling tank. The ammonia is liquefied and removed to pressurize storage vessels.

Stage 5: The unreacted H2 and N2 gases are recycles back into the system and it starts over again.

23
Q

What happens to yield as pressure increases on x - axis ?

A

Yield increases at any temperature.

24
Q

What happens to yield as temperatures decreases on y - axis ?

A

the yield increases

25
Q

What’s re the economic conditions in the Haber peocess?

A
  • Readily available and inexpensive to purify
  • Nitrogen: From the air
  • Hydrogen: From natural gas
26
Q

What are the conditions needed for Haber process?

a) Temperature
b) Pressure
c) catalyst

A

a) Temperature - 450°C
b) Pressure - 200atm
c) catalyst - iron

27
Q

What will happen at a higher temperature for Haber process?

A
  • Favour the reverse reaction as it is endothermic (takes in heat) so a higher yield of reactants would be made.
28
Q

What will happen at a lower temperature for Haber process?

A

It favors the forward reaction as it is exothermic (releases heat) so a higher yield of products would be made.

29
Q

What will happen at Lower pressure for the Haber process?

A
  • Favor the reverse reaction, the system will try to increase the pressure by creating more molecules, so a higher yield of reactant will be made
30
Q

What will happen at higher pressure for the Haber process?

A

Favor the forward reaction as it will try to decrease the pressure by creating less molecules, so a higher yield of products will be made.

31
Q

What will happen for catalyst iron in Haber process?

A

It allows an acceptable yield to be achieved at a lower temperature by lowering the activation energy required

32
Q

What is a contact process?

A
  • sulfuric acid synthesized by the contact process.
  • concentrated sulfuric acid is used in car batteries, making fertilizers, soaps and detergents
33
Q

What are the stages of contact process?

A

Stage 1: Production of sulfur dioxide, with by burning sulfur to oxidise the sulfur, or roasting sulfide ores.

Stage 2: the oxidation of sulfur dioxide to sulfur trioxide using vanadium (V) oxide, V2O5, catalyst.

O2 is obtained from the air.

34
Q

What are the conditions needed for Haber process?

a) Temperature
b) Pressure
c) catalyst

A

a) Temperature - 450°C
b) Pressure - 200kPa
c) catalyst - vanadium (V) oxide

35
Q

Why is increasing the temperature Good in contact process?

A
  • Forward reaction is exothermic, it shifts the equilibrium to the left of the reactants
  • higher temperature, lowers the yield of sulfur trioxide
36
Q

Why is increasing the pressure in contact process Good?

A
  • Shifts the equilibrium to the right, in direction of a smaller no. molecules
  • equilibrium lies far to the right
37
Q

Why the contact process carried just above atmospheric pressure?

A
  • High pressures can be dangerous and very expensive equipment is needed
  • A higher pressure causes the sulfur dioxide to liquefy

Chemistry - IGCSE (24 decks)

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