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Chemistry > Topic 9: Reversible Reactions > Flashcards

Topic 9: Reversible Reactions Flashcards

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1
Q

What is a reversible reaction?

A

A chemical change that is able to go backwards and forwards.

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2
Q

To represent a chemical process we use….?

A

Half arrows (=)

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3
Q

Experiment 1: Reversible reaction of acids and bases (3rd form)?

A

Change color of Phenolpholein by adding a few drops of NaOH (aq) to change the solution -> pink, then changing it back by adding HCL (aq) -> colorless

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4
Q

Experiment 2: Reversible reaction, testing for water?

A

CuSO4. 5H2O(s) ->(heat) (H2O)<- CuSO4(s) 5H2O

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5
Q

Experiment 3: Reversible reaction, of states of matter 3rd form - diffusion?

A

NH4Cl(s)(white solid) ->(heat) (cool)<- NH3(g) + HCL(g) (colorless)

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6
Q

What is Chemical Equilibrium?

A

This is “When the rate of forward reaction equals the rate of the backwards reaction”, the reaction is said to be in equilibrium.

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7
Q

What is a dynamic Equilibrium?

A

The type of equilibrium that occurs in chemical reactions is called a dynamic equilibrium.

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8
Q

How is the position of a Equilibrium changed?

A

The position of a equilibrium can be changed by altering the concentrations of reactants or products, temperature or pressure.

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9
Q

How can the concentration change the position of the equilibrium?

A

A + B == C + D

- If more A is added the equilibrium moves to the right to reduce the concentration of A.

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10
Q

How can the temperature change the position of the equilibrium?

A

A + B == C + D = Heat
- When the forward reaction is exothermic, if the temperature is increased, the equilibrium moves to the left to get rid of extra heat.

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11
Q

How can the pressure change the position of the equilibrium?

A

A(g) + B(g) == C(g)
- If the pressure is increased the equilibrium will move to the side with the fewest number of gas molecules to reduce the pressure.

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12
Q

The Chemical equilibrium rule?

A

A chemical equilibrium will move to counteract any change imposed on it.

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13
Q

Equation for the Bromine water experiment?

A

Br2(aq) +H2O(l) (yellow) == Br(aq) + OBr(aq) +H+(aq) (colorless)

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14
Q

Ammonia to ammonia chloride reaction?

A

ammonia (NH3(g)) + hydrogen chloride (HCL(g)) == ammonium chloride (NH4Cl(s).

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15
Q

Properties of Ammonia? NH3

A
  • Colorless
  • Colorless gas
  • Vary soluble in water
  • Pungent smell
  • Gas at room temperature
  • Base produces a solution of PH 10-11 when dissolved in water.
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16
Q

Ammonia is needed and the starting material for which products?

A

Nitric acid and ammonia nitrate (a fertilizer)

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17
Q

Main Equation for the Habour process?

A

nitrogen(N2(g)) + hydrogen(3H2(g)) == ammonia(2NH3(g))

18
Q

The reaction for the Habour process is endothermic or exothermic?

A

Exothermic. (delta)H = -80kJmol-1

19
Q

What is the catalyst used in the main Habour process reaction and why is it used?

A
  • Iron catalyst is used.
  • The catalyst (as with all reversible reactions) speeds up the reaction in both directions equally. So it simply reduces the amount of time taken to reach equilibrium.
20
Q

To increase yield in the Main Habour Process reaction we could?

A
  • Increase the pressure.

- reduce the temperature.

21
Q

Conditions used for the main Habour Process reaction?

A
  • Fe(Iron) Catalyst
  • Pressure of 200 atm
  • Temperature at 400o
22
Q

Why is 450o used in Main Habour Process Reaction?

A

This is a compromise, it is hot enough to enable that reaction to take place quickly but not too hot to ensure the equilibrium sits for enough towards the product.

23
Q

Why is 200atm used in Main Habour Process Reaction?

A

This is a compromise - it is high enough to increase yield but isent to expensive to maintain.

24
Q

How is H2 created in the Habour Process?

A

Obtained by reacting steam with CH4

25
Q

How is N2 created in the Habour Process?

A

Obtained for the air.

26
Q

What form is ammonia collected in?

A

NH3 is cooled and collected as a liquid.

27
Q

What does the statement ‘that a reaction has reached equilibrium’ mean?

A

Rate of forwards reaction = rate of backwards reaction.

28
Q

Why is nitrogen important for plants?

A

Nitrogen is needed for proteins in the leaves and stalks.

29
Q

If 80% of the air is nitrogen why can’t plants use this?

A

This is because it needs to be in the form of nitric acid. In a soluble form.

30
Q

What happens when to much fertilizers are put on the fields?

A

Leaching occurs, Port from Biology, fertilizers in the water cause eutophication. Which causes other animals in the water to die.

31
Q

What happens when nitrates are ingested?

A
  • Stomach cancer

- Blue Baby Syndrome, not enough oxygen in the blood to aid respiration.

32
Q

Step 1) in the production of H2SO4 - The Contact Process?

A

1) - Sulpher(S(s)) + Oxygen(O2(g)) = Sulpher dioxide(SO2(g))

33
Q

Step 2) in the production of H2SO4 - The Contact Process?

A

2) Sulpher dioxide(2SO2(g)) + Oxygen(O2(g)) = Sulpher monoxide(2SO3(g))
- Temperature used : 440oC
- Catalyst used : V2O5
- High pressures are not needed as % conversion is already good enough.

34
Q

Step 3) in the production of H2SO4 - The Contact Process?

A

3) Sulpher monoxide(SO3(g)) + Water(H2O(l)) = Sulpheric Acid(H2SO4(l)) - diluted and sent to customers.

35
Q

Uses of Sulpheric Acid?

A
  • Production of pharmaceuticals
  • Production of Paint, fertilizers and explosives
  • Used in metal treatment.
36
Q

In the Habour Process what will be present in the equilibrium mixture with ammonia?

A
  • Un-reacted gasses ie. H2 and N2 will be present when the gasses are cooled and condense to a liquid. They are recycled before reaching the iron catalyst.
37
Q

In the Habour Process, How will the rate of reaction of nitrogen with hydrogen be affected by increasing the temperature.

A

The rate of reaction should increase because there is going to be more collisions between the atoms as the kinetic energy increases.

38
Q

What is seen when excess ammonia solution is added gradually to copper (II) chloride solution. With formula.

A

light blue precipitate
darker blue solution
[Cu(NH3)4(H2O)2]2+

39
Q

Nitric Acid?

Amonia?

A

HNO3

NH3

40
Q

Explain why increasing the concentration of X has this effect on the rate of the reaction?

A

more particles
more successful collisions.
more frequently

Chemistry (20 decks)

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