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Chemistry > S5 - Unit 3 > Flashcards

S5 - Unit 3 Flashcards

1
Q

What do industrial processes aim to do?

A

Maximise profit, minimise environmental impact

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2
Q

How do you make a standard solution?

A
  • Weigh the solid into a small, clean beaker
  • Dissolve in a small volume of water
  • Transfer to a volumetric flask
  • Make it up to the graduation mark with water
  • Insert a stopper and invert several times to mix
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3
Q

What is a limiting reactant?

A

The reactant used up in a reaction which determines the mass of product formed

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4
Q

What is percentage yield?

A

The amount of product you actually make as a percentage of the amount you should theoretically make

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5
Q

What is atom economy?

A

A measure of the percentage of reactants that become useful products

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6
Q

Why must reaction rates be controlled in industrial processes?

A

Because if reaction rates are too high there will be the risk of explosion and if they’re too low the process will not be economical

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7
Q

What factors affect the rate of reaction?

A
  • Concentration
  • Particle size
  • Temperature
  • Pressure
  • Collision geometry
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8
Q

What does it mean if a reaction is at equilibrium?

A

The rate of the forward reaction is equal to the reverse reaction

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9
Q

What happens when equilibrium is reached?

A

The concentrations of products and reactants remain constant

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10
Q

What factors affect the position of equilibrium?

A
  • Concentration
  • Particle size
  • Temperature
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11
Q

What do catalysts do to the equilibrium?

A

Nothing, they only help reach equilibrium faster

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12
Q

What will happen when there is an increase in pressure when a reaction is in a state of equilibrium?

A

Will favour the side with the least gas moles

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13
Q

What will happen when there is an increase in temperature when a reaction is in a state of equilibrium?

A

Will favour the endothermic side

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14
Q

What will happen when there is an increase in a certain element when a reaction is in a state of equilibrium?

A

Will favour the side with the smaller volume of that element

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15
Q

What will happen when there is a decrease in pressure when a reaction is in a state of equilibrium?

A

Will favour the side with more gas moles

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16
Q

What will happen when there is a decrease in temperature when a reaction is in a state of equilibrium?

A

Will favour the exothermic side

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17
Q

What will happen when there is a decrease in a certain element when a reaction is in a state of equilibrium?

A

Will favour the side with the larger volume of that element

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18
Q

What will happen when an alkali is added to an equilibrium reaction?

A

The H ions will be removed

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19
Q

What will happen when an acid is added to an equilibrium reaction?

A

The H ions will increase

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20
Q

What must happen before products can be formed?

A

Reactant molecules must collide in the correct way

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21
Q

What do the collisions of reactant molecules provide?

A

The energy needed to break the bonds between them and the energy needed to form the bonds on the new products

22
Q

What factors must be present at the same time for a reaction to be successful?

A
  • Sufficient energy
  • Correct geometry
23
Q

What is activation energy?

A

The minimum kinetic energy required for a reaction to occur

24
Q

What type of reaction has taken place in the diagram?

A

Exothermic

25
What type of reaction has taken place in the diagram?
Endothermic
26
What are the blanked out words?
27
What are the blanked out words?
28
What is the enthalpy of combustion?
The heat energy given out when 1 mole of fuel burns completely in oxygen
29
What is the enthalpy of solution?
The energy change when 1 mole of a substance dissolves completely in water
30
What is enthalpy of neutralisation?
The heat energy given out when 1 mole of water is formed in a neutralisation reaction
31
What does Hess' law state?
The enthalpy change for a reaction is independent of the route taken
32
What is the enthalpy of formation?
The energy needed to make 1 mole of a compound from its elements in their standard state
33
What type of reaction is the breaking of bonds?
Endothermic
34
What type of reaction is the making of bonds?
Exothermic
35
What is the symbol that represents an exothermic reaction?
-ΔH
36
What is the symbol that represents an endothermic reaction?
+ΔH
37
What is chromatography?
An important analytic technique which allows chemists to separate substances and identify unknown substances
38
How does chromatography work?
Substances are separated as they travel in a mobile phase which passes through a stationary phase
39
What are the two phases in paper chromatography?
Stationary; a sheet of chromatography paper Mobile; water
40
What is an advantage of thin layer chromatography?
The mobile phase moves more quickly through the stationary phase
41
What is gas chromatography used for?
To separate complex mixtures
42
What factor effect retention time?
- polarity - volatility - mass of a substance
43
How do you calculate the enthalpy change for a forward reaction?
Products - reactants
44
How do you calculate the enthalpy change for a reverse reaction?
Reactants - products
45
What is an activated complex?
An intermediate state where particles can either form products or go back to particles of the reactants
46
What do catalysts do to the activation energy?
Lower the activation energy
47
What are the principles of chemical industry design?
Availability, cost and sustainability of feedstocks
48
What is considered to be a raw material in the chemical industry?
- fossil fuels - water - air - metal ores - minerals
49
What are feedstocks in the chemical industry?
Simple chemicals or mixtures derived from raw materials used in further manufacture
50
What is considered in the chemical industry?
- what the cost is - if the feedstocks are sustainable - if any by-products can be recycled

Chemistry (9 decks)

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