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Chemistry > The Rate and Extent of Chemical Change > Flashcards

The Rate and Extent of Chemical Change Flashcards

1
Q

If you want to measure the rate of a reaction you can measure how fast one of the __________ is formed. What one word completes this sentence?

A

products

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2
Q

If you want to measure the rate of a reaction you can measure how fast one of the __________ is used up. What one word completes this sentence?

A

reactants

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3
Q

A reaction between two particles cannot happen unless the particles have enough __________ when they collide. What is the missing word?

A

energy

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4
Q

If you want to increase the rate of a reaction, should you increase, decrease or make no change to the pressure?

A

increase

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5
Q

True or false? Decreasing the temperature increases the number of collisions between reacting particles.

A

false

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6
Q

Magnesium reacts with acid to give a salt and hydrogen. Will this reaction happen faster using magnesium ribbon or magnesium powder?

A

magnesium powder

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7
Q

Magnesium reacts with acid to give a salt and hydrogen. Why does the reaction happen faster because you use magnesium powder?

A

Powdered solids have a faster rate of reaction because they have a larger surface area.

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8
Q

For a reaction to happen the reacting particles must successfully __________ with one another. What word completes this sentence?

A

bond

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9
Q

True or false? If the same reaction is carried out twice, once at high pressure and once at low pressure, the reaction at low pressure will have a shorter reaction time.

A

false

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10
Q

At ____ ______, there are more particles per unit volume.

A

higher pressures

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11
Q

At higher pressures, there are more ________ per unit volume.

A

particles

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12
Q

the amount of energy needed for the reaction to occur

A

activation energy

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13
Q

Does increasing the surface area of a solid reactant increase, decrease or have no effect on the frequency of collisions between the reacting particles?

A

increase

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14
Q

True or false? Increasing the temperature rarely has an effect on the speed of the reacting particles.

A

false

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15
Q

Does decreasing the temperature increase the rate of a reaction?

A

no

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16
Q

Why does increasing the concentration of reactants increases the reaction rate?

A

the reactant particles are more crowded so they collide more often

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17
Q

What word is used to describe how fast or slow a reaction is?

A

rate

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18
Q

True or false? Catalysts do not change the rates of chemical reactions.

A

false

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19
Q

Does a catalyst increase, decrease or have no effect on the rate of a reaction?

A

increase

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20
Q

An iron catalyst is used to lower the activation energy of a reaction. What effect will this have on the overall energy change of the reaction?

A

stay the same

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21
Q

Catalysts work by lowering the __________ __________. What two words complete the sentence?

A

activation energy

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22
Q

True or false? Different reactions require different catalysts.

A

true

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23
Q

What name is given to any chemical which increases the rate of a chemical reaction?

A

catalyst

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24
Q

True or false? Catalysts are important in industrial processes because they reduce costs.

A

true

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25
Q

Increasing the temperature means that the particles have more energy and so collide __________.

A

more frequently

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26
Q

True or false? Endothermic reactions cannot be catalysed.

A

false

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27
Q

True or False? Every reaction can potentially be catalysed.

A

true

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28
Q

True or false? A catalyst provides a different pathway for a reaction with a higher activation energy for a reaction.

A

false

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29
Q

The number of collisions between the particles of hydrogen and nitrogen is increased by using high pressure and __________.

A

temperature

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30
Q

True or false? Only a small amount of a catalyst is needed to catalyse large amounts of reactants.

A

true

31
Q

Will decreasing the pressure increase, decrease or have no effect on the number of collisions between the particles of two reacting gases?

A

decrease

32
Q

How does using a catalyst change the activation energy?

A

decreases

33
Q

What is the name of a biological catalyst?

A

enzyme

34
Q

What name is given to a substance that changes the rate of a chemical reaction without being used up in the reaction?

A

catalyst

35
Q

Will increasing the concentration of reactants increase or decrease the rate of a reaction?

A

increase the rate of reaction

36
Q

True or false? Changing the temperature will always change the position of the equilibrium for a reversible reaction.

A

true

37
Q

When products are being made as quickly as reactants, the reaction is said to have reached… what?

A

equilibrium

38
Q

Equilibrium is reached when the forward reaction happens at exactly the same __________ as the backward reaction. What one word completes this sentence?

A

rate or speed

39
Q

If the temperature of a reversible reaction is raised, the yield from the exothermic reaction… what?

A

decreased

40
Q

True or false? Only reversible reactions in open systems can reach equilibrium.

A

false

41
Q

True or False? Equilibrium can only be reached in a closed system.

A

true

42
Q

True or false? A reversible reaction is always exothermic in one direction and endothermic in the other.

A

true

43
Q

We can use Le Chatelier’s Principle to predict what will happen to a reversible reaction that is at __________ if we change its temperature, concentration or pressure. What word completes the sentence?

A

equilibrium

44
Q

This symbol equation shows the production of ammonia: N2 (g) + 3H2 (g) ⇌ 2NH3 (g). Which direction will the equilibrium position shift if the pressure is increased?

A

to the right

45
Q

For gaseous reactions at equilibrium a decrease in pressure causes the equilibrium position to shift towards the side with the __________ number of molecules. What word is missing from this sentence?

A

larger

46
Q

If the temperature is raised, the yield from the endothermic reaction… what?

A

increases

47
Q

A system is at equilibrium. If its temperature is increased, the relative amount of products will __________ for the endothermic reaction. What is missing from this sentence?

A

increase

48
Q

A system is at equilibrium. If its temperature is decreased, the relative amount of products will __________ for the exothermic reaction. What is missing from this sentence?

A

increases

49
Q

Here is the symbol equation for the production of ammonia: N2 (g) + __H2 (g) ⇌ 2NH3 (g). What number should be put in the space before H2 (g) to balance this symbol equation?

A

3

50
Q

True or false? Changing the pressure has no effect on a reversible reaction unless one of the products or reactants is a gas.

A

true

51
Q

The symbol equation for manufacturing ethanol is: H2O (g) + C2H4 (g) ⇌ C2H5OH (g) The manufacture of ethanol is exothermic. What would happen to the yield of ethanol if the temperature of the reaction is increased?

A

it would decrease

52
Q

For gaseous reactions at equilibrium an increase in pressure causes the equilibrium position to shift towards the side with the __________ number of molecules. What word is missing from this sentence?

A

smaller

53
Q

True or false? An equilibrium position always responds to oppose any change in the reaction conditions.

A

true

54
Q

Here is the symbol equation for the production of ammonia: N2 (g) + 3H2 (g) ⇌ 2NH3 (g). What does the state symbol (g) mean?

A

gas

55
Q

A reversible reaction is always exothermic in one direction and endothermic in the other. If the temperature is lowered, this will favour the __________ reaction. Which word completes the sentence?

A

exothermic

56
Q

True or false? Changing the pressure will always change the position of the equilibrium for a reversible reaction.

A

false

57
Q

Here is the equation for manufacturing ethanol: H2O (g) + C2H4 (g) ⇌ C2H5OH (g) The manufacture of ethanol is exothermic. Where would the position of the equilibrium move if the temperature of the reaction increased?

A

left

58
Q

This symbol equation shows the production of ammonia: N2 (g) + 3H2 (g) ⇌ 2NH3 (g). Where would the direction of the equilibrium shift if the pressure decreased?

A

to the left

59
Q

The symbol equation for manufacturing ethanol is: H2O (g) + C2H4 (g) → C2H5OH (g) Increasing the temperature lowers the yield of ethanol because the forward reaction is __________. What is the missing word in this sentence?

A

exothermic

60
Q

If a change occurs when a system is at equilibrium, the equilibrium position shifts in order to counteract the change. This is known as __________’s Principle. What name completes the sentence?

A

Le Chatelier

61
Q

the rate of a chemical reaction is how fast the _________ are changed into _________.

A

reactants are changed into products

62
Q

example of slow reactions

A

chemical weathering

63
Q

example of slowest reaction

A

rusting iron

64
Q

example of moderate speed reaction

A

metal magnesium react with an acid to produce bubbles

65
Q

example of fastest reaction

A

burning or explosion

66
Q

steeper the line on the graph the ________ the rate of reaction.

A

faster

67
Q

why does the line on the line graph become less steep over time

A

reactants are slowly used up

68
Q

rate of chemical reaction depends on…. what?

A
  • collision frequency
  • energy transferred during a collision
69
Q

activation energy

A

the amount of energy needed for the reaction to occur

70
Q

position of equilibrium depends on what conditions?

A
  • temperature
  • pressure
  • concentration
71
Q

what is Le Chatelier’s Principle used to predict?

A

the effect of any change you make to a reaction system

72
Q

If you increase the pressure, the equilibrium tries to reduce it. It moved in the direction where there are ______ ____________ __ ___.

A

fewer molecules of gas

73
Q

If you decrease the pressure, the equilibrium tries to increase it. It moves in the direction where there are _____ __________ __ ___.

A

more molecules of gas

74
Q

If you change the concentration of either the reactants or the products, the system will __ ________ __ __ ___________.

A

no longer be at equilibrium

Chemistry (9 decks)

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