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Chemistry ✦ (Form 4) > Chapter 7 > Flashcards

Chapter 7 Flashcards

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1
Q

What are the two classifications of reactions based on speed?

A

Fast reactions. Slow reactions

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2
Q

What are some examples of slow reactions?

A

Food decay. Photosynthesis. Rock erosion. Fermentation. Corrosion of metals

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3
Q

What are some examples of fast reactions?

A

Fireworks. Electric cell reactions. Ignition of matches. Combustion of gases

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4
Q

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A
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5
Q

How is the rate of reaction defined?

A

The rate of reaction is the change in the quantity of reactant or product per unit time.

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6
Q

How is the rate of reaction related to the time of reaction?

A

The rate of reaction is inversely proportional to the time of reaction.

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7
Q

What is the relationship between the rate of reaction and the time of reaction?

A

The reaction with a shorter time of reaction has a higher rate of reaction and vice versa.

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8
Q

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A
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9
Q

What are some changes that can be measured to determine the rate of reaction?

A

Reduction in the mass or concentration of reactant. Increase in mass or concentration of product. Increase in volume of gas released. Production of precipitate. Change of temperature

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10
Q

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A
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11
Q

What are the two types of rate of reaction?

A

Average rate of reaction. Instantaneous rate of reaction

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12
Q

What is the average rate of reaction?

A

The speed of a reaction over a specific time interval.

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13
Q

What is the instantaneous rate of reaction?

A

The rate of reaction at any given moment in time.

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14
Q

How is the instantaneous rate of reaction obtained?

A

It is obtained from the gradient of the tangent on the graph of change in the amount of reactant or product against time.

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15
Q

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A
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16
Q

What are the five main factors affecting the rate of reaction?

A

Size of the reactant. Concentration of the reactant.Temperature of the reaction. Catalyst. Pressure

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17
Q

How does the size of the reactant affect the rate of reaction for solid reactants?

A

The smaller the size of the reactant. the larger the exposed surface area. leading to a higher rate of reaction.

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18
Q

What is the effect of size on the rate of reaction with respect to surface area?

A

Smaller particles have a larger surface area. which increases the rate of reaction.

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19
Q

How does the concentration of the reactant affect the rate of reaction in solutions?

A

The higher the concentration of the reactant. the more particles are present per unit volume. leading to a higher rate of reaction.

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20
Q

How does temperature affect the rate of reaction?

A

The higher the temperature. the higher the kinetic energy of the particles. which increases their speed and leads to a higher rate of reaction.

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21
Q

How is the relationship between temperature and rate of reaction explained?

A

This is related to collision theory. where increased temperature causes particles to collide more frequently and with greater energy.

22
Q

What is a catalyst?

A

A catalyst is a substance that changes the rate of a chemical reaction without being consumed or altered in the process.

23
Q

What are the characteristics of a catalyst?

A

Remains unchanged chemically or quantitatively. Does not affect the amount of product. Only a small amount is required. Increases the rate of reaction. Its action is specific

24
Q

How does pressure affect the rate of reaction for gaseous reactants?

A

Increasing pressure makes the gas denser. which increases the rate of reaction.

25
Q

How does size of the reactant apply in real life?

A

Chicken is cut into smaller pieces to cook faster. Smaller medicine tablets act faster in the body.

26
Q

How does concentration affect reactions in real life?

A

Corrosion by acid rain. Combustion of gasoline in car engines.

27
Q

How does temperature affect reactions in real life?

A

Sugar dissolves faster in hot water. Washing clothes is more efficient in warm water.

28
Q

How is a catalyst applied in industry?

A

Vanadium(V) oxide is used in the Contact process to speed up reactions.

29
Q

How does pressure affect cooking in real life?

A

Cooking meat in a pressure cooker increases the rate of cooking.

30
Q

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A
31
Q

How does the size factor apply to the action of medicines?

A

Antacid tablets are broken into smaller pieces. increasing the surface area and speeding up the reaction between the medicine and stomach acid.

32
Q

How does the size factor apply to cooking food?

A

Cutting potatoes into thin slices or strips increases the surface area exposed to cooking oil. allowing them to cook faster.

33
Q

How does the concentration factor affect corrosion due to acid rain?

A

In industrial areas. the higher concentration of sulfur dioxide increases the level of acid rain. which accelerates the corrosion of buildings made of iron.

34
Q

How does the concentration factor apply to the combustion of petrol in car engines?

A

In a car engine. compressing petrol vapour and air increases the concentration. allowing the petrol to burn more quickly. powering the car.

35
Q

How does the temperature factor apply to cleaning?

A

Washing clothes with hot water and detergent speeds up the washing process due to the increased rate of reaction.

36
Q

How does the temperature factor affect cooking food?

A

High temperatures. like frying food in oil. cook food faster than boiling water at 100°C because oil reaches higher temperatures (up to 180°C).

37
Q

How does the catalyst factor apply to modern cars?

A

Cars are fitted with catalytic converters to reduce atmospheric pollution by speeding up the reactions that neutralize harmful gases in the exhaust.

38
Q

How does the catalyst factor apply to making alcohol?

A

Ethanol. the main ingredient in alcoholic drinks. is produced by fermenting glucose with the help of an enzyme in yeast as a catalyst at 37°C.

39
Q

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A
40
Q

What does collision theory explain?

A

Collision theory explains how factors affect the rate of reaction by considering particle collisions.

41
Q

What must happen for a chemical reaction to occur according to collision theory?

A

Particles must collide with sufficient energy and in the correct orientation for an effective collision to cause a reaction.

42
Q

What is the condition for an effective collision in collision theory?

A

Particles must collide with enough energy (at least the activation energy) and in the correct orientation.

43
Q

What is activation energy?

A

Activation energy is the minimum energy needed by reactants for a chemical reaction to occur.

44
Q

What is an energy profile diagram?

A

An energy profile diagram shows the activation energy and the energy changes between reactants and products.

45
Q

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A
46
Q

How does the size of the reactant affect the rate of reaction?

A

Size of reactant smaller. Higher total exposed surface area. Higher collision frequency. Higher effective collision frequency. Higher rate of reaction.

47
Q

How does the concentration of the reactant affect the rate of reaction?

A

Higher concentration means more particles per unit volume. leading to more collisions/ effective collisions frequency a higher rate of reaction.

48
Q

How does the temperature of the reaction affect the rate of reaction?

A

Higher temperature increases particle kinetic energy. leading to more frequent and effective collisions frequency. and thus a higher rate of reaction.

49
Q

How does a catalyst affect the rate of reaction?

A

A catalyst lowers the activation energy. leading to more effective collisions frequency and a higher rate of reaction.

50
Q

How does pressure affect the rate of reaction?

A

Higher pressure increases the frequency of collisions

Chemistry ✦ (Form 4) (11 decks)

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