Rates of Reaction Flashcards

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1
Q

The smaller the particle size

A

the greater the surface area and the faster the reaction

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2
Q

The higher the concentration of the reaction

A

the faster the reaction

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3
Q

The higher the temperature

A

the faster the reaction

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4
Q

The higher the activation energy

A

The slower the reaction

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5
Q

For a chemical reaction to occur what are the two things needed

A

KINETIC ENERGY AND SPEED

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6
Q

Why is energy needed In a chemical reaction?

A

The energy is needed to overcome the repulsive force between the atoms and molecules and to start the breaking of bonds

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7
Q

What is activation energy

A

It is the minimum kinetic energy required for a SUCCESSFUL COLLISION to occur.

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8
Q

What is the unit for activation energy

A

(EA).

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9
Q

Explain what is meant by the term ‘activated complex’

A

It is when the reactant particles collide with the required activation energy.

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10
Q

Explain in terms of the collision theory how increasing SURFACE AREA increases the rate of reaction

A

Increase Collision Frequency: When the surface area is increased, the total area available for reactant particles to collide with each other also increases and this leads to a higher frequency of collisions of particles which can lead to a reaction.

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11
Q

Explain in terms of the collision theory how increasing the CONCENTRATION increases the rate of reaction

A

When the concentration of a reactant is increased, the number of particles also increases. This leads to an increase in the frequency of collisions between reactant particles which can lead to a reaction.

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12
Q

What is the formula for calculating rate?

A

1/time
(s-1)

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13
Q

An increase in pressure will

A

will increase the rate of the reaction

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14
Q

What is pressure

A

Pressure is a measure of the number of particles within a stated volume

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15
Q

What is temperature?

A

Temperature is a measure of the average kinetic energy of all the particles in a substance

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16
Q

An increase in temperature affects the rate of the reaction in two ways which are?

A
  1. Particles move faster and thus collide more regularly leading to an increase in successful collisions.
  2. More particles have equal to or more than the activation energy.
17
Q

What is the formula for calculating time

A

1/rate

18
Q

A catalyst is thought to help in the formation of?

A

The activated complex by helping the particles to collide with the correct geometry.

19
Q

How does a catalyst affect the activation energy

A

Catalyst lowers the activation energy for a reaction, making it easier to form the activated complex

20
Q

The enthalpy change for a reaction is the energy difference between?

A

Reactants and Products

21
Q

What does the area under the graph in a kinetic energy distribution diagram represent?

A

The total number of molecules in a reaction

22
Q

What is the name given to the unstable arrangement of atoms that forms at the peak of a potential energy diagram?

A

Activated complex

23
Q

List things that increases the rate of the reaction

A

Adding a catalyst
Increase in Concentration
Increase in surface area
Increase in temperature
Decrease in particle size
Decrease in Activation Energy

24
Q

If a reaction is endothermic what will happen to the temperature

A

The temperature will decrease

25
Q

If a reaction is EXOTHERMIC what will happen to the temperature

A

The temperature will increase

26
Q

What sign will the enthalpy change of an EXOTHERMIC reaction have

A

A negative sign

27
Q

What sign will the enthalpy change of an ENDOTHERMIC reaction have

A

A positive sign

28
Q

For a collision to be successful what are the two things needed

A

Have the minimum energy
Collide with the correct geometry

29
Q

In terms of reactant particles explain why rates decreases as the reaction proceeds

A

This is because at the start of the reaction the concentration of the reactant is very high and with time the concentration decreases due to less SUCCESSFUL COLLISION

30
Q

In terms of collision theory explain why a reaction will be quicker using marble chips.

A

This is because it has more surface area for the particles to react which makes it quicker as there is an increase in SUCCESSFUL COLLISION

31
Q

What are the reasons for not getting the exact values of combustion for ethanol

A

Heat loss to the surrounding

Incomplete combustion

32
Q

How does increasing temperature increase the rate of a reaction?

A

It increases the number of particles with (sufficient energy) to form the activated complex

There are more successful collisions