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Chemistry AS 2015-16 > 1.5 Kinetics > Flashcards

Flashcards in 1.5 Kinetics Deck (29)
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1

5 Variables that affect the rate of reaction

Temperature,
Concentration,
Surface area,
Pressure,
Presence of a catalyst

2

Definition of activation energy

The minimum energy particles must collide with in order to react

3

Definition of rate of reaction

The amount of product formed/ amount of reactant used up in a given time

4

Why do most collisions of particles not result in a reaction?

In order for molecules to react, the colliding molecules must have enough kinetic energy to overcome the repulsive and bonding forces in the reactants or the collisions are not in the right orientation

5

What effect does increasing the temperature have on the rate of reaction?

The particles have more kinetic energy so move about faster, so there are more frequent collisions, with enough activation energy to react so the rate of reaction is faster

6

What does increasing the concentration have on the rate of reaction?

There are more particles in the same volume so there are more frequent collisions and the reaction happens faster

7

What effect does decreasing the pressure in a gaseous reaction have on the rate of reaction?

It's reduces the rate of reaction as there are less molecules in a given volume so there are less frequent collisions

8

The effect of increasing the surface area on the rate of reaction

Increasing the surface area means that there are more sites for the reaction to take place so the reaction happens faster

9

Why a small temperature increase can lead to a large increase in rate of reaction (in terms of Maxwell-Boltzmann distribution)

A higher temperature means more of the molecules have energy greater than Activation energy so a higher percentage of collisions will result in a reaction occurring

10

The effect of a catalyst on the rate of reaction

It decreases the activation energy as it provides an alternate route for the reaction to occur and so the rate of reaction is increased

11

Which distribution compares the fraction of particles and the amount of energy that they have?

The Maxwell Boltzmann Distribution

12

How does increasing concentration of a solution increase the rate of a chemical reaction?

There are more particles in the solution, therefore there is a higher chance of successful collisions

13

Which type of reaction leads to the products have more energy than the starting reactants?

Endothermic reactions

14

How do catalysts lower the activation energy for a reaction?

Provide a different pathway that requires less energy

15

True or false: catalysts affect the enthalpy change of reactions.

False - catalysts do not affect enthalpy change

16

True or false: catalysts don't affect the position of equilibrium in a reversible reaction

True

17

What is the definition of a catalyst

A substance that affects the rate of chemical reactions without being changed up or used in the process.

18

The curve on the Maxwell-Boltzmann distribution never touches the X axis. What does this tell us about particle energy?

No particles have 0 energy

19

Why does temperature increase the rate of reaction

Particles have mor

20

Which distribution compared the fraction of particles with the amount of energy they have?

The Maxwell Boltzmann distribution

21

How does increasing concentration increase the rate of reaction?

More particles mean a higher chance of a collision, which gives a higher chance of the particles reacting

22

Which type of reaction results in the reactants having less energy than the products?

Endothermic

23

How do catalasts lower the activation energy needed for a reaction

They provide a different pathway (that requires less energy)

24

True or false: catalysts affect the enthalpy change of a reaction

False

25

Do catalysts affect the position of equilibrium in reversible reactions?

No

26

What is the definition of a catalyst?

A substance which affects the rate of a chemical reaction without being changed or used up in the process

27

The curve on the Maxwell Boltzmann Distribution never touches the X axis. What does this tell us?

No particles have 0 energy

28

Why does the increase of temperature affect reaction rate?

The particles have more kinetic energy, so move fast which gives a higher chance of successful collisions

29

Raising temperature by 10 degrees Celsius does what to the reaction rate? (Approximately)

Doubles rate of reaction