Reaction rates 3.4

Question 1

What is rate of reaction?

Answer 1

Measures how fast a reactant is being used up or how fast a product is being formed?

Question 2

What is the equation for rate of reaction?

Answer 2

Change in conc./ time

Question 3

What are the units for rate of reaction?

Answer 3

moldm-3 s-1

Question 4

What is the collision theory?

Answer 4

The theory that all particles must collide with sufficient energy and in the correct orientation

Question 5

What affects rate of reaction?

Answer 5

• temperature
• conc.
• catalyst
• pressure
• surface area

Question 6

How does temperature affect rates of reaction?

Answer 6

• increases
• more frequent collisions
• more kinetic energy
• more particles meet activation energy

Question 7

How does concentration affect rates of reaction?

Answer 7

• increases
• more reacting particles
• increased chance/ frequencey of collisions

Question 8

How does pressure affect rates of reaction?

Answer 8

• increases
• same number of particles in a smaller volume
• increased chance/ frequencey of collisions

Question 9

How does surface area affect rates of reaction?

Answer 9

• increases
• more particles exposed to react
• increased chance/ frequencey of collisions

Question 10

How do you measure rates of reaction?

Answer 10

• colour change
• change in mass
• volume of gas given off

Question 11

What does a catalys do?

Answer 11

• icreases rate of reaction without being used up
• doesnt undergo permanent change
• lowers activation energy
• provides alternative route

Question 12

What is a heterogeneous catalyst?

Answer 12

Different phase to the reactants

Question 13

What is a homogeneous catalyst?

Answer 13

Same phase as the reactants

Question 14

What are the advantages of a catalyst?

Answer 14

• lowers energy demands
• less fossil fules used
• less CO2 produced
• less environmental impact
• lower production costs

Question 15

What does the area under the maxwell-Boltzman distribution graph show?

Answer 15

Number of particles in the system

Question 16

What is the peak on the graph?

Answer 16

Most probable energy

Question 17

Where is the mean on the graph?

Answer 17

Slightly right of the peak

Question 18

What is equilibrium?

Answer 18

A reversible reaction where the rate of the forwards and backwards reactions are equal and the conc. of the products and reactants remain constant

Question 19

What are le chatelieres principles?

Answer 19

If a dynamic equilibrium has its conditions changed the position of equilibrium will shift to counteract the change

Question 20

What are the optimum conditions?

Answer 20

• best conditions for max yield
• profit margin
• environmental impact
• safety

Question 21

What is the formula for Kc?

Answer 21

[products]/ [reactants]

Question 22

What is the value of Kc affected by?

Answer 22

Change in temperature

Question 23

What is the value of Kc not affected by?

Answer 23

• change in pressure
• adding a catalyst
• change in conc. of products/ reactants

Question 24

What does a Kc of 1 mean?

Answer 24

Equilibrium is halfway between products and reactants

Question 25

What does a Kc of >1 mean?

Answer 25

Equilibrium is shifted to the products

Question 26

What does a Kc of <1 mean?

Answer 26

Equilibrium is shifted to the reactants

Question 27

What are the 4 rows needed in a table to calculate Kc?

Answer 27

• initial mol
• change in mol
• equilibrium in mol
• equilibrium in conc.

Question 28

What is Kc?

Answer 28

Equilibrium constant

Question 29

What are the normal units of Kc?

Answer 29

mol dm-3