Unit five JT

Question 1

define rate of reaction

Answer 1

the change in concentration of a reactant or product per unit time

Question 2

define initial rate of reaction

Answer 2

the change in concentration of a reactant or product , per unit time at the start of the reaction when T=0

Question 3

how would an increase in temperature effect rate of reaction?

Answer 3

particles would have more kinetic energy, this increases frequency of collisions. A greater proportion of molecules will have the activation energy or greater to react

Question 4

how would an increase in pressure/concentration effect rate of reaction?

Answer 4

more particles in the same volume increases the frequency of collisions

Question 5

how would the presence of a catalyst effect rate of reaction?

Answer 5

catalysts reduce activation energy so a greater proportion on particles will have enough energy to react

Question 6

how would an increase in surface area effect rate of reaction?

Answer 6

as surface area increases, the rate of reaction generally increases

Question 7

equation for rate of reaction

Answer 7

change in concentration (or moles) of product / time

Question 8

catalyst definition

Answer 8

an enzyme that lowers the activation energy of the reaction by providing an alternate lower energy pathway for the reaction to follow

Question 9

homogenous catalyst definition

Answer 9

the catalyst is in the same physical state as the reactants

e.g. making esters with sulfuric acid as a catalyst

Question 10

heterogenous catalyst definition

Answer 10

the catalyst is in a different physical state than the reactants
e.g. the Haber process

Question 11

the Haber process

Answer 11

H2(g) + 3h2(g) –>

Question 12

the Contact process

Answer 12

2SO2(g) + O2(g) –>

Question 13

what is the catalyst in the contact process?

Answer 13

vanadium oxide (V2O5)

Question 14

list three advantages of using a catalyst

Answer 14

lower energy demands, less carbon dioxide produced, less environmental impact

Question 15

convert 1cm3 into dm3

Answer 15

divide by 1000

0.001dm3 = 1cm3

Question 16

Le Chatelier’s Principle

Answer 16

When a system in dynamic equilibrium is subject to change, the position of the equilibrium will shift to minimise the effect

Question 17

Whats happens to the equilibrium when you increase pressure?

Answer 17

It will shift to the side with the fewest moles of gas as the system will oppose the change by trying to decrease the pressure

Question 18

Whats happens to the equilibrium when you increase temperature?

Answer 18

It will favour the endothermic reaction as the system will try to oppose the change by trying to reduce the temperature

Question 19

what is the reaction if delta H is positive?

Answer 19

endothermic

Question 20

what is the reaction if delta H is negative?

Answer 20

exothermic

Question 21

Whats happens to the equilibrium when you add a catalyst?

Answer 21

the position of the equilibrium will not change as the catalyst will increase the rate of both the forwards and reverse reactions equally

Question 22

what does Avogadro’s number represent?

Answer 22

The number of atoms per mole of the carbon-12 isotope

6.023 x 10^23

Question 23

Heterogeneous equilibrium definition

Answer 23

A reaction equilibrium in which some of the reactants and products are in different states

Question 24

Homogeneous equilibrium definition

Answer 24

A reaction equilibrium in which the reactants and products are all in the same state

Question 25

Kc=

Answer 25

[C]c x [D]d

[A]a x [B]b

Question 26

What does the capital letter represent in the Kc equasion

Answer 26

concentration (moldm-3)

Question 27

What does the lowercase letter represent in the Kc equasion

Answer 27

number of moles

Question 28

What is the equilibrium constant?

Answer 28

A measure of the position of the equilibrium in dynamic equilibrium

Question 29

Where is the equilibrium of Kc = 1

Answer 29

halfway between the reactants and products

Question 30

Where is the equilibrium of Kc < 1

Answer 30

right hand side, backwards reaction and reactants are favoured

Question 31

What is the temperature in the Haber process?

Answer 31

450C

Question 32

What is the pressure in the Haber process?

Answer 32

200 atmospheres

Question 33

What is the catalyst in the Haber process?

Answer 33

Iron

Question 34

X axis on the boltzmann distribution diagram

Answer 34

Number of molecules with a given energy

Question 35

Y axis on the boltzmann distribution diagram

Answer 35

energy