extent of chemical reactions

Question 1

rate of reaction formula

Answer 1

change in concentration/time

OR

n/V

Question 2

Collision theory (for a reaction to occur, the reactant particles must…)

Answer 2

1. collide with each other
2. collide with sufficient energy to break the bonds within the reaction (energy greater than or equal to the activation energy)
3. collide with the correct orientation to break the bonds within the reactants to allow the formation of new products

Question 3

activation energy

Answer 3

a reaction with a larger activation energy will have a lower rate of reaction at a particular temperature than a reaction with a smaller activation energy)

Question 4

To increase the rate of reaction, you can increase :

Answer 4

1.frequency
2.proportion

Question 5

how to increase the proportion of collisions that can increase the rate of reaction

Answer 5

the PROPORTION of collisions that have energy that is greater than or equal to Ea by increasing ENERGY of collisions

Question 6

how to increase the frequency of collisions that can increase the rate of reaction

Answer 6

the FREQUENCY of successful collisions by increasing TOTAL NUMBER OF COLLISIONS that can occur at a given time

Question 7

what increases the frequency of collisions?

Answer 7

1. increasing concentration of reactants
2. increasing pressure of reactants
3. increasing S.A of solids

Question 8

Sample response for increasing the concentration/particles

Answer 8

1. particles are moved closer together
2. frequency of total collisions increases
3. frequency of successful collisions with correct orientation increases
4. therefore overall rate of reaction reaction increases

Question 9

increasing the Surface Area of solids

Answer 9

Breaking bigger particles into small powder increases the S.A as a result of more exposure

Question 10

what increases the proportion of collisions

Answer 10

1. increase in temperature
2. catalysts

Question 11

increase in temperature

Answer 11

As temperature increases, average kinetic energy increases, therefore average speed of the particles increases

Question 12

sample response for increase in temperature

Answer 12

increased temperature -> increased kinetic energy -> increased frequency of total collisions -> increased frequency of successful collisions with correct orientation

Question 13

catalysts

Answer 13

provides an alternative reaction pathway that has a lower activation energy, not used up in the reaction

Question 14

heterogenous catalysts used in the industry because…

Answer 14

they are in a different physical state so…
-they are easier to seperate
-easier to resuse
-can be used at high temps

Question 15

Open systems

Answer 15

can exchange both matter and energy with surroundings (e.g a boiling saucepan with no lid)

Question 16

closed systems

Answer 16

-only exchanges energy with surroundings (not matter) (e.g a sealed reaction vessel)
-reversible reactions reach a state of equilibrium here

Question 17

extent of reaction

Answer 17

how far the reaction has proceeded in the forward reaction when equilibrium is reached

Question 18

the equilibrium law

Answer 18

Q=K

Question 19

Q>K

Answer 19

moves to the LEFT

Question 20

Q<K

Answer 20

moves to the RIGHT

Question 21

Q=K

Answer 21

at equilibrium

Question 22

K = …

Answer 22

[products] / [reactants]

Question 23

reversed equation

Answer 23

[reactants] / [products]

Question 24

coefficients of equation are doubled

Answer 24

K^2

Question 25

coefficents of equation are halved

Answer 25

root of K

Question 26

extent of reaction when 10^-4 < K < 10^4

Answer 26

significant and present at equilibrium

Question 27

K > 10^4

Answer 27

almost complete reaction, concentration of products are higher than reactants

Question 28

K < 10^-4

Answer 28

Very small extent of reaction. Concentrations of reactants are higher than products

Question 29

RICE tables

Answer 29

Reaction Initial (mols) Change (mols) Equilibrium (mols) + Concentration (n/v)

Question 30

Le Chateliers Principle

Answer 30

if a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium shifts to counteract the change to reestablish an equilibrium

Question 31

position of equilibrium can be changed by :

Answer 31

1. adding or removing a reactant or product 2. changing the pressure by changing the volume (involves gases) 3. dilution (involves solutions) 4. changing the temperature

Question 32

how can the value of K be changed

Answer 32

by changing the temperature

Question 33

adding a reactant

Answer 33

formation of more products (favours forward reaction)

Question 34

adding a product

Answer 34

favours reverse reaction

Question 35

removing a product

Answer 35

favours a forward reaction

Question 36

decrease in pressure

Answer 36

direction of most particles

Question 37

adding a catalyst

Answer 37

no change in equilibrium position

Question 38

adding an inert gas

Answer 38

increases overall pressure and frequency of total collisions but does not impact rate of reaction

Question 39

adding water

Answer 39

direction of most particles

Question 40

increasing temperature for exothermic reactions

Answer 40

reactants <-> products + heat if you add more heat, it will counteract this by going in the reverse direction

Question 41

increasing temperature for endothermic reactions

Answer 41

reactants + heat <-> products if you add more heat, it will counteract this by going in the forward reaction