the rate and extent of chemical change

Question 1

mean rate of reaction=

Answer 1

amount of reactant used /
product formed
———————————
time

Question 2

measuring the amount of reactants used:

Answer 2

(gas)

measure both before and after the reaction

Question 3

measuring the amount of products formed

Answer 3

(gas)

measure the total volume of gas with gas syringe

Question 4

measuring the time it takes for a reaction mixture to become opaque

Answer 4

• time how long it takes for the mixture to change colour

Question 5

rate of reaction=

reaction mixture colour

Answer 5

1
——————————————————
time taken for solution to change colour

Question 6

What is collision theory?

Answer 6

Chemical reactions only occur when reacting particles collide with each other

Question 7

What is activation energy?

Answer 7

The minimum amount of energy required to cause a reaction

Question 8

4 factors which affect the rate of reaction

Answer 8

• temperature
• concentration
• surface area
• catalyst

Question 9

temperature:

Answer 9

• in a hot reaction mixture particles move quicker
• collide more often with greater energy
• so more collisions are successful

Question 10

concentration:

Answer 10

• at higher concentration particles are crowded close together
• so collide more often -> more successful collisions

increasing pressure -> increases frequency collisions

Question 11

surface area:

Answer 11

larger surface area =

• more particles exposed
• available for collisions
• so there are more collisions and faster reaction

Question 12

reaction rate graph steepness:

Answer 12

• steeper the line = faster reaction

Question 13

What happens when one of the reactants is used up?

Answer 13

The reaction stops

line becomes horizontal

Question 14

gradient=

Answer 14

difference in amount of product formed
——————————————————
time

Question 15

catalyst:

Answer 15

A substance that increases the rate of a chemical reaction without being used up in the process

Question 16

what does a catalyst do?

Answer 16

• reduces the amount of energy needed for a successful collision
• makes collision successful
• speeds up the reaction
• povides a service for the molecule To attach to which increases the chances of bumping into each other

Question 17

catalyst in biological systems:

Answer 17

enzymes

Question 18

What is the catalyst in the cracking of hydrocarbon?

Answer 18

Broken pottery

Question 19

What is the catalyst used in the manufacturing of ammonia?

Answer 19

iron

Question 20

Why is increasing the rate of chemical reaction important in Industry?

Answer 20

reduces cost

Question 21

Reversible reactions

Answer 21

Forward or backwards

Products can produce original reactants

Question 22

How can the direction of reversible reaction change?

Answer 22

The direction of reversible reactions can be changed by changing the conditions

Question 23

Closed system

Answer 23

no reactants added

no products removed

Question 24

What happens when a reversible reaction occurs in a closed system?

Answer 24

an equilibrium is achieved when the rate of the forward reaction is equal to the rate of the backward reaction

Question 25

Changing reaction conditions,

exothermic:

Answer 25

• If temperature is raised yield decreases

- If temp is Lowered yield increases

Question 26

Changing reaction conditions,

Endothermic:

Answer 26

• If temperature is raised yield increases

- If temperature is Lowood yield decreases

Question 27

If concentration of reactants or products is changed:

Answer 27

• The system is no longer in equilibrium

- The system just until it can reach equilibrium once more