(Topic 6) Rate And Extent Of Chemical Change (CGP book)

Question 1

What is rate of reaction?

Answer 1

How fast the reactants are changed into products

Question 2

Examples of rates of reaction?

Answer 2

Slow - Rusting
Moderate - Magnesium and acid
Fast - Burning and explosions

Question 3

How to find rate of reaction?

Answer 3

Amount of product formed or reactant used up over time

Question 4

Rate of reaction graphs?

Answer 4

Steeper line - faster rate of reaction
Over time line plateaus as reactants are used up

Question 5

What is collision theory?

Answer 5

Collision frequency - More collisions there are, the faster the reaction
Energy transferred - Particles have to collide with enough energy to have a successful collision

Question 6

What does rate of reaction depend on?

Answer 6

Temperature
Concentration of solution / pressure of gas
Surface area
Catalyst

Question 7

How to increase rate of reaction?

Answer 7

Increase temp
Increase concentration/ pressure
Decrease surface area in which particles are
Use a catalyst

Question 8

What is used to measure rate of reaction?

Answer 8

Gas = cm*3
Solid = (g)
Seconds = (s)

Question 9

How to calculate mean rate of reaction from a graph?

Answer 9

Change in y / change in x

Question 10

What is required for equilibrium to occur in a reversible reaction?

Answer 10

A closed system - no reactants of products can escape and nothing else can get in

Question 11

Steps of a reversible reaction?

Answer 11

• reactants react, their concentrations fall so forward reaction slows down
• as more and more products are made, their concentrations rise so backward reaction speeds up
• eventually, both are at same speed so system is at equilibrium

Question 12

What happens at equilibrium?

Answer 12

Both forward and backward reactions are happening, but there is no overall effect, meaning concentrations of reactants and products have reached a balance and won’t change

Question 13

What happens if equilibrium is at right?

Answer 13

Concentration of products is greater than reactants

Question 14

What happens if equilibrium is at left?

Answer 14

Concentration of reactants is greater than that of products

Question 15

What does the position of equilibrium depend on?

Answer 15

Temperature
Pressure
Concentration of reactants and products

Question 16

What is le chateliers principle?

Answer 16

The idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract that change
Can be used to predict effect of any changes you make to a reaction system

Question 17

What happens if you decrease temperature in a reaction?

Answer 17

Equilibrium will move to exothermic direction to produce more heat, this means you will have more products for exothermic reaction and fewer for endothermic

Question 18

What happens if you raise temperature in a reaction?

Answer 18

Equilibrium moves to endothermic direction to try and decrease it, this means you will get more products for endothermic reaction and fewer for exothermic

Question 19

What happens to equilibrium if you change the pressure in a reaction?

Answer 19

(Only works for gases)
Increase - equilibrium tries to reduce so moves in direction of fewer molecules of gas
Decrease - equilibrium tries to increase sp moves in direction of more gas molecules

Question 20

What happens to equilibrium in a reaction if you change concentration?

Answer 20

• change concentration of reactants or products, system no longer at equilibrium
• system responds to bring back equilibrium
  Increase reactants - system tries to decrease by making more products
  Decrease products - system tries to increase by reducing amount of reactants