C8

Question 1

what’s the collision theory

Answer 1

the more collisions the higher the chance of particles colliding in the correct orientation which increases the rate of reaction

Question 2

what is the rate of reaction

Answer 2

how much of the product is made each second

Question 3

what are the 2 ways to measure the rate of a reaction

Answer 3

the rate at which a reactant is used up
the rate at which a product is made

Question 4

how does the speed of a reaction change as it progresses

Answer 4

a reaction is fastest at the start but then decreases and is slowest at the end

Question 5

what effects the rate of a reactant

Answer 5

temperature, concentration/pressure of a gas, surface area and catalysts

Question 6

whats needed for a chemical reaction to occur

Answer 6

-the activation energy
-the correct orientation in which particles need to collide

Question 7

what is a precipitate

Answer 7

an insoluble solid which makes a solute go cloudy

Question 8

what are the different ways in which you can measure the rate of a reaction happening

Answer 8

• testing the levels of light being able to pass through the solute
• testing how fast a product is made
• testing how fast a reactant is used up

Question 9

what is a limiting reactant

Answer 9

a reactant that is not in excess and is completely used up by the end of the reaction

Question 10

what effects the rate of a chemical reaction

Answer 10

temperature
surface area
catalysts
concentration/pressure

Question 11

how does temperature affect the rate of a chemical reaction

Answer 11

temperature affects the rate at which collisions happen which means more of these collisions have the activation energy so the rate of reaction is faster

Question 12

how does increasing the concentration affect the rate of a chemical reaction

Answer 12

increasing the concentration means increasing the amount of particles in a volume which increases the amount of collisions that happens per second and so increase the rate of reaction

Question 13

how does increasing the surface area affect the rate of a reaction

Answer 13

increasing the surface area means that you’re increasing the surface area : volume ratio which means there’ll be more frequent collisions so the rate of reaction will be faster

Question 14

what is a catalyst

Answer 14

a substance which increase the rate of a reaction without being used up or chemically changed.

Question 15

how do catalysts work

Answer 15

they reduce the activation energy of a reaction by giving an alternate route for the reaction to take place

Question 16

what do catalysts do in a car exhaust

Answer 16

platinum helps convert carbon monoxide and nitrogen oxide into nitrogen and carbon dioxide

Question 17

what do catalysts do in a car exhaust

Answer 17

platinum helps convert carbon monoxide and nitrogen oxide into nitrogen and carbon dioxide

Question 18

what are reversible reactions

Answer 18

reactions in which the products turn into the reactants but the reactants can turn into the products 2

Question 19

how much joules is needed if 330J of energy is required for the forward reaction

Answer 19

330J as the amount of energy for the forward reaction is always the same as the backward reaction

Question 20

if one of the reaction is endothermic in one direction then what is the type of reaction in the other direction

Answer 20

exothermic

Question 21

what is dynamic equilibrium

Answer 21

the rate of the forward reaction is the same as the rate of the backward reaction

Question 22

what is le chateliers principle

Answer 22

whenever a change in the equilibrium occurs, the position of the equilibrium changes to cancel out the change

Question 23

if you increase the pressure in a reaction what will happen

Answer 23

the equilibrium will shift to the the side of the reaction with less gas which can be found from looking at the number in front of molecules. e.g 6H = 6 hydrogen

Question 24

if you increase the temperature of a reaction what will happen

Answer 24

the equilibrium will shift to the side which favours the endothermic reaction

Question 25

when can dynamic equilibrium be achieved

Answer 25

when its in an enclosed system where no reactants or products can get in or out