Rate of Reaction

Question 1

how can you define the rate of reaction

Answer 1

the speed of the reaction

Question 2

what are the 5 ways to speed up a reaction

Answer 2

increase temperature
increase the concentration of a liquid
increase the pressure of gases
increase surface area of solid
use a catalyst

Question 3

what is the colllision theory

Answer 3

if a reaction happens:

-particles are constantly moving

-for the collision to be successful the particles must have the right amount of activation energy. the minimum amount of activation energy required for an effective collision is called activation energy

-more frequent collisions

-then new substances are formed

Question 4

rate of reaction equation

Answer 4

amount of reactant used or amount of product made
/
time taken

Question 5

what are the units for rate of reaction

Answer 5

the units of the amount of reactant or product divided by the unit of time taken

Question 6

why does increasing temperature increase the rate of reaction

Answer 6

the particles have more kinetic energy and move faster
so there are more frequent collisions
and more particles have the activation energy

Question 7

why does increasing concentration increase the rate of reaction

Answer 7

there are more particles
so there are more frequent collisions

Question 8

why does increasing pressure increase the rate of reaction

Answer 8

there are more particles
so there are more frequent collisions

Question 9

how do you calculate the surface area of a cube

Answer 9

(length x height) x no of faces

Question 10

how does increasing surface area increase the rate of reaction

Answer 10

to increase the surface area you need to make the substance smaller eg powdered
this causes more frequent collisions

Question 11

specific points on catalysts (4)

Answer 11

catalysts speed up a reaction but are not used up
only small amounts are needed
catalysts are specific to a reaction
they are not included in the chemical equation

Question 12

how do catalysts increase the rate of a reaction

Answer 12

they provide a different pathway for the reaction that has a lower activation energy

Question 13

how to work out the rate of a straight line (4 steps)

Answer 13

1 - make a triangle using your line
2- work out change in y axi
3- work out change in x axis
4- work out the gradient

Question 14

how do you work out the rate of a curved line (5 steps)

Answer 14

question will include a value to find
1 - find that point on the curve
2- draw a straight line that touches the point and make a triangle
3- work out the change in the y axis
4- work out the change in the x axis
5- work out the gradient

Question 15

points to learn about reversible reactions (3)

Answer 15

• the reaction goes both forwards and backwards
• the reactants change into products
• as soon as some products are made, they react to form the reactants

Question 16

how can you tell if a reaction is exothermic?

Answer 16

the energy change is negative

Question 17

when is an equilibrium reached

Answer 17

when the rate of forward reaction is the same as the rate of backwards reaction in a closed system

Question 18

what is a closed system

Answer 18

a system that stops any reactants or products escaping

Question 19

which three conditions can we change to change the equilibrium

Answer 19

concentration
pressure
temperature

Question 20

what is the rule for increasing the concentration of a product

Answer 20

if you increase the concentration of a product, it moves to the reactants

Question 21

what is the rule for increasing the concentration of a reactant

Answer 21

if you increase the concentration of the reactant it moves to the side of the products

Question 22

steps for presenting an answer about what happens if you increase the concentration of a substance (4 steps)

Answer 22

1 - write the rule
2- write which direction the equilibrium will move
3- write what happens to the amount of product you make
4- write what you make

Question 23

what is the rule for increasing pressure

Answer 23

if we increase the pressure, the equilibrium moves to the side with less molecules

Question 24

what is the rule for decreasing pressure

Answer 24

if you decrease the pressure , the equilibrium moves to the side with more molecules

Question 25

how do you present an answer about what happens if you increase/ decrease pressure (4 steps)

Answer 25

1- work out the number of molecules on each side
2- write the rule
3- write which direction the equilibrium will move
4- write what happens to the amount of product you make

Question 26

what is the rule for increasing temperature

Answer 26

when you increase the temperature, the equilibrium moves in the endothermic direction

Question 27

what is the rule for decreasing temperature

Answer 27

when you decrease the temperature, the equilibrium moves in the exothermic direction

Question 28

how do you present an answer about an increase/ decrease in temperature on equilibrium (4 steps)

Answer 28

1 write on the equation the endothermic and exothermic directions
2- write the rule
3- write which direction the equilibrium will move
4- write what happens to the amount of product you make