Rates of Reaction

Question 1

What is a rate of reaction?

Answer 1

a measure of how quickly a reactant is used up

Question 2

What is needed for a chemical reaction?

Answer 2

1. reactants must collide
2. must have enough energy to react

Question 3

What is activation energy?

Answer 3

the minimum amount of energy that particles need for a reaction

Question 4

what is a catalyst?

Answer 4

a substance that changes the rate of a chemical reaction

Question 5

How do catalysts work?

Answer 5

providing alternative reaction pathways

Question 6

What is an endothermic reaction?

Answer 6

takes in the energy from the surroundings so temperature decreases

Question 7

What are 3 examples of exothermic reactions

Answer 7

Combustion
Neutralisation
Oxidation

Question 8

What are two endothermic reactions?

Answer 8

Citric acid + sodium hydrogen carbonate
Thermal decomposition

Question 9

what is a reaction profile diagram?

Answer 9

a diagram that shows the energy change in a chemical reaction

Question 10

What is the formula for calculating the rate of a reaction

Answer 10

mass of product made or lost / time taken

Question 11

What are ways of measuring the rate of reaction

Answer 11

change in mass
precipitation or colour change
volume of gas gained or lost

Question 12

What is an exothermic reaction?

Answer 12

transfers energy to the reaction increasing the temperature

Question 13

How can you measure precipitation?

Answer 13

measure the time it takes for a mark to disappear

Question 14

How do you measure colour change?

Answer 14

the time it takes for the colour to change

Question 15

What are issues with measuring the rate of reaction by observing colour change and precipitation?

Answer 15

It is subjective
you can’t use your results to plot a graph

Question 16

How can you calculate the Rate of Reacting by measuring change in mass?

Answer 16

Use a balance
Take measurements regularly
Plot your results on a graph
Draw and tangent and calculate its gradient to find rate

Question 17

What is the most accurate way to measure rate of reaction?

Answer 17

Change in mass

Question 18

How can you use a gas syringe to measure the rate of a chemical reaction?

Answer 18

Use a gas syringe to monitor how the volume of gas changes over time

Question 19

What are factors that affect the rate of a chemical reaction?

Answer 19

Temperature
Concentration of solution or gas
Surface area
presence of a catalyst

Question 20

Why how does increasing the temperature increase rate of reaction?

Answer 20

Particles move faster
They will collide frequently
will have more kinetic energy

Question 21

How does creating the concentration or pressure increase rate of reaction?

Answer 21

the number of particles per unit will increase
increase collisions

Question 22

How does increasing the surface area of a solid affects rate of reaction?

Answer 22

more frequent collisions in a greater number of reactions

Question 23

What is collision theory?

Answer 23

for particles to react they have to collide with sufficient energy in the right direction

Question 24

How does a catalyst increase rate of reaction?

Answer 24

speed up reactions by lowering activation energy
by giving them a different reaction oathway

Question 25

What is activation energy?

Answer 25

the minimum amount of energy that particles require to react together.

Question 26

Why do particles need activation energy?

Answer 26

They need energy to break bonds of reactants so reaction can start

Question 27

On a time graph of a chemical reaction what does a steep gradient of the line tell us?

Answer 27

reaction was fast

Question 28

Why do concentration/time graphs plateau?

Answer 28

the reactants are used up

Question 29

What is the formula to find the gradient of a line?

Answer 29

Gradient = change in y / change in x

Question 30

What can be used for empirical formula?

Answer 30

Mass
Ram
Divide
Dsmall
F