Unit 1 - Rates Of Reaction

Question 1

What affects the rate of a reaction?

Answer 1

Temperature
Concentration
Surface area/ particle size
Catalyst

Question 2

How to measure the rate of reaction?

Answer 2

1) Measure how fast the product is produced.
2) measure how fast the reactant is used up.

• changes in the concentration of the reactants or products.
• changes in the mass of the reactants or products.
• changes in the volume of the reactants or products.

Bubbles - gas
Smell
Temp

Question 3

What INCREASES the rate of a reaction?

Answer 3

To increase the rate of reaction, the number of collisions in a reaction need to be increased.

increase temperature - gives the particles more energy and they will move faster and make more collisions.

Increase concentration - this increases the number of particles. The more particles then the more collisions.

Increass surface area/ decrease particle size - more surface area for the reaction to take place.

Using a catalyst

Question 4

What is a catalyst?

Answer 4

A catalyst speeds up the rate of reaction and is not used up in the reaction.

Question 5

How does temperature effect the ROF?

Answer 5

If temp is increased, the particles have more energy therefore move around faster and collide more often with more energy.

If temp is decreased then less energy - slower movement, less collisions with little energy.

Question 6

How does concentration effect the R.O.F?

Answer 6

If the concentration of reactants is increased, there are more reactant particles taking place in the reaction. This means there will be more collisions and so the reaction rate is increased.

If decreased- less particles moving together, less collisions

Question 7

How does particle size effect the R.O.F?

Answer 7

Smaller reactant particles means increased surface area which allows more collisions.

Larger reactants - deceased surface area, less collisions, slower rate of reaction.

Increases surface area = decreased time/increase reaction rate

Question 8

How does the use of a catalyst affect the rate of reaction?

Answer 8

If a catalyst is present, the reacting particles can collide more successfully with less energy and so the reaction can take place at a lower temperature.

Catalysts are substances that speed up a chemical reaction without being used up in the reaction.

Question 9

What is the rate of reaction?

Answer 9

It is a measure of how fast the reactants are being used up and how fast the products are being made.

Question 10

Signs of a chemical reaction

Answer 10

Fizzing - gas released
Temperature/ energy change 
Neutralises
White light heat
Makes a new product 
Not easily reversed
Colour change
Change of state (s,l,g)
...

Question 11

Calculating the rate of reactions - formula

Answer 11

The rate of reaction (at different points in the reaction) can be calculated from the GRADIENT of the graph.

m = y2-y1 / x2-x1
(Change in y-axis / change in x-axis)

Rate of reaction = change in quantity / change in time