Rates of Reaction

Question 1

How can the rate of reaction be measured?

Answer 1

By measuring either:

a) The loss of a reactant
b) The gain of a product
c) by measurement of a physical property over time

Question 2

What method is used to measure the rate of reaction when a gas is produced?

Answer 2

• Change in mass over time; using a scale and stopwatch [measuring REACTANT LOSS]
• Volume of gas produced over time; this can be measured using an inverted measuring cylinder OR gas syringe [measuring PRODUCT FORMED]

Question 3

What method is used to measure the rate of reaction when a precipitate is formed?

Answer 3

-Measure colour change; use a colorimeter OR place a beaker containing the reactants over an “X” drawn on paper, and measure how long it takes for the “X” to ‘disappear’

Question 4

What is the collision theroy?

Answer 4

For two particles to react, they must collide at the correct orientation and have sufficient energy
-The more collisions, the higher the rate of reaction

Question 5

How does concentration/ pressure affect the rate of reaction?

Answer 5

• Increasing concentration/ pressure increases the number of particles in a given space
• This increases the number of successful collisions;
• The rate increases with concentration

Question 6

How does temperature affect the rate of reaction?

Answer 6

• Increasing temperature, gives the particles more kinetic energy
• This increases how quickly the particles are moving around
• This increases the likelihood of particles banging into each other, and as a result the rate increases with temperature

Question 7

How does surface area/ particle size affect the rate of reaction?

Answer 7

• Increasing particle size/ decreasing surface area decreases the rate of reaction;
• If less particles are exposed there will be less frequent collisions
• Less successful collisions

Question 8

How would a catalyst affect the rate of reaction?

Answer 8

• Using a catalyst decreases how much power the collision has to happen with for a reaction to take place
• More of the collisions will result in successful collisions
• The rate of reaction is increased if a catalyst is used

Question 9

What is meant by the term “activation energy”?

Answer 9

The minimum amount of energy a particle must have to successfully react upon collision

Question 10

What is a catalyst?

Answer 10

A substance that speeds up a chemical reaction without being used up

Question 11

How does a catalyst work to increase the rate of reaction?

Answer 11

A catalyst works by providing an alternative route (mechanism) for the reaction with a lower activation energy