Reaction Rates (kinetics)

Question 1

Reaction rate

Answer 1

Number of moles of product formed per second
OR
Numberof moles of reactant used per second

Question 2

What are the methods of measuring the rate of a reaction?

Answer 2

• Mass change
• Volume of gas
• Solid disappearing
• Color change

Question 3

How doe you measure the rate of a reaction using mass change?

Answer 3

Question 4

How doe you measure the rate of a reaction using volume of gas?

Answer 4

By using two different methods. Either the dispalcement of water, or a gas syringe.

Question 5

How do you measure the rate of a reaction using solid disappearing?

Answer 5

1. Measure time until solid disappears
2. Do this several times
3. Calulate average

Question 6

How doe you measure the rate of a reaction using color change

Answer 6

1. Time until color change is observed
2. Calculate the rate

Question 7

What is the problem of measuring the rate of reactions uing solid disappearing?

Answer 7

• There is no graph and so, you can only calculate the average rate.

Question 8

What is the problem of uing color change to measure the rate of reactions?

Answer 8

• There is no graph
• It is subjective

Question 9

How do you calculate the rate of a reaction at a specific point?

Answer 9

By using the graph and finding the tangent and calculating the gradient of that tangent.

Question 10

What is the trends with the rate of the reaction?

Answer 10

The rate of a reaction ALWAYS decreases from the beginging to the end. The initial rate is always the highest.

Question 11

Why does the rate decrease as time passes?

Answer 11

Because the frequency of collisions decreases (collisions of particles colliding with eachother with eachother per second).

Question 12

Why does the frequency of collisions decrease as the time increases?

Answer 12

This is because the reactants are used up during the reaction causing fewer to be availabe to react. At the end of the reaction there are no more reactants available. Therefore, no collisions can occur.

Question 13

What needs to occure for a reaction to happen?

Answer 13

During a reaction, particles need to collide. These collisions require 2 properties in order to be successful.

Question 14

What properties do the collision of particles require in order to be successful?

Answer 14

• Sufficient energy (activation energy)
• Correct orientation

Question 15

What factors can affect the rate of a reaction?

Answer 15

• Surface area
• Temperature
• Catalyst
• Concentration/preassure

Question 16

When do you use mass change to measure the rate of a reaction?

Answer 16

When a reaction produces gas or makes gas

Question 17

When do you use the volume of gas to measure the rate of a reaction?

Answer 17

when a reaction produces gas and there was no gas initially.

Question 18

When do you use dolid disappearing to measure the rate of a reaction?

Answer 18

When an (aq) is produced from a solid and liquid.