Rate of reaction

Question 1

What is the equation for the mean rate of reaction

reactant

Answer 1

Quantity of reactant (g) / times(s)

Question 2

What is the equation for the mean rate of reaction

products

Answer 2

Quantity of product (g) or (cm^3 if a gas) / time (s)

Question 3

Name the 5 ways in which the rate of a chemical reaction can be increased

Answer 3

1. Increase the concentration of the reactants
   2.** Increase** the temperature
2. Reduce the volume of container
3. Increase the surface area of reactants
   5.** Add** a catalyst

Question 4

Are catalysts used up in chemical reactions?

Answer 4

No

Question 4

Give two ways that you can tell a catalyst has been used to increase the rate of a chemical reaction

Answer 4

1. The rate of the chemical reaction has increased
2. The catalyst is not featured in the chemical equation, showing that it was not used up in the reaction.

Question 5

Explain catalytic action in terms of activation energy

Answer 5

A catalyst provides an alternative pathway for the reaction that has a lower activation energy. It does not increase the frequency of collisions and is not used up in the reaction.

Question 6

According to the collision theory when is it possible for a reaction to take place?

Answer 6

When reacting particles collide with eachother with sufficient energy

Question 7

Explain how increasing the pressure of reacting gases increases the rate of reaction?

Answer 7

When the pressure increases the distance between the particles decreases this increases the frequency of collisions with sufficient energy between particles, and so the rate of the reaction increases.

Question 8

Explain how increasing the temperature of reacting particles will increase the rate of reaction

Answer 8

When the temperature increases, the kinetic energy of the particles increase, causing them to move around faster. This increases the frequency of collisions with sufficient energy** and therefore increases the rate of the reaction.

Question 9

Explain how increasing the concentration of the reactants will increase the rate of reaction?

Answer 9

When the concentration is increased the number of reacting particles per unit volume increases. This increase the frequency of collisions with sufficient energy which increases the rate of reaction.

Question 10

Explain how increasing the surface area of solid reactants increases the rate of reaction

Answer 10

Increasing the surface area of solid reactants means that there are more exposed particles so the frequency of collisions with** sufficient energy** increases which increases the rate of the reaction.

Question 11

What is activation energy?

Answer 11

Theminimum amount of energy required for particles to react

Question 12

Describe how to interpret a rate of reaction graph

Answer 12

1. At 0 seconds no product is formed
2. The gradient of the graph is very steep, there is a high number of reactants so the frequency of collisions is high, this means the** rate of reaction is the fastest**
3. As the reactants are used up he gradient becomes less steep, as the frequency of collisions decreases so the rate of reacton slows down
4. The graph becomes horizontal as the reactants have been used up so no more product is formed

basically, graph=this, so frequency=that so FoC=this so RoR=that

Question 13

Explain why we would have to keep other condidtions* the same if we were changing only one of them to see its affect on the rate of reaction

*temp, pressure, concentration, surface area,catalyst

Answer 13

They are control variables, so they need to be kept the same so they don’t affect the rate of reaction

Question 14

Which will have the slowest rate of reaction,
a large piece of marble,
small chunks of marble,
marble powder?
and why

Answer 14

A large piece of marble bc/
smallest surface area

Question 15

Which will have the fastest rate of reaction,
large piece of marble,
small chunks of marble,
marble powder?

Answer 15

Marble powder bc/
largest surface area

Question 16

What is the definition of a catalyst?

Answer 16

A catalyst is a substance which increases the rate of a chemical reaction without itself being used up

Question 17

How would you describe the rate of reaction when given a graph?

Answer 17

1. The rate of reaction is fastest at (…) seconds.
2. The rate decreases at (…) seconds
3. The reaction stops at (…) seconds, so the rate of reaction is 0

Question 18

What is the test for Carbon Dioxide? What will happen if Carbon Dioxide is present?

Answer 18

1.Limewater test

2.Limewater will turn cloudy

Question 19

What is the test for hydrogen? What will happen in hydrogen is present?

Answer 19

1.Burning a splint

2. Squeeky pop sound will be heard