Rates of Reaction Unit 2 Topic 4

Question 1

What is the rate of reaction?

Answer 1

Measure of hot fast/slow the reaction is

Question 2

How do we measure the rate of reaction?

Answer 2

Measure how quickly products form in a given time OR how quickly reactants are used up in a given time

Question 3

What is the equation for rate of reaction?

What are the units for rate?

Answer 3

Rate = 1/time

s-1

Question 4

Fill in the blanks:

The steeper the slope, the ______ the reaction

Answer 4

The steeper the slope, the faster the reaction

Question 5

What can change the speed of the reaction?

Answer 5

Surface Area
Concentration
Temperature
Catalysts

Question 6

Why are rates of reaction important in the chemical industry?

Answer 6

Commercial products: Ammonia for fertilisers, H2SO4 for detergents + polythene for packaging)
Want reactions to be as fast as possible + good product yield

Question 7

What does collision theory state?

Answer 7

For a reaction to take place, reacting particles must collide with sufficient activation energy.

Question 8

What is activation energy?

Answer 8

Minimum energy required for a reaction to take place between reacting particles

Question 9

As surface area is ________, ____particles are exposed, so there are more frequent collisions.
In a fixed period of time there are ____ collisions with the minimum energy required to react therefore the rate of reaction _______

Answer 9

As surface area is Increased, more particles are exposed so there are more frequent collisions.
In a fixed period of time there are more collisions with the minimum energy required to react therefore the rate of reaction increases.

Question 10

In the reaction between marble chips and hydrochloric acid which particles react?
When there are successful collisions, what is formed?

Answer 10

Hydrogen ions from HCL + carbonate ions from marble chips.

Bubbles of CO2

Question 11

What happens to the reaction rate as time progresses?

Answer 11

As time progresses each reaction slows down. This is because reactants are being used up + as time progresses there are fewer reactants available so a slower reaction.

Question 12

Write the word equation for the reaction between marble chips and hydrochloric acid.

Answer 12

CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + CO2 (g) + H20 (l)

Question 13

As the concentration of one reactant is increased, there are more particles in the ____ volume so there will be ____ collisions.
In a fixed period of time there are ____ collisions with the _______ energy required to react therefore rate of reaction ________.

Answer 13

As the concentration of one reactant is increased, there are more particles in the same volume so there will be more collisions.
In a fixed period of time there are more collisions with the minimum energy required to react therefore rate of reaction increases.

Question 14

As the temperature of the reaction is ________, the particles have more energy. The particles are likely to have energy equal or greater than the activation ______. Therefore there will be ____ successful collisions and the reaction rate will _______.

Answer 14

As the temperature of the reaction is increased, the particles have more energy. The particles are likely to have energy equal or greater than the activation energy. Therefore there will be more successful collisions and the reaction rate will increase.

Question 15

What is a catalyst?

Answer 15

A substance that increases the rate of reaction without being used up.

Question 16

For a reaction to take place, particles must _______and they must have sufficient ______ to overcome the activation energy barrier of the reaction
Catalysts _______ the reaction rate by _____ the activation energy of a reaction. This means that in a catalytic reaction when particles collide ____ of them have sufficient energy to overcome the energy barrier to form products and the reaction is faster.

Answer 16

For a reaction to take place, particles must collide and they must have sufficient energy to overcome the activation energy barrier of the reaction. Catalysts increase the reaction rate by lowering the activation energy of a reaction. This means that in a catalytic reaction when particles collide, more of them have sufficient energy to overcome the energy barrier to form products and the reaction is faster.

Question 17

Give an example of a catalyst and an element?

Answer 17

Iron with Manganese Oxide

Question 18

Explain how a catalyst works using the term activation energy.

Answer 18

Offers alternate route with lower Activation Energy.

Question 19

Give 2 examples of where catalysts are used in the chemical industry?

Answer 19

Iridium compound - Making Ethanoic Acid (Vinegar)

Vanadium Oxide - Making Sulfuric Acid (Contact Process)

Question 20

Why do chemists want to use catalysts and develop use of catalysts?

Answer 20

New ways of making materials which may use less energy or find new lower energy routes to get larger product yields. Also may lower waste products (less chemical pollution)

Question 21

What is a datalogger used for in reaction between sodium thiosulfate + hydrochloric acid?

Answer 21

Connected to computer, plot graph of amount of light passing through against time.

Question 22

What happens if you increase the surface area of reactants?

Answer 22

More particles exposed to other reactant. More frequent collisions with sufficient activation energy, reaction rate increases.

Question 23

How do you collect the gas given off in a reaction?

Answer 23

Gas syringe

Question 24

Does the volume of product increase in these reactions?

Answer 24

No, just the rate.

Question 25

What happens when sodium thiosulfate reacts with an acid? (Colour change)

Answer 25

Yellow suspension of sulfur formed

Solution becomes cloudy

Question 26

What happens when potassium iodate, starch arsenious acid + potassium iodide are added?

Answer 26

Form black iodine.

Question 27

Label the activation energy diagram?

Answer 27

Label from book

Question 28

In the reaction between marble chips + hydrochloric acid, which particles react?

Answer 28

Hydrogen ions (H^+) from HCl + carbonate ions (Co3^2-) from marble chips (CaCO3)

Question 29

What happens if there is a low concentration in a reaction?

Answer 29

Smaller number of collisions in a given time. Only some collisions will have energy greater than or equal to activation energy so reaction rate is slow.

Question 30

If the concentration of a reactant is increased, does the total volume of product increase?

Answer 30

No, it stays the same.

Question 31

Would an increase in concentration or temperature speed up the reaction most?

Answer 31

Temperature as it increases energy rather than just number of particles available of 1 reactant.

Question 32

What do catalytic converters do?

Answer 32

Reduce air pollution as they allow pollutant gases like carbon monoxide and nitrogen oxides to be converted into less harmful gases.