Exothermic and endothermic reactions

Question 1

How can you tell that a chemical reaction is taking place?

Answer 1

The magnesium turned into white powder

Question 2

Name the product from the reaction of magnesium in the figure.

Answer 2

Magnesium oxide

Question 3

The magnesium needed heating before it would react.

What conclusion can you draw from this?

Answer 3

The reaction has a high activation energy

Question 4

What is the pH value of the solution?

Answer 4

9

Question 5

Why are nanoparticles effective in very small quantities?

Answer 5

They have a high surface area to volume ratio

Question 6

Give one advantage of using nanoparticles in sun creams.

Answer 6

better coverage

Question 7

Give one disadvantage of using nanoparticles in sun creams.

Answer 7

Harmful effects on the environment

Question 8

The reaction of zinc with copper sulfate is exothermic.

How can you tell from the student’s results that the reaction is exothermic?

Answer 8

The temperature increases

Question 9

how can you tell from the energy diagram that the reaction is exothermic

Answer 9

energy of products is lower than the energy of reactants

Question 10

Which arrow shows the activation energy in Figure 2?

Answer 10

a

Question 11

When liquids A and B are mixed a chemical reaction takes place.
This reaction is exothermic.
What does exothermic mean?

Answer 11

Reaction in which energy is given out to the surroundings. The surroundings then have more energy than they started with so the temperature increases.

Question 12

When the temperature is increased the time taken for the glue to set ………………………………………

Answer 12

decreases

Question 13

When the temperature is increased the rate of the setting reaction ………………………….

Answer 13

increases

Question 14

two reasons why an increase in temperature affects the rate of reaction.

Answer 14

• It gives the particles more energy

- It makes the particles move faster

Question 15

What name is given to reactions that heat the surroundings? .

Answer 15

Exothermic

Question 16

Which reaction, A, B, or C, would be best to use in a hand warmer?
Give a reason why you chose this reaction.

Answer 16

C Gives out most heat energy

Question 17

When water is added to anhydrous copper sulfate the temperature of the mixture……………………

Answer 17

increases

Question 18

Anhydrous copper sulfate is white.

What colour is seen after water is added to the anhydrous copper sulfate?

Answer 18

blue

Question 19

What does the symbol mean?

Answer 19

reversible

Question 20

The student heated a tube containing hydrated copper sulfate.
Name the solid substance produced.

Answer 20

Anhydrous copper sulphate

Question 21

The reaction is exothermic.
(i) What measurements would the student make to show that the reaction is
exothermic?

Answer 21

the temperature at the start and the temperature at the end

Question 22

How would these measurements show that the reaction is exothermic?

Answer 22

The temperature increases

Question 23

Suggest one control variable in this investigation

Answer 23

Size of magnesium ribbon

Question 24

Which test tube, A, B, C or D, contained the greatest concentration of hydrochloric
acid?

Answer 24

B

Question 25

Why did you choose this test tube?

Answer 25

because Produces more bubbles faster

Question 26

The student predicted that if the temperature of the acid was increased the reaction would take place faster. state two statements in the table which explain why.

Answer 26

The particles move faster | The particles collide more often

Question 27

The table lists some statements about catalysts. Only two statements are correct. state the two correct statements.

Answer 27

- A catalyst can speed up a chemical reaction. | - Different reactions need different catalysts

Question 28

Complete the sentence. The size of nanosized particles is ........................................ than normal sized particles.

Answer 28

smaller

Question 29

The catalysts contain platinum. | Suggest why a manufacturer of catalytic converters would want to use less catalyst.

Answer 29

The three-way catalyst used for petrol vehicles must also be able to reduce NOx to nitrogen as well as oxidize CO and hydrocarbons

Question 30

Which make of crisp, 1, 2, 3 or 4, releases the most energy? Make ................................................... Give a reason for your answer.

Answer 30

3 because biggest temperature rise

Question 31

Eating too many crisps is thought to be bad for your health. Use the information above and your knowledge to explain why.

Answer 31

Crisps contain salt too much salt can cause high blood pressure Also crisps have a lot of calories so if you take in more energy than You need the excess is stored as fat

Question 32

In an exothermic reaction, energy is given out. | Draw a ring around the correct answer to complete the sentence.

Answer 32

In an exothermic reaction, the temperature goes up.

Question 33

``` Which energy change, A, B or C, is the activation energy? ```

Answer 33

B

Question 34

``` Which energy change, A, B or C, shows that this reaction is exothermic? ```

Answer 34

A

Question 35

Draw a ring around the correct answer to complete each sentence.

Answer 35

magnesium(iv) oxide is a catalyst

Question 36

Draw a ring around the correct answer to complete each sentence. PT2

Answer 36

The manganese(IV) oxide has lowered the activation energy.

Question 37

Suggest why the student stirred the mixture before recording the highest temperature.

Answer 37

To get the correct temperature