S2 Chemical Reactions

Question 1

What is the difference between a physical change and a chemical reaction?

Answer 1

Physical change – no new substance is formed and it is reversible.
Chemical reaction – a new chemical is formed and it is very difficult to reverse.

Question 2

What are the 5 physical changes?

Answer 2

Freezing, melting, evaporating, condensing and dissolving.

Question 3

What is made in a chemical reaction?

Answer 3

A new substance (chemical) and energy.

Question 4

What are the 4 signs of a chemical reaction?

Answer 4

A gas being given off, a change in colour, a solid forming, and a change in temperature

Question 5

What are the 4 things which affect the rate of a reaction?

Answer 5

Particle size, temperature, concentration and the use of a catalyst

Question 6

How would you test a gas to see if it was hydrogen?

Answer 6

Hydrogen burns with a squeaky pop

Question 7

How would you test a gas to see if it was oxygen?

Answer 7

Oxygen relights a glowing splint

Question 8

How would you test a gas to see if it was carbon dioxide?

Answer 8

Carbon dioxide turns limewater cloudy

Question 9

What is meant by the ‘rate’ of a chemical reaction?

Answer 9

The speed at which a chemical reaction occurs

Question 10

How could I increase the rate of a chemical reaction?

Answer 10

Decrease particle size, use a catalyst, increase the temperature, increases concentration

Question 11

How could I decrease the rate of a chemical reaction?

Answer 11

Use larger particle size, decrease the temperature, decrease concentration

Question 12

What speeds up a chemical reaction without being used up?

Answer 12

A catalyst

Question 13

Physical change or chemical reaction?

Frying an egg

Answer 13

Chemical reaction

Question 14

Physical change or chemical reaction?

A car rusting

Answer 14

Chemical reaction

Question 15

Physical change or chemical reaction?

Paint drying

Answer 15

Physical change

Question 16

Physical change or chemical reaction?

Boiling a kettle

Answer 16

Physical change

Question 17

Physical change or chemical reaction?

Pouring how water onto coffee granules

Answer 17

Physical change

Question 18

Physical change or chemical reaction?

Making salt crystals from salt water on a windowsill

Answer 18

Physical change

Question 19

Physical change or chemical reaction?

Burning wood

Answer 19

Chemical reaction

Question 20

Physical change or chemical reaction?

Chopping wood into smaller pieces

Answer 20

Physical change

Question 21

Decreasing particle size ___________ the rate of a reaction

Answer 21

Decreasing particle size increases the rate of a reaction

Question 22

Use a catalyst ____________ the rate of a reaction

Answer 22

Use a catalyst increasesthe rate of a reaction

Question 23

Increasing the temperature ____________ the rate of a reaction

Answer 23

Increasing the temperature increases the rate of a reaction

Question 24

Increasing concentration ____________ the rate of a reaction

Answer 24

Increasing concentration increases the rate of a reaction

Question 25

Using a larger particle size ____________ the rate of a reaction

Answer 25

Using a larger particle size decreases the rate of a reaction

Question 26

Decreasing the temperature ____________ the rate of a reaction

Answer 26

Decreasing the temperature decreases the rate of a reaction

Question 27

Decreasing concentration ____________ the rate of a reaction

Answer 27

Decreasing concentration decreases the rate of a reaction