Reactions

Question 1

What are the two types of changes in reactions?

Answer 1

Chemical and physical changes

Question 2

What are some factors of physical changes?

Answer 2

• no new compounds formed
• melting, boiling, freezing, condensing etc.

Question 3

What are some factors of chemical changes?

Answer 3

• new compound formed
• Signs:
• temp change
• bubbles
• colour change

Question 4

What is another word for bubbles?

Answer 4

Effervesces

Question 5

What are the three types of variable?

Answer 5

Independent
Dependant
Controll

Question 6

Which variable is the one that changes

Answer 6

Independent variable

Question 7

What does the dependant variable do?

Answer 7

Feature that is measured

Question 8

What does the control variable do?

Answer 8

A feature that is kept constant

Question 9

Name two examples of reaction

Answer 9

• oxidation
• thermal decomposition

Question 10

What happens to mass in chemical reactions?

Answer 10

It is never lost or gained (law of conservation of mass)

Question 11

Define exothermic reaction

Answer 11

Gives out thermal energy to the environment

Question 12

Does the temperature rise or fall in an exothermic reaction?

Answer 12

It rises and gets hot

Question 13

Give two examples of exothermic reactions

Answer 13

Combustion and most catalysts

Question 14

Define endothermic reaction

Answer 14

Takes in thermal energy from the environment

Question 15

Which type of reaction ( endothermic or exothermic ) does the temp fall?

Answer 15

Endothermic

Question 16

Name two examples of endothermic reactions

Answer 16

Thermal decomposition and ammonium nitrate

Question 17

What are catalysts and what do they do?

Answer 17

Speeds up a reaction without being used up and provides an alternate easier pathway for reactions to occur (lowers energy for the reaction to occur)

Question 18

What are the two types of catalysts?

Answer 18

Industrial catalysts (usually contain transitional metals)
Biological catalysts (enzymes)

Question 19

Give two examples of industrial catalysts

Answer 19

• platinum speeds up combustion
• iron used in the Haber process

Question 20

Give two examples of biological catalysts

Answer 20

• catalase (lipase) found in the liver
• amylase found in saliva

Question 21

Define combustion

Answer 21

When a fuel reacts with oxygen (exothermic reaction)

Question 22

What are some features of complete combustion? (

Answer 22

• ample oxygen present
• products = water and co2 (greenhouse gas)

Question 23

What are some factors of incomplete combustion?

Answer 23

• little oxygen present
• products= water,Co (toxic gas), soot (can irritate the lungs if inhaled)

Question 24

Give the equation for complete combustion

Answer 24

Fuel + oxygen ~> carbon dioxide + water

Question 25

Give the equation for incomplete combustion

Answer 25

Fuel + oxygen ~> carbon monoxide OR Carbon + water

Question 26

What is thermal decomposition?

Answer 26

The breakdown of a compound into similar substances due to heat

Question 27

What are carbonates?

Answer 27

Compounds that contain carbon and oxygen

Question 28

What atoms do carbonates usually consist of?

Answer 28

A metal, a carbon atom and three oxygen atoms (e.g CaCo3 calcium carbonate)

Question 29

What do metal carbonates breakdown into?

Answer 29

Metal oxide and carbon dioxide

Question 30

How do we test for carbon dioxide?

Answer 30

By bubbling gas through limewater if the limewater turns cloudy there is carbon dioxide present

Question 31

What is the equation for thermal decomposition

Answer 31

Metal carbonate ~> metal oxide + carbon dioxide

Question 32

What is another word for the clamp stand?

Answer 32

A retort stand

Question 33

What type of tube should the horizontal test tube be?

Answer 33

A boiling tube

Question 34

What are three safety precautions with the limewater testing?

Answer 34

- hair tied back - goggles - remove limewater before stopping heating

Question 35

What 4 things do you need to do when planning an investigation?

Answer 35

- choose variables - ensure control variable remains the same - trial run - set the interval - the size of the step between max and min

Question 36

What does precision mean?

Answer 36

When the results are all really close together

Question 37

What is an anomalous result?

Answer 37

When there is a result that is very different from the rest

Question 38

What does it mean is something is bias?

Answer 38

When an experimenter has a theory that they believe is true and frames data so that their conclusion agrees with the theory

Question 39

What’s an example of a bias experiment?

Answer 39

Tobacco companies setting experiments that minimise the signs of negative effects of smoking

Question 40

What are the signs of each state?

Answer 40

Solid - S Liquid - L Gas - g Aqueous - aq