Chapter 11. Chemical Changes

Question 1

Matter

Answer 1

Anything that has mass or volume

Question 2

Composition

Answer 2

Types and amounts of simpler substances that make up a sample of a matter

Question 3

Properties

Answer 3

The characteristics that give each substance a unique identity

Question 4

Physical properties

Answer 4

Properties a substance shows itself without interaction with another substance:

• Colour
• Boiling point
• Melting point
• Density

Question 5

Chemical properties

Answer 5

Properties a substance shows as it interacts with, or transforms into, other substances:

• Flammability
• Corrosiveness

Question 6

Physical vs chemical change

Answer 6

In physical changes, the appearance or form of the matter changes but the kind of matter in the substance does not
- Changes in the physical state are reversible (by temperature)

In chemical changes, at least one new substance is created with different properties
- Cannot be reversed using physical methods

Question 7

Law conservation of mass

Answer 7

Matter cannot be created nor destroyed by chemical reactions or physical changes
- Mass stays the same before and after the reaction
- Number and type of atoms do not change

Question 8

Particle arrangement of solids

Answer 8

Particles are close together and organised

Question 9

Particle arrangement of liquids

Answer 9

particles are close together but disorganised

Question 10

particle arrangement of gases

Answer 10

particles are far apart and disorganised

Question 11

Types of chemical changes

Answer 11

1. Combustion
2. Thermal decomposition
3. Oxidation
4. Neutralisation

Question 12

Combustion

Answer 12

Chemical reaction is which a substance is heated in the presence of oxygen

Question 13

Thermal decomposition

Answer 13

A process in which a substance breaks into two or more simpler substances upon heating

Question 14

Oxidation

Answer 14

Gain of oxygen

Question 15

Neutralisation

Answer 15

A neutralisation reaction is where an acid and a base react to each other to form water and salt

Question 16

acid + metal =

Answer 16

salt + hydrogen

Question 17

acid + carbonate =

Answer 17

salt + carbon dioxide + water

Question 18

acid + alkali =

Answer 18

salt + water

Question 19

Effervescence

Answer 19

bubbles

Question 20

Test for carbon dioxide (acid + carbonate)

Answer 20

Lime water (calcium hydroxide)
- Bubble the gas into limewater
> White precipitate will form in the presence of carbon dioxide

Question 21

Test for hydrogen (acid + metal)

Answer 21

Lighted splint
- Introduce a lighted splint into the gas
> Will be extinguished with a “pop” sound in the presence of hydrogen

Question 22

Water

Answer 22

H20

Question 23

Hydrogen gas

Answer 23

H2

Question 24

Carbon dioxide

Answer 24

CO2

Question 25

Oxygen gas

Answer 25

O2

Question 26

Sulfate ion

Answer 26

SO4 2-

Question 27

Hydroxide ion

Answer 27

OH -

Question 28

Nitrate ion

Answer 28

NO3 -

Question 29

Carbonate ion

Answer 29

CO3 2-

Question 30

Chloride ion

Answer 30

Cl -

Question 31

Sodium ion

Answer 31

Na +

Question 32

Potassium ion

Answer 32

K +

Question 33

Magnesium ion

Answer 33

Mg 2+

Question 34

Calcium ion

Answer 34

Ca 2+

Question 35

Copper (II) ion

Answer 35

Cu 2+

Question 36

Iron (II) ion

Answer 36

Fe 2+

Question 37

Iron (III) ion

Answer 37

Fe 3+

Question 38

Silver ion

Answer 38

Ag +

Question 39

Zinc ion

Answer 39

Zn 2+

Question 40

Aluminium ion

Answer 40

Al 3+

Question 41

PH scale

Answer 41

- Set number 1-14 - Indicates if a solution is acidic, neutral or alkaline - the pH of a solution is related to the concentration of H+ and OH- present in solution.

Question 42

pH 0-6

Answer 42

Acid (Strong acid -> weak acid)

Question 43

pH 7

Answer 43

Neutral

Question 44

pH 8-14

Answer 44

alkali (weak alkali -> strong alkali)

Question 45

Indicators

Answer 45

Subtances that show different colours in acidic and alkalic solution

Question 46

Litmus

Answer 46

Alkali: Blue Acid: Red

Question 47

Methyl orange

Answer 47

Acid: Red Alkali: Yellow

Question 48

Screened methyl orange

Answer 48

Acid: violet Alkali: green

Question 49

Phenolphthalein

Answer 49

acid: colourless alkali: pink

Question 50

Application of pH scale

Answer 50

pH of soil > Important to control pH of soil because it will affect the growth and development of plants (e.g. potatoes grow well at pH 5.5 - 6.5 , while cabbages grow well at pH 7.5 - 8.5) * Most plants grow well in neutral or slightly acidic soils

Question 51

pH of soil may become unsuitable for plant growth due to

Answer 51

- Too much fertiliser - Environmental pollution (acid rain)

Question 52

To treat acidity in soil, add

Answer 52

- Calcium oxide (quicklime) - Calcium hydroxide (slaked lime) *This process is known as liming. These bases neutralise the acid in the soil