5
5.1
The wonderful solvent - water
Class:___
Name:_________(
)
Importance of water (Book 1B, p. 63)

Water is important for many body functions.

In addition, we need water in many daily activities, such as:
(1) __________________
5.2
A

(2) __________________
(3) __________________
Making water safe to drink (Book 1B, p. 64)
Impurities in natural water
Natural water contains different types of impurities (雜質),
including (1) _________________ (可溶的) impurities, e.g. ____________
_______ (礦物鹽)
(2) _____________ (不可溶的) impurities, e.g. ____________
(3) ____________________. e.g. ____________ (大腸桿菌) and ____________ (變形蟲)
B
Methods of water purification
(把水淨化) (Book 1B, p. 66)
1
Sedimentation (沉積法) (Book 1B, p. 67)

Sedimentation can remove large and heavy (8) _______________ impurities

They are allowed to settle(沉澱) , forming a layer of (9) _______________ (沉積物).

Adding (10) _______________ (明礬) can help stick (黏住) the fine solid impurities suspending(懸
浮)
in water together to form larger particles. The larger particles then sink(下沉) to the bottom of
the water.

A beaker of pond water after standing (靜置)for some time
fine solids
suspending in
water
fine solids
floating on water
sediment
2
Filtration(過濾法)

Filtration can remove most (11) _______________ impurities in water.

Examples of filters(過濾器): (13) __________________ (過濾柱) and (14) _________________ (濾紙).

Filtration cannot remove micro-organisms and (15) _______________ impurities in water.
(Book 1B, p. 69)
the solid impurities left on the filter paper are called
(16) _______________殘餘物
filter funnel 漏斗
filter paper 濾紙
the liquid obtained is called
(17) _____________濾液
 using filter column
 using filter paper
3
Distillation(蒸餾法) (Book 1B, p. 75)

Distillation can remove the (18) _______________ impurities,
(19) ___________________ impurities and (20) ____________________ in water.

The process(過程) of distillation:
3
1
The steam goes into the (23)
Pond water is boiled to
_______________(冷凝管). It cools
(21) _______________.
down and (24) _______________(凝
Micro-organisms in the water are killed.
結) to
form liquid water.
water out
thermometer
condenser
water in
round-bottom flask
pond water



distillate

2
As water changes to steam, the
4
The pure water obtained is called (25)
(22) ______________ are left
____________________ (餾出物)or
behind.
(26) _______________ water. (蒸餾水)
4. Method of
water
purification
Types of impurities removed
Insoluble impurities
Soluble
impurities
Large and heavy solids
Fine solids
Micro-organisms
Sedimentation
Filtration
Distillation
remove … (Types of impurities), but cannot remove … (Types of impurities)…
2. Both …(Method of purification)… and …(Method of purification)… can remove … (Types of impurities).
3. Only …(Method of purification)… can remove …(Types of impurities).
1.
…(Method of purification)… can
5.3

The water cycle (Book 1B, p. 85)
When water particles in liquid water absorb enough heat energy, they escape from the water
surface to become water vapour. This process is called (1) __________________ (蒸發).

When water vapour cools down, water particles stick together to form water droplets. This process
is called (2) __________________ (凝結).
Factors affecting the rate of evaporation of water (Book 1B, p. 88)

The rate of evaporation of water increases when:
a
the _______________increases;
b
the _______________ increases;
c
the surface area ________________________
increases;
d
the _______________ decreases.



plastic wrap
hot water
hot water

closed container
5.4
Water pollution (Book 1B, p. 97)
C
Causes of water pollution
Consequence 後果
Pollutant
Source 來源
Sewage
Homes,
restaurants

and farms

Sewage from farms contains (11) ______________.(肥料)

Both contain (12) ______________(磷酸鹽) that promote the
(污水)
Sewage from homes and restaurants contains
(10) _______________.(洗潔劑)
growth
of
algae
( 藻 類 )
and
may
cause
(13)
______________________. (紅潮)

During a red tide, algae use up the (14) _______________
in water. Aquatic life(水中生物) may die because of a lack of
oxygen. (缺乏氧)

The (15) _______________(毒素) produced by the algae
will kill aquatic life.

We may get poisoned if we eat the seafood contaminated
with the toxins. (受毒素污染)
Homes and
farms

Human and animal waste in the sewage may carry harmful
(16) _____________________.

If we eat the contaminated seafood, we may suffer from
(17) _______________________.
Factories

The sewage may contain toxic (18)_____________.(化學品)

If we eat the contaminated seafood, we may suffer from
(19) _______________________.
Dumped (傾
倒) by
Solid
waste

Solid waste does not (20)__________(分解)easily in nature.

Sea animals may die when they eat the waste or get
people
Oil
Accidental
spills (泄漏)
(21) _______________(被纏著) in it.

Oil floating on water blocks(阻礙) (22) ______________
from going into the water.

Sea animals may die due to a lack of (23) ______________.

Seabirds die of (24) _____________ as their feathers are
stuck by oil and cannot fly
D

Controlling water pollution (Book 1B, p. 100)
What can be done to control water pollution?
Measure
I
Individual
a
Running sewage treatment works (污水處理廠)
II
Government
b
Passing laws to control water pollution
c
Not throwing rubbish into the seas or rivers
d
Treating waste water that contains harmful chemicals
e
Using less detergent when washing dishes
f
Introducing the sewage services charging scheme(污水
處理服務收費計劃)
I: (25) ______, ______
5.5

II: (26) ______, ______, ______, ______
Dissolving(溶解)(Book 1B, p. 104)
(1) _______________ (溶質) +(2) _______________ (溶劑)  (3) _______________ (溶液)
When a solute dissolves in a solvent, a solution is formed.

Identify the solute, solvent and solution in the case below:
Salt
(4) (
dissolving
)
Water
(5) (

salt solution
)
(6) (
(7) _______________ is a good solvent but it cannot dissolve everything.
)
A

Saturated solutions (Book 1B, p. 106)
When no more solute can dissolve in a fixed amount of solvent, a (8) ____________________ (飽
和溶液) is

formed.
A substance with a higher (9) ______________ (溶解度) can dissolves a larger amount in a fixed
amount of solvent of the same temperature.
[物質的溶解度愈高，在同等份量和相同温度溶液中，能溶解的份量愈多。]
Factors affecting the rate of dissolving (Book 1B, p. 107) [≠solubility]
B

A solute dissolves faster when

the temperature of the solvent is (10) _______________;

the solute pieces are (11) _______________ in size;

the solution is (12) __________________.
5.6

Growing crystals (Book 1B, p. 112)
Crystals (晶體) can be formed by (1) __________________a hot saturated solution. The formation
of crystals in a solution is called (2) __________________.

Crystals have (3) __________________ shapes and (4) __________________ surfaces.

Crystals of the same kind may have (5) __________________ sizes but their shapes are (6)
__________________.

Crystals of different substances may have (7) __________________ colours and shapes.
The crystal formed
Method of growing crystal
Size
(8)
Cooling down a hot
saturated solution
quickly
Cooling down a hot
saturated solution
hot saturated
copper sulphate
solution
cavity slide
a well-shaped
crystal as seed
slowly
hot saturated
solution
(9)
Shape
(10)
5.7
Solvents other than water (Book 1B, p. 117)

Some substances, such as oil, dissolve in solvent other than (1) _______________.

Examples of solvents other than water and their functions:
Solvent
Function
I
alcohol
a
II
thinner
b To clean clothing and other articles without using water
III dry-cleaning liquid
I: (2) ______

c
II: (3) ______
To remove oil stains
To dilute oil paints
III: (4) ______
We must take precautions when handling solvents other than water.
Flammable
Alcohol
 Read the hazard warning labels
before using solvents
5 The wonderful solvent – water (ANSWERS)
5.1
1
taking showers
2
cooking
3
washing clothes
5.2
1
soluble, mineral salts 2
insoluble, sand
3
micro-organisms, E.coli, Amoeba
8
solid
9
sediment
10
alum
11
solid
13
Filter columns
14
filter papers
15
soluble
16
residue
17
filtrate
18
soluble
19
insoluble
20
micro-organisms
21
steam
22
impurities
23
condenser
24
condenses
25
distillate
26
distilled
`
Method of
water
purification
Types of impurities removed
Insoluble impurities
Soluble
impurities
Large and heavy solids
Fine solids
Micro-organisms
Sedimentation
✓
✗
✗
✗
Filtration
✓
✓
✗
✗
Distillation
✓
✓
✓
✓
5.3
1
Evaporation
2
condensation
3
air speed
4
temperature
5
exposed to air
6
humidity
10
detergents
11
fertilizers
12
phosphates
13
red tide
14
oxygen
18
chemicals
15
toxins
16
micro-organisms
17
food poisoning
19
food poisoning
20
decompose
21
trapped
22
air
23
oxygen
24
hunger
1
solute
2
solvent
3
solution
4
solute
5
solvent
6
solution
7
Water
8
saturated solution
9
solubility
10
higher
11
smaller
12
stirred
1
cooling down
2
crystallization
3
regular
4
smooth
5
different
6
the same
7
different
8
smaller
9
larger
10
same
water
2
a
3
c
5.4
25
c, e
26
a, b, d, f
5.5
5.6
5.7
1
4
b