04/05/2010 (Day 3)

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Chapter 5The wonderful solvent - WATER

Solvent – 溶劑 A liquid that many substances can dissolve in it.

5.1 Water purification (P.53)

5.1 Water purification (P.53)

Impurities in natural water(P.55)

Impurities (P.55)3 types of impurities:- soluble

- insoluble- micro-organisms

Impurities (P.55)

- soluble impurities???- insoluble impurities???- micro-organism???

Check-point 1 (P.57)1. (a)

die

uses

Water is very important to all living things. Without water, living things will _________.1.

(b)The demand for clean water is very high because water has many different __________.

How to remove impurities from water (P.58)

The process of cleaning water is called purification.

How to remove impurities from water (P.58)

Sedimentation 沉積法3 different methods remove different types of impurities.

Filtration 過濾法Distillation 蒸餾法

Sedimentation 沉積法 (P.59)Remove large and

insoluble impurities from water.

Experiment 5.1 (P.60)Removing large solid impurities by sedimentation

1. Solid particles in water slowly sink to the bottom of the beaker.

Experiment 5.1 (P.60)Removing large solid impurities by sedimentation

2. The ________ portion of water is clearer.

top

Experiment 5.1 (P.61)Removing large solid impurities by sedimentation

Alum( 明礬 ) –Aluminium Sulphate

Experiment 5.1 (P.61)Removing large solid impurities by sedimentation

3.(a)

Water in the top portion becomes clearer.

3.(b)

Alum makes the solid impurities to settle more quickly.

Experiment 5.1 (P.61)DISCUSSION

Q: Is the water purified by this method safe to drink? Why?

A: No. It is because the water may contain soluble

impurities and micro-organisms.

Filtration 過濾法 (P.61)Remove fine solid impurities.

Experiment 5.2 (P.62)II. Using the filter paper

HOMEWORKWORKBOOK

Revision Exercise P.50Part A and B

Due date: 5-5-2010