• Part 1 Introduction

• Part 2 What are the properties of acids? What precautions we have to take in diluting acid?

• Part 3 Daily examples of acids

• Part 4 Questions

In this lesson, we use• pictures to recall

students’ memory • photos and graphics to

show the properties of acid

• sound effect in the quiz

• Introduction of acids

in daily life

• Properties of acids

• Common use of acids

• Danger of acids

• A small quiz

What acidic substance can we find in daily life?

• Most acids have a sour taste.

• The word “acid” means “sour”.

• Acids show a pH test colour of orange or red.

• Acidity can be measured by pH meter.

• Acids show the pH in the range from 1 to 6.

• All dilute acids can conduct electricity.

• Concentrated acids are very corrosive and represented by a symbol as :

C O R R O SIVE

Corrosive properties

of acids

On metal

On cloth/paper

Acid rain on marble

Metal terminal of battery

• Dehydration of sugar

sugar + acid carbon

+

• Volatile

• Fruits(e.g. oranges, lemons and pineapples) contain citric acid

• Common Household Acids

ACIDS

Name Formula Locations

Acetic acid HC2H3O2 Vinegar

Acetylsalicylic acid HC9H7O4 Aspirin

Ascorbic acid H2C6H6O6 Vitamin C

Citric acid H3C6H5O7 Lemon juice, citrus fruits

Hydrochloric acid HCI Gastric juices(digestive fluid in stomach)

Sulfuric acid H2SO4 Batteries

• Soft drinks contain carbonic acid.

• Vinegar and tomato sauce contain ethanoic acid.

• Yoghurt and sour milk contain lactic acid.

• Tea contains tannic acid.

• Domestic cleaners contain methanoic acid.

• Car battery contains sulphuric acid.

• Our stomach secretes hydrochloric acid to help us digest food.

Concentrated acid

Adding water

A lot of heat is given out and cause acid to jump out.

water

Adding concentrated acid

Wearing goggle

Wearing gloves

Click T or F for the correct answer .

For correct answer For incorrect answer

1. Vinegar is a dilution solution of ethanoic acid. T/F

2. Most acids have a bitter taste. T/F

3. Acids can turn litmus paper from red to blue. T/F

4. Acid-alkali neutralizations produce salts. T/F

5. When you dilute a concentrated acid, always

add the acid slowly to a large amount of water. T/F