Date post: | 14-Dec-2015 |
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• 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