Acids-Bases-and-Salts.pdf/7th class science

Here's a description of Acids, Bases, and Salts for 7th class:


Acids, Bases, and Salts


Acids:

- Substances that release hydrogen ions (H+) in solution
- Turn blue litmus red
- Have a sour taste
- Examples: Hydrochloric acid (HCl), Sulphuric acid (H2SO4), Citric acid


Bases:

- Substances that release hydroxide ions (OH-) in solution
- Turn red litmus blue
- Have a bitter taste
- Examples: Sodium hydroxide (NaOH), Calcium hydroxide (Ca(OH)2), Soap


Salts:

- Compounds formed by the reaction between acids and bases
- Neutral in nature (neither acidic nor basic)
- Examples: Sodium chloride (NaCl), Calcium carbonate (CaCO3)


Types of Acids:

1. Strong acids (e.g., HCl, H2SO4)
2. Weak acids (e.g., citric acid, acetic acid)
3. Organic acids (e.g., amino acids)
4. Inorganic acids (e.g., HCl, H2SO4)


Types of Bases:

1. Strong bases (e.g., NaOH, Ca(OH)2)
2. Weak bases (e.g., ammonia, baking soda)
3. Organic bases (e.g., amines)
4. Inorganic bases (e.g., NaOH, Ca(OH)2)


Importance of Acids, Bases, and Salts:

1. Industrial applications (e.g., manufacturing, textiles)
2. Biological processes (e.g., digestion, respiration)
3. Environmental significance (e.g., soil pH, water quality)
4. Medicinal uses (e.g., antacids, acid reflux treatment)


Key Terms:

1. pH scale
2. Neutralization
3. Chemical reaction
4. Ion exchange


Experiments:

1. Testing acidity/basicity using litmus paper
2. Preparing salts through acid-base reactions
3. Observing the effects of pH on plants


Key Questions:

1. What are acids and bases?
2. How are salts formed?
3. What are the properties of acids, bases, and salts?
4. What are the uses and importance of acids, bases, and salts?


This description provides a comprehensive overview of acids, bases, and salts for 7th-class students, covering definitions, types, importance, and key concepts.

1. Acids, Bases
and Salts
We use many substances in daily life like lemon, salt, and vinegar. These
have different tastes due to their chemical nature. Some are acidic, some
basic, and some neutral. This chapter explores acids, bases, and their
properties.
by sandeep swamy

2. Common Substances
and Their Tastes
1
Sour Substances
Lemon juice, orange juice, vinegar, and curd have a sour taste due
to acids.
2
Bitter Substances
Baking soda has a bitter taste and soapy feel, indicating it is a base.
3
Other Tastes
Sugar is sweet, while common salt is salty. These are neutral
substances.

3. Acids and Bases
Acids
Substances that taste sour and contain acids. The word
"acid" comes from Latin "acere" meaning sour.
Bases
Substances that taste bitter and feel soapy. They do not
contain acids.

4. Indicators
Definition
Special substances used to test if a solution is acidic or basic.
Color Change
Indicators change color when added to acidic or basic solutions.
Natural Indicators
Turmeric, litmus, and China rose petals are examples of natural
indicators.

5. Common Acids in Nature
Acetic acid Vinegar
Formic acid Ant's sting
Citric acid Citrus fruits
Lactic acid Curd
Oxalic acid Spinach

6. Common Bases in
Nature
Calcium hydroxide Lime water
Ammonium hydroxide Window cleaner
Sodium/Potassium hydroxide Soap
Magnesium hydroxide Milk of magnesia

7. Litmus: A Natural
Indicator
1
Source
Extracted from lichens
2
Color in Water
Mauve (purple) in distilled water
3
Reaction with Acids
Turns red in acidic solutions
4
Reaction with Bases
Turns blue in basic solutions

8. Testing Substances with Litmus
Paper
1
Step 1
Mix water with test substance in a container.
2
Step 2
Put a drop of solution on red litmus paper.
3
Step 3
Observe any color change.
4
Step 4
Repeat with blue litmus paper.

9. Neutral Solutions
Definition
Solutions that do not change the color of either red or blue litmus.
Nature
Neither acidic nor basic.
Examples
Pure water, sugar solution, salt solution.

10. Turmeric as a Natural
Indicator
1
Preparation
Make a paste with turmeric powder and water.
2
Paper Making
Deposit paste on filter paper and dry it.
3
Testing
Put a drop of test solution on the turmeric paper.

11. China Rose as an
Indicator
1
Preparation
Soak China rose petals in warm water to extract color.
2
Acidic Reaction
Turns dark pink (magenta) in acidic solutions.
3
Basic Reaction
Turns green in basic solutions.

12. Testing Common
Solutions
Solution Litmus Turmeric China Rose
Lemon juice Red No change Pink
Soap solution Blue Red Green
Salt solution No change No change No change

13. Acid Rain
1
Formation
Pollutants like CO2, SO2, and NO2 dissolve in rainwater.
2
Acids Formed
Carbonic, sulphuric, and nitric acids form in raindrops.
3
Effects
Damages buildings, monuments, plants, and animals.

14. Safety with Acids and
Bases
Caution
Laboratory acids and bases are corrosive and harmful to skin.
Protection
Wear protective gear when handling these substances.
Emergency
Know the location of safety equipment like eyewash stations.

15. Neutralization
1
Mixing
An acid solution is mixed with a base solution.
2
Reaction
The acid and base neutralize each other's effects.
3
Result
A salt is formed, along with water and heat.

16. Phenolphthalein
Indicator
Acidic Solution
Phenolphthalein remains colorless in acidic solutions.
Basic Solution
It turns pink in basic solutions.
Neutralization
Used to determine the endpoint of acid-base neutralization.

17. Neutralization Reaction
Reactants
Acid + Base
Products
Salt + Water
Energy
Heat is evolved

18. Indigestion and Antacids
Cause
Excess hydrochloric acid in the stomach causes
indigestion and pain.
Treatment
Antacids like milk of magnesia (magnesium hydroxide)
neutralize excess stomach acid.

19. Treating Ant Bites
1
Sting
Ants inject formic acid into the skin when they bite.
2
Neutralization
Apply baking soda (sodium hydrogencarbonate) or
calamine solution (zinc carbonate).
3
Relief
The base neutralizes the acid, reducing pain and irritation.

20. Soil Treatment
Acidic Soil
Treated with quick lime (calcium oxide) or slaked lime
(calcium hydroxide).
Basic Soil
Treated with organic matter (compost) which releases
acids.

21. Factory Waste
Treatment
1
Problem
Acidic factory wastes can harm aquatic life.
2
Solution
Neutralize wastes by adding basic substances.
3
Result
Treated water is safer for the environment.

22. Acids in the Human Body
DNA
Deoxyribonucleic acid controls our genetic features.
Proteins
Made of amino acids, essential for cell structure.
Fats
Contain fatty acids, important for energy storage.

23. Identifying Unknown Solutions
Acid
Turns blue litmus red, turmeric
unchanged.
Base
Turns red litmus blue, turmeric
red.
Neutral
No change in litmus or turmeric
color.

24. Secret Messages
with Acids and Bases
1
Writing
Use baking soda solution to write invisible message.
2
Revealing
Rub beetroot slice over the paper to reveal the message.
3
Science
Acid in beetroot reacts with base, changing color.

25. Red Cabbage
Indicator
1
Preparation
Boil red cabbage in water to extract pigment.
2
Acidic
Turns red in acidic solutions.
3
Neutral
Remains purple in neutral solutions.
4
Basic
Turns blue or green in basic solutions.