Acids, Bases and Salts | Class 10 | Activity 2.15 with Solution

Activity 2.15  

• Heat a few crystals of copper sulphate in a dry boiling tube.
• What is the colour of the copper sulphate after heating?

✅ Answer: White. 

• Do you notice water droplets in the boiling tube? Where have these come from?

✅ Answer: Copper sulphate crystals contain water of crystallisation. When heated the crystals, this water is removed and the salt turns white.

• Add 2-3 drops of water to the sample of copper sulphate obtained after heating.
• What do you observe? Is the blue colour of copper sulphate restored?

✅ Answer: Copper sulphate crystals restore its blue colour. 

• Activity 2.1
• Activity 2.2
• Activity 2.3
• Activity 2.4
• Activity 2.5
• Activity 2.6
• Activity 2.7
• Activity 2.8
• Activity 2.9
• Activity 2.10
• Activity 2.11
• Activity 2.12
• Activity 2.13
• Activity 2.14
• Activity 2.15

👉 Other Chapters

Acids, Bases and Salts | Class 10 | Activity 2.14 with Solution

Activity 2.14

• Collect the following salt samples – sodium chloride, potassium nitrate, aluminium chloride, zinc sulphate, copper sulphate, sodium acetate, sodium carbonate and sodium hydrogen carbonate (some other salts available can also be taken).
• Check their solubility in water (use distilled water only).
• Check the action of these solutions on litmus and find the pH using a pH paper.
• Which of the salts are acidic, basic or neutral?
• Identify the acid or base used to form the salt.
• Report your observations in Table 2.4.

Salt	pH	Acid used	Base used

✅ Answer:

Salt	pH	Acid used	Base used
Sodium chloride	7	HCl	NaOH
Potassium nitrate	7	HNO3	KOH
Aluminium chloride	7	HCl	Al(OH)3
Zinc sulphate	7	H2SO4	Zn(OH)2
Copper sulphate	< 7	H2SO4	Cu(OH)2
Sodium acetate	> 7	CH3COOH	NaOH
Sodium carbonate	> 7	H2CO3	NaOH
Sodium hydrogen carbonate	> 7	H2CO3	NaOH

• Activity 2.1
• Activity 2.2
• Activity 2.3
• Activity 2.4
• Activity 2.5
• Activity 2.6
• Activity 2.7
• Activity 2.8
• Activity 2.9
• Activity 2.10
• Activity 2.11
• Activity 2.12
• Activity 2.13
• Activity 2.14
• Activity 2.15

👉 Other Chapters

Acids, Bases and Salts | Class 10 | Activity 2.13 with Solution

Activity 2.13  

• Write the chemical formulae of the salts given below.

Potassium sulphate, sodium sulphate, calcium sulphate, magnesium sulphate, copper sulphate, sodium chloride, sodium nitrate, sodium carbonate and ammonium chloride.

• Identify the acids and bases from which the above salts may be obtained.

✅ Answer:

Salts & their Chemical formulae	Formed from which Acids & bases?
Potassium sulphate (K2SO4)	H2SO4 & KOH
Sodium sulphate (Na2SO4)	H2SO4 & NaOH
Calcium sulphate (CaSO4)	H2SO4 & CaCO3
Magnesium sulphate (MgSO4)	H2SO4 & Mg(OH)2
Copper sulphate (CuSO4)	H2SO4 & Cu(OH)2
Sodium chloride (NaCl)	HCl & NaOH
Sodium nitrate (NaNO3)	HNO3 & NaOH
Sodium carbonate (Na2CO3)	H2CO3 & NaOH
Ammonium chloride (NH4Cl)	HCl + NH4OH

• Salts having the same positive or negative radicals are said to belong to a family. For example, NaCl and Na2SO4 belong to the family of sodium salts. Similarly, NaCl and KCl belong to the family of chloride salts. How many families can you identify among the salts given in this Activity?

✅ Answer: Na₂SO₄, NaCl, NaNO₃ and Na₂CO₃ belong to the family of sodium salts. K₂SO₄, Na₂SO₄, CaSO₄, MgSO₄, CuSO₄ belong to the family of sulphate salts. NaCl and KCl belong to the family of chloride salts.

• Activity 2.1
• Activity 2.2
• Activity 2.3
• Activity 2.4
• Activity 2.5
• Activity 2.6
• Activity 2.7
• Activity 2.8
• Activity 2.9
• Activity 2.10
• Activity 2.11
• Activity 2.12
• Activity 2.13
• Activity 2.14
• Activity 2.15

👉 Other Chapters

Acids, Bases and Salts | Class 10 | Activity 2.12 with Solution

Activity 2.12  

• Put about 2 g soil in a test tube and add 5 mL water to it.
• Shake the contents of the test tube.
• Filter the contents and collect the filtrate in a test tube.
• Check the pH of this filtrate with the help of universal indicator paper.
• What can you conclude about the ideal soil pH for the growth of plants in your region?

✅ Answer: Ideal soil pH for the growth of plants = 6 to 7.

• Activity 2.1
• Activity 2.2
• Activity 2.3
• Activity 2.4
• Activity 2.5
• Activity 2.6
• Activity 2.7
• Activity 2.8
• Activity 2.9
• Activity 2.10
• Activity 2.11
• Activity 2.12
• Activity 2.13
• Activity 2.14
• Activity 2.15

👉 Other Chapters

Acids, Bases and Salts | Class 10 | Activity 2.11 with Solution

Activity 2.11

• Test the pH values of solutions given in Table 2.2.
• Record your observations.
• What is the nature of each substance on the basis of your observations?

Solution	Colour of pH paper	Approximate pH value	Nature of substance
1.    Saliva (before meal)
2.    Saliva (after meal)
3.    Lemon juice
4.    Colourless aerated drink
5.    Carrot juice
6.    Coffee
7.    Tomato juice
8.    Tap water
9.    1M NaOH
10. 1M HCl

✅ Answer:

Solution	Colour of pH paper	Approximate pH value	Nature of substance
1.    Saliva (before meal)	Green	6.8 – 7.4	Slightly acidic to basic
2.    Saliva (after meal)	Yellow green	5.8	Acidic
3.    Lemon juice	Orange	2.2	Acidic
4.    Colourless aerated drink	Yellow	4.0	Acidic
5.    Carrot juice	Yellow green	6.0	Acidic
6.    Coffee	Yellow	4.5	Acidic
7.    Tomato juice	Yellow	4.3	Acidic
8.    Tap water	Green	6 – 8.5	Varied
9.    1M NaOH	Dark blue	14	Basic
10. 1M HCl	Red	0	Acidic

• Activity 2.1
• Activity 2.2
• Activity 2.3
• Activity 2.4
• Activity 2.5
• Activity 2.6
• Activity 2.7
• Activity 2.8
• Activity 2.9
• Activity 2.10
• Activity 2.11
• Activity 2.12
• Activity 2.13
• Activity 2.14
• Activity 2.15

👉 Other Chapters