CLASS 10 CBSE CHEMISTRY PRACTICAL

EXPERIMENT: Studying the Properties of Acids and Bases (HCl & NaOH) on the Basis of their Reaction with Litmus Solution, Zinc Metal, and Solid Sodium Carbonate

---

AIM:

To study the properties of acids and bases (HCl & NaOH) by their reaction with:

• Litmus solution (Blue/Red)
• Zinc metal
• Solid sodium carbonate

---

MATERIALS REQUIRED:

1. Test tubes (6)
2. Test tube stand
3. Test tube holder
4. Droppers (2)
5. Beaker
6. Dilute Hydrochloric acid (HCl)
7. Dilute Sodium hydroxide (NaOH) solution
8. Red litmus solution
9. Blue litmus solution
10. Zinc granules
11. Solid sodium carbonate (Na₂CO₃)
12. Splinter/matchstick

---

THEORY:

Acids: Substances that produce hydrogen ions (H⁺) when dissolved in water. They have a sour taste and turn blue litmus red.

Bases: Substances that produce hydroxide ions (OH⁻) when dissolved in water. They have a bitter taste, soapy touch, and turn red litmus blue.

Properties of Acids:

1. With Litmus: Acids turn blue litmus red and have no effect on red litmus.
2. With Metals: Acids react with active metals like zinc to produce hydrogen gas and a salt.

• Reaction: Zn + 2HCl → ZnCl₂ + H₂↑

1. With Carbonates: Acids react with carbonates to produce carbon dioxide gas, water, and a salt.

• Reaction: Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂↑

Properties of Bases:

1. With Litmus: Bases turn red litmus blue and have no effect on blue litmus.
2. With Metals: Bases react with certain metals like zinc to produce hydrogen gas and a salt.

• Reaction: Zn + 2NaOH → Na₂ZnO₂ + H₂↑

1. With Carbonates: Bases generally do not react with carbonates (no observable reaction).

Tests for Gases:

• Hydrogen gas (H₂): Burns with a pop sound when a burning splinter is brought near it.
• Carbon dioxide (CO₂): Turns lime water milky.

---

PROCEDURE:

A. Reaction with Litmus Solution:

1. Take four clean test tubes and label them as 1, 2, 3, and 4.
2. Pour 2 mL of dilute HCl in test tubes 1 and 2.
3. Pour 2 mL of dilute NaOH in test tubes 3 and 4.
4. Add 2-3 drops of blue litmus solution to test tubes 1 and 3.
5. Add 2-3 drops of red litmus solution to test tubes 2 and 4.
6. Observe the color changes and record your observations.

B. Reaction with Zinc Metal:

1. Take two clean test tubes and label them as A and B.
2. Pour 5 mL of dilute HCl in test tube A.
3. Pour 5 mL of dilute NaOH in test tube B.
4. Add a few zinc granules to both test tubes.
5. Observe the reactions carefully. Look for effervescence (bubbles).
6. After a few minutes, bring a burning matchstick/splinter near the mouth of each test tube.
7. Listen for a pop sound (indicates hydrogen gas).
8. Record your observations.

C. Reaction with Solid Sodium Carbonate:

1. Take two clean test tubes and label them as X and Y.
2. Put a pinch of solid sodium carbonate (Na₂CO₃) in both test tubes.
3. Add 2-3 mL of dilute HCl to test tube X.
4. Add 2-3 mL of dilute NaOH to test tube Y.
5. Observe the reactions carefully. Look for effervescence.
6. Record your observations.

---

OBSERVATION:

Table 1: Reaction with Litmus Solution

Test Tube	Solution	Litmus Added	Color Change	Observation
1	Dilute HCl	Blue litmus	Blue → Red	Acidic nature
2	Dilute HCl	Red litmus	No change (remains red)	Acidic nature
3	Dilute NaOH	Blue litmus	No change (remains blue)	Basic nature
4	Dilute NaOH	Red litmus	Red → Blue	Basic nature

---

Table 2: Reaction with Zinc Metal

Test Tube	Solution	Observation	Gas Evolved	Test	Inference
A	Dilute HCl	Brisk effervescence, zinc dissolves	Hydrogen (H₂)	Pop sound with burning splinter	HCl reacts with Zn
B	Dilute NaOH	Effervescence, zinc dissolves slowly	Hydrogen (H₂)	Pop sound with burning splinter	NaOH reacts with Zn

Chemical Equations:

• Zn + 2HCl → ZnCl₂ + H₂↑
• Zn + 2NaOH → Na₂ZnO₂ + H₂↑

---

Table 3: Reaction with Solid Sodium Carbonate

Test Tube	Solution	Observation	Gas Evolved	Inference
X	Dilute HCl	Brisk effervescence, Na₂CO₃ dissolves	Carbon dioxide (CO₂)	HCl reacts with Na₂CO₃
Y	Dilute NaOH	No effervescence, no reaction	No gas	NaOH does not react with Na₂CO₃

Chemical Equation:

• Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂↑

---

RESULT:

1. HCl (Acid):

• Turns blue litmus red
• Reacts with zinc metal to produce hydrogen gas
• Reacts with sodium carbonate to produce carbon dioxide gas

1. NaOH (Base):

• Turns red litmus blue
• Reacts with zinc metal to produce hydrogen gas
• Does not react with sodium carbonate

---

PRECAUTIONS:

1. Use dilute solutions of HCl and NaOH to avoid harm.
2. Handle acids and bases carefully. Avoid direct contact with skin and eyes.
3. Perform the experiment in a well-ventilated area.
4. Do not inhale the gases evolved directly.
5. While testing for hydrogen gas, do not bring the burning splinter too close initially.
6. Clean zinc granules should be used for better results.
7. Add sodium carbonate slowly to avoid excessive frothing.
8. Use test tube holder while handling test tubes during reactions.
9. Wear safety goggles if available.
10. Wash hands thoroughly after completing the experiment.

---

Signature of Teacher: ___