2.1.4 Acids

Question 1

What is the formula of Hydrochloric acid (HCl) and its dissociation in water?

Answer 1

Formula: HCl
In water: HCl (aq) -> H+ (aq) + Cl- (aq)

Question 2

What is the formula of Sulfuric acid (H₂SO₄) and its dissociation in water?

Answer 2

Formula: H₂SO₄
In water:
H₂SO₄ (aq) → H+ (aq) + HSO₄- (aq)
HSO₄- (aq) → H+ (aq) + SO₄²- (aq)

Question 3

What is the formula of Nitric acid (HNO₃) and its dissociation in water?

Answer 3

Formula: HNO₃
In water:
HNO₃ (aq) → H+ (aq) + NO₃- (aq)

Question 4

What is the formula of Acetic acid (CH₃COOH) and its dissociation in water?

Answer 4

Formula: CH₃COOH
In water:
CH₃COOH (aq) ⇌ CH₃COO- (aq) + H+ (aq)

Question 5

What is the formula of Sodium hydroxide (NaOH) and its dissociation in water?

Answer 5

Formula: NaOH
In water:
NaOH (aq) → Na+ (aq) + OH- (aq)

Question 6

How does Ammonia (NH₃) act as an alkali in water?

Answer 6

Formula: NH₃
In water:
NH₃ (aq) + H₂O (l) ⇌ NH₄+ (aq) + OH- (aq)

Question 7

What is the difference between strong and weak acids?

Answer 7

• Strong acids completely dissociate in water (e.g., HCl, HNO₃).
• Weak acids partially dissociate in water (e.g., CH₃COOH).

Question 8

What happens during neutralization?

Answer 8

During neutralization, H+ ions from an acid react with OH- ions from a base to form water.
General equation:
H+ (aq) + OH- (aq) → H₂O (l)

Question 9

What is the reaction between an acid and an alkali? (e.g., HCl + NaOH)

Answer 9

Acid + alkali → Salt + water
HCl (aq) + NaOH (aq) → NaCl (aq) + H₂O (l)

Question 10

What is the reaction between an acid and a metal oxide? (e.g., HCl + CuO)

Answer 10

Acid + Metal oxide → Salt + water
2HCl (aq) + CuO (s) → CuCl₂ (aq) + H₂O (l)

Question 11

What is the reaction between an acid and a carbonate? (e.g., H₂SO₄ + Na₂CO₃)

Answer 11

Acid + metal carbonate → Salt + Carbon dioxide + water
H₂SO₄ (aq) + Na₂CO₃ (aq) → Na₂SO₄ (aq) + CO₂ (g) + H₂O (l)

Question 12

What are the steps for preparing a standard solution?

Answer 12

1. Weigh the required amount of solute.
2. Dissolve the solute in a small amount of distilled water.
3. Transfer to a volumetric flask.
4. Add distilled water to the mark and mix.

Question 13

What is the procedure for performing an acid-base titration?

Answer 13

1. Add a known volume of the standard solution to a conical flask.
2. Add a few drops of indicator.
3. Fill the burette with the acid.
4. Slowly add acid to the standard solution until the endpoint (color change) is reached.
5. Record the volume of acid used.

Question 14

How do you calculate the concentration of an unknown solution using titration results?

Answer 14

Use the equation:
C₁V₁ = C₂V₂
Where:
- C₁, V₁ = concentration and volume of acid
- C₂, V₂ = concentration and volume of base

Question 15

Example of a titration calculation: If 25.0 cm³ of NaOH is titrated with 0.100 mol/dm³ HCl and requires 20.0 cm³ of HCl, what is the concentration of NaOH?

Answer 15

Convert volumes into dm³ by multiplying by 10-³
Using the equation:
C₁ × 0.0250 = 0.100 × 0.0200
C₁ = (0.100 × 0.0200) / 0.0250 = 0.0800 mol/dm³