2.1.4 Acids Flashcards
Define an acid
A proton donator that releases hydrogen protons in aqueous solution
Define a base
A proton acceptor
Define an alkali
A base that releases hydroxide ions in aqueous solutions
Define a salt
A compound formed when the hydrogen proton of an acid is replaced by a positive ion or metal ion in an acid-base reaction
Define amphoteric substance
A compound that can act as both an acid and base
What is the formula of Hydrochloric acid (HCl) and its dissociation in water?
Formula: HCl
In water: HCl (aq) -> H+ (aq) + Cl- (aq)
What is the formula of Sulfuric acid (H₂SO₄) and its dissociation in water?
Formula: H₂SO₄
In water:
H₂SO₄ (aq) → H+ (aq) + HSO₄- (aq)
HSO₄- (aq) → H+ (aq) + SO₄²- (aq)
What is the formula of Nitric acid (HNO₃) and its dissociation in water?
Formula: HNO₃
In water:
HNO₃ (aq) → H+ (aq) + NO₃- (aq)
What is the formula of Acetic acid (CH₃COOH) and its dissociation in water?
Formula: CH₃COOH
In water:
CH₃COOH (aq) ⇌ CH₃COO- (aq) + H+ (aq)
What is the formula of Sodium hydroxide (NaOH) and its dissociation in water?
Formula: NaOH
In water:
NaOH (aq) → Na+ (aq) + OH- (aq)
How does Ammonia (NH₃) act as an alkali in water?
Formula: NH₃
In water:
NH₃ (aq) + H₂O (l) ⇌ NH₄+ (aq) + OH- (aq)
What is the difference between strong and weak acids?
- Strong acids completely dissociate in water (e.g., HCl, HNO₃).
- Weak acids partially dissociate in water (e.g., CH₃COOH).
What happens during neutralization?
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)
What is the reaction between an acid and an alkali? (e.g., HCl + NaOH)
Acid + alkali → Salt + water
HCl (aq) + NaOH (aq) → NaCl (aq) + H₂O (l)
What is the reaction between an acid and a metal oxide? (e.g., HCl + CuO)
Acid + Metal oxide → Salt + water
2HCl (aq) + CuO (s) → CuCl₂ (aq) + H₂O (l)
What is the reaction between an acid and a carbonate? (e.g., H₂SO₄ + Na₂CO₃)
Acid + metal carbonate → Salt + Carbon dioxide + water
H₂SO₄ (aq) + Na₂CO₃ (aq) → Na₂SO₄ (aq) + CO₂ (g) + H₂O (l)
What are the steps for preparing a standard solution?
- Weigh the required amount of solute and transfer to a beaker - record mass of empty weighing boat, mass of weighing boat with solute and mass of weighing boat once solute is transferred to a beaker
- Dissolve the solute in a small amount of distilled water.
- Transfer to a volumetric flask - rinse the beaker to get all dissolved solute
- Add distilled water to the mark and mix by inverting volumetric flask
What is the procedure for performing an acid-base titration?
- Add a known volume of the standard solution to a conical flask using a pipette.
- Add a few drops of indicator.
- Fill the burette with the acid/unknown solution
- Slowly add unknown solution to the standard solution until the endpoint (colour change) is reached.
- Record the volume of acid used.
How do you calculate the concentration of an unknown solution using titration results?
Use the equation:
C₁V₁ = C₂V₂
Where:
- C₁, V₁ = concentration and volume of acid
- C₂, V₂ = concentration and volume of base
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?
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
