Acids
General Acid equation
HA + H₂O ⇌ H₃O⁺ + A⁻
General Base equation
B + H₂O ⇌ OH⁻ + BH⁺
Q: Predict whether the solution of KCN is acidic, basic, or neutral, and explain why.
A: What is basic, because CN⁻ is the conjugate base of the weak acid HCN.
What makes up a Buffer solution
Either a weak base and its conjugate acid, or weak acid and its conjugate base.
What are the strong bases
Group 1 (alkali metal hydroxides)
Group 2 (alkaline earth hydroxides)(only if the concentration of the base is less than 0.1 M)
What are the strong bases
HBr – hydrobromic acid
HI – hydroiodic acid
HCl – hydrochloric acid
HNO₃ – nitric acid
H₂SO₄ – sulfuric acid (first proton only is strong)
HClO₃ HClO₄ – chloric acid & perchloric acid
What is the point of a buffer?
They resist change in pH. Especially when strong acid or base is added to it.
Q: A solution contains 0.10 M NaHCO₃. This salt can act as both an acid and a base. Predict whether the solution is acidic, basic, or neutral, and justify.
Ka₁ (for H₂CO₃) = 4.3 × 10⁻⁷
Ka₂ (for HCO₃⁻) = 4.8 × 10⁻¹¹
A: Slightly basic, because HCO₃⁻ has both Ka (acidic) and Kb (basic) behavior, but Kb > Ka.
Q: The Ka for HF is 6.8×10⁻⁴. Calculate the pH of 0.10 M NaF.
→ pH ≈ 8.08