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Assessment: Acid-Base Reactions

Answer every question, then submit to see your score and which topics to review.

Part A — Concept Questions

How does Brønsted–Lowry theory define an acid?

Medium

A very dilute solution of hydrochloric acid is prepared. Is it still classified as a "strong" acid?

Medium

Part B — Formula & Application

A solution has [H⁺] = 1.0 × 10⁻⁵ mol/L. Find its pH.

Medium

A solution has [H⁺] = 1.0 × 10⁻⁶ mol/L. What is [OH⁻] at 25°C?

Medium

Part C — Problem Solving

A weak acid has Ka = 9.0 × 10⁻⁶ and a starting concentration of 0.40 mol/L. Estimate [H⁺] (mol/L), assuming the ionised amount is small compared to 0.40.

Hard
mol/L

A buffer has pKa = 4.74, with [A⁻] = 0.10 mol/L and [HA] = 0.20 mol/L. Find the pH (log₁₀0.5 ≈ −0.30).

Hard

Part D — Real-Life Application

Ammonium chloride (NH₄Cl), formed from a weak base (NH₃) and a strong acid (HCl), is dissolved in water. Is the resulting solution acidic, basic, or neutral?

Medium

Part E — Challenge

A buffer made of acetic acid and sodium acetate has a small amount of strong acid added. What happens?

Hard

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