Strong Acids & Bases

Related Examples and Practice Problems

Additional Worked Out Examples/ Practice

  • Identifying classification types: Differentiation between elements, compounds or mixtures and homogeneous and heterogenous mixtures

  • Separation techniques: Selected and explaining limitation of appropriate separation

  • Relating Properties to Composition: Predicting classification based on descriptive properties

Topic Summary & Highlights
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Core Concept

Strong Acids: Acids that completely dissociate into their ions in aqueous solution.

  • Example: HCl dissociates completely into H^+ and Cl^−. HCl \rightarrow H^+ + Cl^-HCl→H++Cl−

Strong Bases: Bases that completely dissociate into their ions in aqueous solution.

  • Example: NaOH dissociates completely into Na^+ and OH^−. $NaOH \rightarrow Na^+ + OH^-$

Practice Tips

  • Strong acids and bases dissociate completely in water, resulting in high ion concentrations.

  • The pH of strong acids is very low (≈0−1), while the pH of strong bases is very high (≈13−14).

  • Memorize common examples of strong acids and bases to identify them easily in chemical reactions.

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Key Properties of Strong Acids and Bases

Strong Acids:

  • Complete Ionization: Strong acids release all of their hydrogen ions ($H^+$) into the solution.

  • High Conductivity: Due to complete dissociation, they produce a high concentration of ions, making the solution a good conductor of electricity.

  • High Reactivity: Strong acids react vigorously with metals, bases, and other compounds.

Strong Bases:

  • Complete Dissociation: Strong bases release all of their hydroxide ions ($OH^−$) into the solution.

  • High Conductivity: The high concentration of ions results in excellent electrical conductivity.

  • High Reactivity: Strong bases react strongly with acids, amphiprotic substances, and organic compounds (e.g., saponification).

Particle Level Diagram

Strong Acid

What the Diagram Shows:

  • In the particle-level representation of a strong acid (e.g., HCl), you will see:

    • A mixture of free ions: H3O+\text{H}_3\text{O}^+H3​O+ (or H+\text{H}^+H+) and the conjugate base (e.g., Cl−\text{Cl}^-Cl−).

    • No intact acid molecules because they have all dissociated.

  • The solution is highly ionic, with a large concentration of H3O+\text{H}_3\text{O}^+H3​O+, which makes it highly conductive.

Weak Acid

What the Diagram Shows:

  • In the particle-level representation of a weak acid (e.g., CH₃COOH):

    • A mix of intact acid molecules and a few dissociated ions (H3O+\text{H}_3\text{O}^+H3​O+ and CH3COO−\text{CH}_3\text{COO}^-CH3​COO−).

    • The majority of particles are undissociated acid molecules.

    • The solution has a much lower concentration of ions compared to a strong acid, making it less conductive.

List of Strong Acids and Bases

There are 6 Strong Acids

Acid Formula
Hydrochloric acid HCl
Nitric acid HNO3
Sulfuric acid H2SO4
Perchloric acid HClO4
Hydrobromic acid HBr
Hydroiodic acid HI

It is common that students are expected to MEMORIZE the strong acids. (Double check with your teacher.) Here is a way that can help you memorize:

"So I Bring No Clean Clothes"

Where each word corresponds to one of the strong acids:

  • So → H₂SO₄ (Sulfuric acid)

  • I → HI (Hydroiodic acid)

  • Bring → HBr (Hydrobromic acid)

  • No → HNO₃ (Nitric acid)

  • Clean → HCl (Hydrochloric acid)

  • Clothes → HClO₄ (Perchloric acid)

Strong Bases (Group I & II hydroxides)

The common ones are below:

Base Formula
Sodium hydroxide NaOH
Potassium hydroxide KOH
Calcium hydroxide Ca(OH)2
Barium hydroxide Ba(OH)2
Lithium hydroxide LiOH

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