Acid-base theory concept questions and answers

  1. What is an acid according to Arrhenius theory?

    According to the Arrhenius theory, an acid is a substance that increases the concentration of hydronium ions (H₃O⁺) when dissolved in water.

  2. What is a base according to Arrhenius theory?

    According to the Arrhenius theory, a base is a substance that increases the concentration of hydroxide ions (OH⁻) when dissolved in water.

  3. What is the Bronsted-Lowry theory of acids and bases?

    The Bronsted-Lowry theory states that an acid is a proton (H⁺) donor, and a base is a proton (H⁺) acceptor.

  4. How does the Lewis theory define acids and bases?

    The Lewis theory defines an acid as a species that accepts an electron pair, and a base as a species that donates an electron pair.

  5. What is a conjugate acid-base pair?

    A conjugate acid-base pair consists of two species that differ only by the presence or absence of a proton. A conjugate acid is formed by protonation of a base, while a conjugate base is formed by deprotonation of an acid.

  6. What is an example of a conjugate acid-base pair?

    An example of a conjugate acid-base pair is NH₄⁺ (ammonium) and NH₃ (ammonia). NH₄⁺ is the conjugate acid of NH₃, and NH₃ is the conjugate base of NH₄⁺.

  7. What is the pH scale?

    The pH scale is a logarithmic scale that measures the acidity or basicity of a solution. It is defined as the negative logarithm (base 10) of the concentration of hydronium ions (H₃O⁺). A pH of 7 is neutral, values less than 7 are acidic, and values greater than 7 are basic.

  8. What is an amphoteric substance?

    An amphoteric substance is a substance that can act as both an acid and a base. For example, water can donate a proton (acting as an acid) or accept a proton (acting as a base).

  9. How is the pOH of a solution related to its pH?

    The pOH of a solution is defined as the negative logarithm (base 10) of the concentration of hydroxide ions (OH⁻). For any aqueous solution at 25°C, the sum of the pH and the pOH is always 14.

  10. What is a strong acid?

A strong acid is an acid that completely ionizes in aqueous solution, releasing all its protons into the solution. Examples include hydrochloric acid (HCl), nitric acid (HNO₃), and sulfuric acid (H₂SO₄).

  1. What is a strong base?

A strong base is a base that completely dissociates in water to produce hydroxide ions (OH⁻). Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).

  1. What is a weak acid?

A weak acid is an acid that only partially ionizes in aqueous solution, releasing only some of its protons into the solution. An example is acetic acid (CH₃COOH).

  1. What is a weak base?

A weak base is a base that only partially dissociates in water to produce hydroxide ions (OH⁻). An example is ammonia (NH₃).

  1. What is Kw, the ion product of water?

Kw, the ion product of water, is the product of the concentrations of hydronium ions (H₃O⁺) and hydroxide ions (OH⁻) in pure water. At 25°C, Kw is 1.0 x 10⁻¹⁴.

  1. What is the autoionization of water?

The autoionization of water is the process by which water undergoes a self-ionization reaction, producing hydronium (H₃O⁺) and hydroxide (OH⁻) ions: 2H₂O ⇌ H₃O⁺ + OH⁻.

  1. What are titrations used for in the context of acids and bases?

Titrations are used to determine the concentration of an unknown acid or base by neutralizing it with a solution of a base or acid of known concentration.

  1. What is an indicator in acid-base titrations?

An indicator is a compound that changes color at or near the equivalence point in an acid-base titration. The color change signals that the correct amount of acid or base has been added to neutralize the solution.

  1. What is a buffer solution?

A buffer solution is a solution that resists changes in pH when small amounts of acid or base are added or when the solution is diluted. Buffers are typically made from a weak acid and its conjugate base, or a weak base and its conjugate acid.

  1. What is the Henderson-Hasselbalch equation?

The Henderson-Hasselbalch equation is a simplified expression of the acidity constant of a weak acid or base. It is pH = pKa + log([A⁻]/[HA]), where [A⁻] is the concentration of the base and [HA] is the concentration of the acid.

  1. What is the role of water in acid-base reactions?

Water can act as an acid or a base in acid-base reactions. In the presence of a base, water acts as an acid by donating a proton to form a hydroxide ion. In the presence of an acid, water acts as a base by accepting a proton to form a hydronium ion.

Print Friendly, PDF & Email