Acids and Bases Equations

In the reaction H₂C₂O₄(aq) + CH₃NH₂(aq) <=> HC₂O₄⁻(aq) + CH₃NH₃⁺(aq), which is a conjugate acid-base pair?

• H₂C₂O₄(aq) and CH₃NH₂(aq)

• H₂C₂O₄(aq) and CH₃NH₃⁺(aq)

• CH₃NH₂(aq) and CH₃NH₃⁺(aq)

• HC₂O₄⁻(aq) and CH₃NH₃⁺(aq)

Answer explanation

In the reaction, CH₃NH₂ acts as a base and accepts a proton to form CH₃NH₃⁺, its conjugate acid. Thus, CH₃NH₂ and CH₃NH₃⁺ are a conjugate acid-base pair, making this the correct choice.

For the reaction: HClO₄(aq) + H₂O(l) → H₃O⁺(aq) + ClO₄⁻(aq) Which is a conjugate acid-base pair?

• HClO₄(aq) and H₂O(l)

• HClO₄(aq) and ClO₄⁻(aq)

• H₃O⁺(aq) and ClO₄⁻(aq)

• HClO₄(aq) and H₃O⁺(aq)

Answer explanation

In the reaction, HClO₄ donates a proton to H₂O, forming H₃O⁺ and ClO₄⁻. HClO₄ is the acid and ClO₄⁻ is its conjugate base, making HClO₄ and ClO₄⁻ the correct conjugate acid-base pair.

In the reaction HF(aq) + H₂O(l) ⇌ H₃O⁺(aq) + F⁻(aq), which is a conjugate acid-base pair?

• F⁻(aq) and H₂O(l)

• H₃O⁺(aq) and HF(aq)

• HF(aq) and F⁻(aq)

• HF(aq) and H₂O(l)

Answer explanation

In the reaction, HF donates a proton to H₂O, forming H₃O⁺ and F⁻. HF is the acid and F⁻ is its conjugate base, making HF and F⁻ a conjugate acid-base pair.

If [OH-] = 6.4 × 10⁻⁵ M, what is [H₃O⁺]?

Answer explanation

To find [H₃O⁺], use the relation [H₃O⁺] = 1.0 × 10⁻¹⁴ / [OH⁻]. Substituting [OH⁻] = 6.4 × 10⁻⁵ M gives [H₃O⁺] = 1.56 × 10⁻¹⁰ M.

What is the pH of a solution with [OH^-] = 1.7 x 10⁻⁵ M?

Answer explanation

To find pH from [OH-], use pOH = -log[OH-]. Here, pOH = -log(1.7 x 10⁻⁵) ≈ 4.77. Then, pH = 14 - pOH = 14 - 4.77 = 9.23. Thus, the pH of the solution is approximately 9.23.

What is the pH of a solution with [H₃O⁺] = 0.0040 M?

Answer explanation

To find the pH, use the formula pH = -log[H₃O⁺]. For [H₃O⁺] = 0.0040 M, pH = -log(0.0040) ≈ 2.40. Thus, the pH of the solution is approximately 2.40.

A solution with pH 6.5 at 25 °C

• is neutral.

• is acidic.

• is basic.

• could be neutral, basic, or acidic.

Answer explanation

A solution with pH 4.0 is acidic because pH values below 7 indicate acidity. Neutral solutions have a pH of 7, while values above 7 are basic.

What is the pH of a solution with [H₃O⁺] = 0.0001 M?

Answer explanation

To find the pH, use the formula pH = -log[H₃O⁺]. For [H₃O⁺] = 0.0001 M, pH = -log(0.0001) = 4. Therefore, the pH of the solution is 4.

What is the hydroxide ion concentration, [HO⁻], in a solution with pH 6.0?

Answer explanation

To find [HO⁻], use the formula [HO⁻] = 10^(-14) / [H⁺]. With pH 6.0, [H⁺] = 10^(-6). Thus, [HO⁻] = 10^(-14) / 10^(-6) = 10^(-8) M.

What is the [OH⁻] in a solution with a pOH of 8.0?

Answer explanation

To find [OH⁻], use the formula [OH⁻] = 10^(-pOH). For pOH = 8.0, [OH⁻] = 10^(-8.0) = 1.0 x 10^(-8) M. Thus, the hydroxide ion concentration is 1.0 x 10^(-8) M.