Question 1

Toluic acid, HC₈H₇O₂, has an ionization constant with the value: K_a = 1.23 × 10^-5. Calculate the value of pK_b for the conjugate base of toluic acid.

Accepted Answer

pKb is calculated using the relation pKa + pKb = 14. Given pKa = -log(1.23 × 10^-5) = 4.91, so pKb = 14 - 4.91 = 9.09.

Question 2

The K_a of hydrocyanic acid (HCN)is 4.9 × 10^-10. What is the K_b of CN^-?

Accepted Answer

The relationship between K_a and K_b is given by K_w = K_a × K_b, where K_w = 1.0 × 10^-14. Solving for K_b gives K_b = K_w / K_a = (1.0 × 10^-14) / (4.9 × 10^-10) = 2.0 × 10^-5.

Question 3

A 0.400 M solution of an acid, HQ, has a pH = 1.301. What is the value of the ionization constant, K_a, for this acid?

Accepted Answer

The pH of 1.301 corresponds to a [H⁺] concentration of 0.050 M. Using the formula for the ionization constant, Kₐ = [H⁺][Q⁻]/[HQ], and assuming [Q⁻] = [H⁺] and [HQ] = 0.400 - 0.050, we calculate Kₐ ≈ 7.14 × 10⁻³.

Question 4

A 0.200 M solution of an acid has a pH = 1.000. What is the value of the ionization constant, K_a, for this acid?

Accepted Answer

The answer of A 0.200 M solution of an acid...

Question 5

A 0.300 M solution of an acid, HZ, has a pH = 1.301. What is the value of the ionization constant, K_a, for this acid?

Accepted Answer

The answer of A 0.300 M solution of an acid,...

Question 6

A 0.200 M solution of a weak base in water has a pH = 10.40 at 25°C. Calculate the value of K_b for this base.

Accepted Answer

The pH of 10.40 corresponds to a pOH of 3.60 (since pH + pOH = 14). The concentration of OH⁻ ions is 10^(-3.60) = 2.51 × 10⁻⁴ M. Using the formula Kb = [OH⁻]² / [Base], we get Kb = (2.51 × 10⁻⁴)² / 0.200 = 3.2 × 10⁻⁷.

Question 7

A 0.075 M solution of a weak base in water has a pH = 11.21 at 25°C. Calculate the value of K_b for this base.

Accepted Answer

The pH of 11.21 corresponds to a pOH of 2.79, giving an OH⁻ concentration of 1.62 × 10⁻³ M. Using the formula Kb = [OH⁻]² / [Base], we find Kb = (1.62 × 10⁻³)² / 0.075 = 3.6 × 10⁻⁵.

Question 8

Calculate the pH of a 0.14 M HNO₂ solution that is 5.7% ionized.

Accepted Answer

The pH is calculated using the concentration of H⁺ ions. If 5.7% of 0.14 M HNO₂ is ionized, the concentration of H⁺ is 0.14 M * 0.057 = 0.00798 M. The pH is -log(0.00798) ≈ 2.10.

Question 9

Calculate the pH of a 0.80 M HOCN solution that is 5.00% ionized.

Accepted Answer

The correct answer is A because the pH of a 0.80 M HOCN solution that is 5.00% ionized is 1.40. This can be calculated using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where pKa is the acid dissociation constant, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the acid. The pKa of HOCN is 3.52, so the pH of a 0.80 M HOCN solution that is 5.00% ionized is 1.40.

Question 10

Calculate the pH of a 0.095 M weak acid solution that is 1.9% ionized.

Accepted Answer

The concentration of H⁺ ions is 0.095 M * 0.019 = 0.001805 M. The pH is calculated as -log(0.001805) = 2.74.

Question 11

The pH of a 0.035 M weak acid solution is 3.30. What is the percent ionization for this acid?

Accepted Answer

The percent ionization is calculated using the formula: (concentration of ionized acid / initial concentration of acid) * 100%. The concentration of ionized acid can be found from the pH: [H+] = 10^(-3.30) = 5.01 x 10^(-4) M. Percent ionization = (5.01 x 10^(-4) / 0.035) * 100% ≈ 1.4%.

Question 12

A 0.100 M solution of an acid, HA, has a pH = 2.00. What is the value of the ionization constant, K_a, for this acid?

Accepted Answer

The answer of A 0.100 M solution of an acid,...

Question 13

The ionization constant, K_a, for benzoic acid, HC₇H₅O₂, is 6.28 × 10^-5. What is the pH of a 0.15 molar solution of this acid?

Accepted Answer

The pH of a weak acid solution can be calculated using the formula: pH = -log[H⁺]. For benzoic acid, the concentration of H⁺ ions can be found using the expression for Kₐ: Kₐ = [H⁺][C₇H₅O₂⁻]/[HC₇H₅O₂]. Assuming x is the concentration of H⁺ ions, Kₐ = x²/(0.15 - x). Solving for x and then calculating the pH gives approximately 2.52.

Question 14

The ionization constant, K_a, for acetic acid, HC₂H₃O₂, is 1.76 × 10^-5. What is the pH of a 0.0800 molar solution of this acid?

Accepted Answer

The pH of a weak acid solution can be calculated using the formula: pH = -log[H⁺]. For acetic acid, the concentration of H⁺ ions can be found using the formula: [H⁺] = √(Kₐ × [acid]). Substituting the given values: [H⁺] = √(1.76 × 10⁻⁵ × 0.0800) = √(1.408 × 10⁻⁶) ≈ 1.186 × 10⁻³. Therefore, pH = -log(1.186 × 10⁻³) ≈ 2.926.

Question 15

What is the pH of a 1.00 molar solution of nitrous acid? The K_a for nitrous acid is 7.1 × 10^-4.

Accepted Answer

The correct answer is A because the pH of a 1.00 molar solution of nitrous acid can be calculated using the following equation: pH = -log[H+], where [H+] is the molar concentration of hydrogen ions in the solution. The Ka for nitrous acid is 7.1 × 10-4, which means that the equilibrium constant for the dissociation of nitrous acid is 7.1 × 10-4. This means that for every 1 mole of nitrous acid that dissociates, 7.1 × 10-4 moles of hydrogen ions are produced. Therefore, the molar concentration of hydrogen ions in a 1.00 molar solution of nitrous acid is 7.1 × 10-4 M. Substituting this value into the equation for pH, we get: pH = -log(7.1 × 10-4) = 1.57.

Question 16

The ionization constant, K_b, for the weak base trimethylamine, (CH₃)₃N, is 7.4 × 10^-5. What is the pH of a 0.040 molar solution of this base?

Accepted Answer

The answer of The ionization constant, K_b, for the weak...

Question 17

The ionization constant, K_a, for dichloroacetic acid, HC₂HO₂Cl₂ , is 5.0 × 10^-2. What is the pH of a 0.15 molar solution of this acid?

Accepted Answer

To find the pH, first calculate the concentration of H⁺ ions using the formula: [H⁺] = √(Kₐ × [HA]). Here, [HA] = 0.15 M and Kₐ = 5.0 × 10⁻². So, [H⁺] = √(5.0 × 10⁻² × 0.15) = √(7.5 × 10⁻³) ≈ 0.0866 M. Then, pH = -log[H⁺] ≈ -log(0.0866) ≈ 1.19.

Question 18

Trihydroxybenzoic acid (THB)is a not-so-weak acid with an ionization constant: K_a = 2.1 × 10^-2. Calculate the [H⁺] and the pH of a 0.050 molar solution of THB.Hint: Simplified assumptions do not work in this case.

Accepted Answer

The concentration of H⁺ ions is calculated using the quadratic formula due to the relatively high ionization constant. Solving the equation gives [H⁺] = 2.4 × 10⁻² M, and the pH is calculated as -log(2.4 × 10⁻²) = 1.63.

Question 19

Dichloroacetic acid HC₂HCl₂O₂, is a not-so-weak acid with an ionization constant:K_a = 5.5 × 10^-2. Calculate the [H⁺] and the pH of a 0.100 molar solution of this acid.Hint: Simplified assumptions do not work in this case.

Accepted Answer

The ionization constant is relatively high, indicating significant ionization. Solving the quadratic equation for [H⁺] gives approximately 5.2 × 10⁻² M, leading to a pH of 1.29.

Question 20

The ionization constant, K_a, for HCN(aq)is 6.2 × 10^-10. What is the pH of a 0.10 molar solution of sodium cyanide, which contains the cyanide ion?

Accepted Answer

The answer of The ionization constant, K_a, for HCN(aq)is 6.2...

Quiz 17: Acid-Base Equilibria in Aqueous Solutions

Toluic acid, HC₈H₇O₂, has an ionization constant with the value: K_a = 1.23 × 10^-5. Calculate the value of pK_b for the conjugate base of toluic acid.

The K_a of hydrocyanic acid (HCN) is 4.9 × 10^-10. What is the K_b of CN^-?

A 0.400 M solution of an acid, HQ, has a pH = 1.301. What is the value of the ionization constant, K_a, for this acid?

A 0.200 M solution of an acid has a pH = 1.000. What is the value of the ionization constant, K_a, for this acid?

A 0.300 M solution of an acid, HZ, has a pH = 1.301. What is the value of the ionization constant, K_a, for this acid?

A 0.200 M solution of a weak base in water has a pH = 10.40 at 25°C. Calculate the value of K_b for this base.

A 0.075 M solution of a weak base in water has a pH = 11.21 at 25°C. Calculate the value of K_b for this base.

Calculate the pH of a 0.14 M HNO₂ solution that is 5.7% ionized.

Calculate the pH of a 0.80 M HOCN solution that is 5.00% ionized.

Calculate the pH of a 0.095 M weak acid solution that is 1.9% ionized.

The pH of a 0.035 M weak acid solution is 3.30. What is the percent ionization for this acid?

A 0.100 M solution of an acid, HA, has a pH = 2.00. What is the value of the ionization constant, K_a, for this acid?

The ionization constant, K_a, for benzoic acid, HC₇H₅O₂, is 6.28 × 10^-5. What is the pH of a 0.15 molar solution of this acid?

The ionization constant, K_a, for acetic acid, HC₂H₃O₂, is 1.76 × 10^-5. What is the pH of a 0.0800 molar solution of this acid?

What is the pH of a 1.00 molar solution of nitrous acid? The K_a for nitrous acid is 7.1 × 10^-4.

The ionization constant, K_b, for the weak base trimethylamine, (CH₃) ₃N, is 7.4 × 10^-5. What is the pH of a 0.040 molar solution of this base?

The ionization constant, K_a, for dichloroacetic acid, HC₂HO₂Cl₂ , is 5.0 × 10^-2. What is the pH of a 0.15 molar solution of this acid?

Trihydroxybenzoic acid (THB) is a not-so-weak acid with an ionization constant: K_a = 2.1 × 10^-2. Calculate the [H⁺] and the pH of a 0.050 molar solution of THB.Hint: Simplified assumptions do not work in this case.

Dichloroacetic acid HC₂HCl₂O₂, is a not-so-weak acid with an ionization constant:K_a = 5.5 × 10^-2. Calculate the [H⁺] and the pH of a 0.100 molar solution of this acid.Hint: Simplified assumptions do not work in this case.

The ionization constant, K_a, for HCN(aq) is 6.2 × 10^-10. What is the pH of a 0.10 molar solution of sodium cyanide, which contains the cyanide ion?

Quiz 17: Acid-Base Equilibria in Aqueous Solutions

Toluic acid, HC8H7O2, has an ionization constant with the value: Ka = 1.23 × 10-5. Calculate the value of pKb for the conjugate base of toluic acid.

The Ka of hydrocyanic acid (HCN) is 4.9 × 10-10. What is the Kb of CN-?

A 0.400 M solution of an acid, HQ, has a pH = 1.301. What is the value of the ionization constant, Ka, for this acid?

A 0.200 M solution of an acid has a pH = 1.000. What is the value of the ionization constant, Ka, for this acid?

A 0.300 M solution of an acid, HZ, has a pH = 1.301. What is the value of the ionization constant, Ka, for this acid?

A 0.200 M solution of a weak base in water has a pH = 10.40 at 25°C. Calculate the value of Kb for this base.

A 0.075 M solution of a weak base in water has a pH = 11.21 at 25°C. Calculate the value of Kb for this base.

Calculate the pH of a 0.14 M HNO2 solution that is 5.7% ionized.

Calculate the pH of a 0.80 M HOCN solution that is 5.00% ionized.

Calculate the pH of a 0.095 M weak acid solution that is 1.9% ionized.

The pH of a 0.035 M weak acid solution is 3.30. What is the percent ionization for this acid?

A 0.100 M solution of an acid, HA, has a pH = 2.00. What is the value of the ionization constant, Ka, for this acid?

The ionization constant, Ka, for benzoic acid, HC7H5O2, is 6.28 × 10-5. What is the pH of a 0.15 molar solution of this acid?

The ionization constant, Ka, for acetic acid, HC2H3O2, is 1.76 × 10-5. What is the pH of a 0.0800 molar solution of this acid?

What is the pH of a 1.00 molar solution of nitrous acid? The Ka for nitrous acid is 7.1 × 10-4.

The ionization constant, Kb, for the weak base trimethylamine, (CH3) 3N, is 7.4 × 10-5. What is the pH of a 0.040 molar solution of this base?

The ionization constant, Ka, for dichloroacetic acid, HC2HO2Cl2 , is 5.0 × 10-2. What is the pH of a 0.15 molar solution of this acid?

Trihydroxybenzoic acid (THB) is a not-so-weak acid with an ionization constant: Ka = 2.1 × 10-2. Calculate the [H+] and the pH of a 0.050 molar solution of THB.Hint: Simplified assumptions do not work in this case.

Dichloroacetic acid HC2HCl2O2, is a not-so-weak acid with an ionization constant:Ka = 5.5 × 10-2. Calculate the [H+] and the pH of a 0.100 molar solution of this acid.Hint: Simplified assumptions do not work in this case.

The ionization constant, Ka, for HCN(aq) is 6.2 × 10-10. What is the pH of a 0.10 molar solution of sodium cyanide, which contains the cyanide ion?

Toluic acid, HC₈H₇O₂, has an ionization constant with the value: K_a = 1.23 × 10^-5. Calculate the value of pK_b for the conjugate base of toluic acid.

The K_a of hydrocyanic acid (HCN) is 4.9 × 10^-10. What is the K_b of CN^-?

A 0.400 M solution of an acid, HQ, has a pH = 1.301. What is the value of the ionization constant, K_a, for this acid?

A 0.200 M solution of an acid has a pH = 1.000. What is the value of the ionization constant, K_a, for this acid?

A 0.300 M solution of an acid, HZ, has a pH = 1.301. What is the value of the ionization constant, K_a, for this acid?

A 0.200 M solution of a weak base in water has a pH = 10.40 at 25°C. Calculate the value of K_b for this base.

A 0.075 M solution of a weak base in water has a pH = 11.21 at 25°C. Calculate the value of K_b for this base.

Calculate the pH of a 0.14 M HNO₂ solution that is 5.7% ionized.

A 0.100 M solution of an acid, HA, has a pH = 2.00. What is the value of the ionization constant, K_a, for this acid?

The ionization constant, K_a, for benzoic acid, HC₇H₅O₂, is 6.28 × 10^-5. What is the pH of a 0.15 molar solution of this acid?

The ionization constant, K_a, for acetic acid, HC₂H₃O₂, is 1.76 × 10^-5. What is the pH of a 0.0800 molar solution of this acid?

What is the pH of a 1.00 molar solution of nitrous acid? The K_a for nitrous acid is 7.1 × 10^-4.

The ionization constant, K_b, for the weak base trimethylamine, (CH₃) ₃N, is 7.4 × 10^-5. What is the pH of a 0.040 molar solution of this base?

The ionization constant, K_a, for dichloroacetic acid, HC₂HO₂Cl₂ , is 5.0 × 10^-2. What is the pH of a 0.15 molar solution of this acid?

Trihydroxybenzoic acid (THB) is a not-so-weak acid with an ionization constant: K_a = 2.1 × 10^-2. Calculate the [H⁺] and the pH of a 0.050 molar solution of THB.Hint: Simplified assumptions do not work in this case.

Dichloroacetic acid HC₂HCl₂O₂, is a not-so-weak acid with an ionization constant:K_a = 5.5 × 10^-2. Calculate the [H⁺] and the pH of a 0.100 molar solution of this acid.Hint: Simplified assumptions do not work in this case.

The ionization constant, K_a, for HCN(aq) is 6.2 × 10^-10. What is the pH of a 0.10 molar solution of sodium cyanide, which contains the cyanide ion?