Question 1

What is the equilibrium hydronium ion concentration of an initially 4.5 M solution of hypoiodous acid,HOI,at 25°C (K_a = )?

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Question 2

What is the equilibrium pH of an initially 0.73 M solution of the monoprotic acid benzoic acid at 25°C (K_a = )?

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Question 3

What is the equilibrium percent ionization of an initially 0.32 M solution of the monoprotic acid valeric acid,HC₅H₉O₂,at 25°C (K_a = )?

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Question 4

In a 0.20 M solution of a diprotic acid H₂A (Ka₁ = 1.3 × 10^-5 and Ka₂ = 2.7 × 10^-10 at 25°C),what is the equilibrium concentration of A^2-?

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Question 5

What is K_a for a weak monoprotic acid if a 0.020 M solution of the acid has a pH of 3.28 at 25°C?

Accepted Answer

The pH of a weak monoprotic acid can be calculated using the following equation: pH = 0.5(pKa - log[H+]) where pKa is the acid dissociation constant and [H+] is the hydrogen ion concentration. To find pKa, we need to rearrange the equation to: pKa = pH + log[H+]/0.5 We know that the pH of the solution is 3.28, so we can substitute that in: pKa = 3.28 + log[H+]/0.5 We also know that the concentration of the acid is 0.020 M, so we can use the dissociation equation to calculate [H+]: Ka = [H+][A-]/[HA] We can assume that since the acid is weak, most of the acid remains undissociated, so we can say that [HA] ≈ [acid] = 0.020 M. We also know that [A-] ≈ [H+], since the acid dissociates to form one H+ ion and one A- ion. So we can say that [H+] ≈ 0.020 M. Now we can substitute [H+] into the equation for pKa: pKa = 3.28 + log(0.020)/0.5 pKa = 3.28 + 0.70 pKa = 3.98 Finally, we can use the equation for Ka to find K_a: Ka = 10-_a 10-_a = 10-^-4 - this is because the question asks for the answer in scientific notation (i.e. with 1 significant figure). Solving for _a: _a = ^-4 _a = 1.4 × 10^-5 Therefore, the answer is B.

Question 6

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH₂CH₂COOH (Ka₁ = 2.9 × 10^-5,Ka₂ = 5.3 × 10^-6),which species is present in the lowest concentration?

Accepted Answer

The fully deprotonated form of the acid, (-OOCCH2CH2COO-), is present in the lowest concentration because it requires the removal of both protons, which is less likely due to the relatively low Ka2 value.

Question 7

What is the pH of a solution prepared by dissolving 0.0163 mol of chloroacetic acid,(HC₂H₂O₂Cl)in 1.30 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

Accepted Answer

First, we need to write the equation for the dissociation of chloroacetic acid, which is: HC₂H₂O₂Cl ⇌ H+ + C₂H₂O2- + Cl- Then, we can set up an ICE table to calculate the concentration of H+ ions: HC₂H₂O₂Cl ⇌ H+ + C₂H₂O2- + Cl- I 0.0163 mol 0 0 C - x + x + x E 0.0163 - x x x The equilibrium constant expression for this reaction is: K_a = [H+][C₂H₂O2-] / [HC₂H₂O₂Cl] We are given that K_a = 1.4 × 10^-3 and the concentration of the acid (HC₂H₂O₂Cl) is 0.0163 mol / 1.30 L = 0.0125 M. Substituting the equilibrium concentrations into the expression for K_a gives: 1.4 × 10^-3 = x^2 / (0.0125 - x) Since the value of x is expected to be small compared to 0.0125 (due to the small value of K_a), we can simplify the expression: 1.4 × 10^-3 ≈ x^2 / 0.0125 Solving for x gives: x = 3.3 × 10^-3 M Therefore, the concentration of H+ ions in the solution is: [H+] = 3.3 × 10^-3 M Taking the negative logarithm of this value gives the pH: pH = -log[H+] = -log(3.3 × 10^-3) ≈ 2.45 So the answer is (B).

Question 8

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH₂CH₂COOH (Ka₁ = 2.9 × 10^-5,Ka₂ = 5.3 × 10^-6),which species is present in the highest concentration?

Accepted Answer

In a 0.01 M solution of 1,4-butanedicarboxylic acid, the species that will be present in the highest concentration is the undissociated form, HOOCCH₂CH₂COOH(aq), because it has the highest initial molality and only a small fraction will dissociate due to its low Ka values. None of the other species listed have a higher concentration than the undissociated form.

Question 9

What is the equilibrium pH of an initially 4.4 M solution of hypochlorous acid,HOCl,at 25°C (K_a = )?

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Question 10

Carbonic acid,H₂CO₃,is a weak diprotic acid.In a 0.1 M solution of the acid,which of the following species is present in the largest amount?

Accepted Answer

Carbonic acid (H2CO3) is a weak diprotic acid, meaning it can donate two protons (H+). In a 0.1 M solution, the majority of the acid remains in its original form, H2CO3, because it does not dissociate completely.

Question 11

Phosphoric acid,H₃PO₄,will undergo three successive ionization reactions to varying extents in water.What is the balanced equilibrium identified as K_a3?

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Question 12

For a 0.05 M H₂SO₃ solution,which of the following relationships is true?

Accepted Answer

EThe correct answers are based on the principle of chemical equilibrium and the dissociation of weak acids in solution. For a weak acid like HS^-, it partially dissociates in solution into H^+ and S^2-. Therefore, the concentration of the undissociated acid ([HS^-]) will be greater than the concentration of its dissociated form ([H^+] and [S^2-]), making options D and E correct.

Question 13

A 8.42-g sample of homogentisic acid,a weak organic acid having K_a = 4.0 × 10^-5,is dissolved in 35.00 mL of water and its pH is measured to be 2.122.What is the molar mass of homogentisic acid?

Accepted Answer

The molar mass of homogentisic acid can be calculated by first determining the concentration of H+ ions in the solution from the given pH, then using the dissociation constant (Ka) to find the concentration of the acid, and finally using the mass and concentration to find the molar mass. The pH of 2.122 corresponds to a [H+] concentration of 10^-2.122 M. Given the Ka and the initial concentration, we can set up an equilibrium expression to solve for the concentration of the acid. However, since the pH and the concentration of H+ ions directly give us the amount of acid that has dissociated, and knowing the volume of the solution allows us to calculate the moles of acid, we can directly calculate the molar mass. The molar mass is found by dividing the mass of the acid sample by the moles of acid, which gives us 168 g/mol as the correct answer.

Question 14

What is the equilibrium concentration of chloroacetic acid,HC₂H₂O₂Cl,in a solution prepared by dissolving 0.0271 mol of HC₂H₂O₂Cl in 1.50 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

Accepted Answer

The correct answer is A because the equilibrium concentration of chloroacetic acid can be calculated using the dissociation constant (K_a) and the initial concentration of the acid. The K_a expression for chloroacetic acid is:K_a = [H+][C₂H₂O₂Cl^-]/[HC₂H₂O₂Cl]At equilibrium, the concentration of the products ([H⁺] and [C₂H₂O₂Cl^-]) will be equal to x, and the concentration of the reactant ([HC₂H₂O₂Cl]) will be equal to (0.0271 mol/1.50 L) - x. Substituting these values into the K_a expression and solving for x gives:1.4 × 10^-3 = x²/(0.0271 mol/1.50 L) - xSolving for x gives x = 4.38 × 10^-3 M. Therefore, the equilibrium concentration of chloroacetic acid is (0.0271 mol/1.50 L) - x = 0.0227 mol/1.50 L = 4.38 × 10^-3 M.

Question 15

Which of the following represents the usual relationship of acid-ionization constants for a triprotic acid?

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Question 16

It is safe to make the simplifying assumption that x can be neglected in the denominator of the equilibrium equation when

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Question 17

What is the percent ionization of a solution prepared by dissolving 0.0175 mol of chloroacetic acid,(HC₂H₂O₂Cl)in 1.30 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

Accepted Answer

First, we need to write the equation for the dissociation of chloroacetic acid: HC₂H₂O₂Cl (aq) + H2O (l) ⇌ H3O+ (aq) + C₂H₂O- (aq) + Cl- (aq) The equilibrium constant expression is: K_a = [H3O+] [C₂H₂O-] / [HC₂H₂O₂Cl] We know the equilibrium constant (K_a = 1.4 × 10^-3) and the initial concentration of chloroacetic acid (0.0175 mol/1.30 L = 0.0135 M). We can assume that the percent ionization is small, so we can simplify the equilibrium expression to: K_a ≈ [H3O+] [C₂H₂O-] / 0.0135 We can also assume that the change in concentration of chloroacetic acid is negligible compared to its initial concentration, so we can write: [H3O+] ≈ [C₂H₂O-] Substituting these values into the equilibrium expression, we get: K_a ≈ [H3O+]2 / 0.0135 Solving for [H3O+], we get: [H3O+] ≈sqrt(K_a x 0.0135) = 6.97x10^-4 M The percent ionization is: % ionization = [H3O+] / 0.0135 x 100% ≈ 27% Therefore, the correct answer is C).

Question 18

For a 0.10 M solution of glutaric acid,HO₂C(CH₂)₃CO₂H (Ka₁ = 4.6 × 10^-5,Ka₂ = 3.9 × 10^-6),rank the following species in order of increasing equilibrium concentration.

Accepted Answer

Glutaric acid is a diprotic acid, meaning it can donate two protons. The species are ranked based on their formation in the dissociation process. The fully protonated form (H2A) has the highest concentration initially. As it donates protons, the concentration of the deprotonated forms (HA- and A2-) increases, but they will always be less than the fully protonated form due to the equilibrium favoring the left side for weak acids. The concentration of OH- (hydroxide ion) is the lowest because it is not directly produced by the dissociation of glutaric acid but rather comes from the autoionization of water, which is minimal compared to the concentrations of the acid and its conjugate bases.

Question 19

What is the hydronium-ion concentration of a 0.30 M solution of HCN (K_a = 4.9 × 10^-10)at 25°C?

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Question 20

The equilibrium hydronium ion concentration of an initially 0.655 M solution of a monoprotic weak acid is  M.The acid dissociation constant is 
At 25°C.What is the pH of this solution?

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Quiz 16: Acid-Base Equilibria

What is the equilibrium hydronium ion concentration of an initially 4.5 M solution of hypoiodous acid,HOI,at 25°C (K_a = ) ?

What is the equilibrium pH of an initially 0.73 M solution of the monoprotic acid benzoic acid at 25°C (K_a = ) ?

What is the equilibrium percent ionization of an initially 0.32 M solution of the monoprotic acid valeric acid,HC₅H₉O₂,at 25°C (K_a = ) ?

In a 0.20 M solution of a diprotic acid H₂A (Ka₁ = 1.3 × 10^-5 and Ka₂ = 2.7 × 10^-10 at 25°C) ,what is the equilibrium concentration of A^2-?

What is K_a for a weak monoprotic acid if a 0.020 M solution of the acid has a pH of 3.28 at 25°C?

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH₂CH₂COOH (Ka₁ = 2.9 × 10^-5,Ka₂ = 5.3 × 10^-6) ,which species is present in the lowest concentration?

What is the pH of a solution prepared by dissolving 0.0163 mol of chloroacetic acid,(HC₂H₂O₂Cl) in 1.30 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH₂CH₂COOH (Ka₁ = 2.9 × 10^-5,Ka₂ = 5.3 × 10^-6) ,which species is present in the highest concentration?

What is the equilibrium pH of an initially 4.4 M solution of hypochlorous acid,HOCl,at 25°C (K_a = ) ?

Carbonic acid,H₂CO₃,is a weak diprotic acid.In a 0.1 M solution of the acid,which of the following species is present in the largest amount?

Phosphoric acid,H₃PO₄,will undergo three successive ionization reactions to varying extents in water.What is the balanced equilibrium identified as K_a3?

For a 0.05 M H₂SO₃ solution,which of the following relationships is true?

A 8.42-g sample of homogentisic acid,a weak organic acid having K_a = 4.0 × 10^-5,is dissolved in 35.00 mL of water and its pH is measured to be 2.122.What is the molar mass of homogentisic acid?

What is the equilibrium concentration of chloroacetic acid,HC₂H₂O₂Cl,in a solution prepared by dissolving 0.0271 mol of HC₂H₂O₂Cl in 1.50 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

Which of the following represents the usual relationship of acid-ionization constants for a triprotic acid?

It is safe to make the simplifying assumption that x can be neglected in the denominator of the equilibrium equation when

What is the percent ionization of a solution prepared by dissolving 0.0175 mol of chloroacetic acid,(HC₂H₂O₂Cl) in 1.30 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

For a 0.10 M solution of glutaric acid,HO₂C(CH₂) ₃CO₂H (Ka₁ = 4.6 × 10^-5,Ka₂ = 3.9 × 10^-6) ,rank the following species in order of increasing equilibrium concentration.

What is the hydronium-ion concentration of a 0.30 M solution of HCN (K_a = 4.9 × 10^-10) at 25°C?

The equilibrium hydronium ion concentration of an initially 0.655 M solution of a monoprotic weak acid is M.The acid dissociation constant is At 25°C.What is the pH of this solution?

Quiz 16: Acid-Base Equilibria

What is the equilibrium hydronium ion concentration of an initially 4.5 M solution of hypoiodous acid,HOI,at 25°C (Ka = ) ?

What is the equilibrium pH of an initially 0.73 M solution of the monoprotic acid benzoic acid at 25°C (Ka = ) ?

What is the equilibrium percent ionization of an initially 0.32 M solution of the monoprotic acid valeric acid,HC5H9O2,at 25°C (Ka = ) ?

In a 0.20 M solution of a diprotic acid H2A (Ka1 = 1.3 × 10-5 and Ka2 = 2.7 × 10-10 at 25°C) ,what is the equilibrium concentration of A2-?

What is Ka for a weak monoprotic acid if a 0.020 M solution of the acid has a pH of 3.28 at 25°C?

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH2CH2COOH (Ka1 = 2.9 × 10-5,Ka2 = 5.3 × 10-6) ,which species is present in the lowest concentration?

What is the pH of a solution prepared by dissolving 0.0163 mol of chloroacetic acid,(HC2H2O2Cl) in 1.30 L of water? For chloroacetic acid,Ka = 1.4 × 10-3.

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH2CH2COOH (Ka1 = 2.9 × 10-5,Ka2 = 5.3 × 10-6) ,which species is present in the highest concentration?

What is the equilibrium pH of an initially 4.4 M solution of hypochlorous acid,HOCl,at 25°C (Ka = ) ?

Carbonic acid,H2CO3,is a weak diprotic acid.In a 0.1 M solution of the acid,which of the following species is present in the largest amount?

Phosphoric acid,H3PO4,will undergo three successive ionization reactions to varying extents in water.What is the balanced equilibrium identified as Ka3?

For a 0.05 M H2SO3 solution,which of the following relationships is true?

A 8.42-g sample of homogentisic acid,a weak organic acid having Ka = 4.0 × 10-5,is dissolved in 35.00 mL of water and its pH is measured to be 2.122.What is the molar mass of homogentisic acid?

What is the equilibrium concentration of chloroacetic acid,HC2H2O2Cl,in a solution prepared by dissolving 0.0271 mol of HC2H2O2Cl in 1.50 L of water? For chloroacetic acid,Ka = 1.4 × 10-3.

Which of the following represents the usual relationship of acid-ionization constants for a triprotic acid?

It is safe to make the simplifying assumption that x can be neglected in the denominator of the equilibrium equation when

What is the percent ionization of a solution prepared by dissolving 0.0175 mol of chloroacetic acid,(HC2H2O2Cl) in 1.30 L of water? For chloroacetic acid,Ka = 1.4 × 10-3.

For a 0.10 M solution of glutaric acid,HO2C(CH2) 3CO2H (Ka1 = 4.6 × 10-5,Ka2 = 3.9 × 10-6) ,rank the following species in order of increasing equilibrium concentration.

What is the hydronium-ion concentration of a 0.30 M solution of HCN (Ka = 4.9 × 10-10) at 25°C?

The equilibrium hydronium ion concentration of an initially 0.655 M solution of a monoprotic weak acid is M.The acid dissociation constant is At 25°C.What is the pH of this solution?

What is the equilibrium hydronium ion concentration of an initially 4.5 M solution of hypoiodous acid,HOI,at 25°C (K_a = ) ?

What is the equilibrium pH of an initially 0.73 M solution of the monoprotic acid benzoic acid at 25°C (K_a = ) ?

What is the equilibrium percent ionization of an initially 0.32 M solution of the monoprotic acid valeric acid,HC₅H₉O₂,at 25°C (K_a = ) ?

In a 0.20 M solution of a diprotic acid H₂A (Ka₁ = 1.3 × 10^-5 and Ka₂ = 2.7 × 10^-10 at 25°C) ,what is the equilibrium concentration of A^2-?

What is K_a for a weak monoprotic acid if a 0.020 M solution of the acid has a pH of 3.28 at 25°C?

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH₂CH₂COOH (Ka₁ = 2.9 × 10^-5,Ka₂ = 5.3 × 10^-6) ,which species is present in the lowest concentration?

What is the pH of a solution prepared by dissolving 0.0163 mol of chloroacetic acid,(HC₂H₂O₂Cl) in 1.30 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

In a 0.01 M solution of 1,4-butanedicarboxylic acid,HOOCCH₂CH₂COOH (Ka₁ = 2.9 × 10^-5,Ka₂ = 5.3 × 10^-6) ,which species is present in the highest concentration?

What is the equilibrium pH of an initially 4.4 M solution of hypochlorous acid,HOCl,at 25°C (K_a = ) ?

Carbonic acid,H₂CO₃,is a weak diprotic acid.In a 0.1 M solution of the acid,which of the following species is present in the largest amount?

Phosphoric acid,H₃PO₄,will undergo three successive ionization reactions to varying extents in water.What is the balanced equilibrium identified as K_a3?

For a 0.05 M H₂SO₃ solution,which of the following relationships is true?

A 8.42-g sample of homogentisic acid,a weak organic acid having K_a = 4.0 × 10^-5,is dissolved in 35.00 mL of water and its pH is measured to be 2.122.What is the molar mass of homogentisic acid?

What is the equilibrium concentration of chloroacetic acid,HC₂H₂O₂Cl,in a solution prepared by dissolving 0.0271 mol of HC₂H₂O₂Cl in 1.50 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

What is the percent ionization of a solution prepared by dissolving 0.0175 mol of chloroacetic acid,(HC₂H₂O₂Cl) in 1.30 L of water? For chloroacetic acid,K_a = 1.4 × 10^-3.

For a 0.10 M solution of glutaric acid,HO₂C(CH₂) ₃CO₂H (Ka₁ = 4.6 × 10^-5,Ka₂ = 3.9 × 10^-6) ,rank the following species in order of increasing equilibrium concentration.

What is the hydronium-ion concentration of a 0.30 M solution of HCN (K_a = 4.9 × 10^-10) at 25°C?