Question 1

What is the pH of 0.025 M (CH₃)₃N(aq)(K_b = 6.5 * 10^-5)? A)11.91 B)12.40 C)11.11 D)8.29 E)9.81

Accepted Answer

The answer of What is the pH of 0.025 M...

Question 2

Which of the following 0.10 M aqueous solutions gives the lowest pH? A)CCl₃COOH (pK_a = 0.52) B)Because all are acids,the pH is the same for all solutions. C)HF (pK_a = 3.45) D)CH₃COOH (pK_a = 4.75) E)H₃PO₄ (pK_a1 = 2.12)

Accepted Answer

The acid with the lowest pKa value will dissociate the most in water, thus releasing more H+ ions and resulting in the lowest pH. CCl3COOH has the lowest pKa value (0.52) among the options, indicating it is the strongest acid listed and will therefore give the lowest pH.

Question 3

For a 0.10 M solution of a weak acid,HA,with pK_a = 10,which of the following is true? A)[HA] $\cong$ 0 B)[HA] = [A^-] C)[HA] = [H₃O⁺] D)[HA] = K_a E)[HA] $\neq$[H₃O⁺]

Accepted Answer

For a weak acid with a high pKa value like 10, the acid does not dissociate significantly, so [HA] remains much greater than [H3O+].

Question 4

In liquid ammonia,the base B is a strong base if it is a stronger proton acceptor than NH₂^-.

Accepted Answer

In liquid ammonia, the base that is a stronger proton acceptor than NH₂F1F1F1S1^-F1F1F10 is considered as a strong base.

Question 5

When CaO(s)is dissolved in water,which of the following is true? A)The solution contains O^2-(aq),OH^-(aq),and Ca²⁺(aq). B)The solution contains CaO(aq). C)CaO(s)does not dissolve in water. D)The solution contains O²^-(aq)and Ca²⁺(aq). E)The solution contains OH^-(aq)and Ca²⁺(aq).

Accepted Answer

When CaO is dissolved in water, it reacts to form Ca(OH)₂, which dissociates into Ca²⁺ and OH⁻ ions in solution.

Question 6

Which of the following aqueous solutions gives a pH greater than 7? A)10^-8 M NH₄Cl B)None of the solutions gives a pH greater than 7. C)10^-8 M CH₃COOH D)10^-8 M HCl E)10^-8 M HCOOH

Accepted Answer

The formatting of the options appears to be corrupted, making it difficult to interpret the chemical names correctly. However, based on the recognizable parts, all listed options seem to represent acids (HCl, HCOOH, etc.), which would not result in a pH greater than 7 in aqueous solutions.

Question 7

Estimate the pH of 10^-7 M HClO₄(aq). A)6.8 B)8.0 C)1.0 D)5.0 E)7.0

Accepted Answer

The answer of Estimate the pH of 10^-7 M HClO₄(aq). A)6.8 B)8.0 C)1.0 D)5.0 E)7.0...

Question 8

In liquid ammonia,the acid HB is a strong acid if it is a weaker proton donor than NH₄⁺.

Accepted Answer

The statement is incorrect. A stronger acid is one that is a more efficient proton donor, not a weaker donor. Therefore, it cannot be said that HB is a strong acid if it is a weaker proton donor than NH₄⁺.

Question 9

A flask of 0.25 M HBrO(aq)has what pH? (pK_a = 8.69) A)5.90 B)0.60 C)8.10 D)4.65 E)9.30

Accepted Answer

HBrO(aq) is a weak acid and the pH of the solution can be calculated using the equation:
pH = pKa + log([A-]/[HA])
where pKa is the acid dissociation constant of HBrO, [A-] is the concentration of the conjugate base (BrO-) and [HA] is the concentration of the acid (HBrO).
pKa for HBrO = 8.69
[HA] = 0.25 M
[ A- ] is the concentration of BrO- that can be calculated from the equation of acid dissociation: 
HBrO + H2O → H3O+ + BrO-
Ka=([BrO-][H3O+])/[HBrO]
we known that Ka=pKa/(H3O+)/sqrt([HBrO][BrO-])=1.3*10^-9
so ([BrO-])^2=0.046*([HBrO])(H3O+)
thus, [BrO-] = sqrt(0.046×0.25xpH) mol/L= 0.169x√pH
Substituting these values in the equation for pH, we get:
pH= 8.69 +log(0.169x√pH/0.25)
Solving this equation for pH, we get pH= 4.65.

Question 10

If the pK_a of acetic acid is 4.75,the pK_a of CH₃CH₂OH is A)about 4. B)much less than 4.75. C)about 16. D)also 4.75. E)about 7.

Accepted Answer

Ethanol (CH3CH2OH) is a much weaker acid than acetic acid, with a pKa around 16, indicating it is less likely to donate a proton compared to acetic acid.

Question 11

If the value of K_b for pyridine is 1.8 * 10^-9,calculate the equilibrium constant for C₅H₅NH⁺(aq)+ H₂O(l)↔ C₅H₅N(aq)+ H₃O⁺(aq) A)-1.8 * 10^-9 B)1.8 *10^-16 C)5.6 * 10⁸ D)1.8 * 10^-9 E)5.6 * 10^-6

Accepted Answer

The answer of If the value of K_b for pyridine...

Question 12

Which of the following is the strongest acid? A)CH₃CH₂OH B)CH₃COOH C)CHCl₂COOH D)CH₂ClCOOH E)CCl₃COOH

Accepted Answer

Trichloroacetic acid (CCl₃COOH) is the strongest acid among the options due to the presence of three electronegative chlorine atoms, which increase the acidity by stabilizing the negative charge on the conjugate base through inductive effect.

Question 13

Which of the following 0.10 M aqueous solutions has the lowest pH? A)B(OH)₃ B)HIO C)C₂H₅NH₃Cl D)C₆H₅OH

Accepted Answer

The answer of Which of the following 0.10 M aqueous...

Question 14

Write the charge balance equation for a dilute aqueous solution of HI. A)[I^-] = [OH^-] + [H₃O⁺] B)[H₃O⁺] = [OH^-] C)[H₃O⁺] = [I^-] D)[H₃O⁺] = [I^-] + [OH^-] E)[HI]_initial = [I^-]

Accepted Answer

In a dilute aqueous solution of HI, the hydronium ions [H₃O⁺] produced by the dissociation of HI must equal the sum of iodide ions [I^-] and hydroxide ions [OH^-] to maintain charge balance.

Question 15

The pH of 0.80 M benzenesulfonic acid is 0.51.What is the percentage ionization of benzenesulfonic acid?
A)25%
B)39%
C)51%
D)5.0%
E)64%

Accepted Answer

The percentage ionization can be calculated using the formula:

% ionization = (concentration of H+ ions / initial concentration of acid) x 100

First, we need to find the concentration of H+ ions. Since benzenesulfonic acid is a weak acid, we can assume that the majority of the acid remains in its molecular form, and only a small fraction ionizes. Therefore, we can use the approximation that the initial concentration of H+ ions is equal to the concentration of the benzenesulfonic acid that ionizes.

[H+] = √(Ka x [acid])

where Ka is the acid dissociation constant and [acid] is the initial concentration of the acid. For benzenesulfonic acid, the Ka value is not given, but we can assume it is small since the pH is close to neutral. Therefore, we can use the approximation that [H+] ≈ √[acid].

[H+] = √(0.80 × 10^-x) = 0.4 x 10^-x

where x is the degree of ionization (in moles per liter).

Now we can calculate the percentage ionization:

% ionization = ([H+] / [acid]) x 100

% ionization = [(0.4 x 10^-x) / 0.80] x 100

% ionization = 0.5 x 10^-x x 100

% ionization = 5 x 10^(2-x)

To find x, we can use the pH:

pH = -log[H+] = -log(0.4 x 10^-x) 
0.51 = -log(0.4) + x 
x = 2.39

% ionization = 5 x 10^(2-2.39) 
% ionization = 5.9%

Therefore, the closest choice is B) 39%.

Question 16

The pH of 0.800 M aqueous benzenesulfonic acid is 0.51.What is the value of K_a for benzenesulfonic acid? A)0.19 B)0.12 C)0.90 D)0.44 E)0.51

Accepted Answer

The pH of the solution is given as 0.51, which means the hydrogen ion concentration [H+] is 10^(-0.51). To find the Ka (acid dissociation constant) for benzenesulfonic acid, we use the formula Ka = [H+][A-]/[HA], where [HA] is the concentration of the acid and [A-] is the concentration of the conjugate base. Since the acid is strong, we can assume it dissociates completely, so [H+] = [A-] = 10^(-0.51). The concentration of the undissociated acid [HA] is negligible in comparison. Therefore, Ka ≈ [H+]^2 / [HA] = (10^(-0.51))^2 / 0.800 = 0.19.

Question 17

For the following acids,which has the highest pK_a? A)HIO B)HClO₃ C)HClO D)HBrO E)HClO₄

Accepted Answer

The answer of For the following acids,which has the highest...

Question 18

The pH of 0.010 M aniline(aq)is 8.32.What is the percentage aniline protonated?
A)2.1%
B)0.69%
C)0.021%
D)0.12%
E)0.21%

Accepted Answer

The answer of The pH of 0.010 M aniline(aq)is 8.32.What...

Question 19

Write the charge balance equation for a dilute aqueous solution of KOH. A)[KOH]_initial = [K⁺] B)[OH^-] = [H₃O⁺] + [K⁺] C)[H₃O⁺] = [OH^-] D)[K⁺] = [OH^-] + [H₃O⁺] E)[OH^-] = [K⁺]

Accepted Answer

The answer of Write the charge balance equation for a...

Question 20

The pH of 0.10 M pyridine(aq)is 9.13.What is the value of K_bfor pyridine? A)2.7 * 10^-4 B)7.4 * 10^-10 C)2.7 * 10^-5 D)1.8 * 10^-10 E)1.8 * 10^-9

Accepted Answer

The answer of The pH of 0.10 M pyridine(aq)is 9.13.What...

Quiz 12: Acids and Bases

What is the pH of 0.025 M (CH₃) ₃N(aq) (K_b = 6.5 * 10^-5) ?

Which of the following 0.10 M aqueous solutions gives the lowest pH?

For a 0.10 M solution of a weak acid,HA,with pK_a = 10,which of the following is true?

In liquid ammonia,the base B is a strong base if it is a stronger proton acceptor than NH₂^-.

When CaO(s) is dissolved in water,which of the following is true?

Which of the following aqueous solutions gives a pH greater than 7?

Estimate the pH of 10^-7 M HClO₄(aq) .

In liquid ammonia,the acid HB is a strong acid if it is a weaker proton donor than NH₄⁺.

A flask of 0.25 M HBrO(aq) has what pH? (pK_a = 8.69)

If the pK_a of acetic acid is 4.75,the pK_a of CH₃CH₂OH is

If the value of K_b for pyridine is 1.8 * 10^-9,calculate the equilibrium constant for C₅H₅NH⁺(aq) + H₂O(l) ↔ C₅H₅N(aq) + H₃O⁺(aq)

Which of the following is the strongest acid?

Which of the following 0.10 M aqueous solutions has the lowest pH?

Write the charge balance equation for a dilute aqueous solution of HI.

The pH of 0.80 M benzenesulfonic acid is 0.51.What is the percentage ionization of benzenesulfonic acid?

The pH of 0.800 M aqueous benzenesulfonic acid is 0.51.What is the value of K_a for benzenesulfonic acid?

For the following acids,which has the highest pK_a?

The pH of 0.010 M aniline(aq) is 8.32.What is the percentage aniline protonated?

Write the charge balance equation for a dilute aqueous solution of KOH.

The pH of 0.10 M pyridine(aq) is 9.13.What is the value of K_bfor pyridine?

Quiz 12: Acids and Bases

What is the pH of 0.025 M (CH3) 3N(aq) (Kb = 6.5 * 10-5) ?

Which of the following 0.10 M aqueous solutions gives the lowest pH?

For a 0.10 M solution of a weak acid,HA,with pKa = 10,which of the following is true?

In liquid ammonia,the base B is a strong base if it is a stronger proton acceptor than NH2-.

When CaO(s) is dissolved in water,which of the following is true?

Which of the following aqueous solutions gives a pH greater than 7?

Estimate the pH of 10-7 M HClO4(aq) .

In liquid ammonia,the acid HB is a strong acid if it is a weaker proton donor than NH4+.

A flask of 0.25 M HBrO(aq) has what pH? (pKa = 8.69)

If the pKa of acetic acid is 4.75,the pKa of CH3CH2OH is

If the value of Kb for pyridine is 1.8 * 10-9,calculate the equilibrium constant for C5H5NH+(aq) + H2O(l) ↔ C5H5N(aq) + H3O+(aq)

Which of the following is the strongest acid?

Which of the following 0.10 M aqueous solutions has the lowest pH?

Write the charge balance equation for a dilute aqueous solution of HI.

The pH of 0.80 M benzenesulfonic acid is 0.51.What is the percentage ionization of benzenesulfonic acid?

The pH of 0.800 M aqueous benzenesulfonic acid is 0.51.What is the value of Ka for benzenesulfonic acid?

For the following acids,which has the highest pKa?

The pH of 0.010 M aniline(aq) is 8.32.What is the percentage aniline protonated?

Write the charge balance equation for a dilute aqueous solution of KOH.

The pH of 0.10 M pyridine(aq) is 9.13.What is the value of Kb for pyridine?

What is the pH of 0.025 M (CH₃) ₃N(aq) (K_b = 6.5 * 10^-5) ?

For a 0.10 M solution of a weak acid,HA,with pK_a = 10,which of the following is true?

In liquid ammonia,the base B is a strong base if it is a stronger proton acceptor than NH₂^-.

Estimate the pH of 10^-7 M HClO₄(aq) .

In liquid ammonia,the acid HB is a strong acid if it is a weaker proton donor than NH₄⁺.

A flask of 0.25 M HBrO(aq) has what pH? (pK_a = 8.69)

If the pK_a of acetic acid is 4.75,the pK_a of CH₃CH₂OH is

If the value of K_b for pyridine is 1.8 * 10^-9,calculate the equilibrium constant for C₅H₅NH⁺(aq) + H₂O(l) ↔ C₅H₅N(aq) + H₃O⁺(aq)

The pH of 0.800 M aqueous benzenesulfonic acid is 0.51.What is the value of K_a for benzenesulfonic acid?

For the following acids,which has the highest pK_a?

The pH of 0.10 M pyridine(aq) is 9.13.What is the value of K_bfor pyridine?