Question 1

Fluffy,your prized Himalayan cat,was outside when your dad was changing the antifreeze in the car.Fluffy licked up a large amount of the antifreeze off the driveway.You live many miles from the veterinarian.What could you give Fluffy to drink to counteract the effects of antifreeze?

Accepted Answer

A strong alcoholic drink can be used as an antidote for antifreeze poisoning because ethanol competes with ethylene glycol (the toxic component of antifreeze) for metabolism by the liver, reducing the formation of toxic metabolites.

Question 2

Which of the following solutions is a good buffer system?

Accepted Answer

A buffer system consists of a weak acid and its conjugate base or a weak base and its conjugate acid. Option A has acetic acid (HC2H3O2) and its conjugate base (LiC2H3O2), making it a good buffer system.

Question 3

You wish to prepare an HC₂H₃O₂ buffer with a pH of 4.24.If the pK_a of is 4.74,what ratio of C₂H₃O₂^-/HC₂H₃O₂ must you use?

Accepted Answer

We can use the Henderson-Hasselbalch equation:

pH = pKa + log([A-]/[HA])

Substituting the given values:

4.24 = 4.74 + log([C2H3O2-]/[C2H4O2])

log([C2H3O2-]/[C2H4O2]) = -0.5

[C2H3O2-]/[C2H4O2] = antilog(-0.5) = 0.32

Therefore, the ratio of [C2H3O2-] to [C2H4O2] must be 0.32. This means that for every 0.32 moles of acetate ion (C2H3O2-) in the buffer, there must be 1 mole of acetic acid (C2H4O2). So the best choice is option C.

Question 4

If the pK_a of HCHO₂ is 3.74 and the pH of an HCHO₂/NaCHO₂solution is 3.11,which of the following is true?

Accepted Answer

The pH is lower than the pKa, indicating that the concentration of the acid (HCHO2) is greater than the concentration of its conjugate base (NaCHO2).

Question 5

You wish to prepare an HC₂H₃O₂ buffer with a pH of 5.44.If the pK_a of is 4.74,what ratio of C₂H₃O₂^-/HC₂H₃O₂ must you use?

Accepted Answer

The answer of You wish to prepare an HC₂H₃O₂ buffer...

Question 6

If the pK_a of HCHO₂ is 3.74 and the pH of an HCHO₂/NaCHO₂solution is 3.74,which of the following is true?

Accepted Answer

The pK_a of HCHO₂ is equal to the pH of the solution, which means that HCHO₂ is exactly half dissociated into H+ and CHO₂-. When an equal amount of NaCHO₂ is added to the solution, the Na+ ions will not have a significant effect on the pH, so the concentration of CHO₂- will remain the same as that of H+. Therefore, [HCHO₂] = [CHO₂-] = [NaCHO₂], so choice B is correct.

Question 7

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 M HClO with 200.0 mL of 0.30 M KClO.The K_a for HClO is 2.9 × 10^-8.

Accepted Answer

The answer of Calculate the pH of a solution formed...

Question 8

Calculate the pH of a solution formed by mixing 150.0 mL of 0.10 M HC₇H₅O₂ with 100.0 mL of 0.30 M NaC₇H₅O₂.The K_a for HC₇H₅O₂ is 6.5 × 10^-5.

Accepted Answer

First, calculate the moles of HC₇H₅O₂ and NaC₇H₅O₂ in the solution: moles HC₇H₅O₂ = (0.10 mol/L) x (0.150 L) = 0.015 mol moles NaC₇H₅O₂ = (0.30 mol/L) x (0.100 L) = 0.030 mol Next, calculate the concentration of HC₇H₅O₂ and NaC₇H₅O₂ in the mixture: [HC₇H₅O₂] = (0.015 mol + 0 mol) / (0.150 L + 0.100 L) = 0.075 mol/L [NaC₇H₅O₂] = (0.030 mol + 0 mol) / (0.150 L + 0.100 L) = 0.150 mol/L Using the expression for the ionization of HC₇H₅O₂, calculate the concentration of H+ ions: HC₇H₅O₂ + H2O ⇌ H3O+ + C₇H₅O- Ka = ([H3O+] [C₇H₅O-]) / [HC₇H₅O₂] Assuming x << [HC₇H₅O₂]: Ka = x^2 / (0.075 - x) Solve for x using the quadratic formula: x = [H3O+] = 2.2 × 10^-5 mol/L Finally, calculate the pH: pH = -log[H3O+] = -(-log(2.2 × 10^-5)) = 4.49

Question 9

Which one of the following statements is true?

Accepted Answer

A buffer solution consists of a weak acid or base and its salt, and it resists changes in pH when small amounts of acid or base are added to it. The buffer solution can absorb or neutralize small amounts of acid or base, preventing a change in pH. However, it is not an unlimited capacity, and when the buffer capacity is exceeded, the pH will change significantly. Therefore, statement B is false. Statement A and D are also false, as buffers solutions are not composed of two weak acids or immune to the effects of strong acids or bases.

Question 10

Calculate the pH of a buffer that is 0.158 M HClO and 0.099 M NaClO.The K_a for HClO is 2.9 × 10^-8.

Accepted Answer

The answer of Calculate the pH of a buffer that...

Question 11

A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in NaF.Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl.The K_a for HF is 3.5 × 10^-4.

Accepted Answer

The answer of A 1.00 L buffer solution is 0.250...

Question 12

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH₄Cl with 100.0 mL of 0.20 M NH₃.The K_b for NH₃ is 1.8 × 10^-5.

Accepted Answer

The answer of Calculate the pH of a solution formed...

Question 13

If the pK_a of HCHO₂ is 3.74 and the pH of an HCHO₂/NaCHO₂solution is 3.89,which of the following is true?

Accepted Answer

The pH is greater than the pKa, indicating that the solution is more basic, meaning the concentration of the conjugate base [NaCHO2] is greater than the concentration of the acid [HCHO2].

Question 14

Which of the following solutions is a good buffer system?

Accepted Answer

A buffer system needs to have a weak acid and its corresponding conjugate base, or a weak base and its corresponding conjugate acid. In choice B, HCN is a weak acid and LiCN is its corresponding conjugate base, making it a good buffer system. The other choices either do not have both a weak acid and its corresponding conjugate base or have a strong acid and its corresponding salt, which does not make a good buffer system.

Question 15

Calculate the pH of a buffer that is 0.105 M HC₂H₃O₂ and 0.146 M KC₂H₃O₂.The K_a for HC₂H₃O₂ is 1.8 × 10^-5.

Accepted Answer

The correct answer is A because the pH of a buffer can be calculated using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where pKa is the negative logarithm of the acid dissociation constant, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the acid. In this case, the pKa of HC2H3O2 is 1.8 × 10-5, [A-] is 0.146 M, and [HA] is 0.105 M. Plugging these values into the equation gives pH = 1.8 × 10-5 + log(0.146/0.105) = 4.89.

Question 16

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M HCHO₂ with 100.0 mL of 0.20 M LiCHO₂.The K_a for HCHO₂ is 1.8 × 10^-4.

Accepted Answer

First, we need to write the balanced chemical equation of the reaction between HCHO₂ and LiCHO₂ to determine which species will act as the acid and which will act as the base: HCHO₂ + LiCHO₂ → CHO₂Li + H2O In this reaction, HCHO₂ acts as the acid (donates a proton) and LiCHO₂ acts as the base (accepts a proton) to form CHO₂Li, which is a salt. Next, we need to calculate the moles of acid (HCHO₂) and base (LiCHO₂) in the mixture: moles of HCHO₂ = (0.15 mol/L) x (0.250 L) = 0.0375 mol moles of LiCHO₂ = (0.20 mol/L) x (0.100 L) = 0.0200 mol Since we have more acid than base, the remaining HCHO₂ will be present in the solution. Using the Henderson-Hasselbalch equation, we can calculate the pH of the solution: pH = pKa + log([base]/[acid]) pKa = -log(Ka) = -log(1.8 × 10^-4) = 3.74 [base] = moles of CHO₂Li / total volume of solution = (0.0375 mol) / (0.250 L + 0.100 L) = 0.107 M [acid] = moles of HCHO₂ remaining / total volume of solution = (0.0375 - 0.0200) mol / (0.250 L + 0.100 L) = 0.0675 M pH = 3.74 + log(0.107/0.0675) = 3.47 Therefore, the pH of the solution is 3.47, which is best represented by choice D.

Question 17

A buffer solution is 0.100 M in both HC₇H₅O₂ and LiC₇H₅O₂ and has a pH of 4.19.Which of the following pH values would you be most likely to see from the addition of a small amount of a dilute solution of a strong base?

Accepted Answer

The buffer resists changes in pH. Adding a small amount of strong base will slightly increase the pH, making 4.49 the most likely value.

Question 18

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH₄Cl with 200.0 mL of 0.12 M NH₃.The K_b for NH₃ is 1.8 × 10^-5.

Accepted Answer

The answer of Calculate the pH of a solution formed...

Question 19

Calculate the pH of a buffer that is 0.058 M HF and 0.058 M LiF.The K_a for HF is 3.5 × 10^-4.

Accepted Answer

To calculate the pH of the buffer, we need to use the Henderson-Hasselbalch equation, which is pH = pKa + log ([A-]/[HA]).
From the given information, pKa of HF is 3.5 × 10-4.
To find out [A-] and [HA], we use the molarities of the buffer components:

[A-] = 0.058 M LiF
[HA] = 0.058 M HF

Now we can plug in these values into the Henderson-Hasselbalch equation:

pH = 3.5 × 10-4 + log (0.058/0.058) = 3.5 × 10-4 + log(1) = 3.5 × 10-4 + 0 = 3.46

Therefore, the answer is D) 3.46.

Question 20

A 1.00 L buffer solution is 0.150 M in HC₇H₅O₂ and 0.250 M in LiC₇H₅O₂.Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl.The K_a for HC₇H₅O₂ is 6.5 × 10^-5.

Accepted Answer

The answer of A 1.00 L buffer solution is 0.150...

Quiz 16: Aqueous Ionic Equilibrium

Fluffy,your prized Himalayan cat,was outside when your dad was changing the antifreeze in the car.Fluffy licked up a large amount of the antifreeze off the driveway.You live many miles from the veterinarian.What could you give Fluffy to drink to counteract the effects of antifreeze?

Which of the following solutions is a good buffer system?

You wish to prepare an HC2H3O2 buffer with a pH of 4.24.If the pKa of is 4.74,what ratio of C2H3O2-/HC2H3O2 must you use?

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.11,which of the following is true?

You wish to prepare an HC2H3O2 buffer with a pH of 5.44.If the pKa of is 4.74,what ratio of C2H3O2-/HC2H3O2 must you use?

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.74,which of the following is true?

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 M HClO with 200.0 mL of 0.30 M KClO.The Ka for HClO is 2.9 × 10-8.

Calculate the pH of a solution formed by mixing 150.0 mL of 0.10 M HC7H5O2 with 100.0 mL of 0.30 M NaC7H5O2.The Ka for HC7H5O2 is 6.5 × 10-5.

Which one of the following statements is true?

Calculate the pH of a buffer that is 0.158 M HClO and 0.099 M NaClO.The Ka for HClO is 2.9 × 10-8.

A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in NaF.Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl.The Ka for HF is 3.5 × 10-4.

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH4Cl with 100.0 mL of 0.20 M NH3.The Kb for NH3 is 1.8 × 10-5.

If the pKa of HCHO2 is 3.74 and the pH of an HCHO2/NaCHO2 solution is 3.89,which of the following is true?

Which of the following solutions is a good buffer system?

Calculate the pH of a buffer that is 0.105 M HC2H3O2 and 0.146 M KC2H3O2.The Ka for HC2H3O2 is 1.8 × 10-5.

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M HCHO2 with 100.0 mL of 0.20 M LiCHO2.The Ka for HCHO2 is 1.8 × 10-4.

A buffer solution is 0.100 M in both HC7H5O2 and LiC7H5O2 and has a pH of 4.19.Which of the following pH values would you be most likely to see from the addition of a small amount of a dilute solution of a strong base?

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH4Cl with 200.0 mL of 0.12 M NH3.The Kb for NH3 is 1.8 × 10-5.

Calculate the pH of a buffer that is 0.058 M HF and 0.058 M LiF.The Ka for HF is 3.5 × 10-4.

A 1.00 L buffer solution is 0.150 M in HC7H5O2 and 0.250 M in LiC7H5O2.Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl.The Ka for HC7H5O2 is 6.5 × 10-5.

You wish to prepare an HC₂H₃O₂ buffer with a pH of 4.24.If the pK_a of is 4.74,what ratio of C₂H₃O₂^-/HC₂H₃O₂ must you use?

If the pK_a of HCHO₂ is 3.74 and the pH of an HCHO₂/NaCHO₂solution is 3.11,which of the following is true?

You wish to prepare an HC₂H₃O₂ buffer with a pH of 5.44.If the pK_a of is 4.74,what ratio of C₂H₃O₂^-/HC₂H₃O₂ must you use?

If the pK_a of HCHO₂ is 3.74 and the pH of an HCHO₂/NaCHO₂solution is 3.74,which of the following is true?

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 M HClO with 200.0 mL of 0.30 M KClO.The K_a for HClO is 2.9 × 10^-8.

Calculate the pH of a solution formed by mixing 150.0 mL of 0.10 M HC₇H₅O₂ with 100.0 mL of 0.30 M NaC₇H₅O₂.The K_a for HC₇H₅O₂ is 6.5 × 10^-5.

Calculate the pH of a buffer that is 0.158 M HClO and 0.099 M NaClO.The K_a for HClO is 2.9 × 10^-8.

A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in NaF.Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl.The K_a for HF is 3.5 × 10^-4.

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH₄Cl with 100.0 mL of 0.20 M NH₃.The K_b for NH₃ is 1.8 × 10^-5.

If the pK_a of HCHO₂ is 3.74 and the pH of an HCHO₂/NaCHO₂solution is 3.89,which of the following is true?

Calculate the pH of a buffer that is 0.105 M HC₂H₃O₂ and 0.146 M KC₂H₃O₂.The K_a for HC₂H₃O₂ is 1.8 × 10^-5.

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M HCHO₂ with 100.0 mL of 0.20 M LiCHO₂.The K_a for HCHO₂ is 1.8 × 10^-4.

A buffer solution is 0.100 M in both HC₇H₅O₂ and LiC₇H₅O₂ and has a pH of 4.19.Which of the following pH values would you be most likely to see from the addition of a small amount of a dilute solution of a strong base?

Calculate the pH of a solution formed by mixing 250.0 mL of 0.15 M NH₄Cl with 200.0 mL of 0.12 M NH₃.The K_b for NH₃ is 1.8 × 10^-5.

Calculate the pH of a buffer that is 0.058 M HF and 0.058 M LiF.The K_a for HF is 3.5 × 10^-4.

A 1.00 L buffer solution is 0.150 M in HC₇H₅O₂ and 0.250 M in LiC₇H₅O₂.Calculate the pH of the solution after the addition of 100.0 mL of 1.00 M HCl.The K_a for HC₇H₅O₂ is 6.5 × 10^-5.