AP Chemistry Unit 8.1-8.5

A buffer solution is prepared by mixing equal volumes of 0.50 M weak acid with 1.0 M of its conjugate base. Based on the data given in the table above, which of the following pairs of chemical solutions should be used to prepare the buffer solution so that the pH will be between 4 and 7?

• CH₃COOH and NH₃

• CH₃COOH and CH₃COONa

• H₂CO₃ and NH₃

• H₂CO₃ and Na₂CO₃

Ascorbic acid, H₂C₆H₆O₆(s), is a diprotic acid with K₁ = 7.9 × 10^–5 and K₂ = 1.6 × 10^–12. In a 0.005 M aqueous solution of ascorbic acid, which of the following species is present in the lowest concentration?

• H₃O⁺(aq)

• H₂C₆H₆O₆(aq)

• HC₆H₆O₆^-(aq)

• C₆H₆O₆^2-(aq)

Tags

NGSS.HS-PS1-5

NGSS.HS-PS1-7

In the titration of a weak acid of unknown concentration with a standard solution of a strong base, a pH meter was used to follow the progress of the titration. Which of the following is true for this experiment?

• The [H⁺] at the equivalence point equals the ionization constant of the acid.

• The pH at the equivalence point depends on the indicator used.

• The graph of pH versus volume of base added rises gradually at first and then much more rapidly.

• The graph of pH versus volume of base added shows no sharp rise.

Which of the following is the correct equilibrium expression for the hydrolysis of CO₃ ^2– ?

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Tags

NGSS.HS-PS1-7

Which of the following best approximates the K_a value for this weak acid?

• 1 x 10^–3

• 1 x 10^–4

• 1 x 10^–5

• 1 x 10^–6

Which point on the titration curve corresponds to the point at which the moles of the added strong base are equal to the moles of the weak acid initially present?

• Q

• R

• S

• T

At point P in the titration, which of the following species has the highest concentration?

• HA

• A^–

• H₃O⁺

• OH^–

Which of the following best represents a 0.100-molar solution of H₂SO₄ in water?

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Tags

NGSS.HS-PS1-5

Equal moles of the indicated acids are dissolved in the amounts of water shown in the beakers below. In which solution will the percent ionization of the acid be the lowest?

• Beaker 1

• Beaker 2

• Beaker 3

• Beaker 4

Tags

NGSS.HS-PS1-3

Mixtures that would be considered buffers include which of the following?

• 0.10 M HCl + 0.10 M NaCl

• 0.10 M HF + 0.10 M NaF

• 0.10 M HBr + 0.10 M NaBr

• 0.10 M HI + 0.10 M NaI