Chemistry Quiz

If Kₐ for HCN is 6.2 × 10⁻¹⁰, what is Kb for CN⁻?

• 6.2 × 10⁻²⁴

• 6.2 × 10⁴

• 1.6 × 10⁻⁵

• 1.6 × 10⁻²³

In a solution prepared by dissolving 0.10 mole of an acid HX in enough water to make 1.00 L of solution, the pH is observed to be 1.35. What is the Ka for this acid?

• 2.0 x 10⁻²

• 3.6 x 10⁻²

• 4.5 x 10⁻²

• 5.0 x 10⁻²

The base KCN is highly toxic; however, it is commonly used in gold mining as a means of extracting gold from a mixture in the presence of oxygen. . (CN^- has a K_b of 2.04 x 10⁻⁵ ) A KCN solution has a pH of 10.82. What is the pOH of the KCN solution?

• 3.18

• 4.18

• 2.18

• 5.18

The value of the acid-dissociation, Ka, for a weak monoprotic acid HA is 2.5 x 10^-6. The pH of 0.40 M HA is closest to:

• 2.0

• 3.0

• 4.0

• 6.0

Which of the following species, if any, acts as a Bronsted-Lowry base in the reversible reaction represented by F⁻(aq) + H₂O(l) ↔ HF(aq) + OH⁻(aq)?

• HF(aq)

• H₂O(l)

• F⁻(aq) only

• Both F⁻ and OH⁻

What is the pH of the buffer solution containing 0.40 mole of formic acid and 0.60 moles of sodium formate? Ka of formic acid is 1.8 x 10^-4

• 3.92

• 4.76

• 2.93

• 7.00

The base KCN is highly toxic; however, it is commonly used in gold mining as a means of extracting gold from a mixture in the presence of oxygen. . (CN^- has a K_b of 2.04 x 10⁻⁵ ) A KCN solution has a pH of 10.82. Determine the initial concentration of the solution. Have 3 significant figures and no units.

At25°C, aqueous solutions with a pH of 8 has a hydroxide ion concentration, [OH], of

• 1.0 x 10^-14

• 1.0 x 10^-8

• 1x 10^-6

• 8.0 M

What is the [H⁺] in a solution which shows a pH of 2.30?

• 2.3 M

• 11.7 M

• 5.0 x 10^-3

• 2.0 x 10^-12

Lactic acid (HC₃H₅O₃) forms within human muscles through extended exercise until its concentration reaches 0.0011M. The Ka for lactic acid = 1.4 x 10^-4. Determine the pH of the lactic acid in blood.