Acid Base Practice

The pH of an aqueous solution of sodium hydroxide is 12.90. What is the molarity of the solution?

• 0.079 M

• 0.0079 M

• 1.3 x 10^-13 M

• 1.3 x 10^-12 M

Answer explanation

The correct molarity is 0.079 M. The pOH = 1.10. The pH of a sodium hydroxide solution can be calculated using the formula pOH = -log[M], where [M] is the molarity. Therefore, 1.10 = -log[M], M = 10^(-1.10) = 0.079 M.

Find the pH of a solution prepared by adding 525mL of water to 175 mL of 0.00125M HBr.

• 2.903

• 2.426

• 3.505

• 3.380

Answer explanation

To find the pH, first calculate the moles of HBr. Then, divide by the total volume of the solution. Finally, use the formula pH = -log[H+]. The correct pH is 3.505.

Calculate the percent ionization of acetic acid in a 0.10 M acetic acid solution with a pH of 2.90.

• 3.4%

• 1.3%

• 4.0%

• 0.034%

Answer explanation

To calculate percent ionization, use the formula: % ionization = 10^(-pH) / initial concentration * 100. % ionization = 10^(-2.90) / 0.10 * 100 = 1.3%

What is the molarity of a solution of the strong base Ca(OH)₂ in a solution that has a pH of 10.80?

• 2.8x10⁻⁴ M

• 1.5x10⁻³ M

• 3.2x10⁻⁴ M

• 6.3x10⁻³ M

Answer explanation

A pH of 10.80 corresponds to a pOH of 3.20. Since Ca(OH)₂ is a strong base, the molarity of OH⁻ ions can be found from the pOH, giving a molarity of OH^- of 6.3x10⁻⁴ M. Divide by 2 since there is a 1:2 ration of Ca(OH)₂ to OH^- .

A 50.00 mL sample of potassium hydroxide is titrated with a 0.8186 M HCl solution. The titration requires 27.87 mL of the HCl solution to reach the equivalence point. What is the molarity of the KOH solution?

• 0.4562 M KOH

• 1.469 M KOH

• 0.4321 M KOH

• 0.4562M KOH

Answer explanation

Use stoichiometry to find the molarity of KOH.

What is the pH of a 0.102 M solution of hydrazoic acid (HN₃) if the [H₃O⁺] is 1.39x10⁻³ M?

• 2.857

• 3.000

• 4.000

• 5.000

Answer explanation

To calculate pH, use the formula pH = -log[H₃O⁺]. Given [H₃O⁺] = 1.39x10⁻³ M, pH = -log(1.39x10⁻³) = 2.857. Therefore, the pH is 2.857.

The pH of a 0.400 M solution of iodic acid, HIO₃, is 0.726 at 25°C. What is the Ka?

• 0.167

• 0.052

• 0.726

• 0.400

Answer explanation

The correct Ka value is 0.167 because it corresponds to the given pH of 0.726 for the iodic acid solution.

A solution of sodium hydroxide with a pH of 12.400 is to be prepared. What mass of sodium hydroxide would be required to make 500.0 mL of this solution? (Molar Mass NaOH = 40.00g/mol)

• 0.502 g

• 502. g

• 0.0336 g

• 33.6 g

Answer explanation

To calculate the mass of NaOH, use the formula: Mass = Volume (L) x Molarity (mol/L) x Molar Mass (g/mol). Convert pOH to molarity of OH-, then use the formula to find the mass. Mass = 0.5 L x molarity x 40 g/mol = 0.502 g.

Ka for hypoiodous acid is 2.3 x 10^-11. The pH of a 0.0500M solution of hypoiodous acid is:

• 2.55

• 1.30

• 5.201

• 5.970

Answer explanation

Set up a chart. Find the concentration of H+ using the short cut (0.05-x) is approximately equal to 0.05. Check the percent dissociation when you are done.

Human blood has a pH between 7.35 and 7.45. Which of the following best describes human blood?

• strongly acidic

• slightly acidic

• strongly basic

• slightly basic

Answer explanation

Human blood has a pH between 7.35 and 7.45, which falls within the slightly basic range. Therefore, the best description for human blood is slightly basic.