Worksheet: Calculating pH

In this worksheet, we will practice describing the pH scale as a logarithmic measure of acid content and calculating values of pH.

Q1:

The hydronium ion concentration of vinegar is approximately 4.0×10 M. What is the corresponding value of the pH?

Q2:

What is the hydronium ion concentration of blood, the pH of which is 7.3 (slightly alkaline)?

  • A4.1 M
  • B7.3 M
  • C 5 . 0 × 1 0 M
  • D 2 . 0 × 1 0 M
  • E 6 . 7 × 1 0 M

Q3:

Water exposed to air contains carbonic acid, HCO23, due to the reaction between carbon dioxide and water, as shown. CO()+HO()HCO()2223aqlaq Air-saturated water has a hydronium ion concentration caused by the dissolved CO2 of 2.0×10 M, about 20 times larger than that of pure water. What is the pH of the solution at 25C?

Q4:

What is the pH of stomach acid, which is a solution of HCl with a hydronium ion concentration of 1.2×10 M, to 2 significant figures?

Q5:

What is the hydronium ion concentration of a solution with a pH of 1.07?

Q6:

To 2 decimal places, what is the pH of 0.200 MHCl at 25C? Assume that HCl ionizes completely.

Q7:

Coffee has a pH of about 5.1. Calculate to 2 significant figures the hydronium ion concentration of coffee at 25C.

  • A 7 . 9 × 1 0 M
  • B 1 . 3 × 1 0 M
  • C 1 . 2 × 1 0 M
  • D 6 . 3 × 1 0 M
  • E 1 . 6 × 1 0 M

Q8:

Calculate to 3 significant figures the hydronium ion concentration in a solution with a pH of 6.52.

  • A 5 . 0 6 × 1 0 M
  • B 3 . 3 1 × 1 0 M
  • C 8 . 9 5 × 1 0 M
  • D 3 . 0 2 × 1 0 M
  • E 6 . 7 9 × 1 0 M

Q9:

Lime juice has a pH of about 2.3. Calculate to 2 significant figures the hydronium ion concentration of lime juice at 25C.

  • A 2 . 0 × 1 0 M
  • B 4 . 5 × 1 0 M
  • C 9 . 3 × 1 0 M
  • D 2 . 2 × 1 0 M
  • E 5 . 0 × 1 0 M

Q10:

What is the pH of 3.0 MHNO3 at 25C? Assume that HNO3 ionizes completely.

Q11:

What is the pH of 0.000259 MHClO4 at 25C?  Assume that HClO4 ionizes completely.

  • A14.48
  • B 1 3 . 5 2
  • C3.59
  • D0.48
  • E13.52

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