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 × 1 0 3 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)?

  • A 7.3 M
  • B 2 . 0 × 1 0 M
  • C 6 . 7 × 1 0 M
  • D 5 . 0 × 1 0 M
  • E 9 . 1 × 1 0 M

Q3:

Water exposed to air contains carbonic acid, H C O 2 3 , due to the reaction between carbon dioxide and water: Air-saturated water has a hydronium ion concentration caused by the dissolved C O 2 of 2 . 0 × 1 0 6 M, about 20 times larger than that of pure water. What is the pH of the solution at 2 5 C ?

Q4:

What is the pH of stomach acid, which is a solution of H C l with a hydronium ion concentration of 1 . 2 × 1 0 3 M?

Q5:

What is the hydronium ion concentration of a solution with a pH of 1 . 0 7 ?

Q6:

To 2 decimal places, what is the pH of 0 . 2 0 0 M H C l at 2 5 C ? Assume that H C l ionizes completely.

Q7:

Coffee has a pH of about 5.1. Calculate to 2 significant figures the hydronium ion concentration of coffee at 2 5 C .

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

Q9:

Lime juice has a pH of about 2.3. Calculate to 2 significant figures the hydronium ion concentration of lime juice at 2 5 C .

  • A 4 . 5 × 1 0 6 M
  • B 2 . 0 × 1 0 1 2 M
  • C 2 . 2 × 1 0 9 M
  • D 5 . 0 × 1 0 3 M
  • E 9 . 3 × 1 0 7 M

Q10:

What is the pH of 3 . 0 M H N O 3 at 2 5 C ? Assume that H N O 3 ionizes completely.

Q11:

What is the pH of 0 . 0 0 0 2 5 9 M H C l O 4 at 2 5 C ? Assume that H C l O 4 ionizes completely.

  • A10.7
  • B10.4
  • C3.29
  • D3.59
  • E4.50

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