9-02: The pH Scale

Compared to a 1.0-liter aqueous solution with a pH of 7.0, a 1.0-liter aqueous solution with a pH of 5.0 contains

• 10 times more hydronium ions

• 100 times more hydronium ions

• 10 times more hydroxide ions

• 100 times more hydroxide ions

When the concentration of hydrogen ions in a solution is decreased by a factor of ten, the pH of the solution

• increases by 1

• increases by 10

• decreases by 1

• decreases by 10

Compared to a solution with a pH value of 7, a solution with a thousand times greater hydronium ion concentration has a pH value of

• 10

• 7

• 3

• 4

Which change in the H⁺ ion concentration of an aqueous solution represents a decrease of one unit on the pH scale?

• a tenfold increase

• a tenfold decrease

• a hundredfold increase

• a hundredfold decrease

The pH of a solution is 7. When acid is added to the solution, the hydronium ion concentration becomes 100 times greater. What is the pH of the new solution?

• 1

• 5

• 9

• 14

The acidity or alkalinity of an unknown aqueous solution is indicated by its

• pH value

• electronegativity value

• percent by mass concentration

• percent by volume concentration

When the pH of an aqueous solution is changed from 1 to 2, the concentration of hydronium ions in the solution is

• decreased by a factor of 2

• decreased by a factor of 10

• increased by a factor of 2

• increased by a factor of 10

As the pH of a solution is changed from 3 to 6, the concentration of hydronium ions

• increases by a factor of 3

• increases by a factor of 1000

• decreases by a factor of 3

• decreases by a factor of 1000

Which pH change represents a hundredfold increase in the concentration of H₃O⁺?

• pH 5 to pH 7

• pH 13 to pH 14

• pH 3 to pH 1

• pH 4 to pH 3

Which of these pH numbers indicates the highest level of acidity?

• 5

• 8

• 10

• 12