Logarithm Word Problems

The pH of carbonated water is 3.9. What is its hydrogen-ion concentration?

• 1.26 × 10⁻⁴ M

• 3.9 × 10⁻³ M

• 2.5 × 10⁻⁵ M

• 7.9 × 10⁻⁴ M

The pH of household ammonia is 11.9. What is its hydrogen-ion concentration?

• 1.26 × 10⁻¹² M

• 1.26 × 10⁻¹¹ M

• 7.94 × 10⁻³ M

• 7.94 × 10⁻¹² M

Stomach acid has a pH of about 2.0. What is the hydrogen-ion concentration?

• 1 × 10⁻² M

• 1 × 10⁻⁴ M

• 1 × 10⁻⁶ M

• 1 × 10⁻¹ M

Blood has a pH of 7.4. What is the hydrogen-ion concentration?

5. Find the pH value of an unknown substance found in the fast food bag you left in your car for the past month, if you know that the concentration of hydrogen ions [H+] is 0.5 moles per liter. (Round the pH value to the nearest tenth.)

• 0.3

• 0.7

• 1.0

• 1.3

6. The hydrogen ion concentration in cheeses ranges from 4.0 x 10^-7 M to 1.6 x 10^-5 M. What is the corresponding range in pH readings?

• 6.4 to 4.8

• 7.0 to 4.0

• 5.4 to 7.2

• 4.8 to 6.0

• 73 dB

• 60 dB

• 85 dB

• 40 dB

8. The intensity level of the sound of a subway train was measured at 98 dB. What is the intensity in W/m^2?

• 6.3 × 10^-3

• 1.0 × 10^-7

• 120 dB

• 100 dB

• 80 dB

• 140 dB

10. The noise from a power mower was measured at 106 dB. The noise level at a concert was measured at 120 dB. What is the ratio of the intensity of the music to that of the power mower?

• 25.1

• .0398

• 1

• 14.3