If one earthquake has a magnitude of 5.2 on the Richter scale and a second earthquake has a magnitude of 6, compare the intensities of the two earthquakes.

Calculate the pH of a swimming pool with a hydrogen ion concentration of 6.21\times 10^{-8} mol/L.

A particular sound is 1 000 000 times more intense than a sound you ca just barely hear. What is the loudness of the sound in decibels?

The loudness of a heavy snore is 69 dB. How many times as loud as a normal conversation of 60 dB is a heavy snore?

Calculate the hydrogen ion concentration of each substance.

• baking soda, with a pH of 9

Calculate the hydrogen ion concentration of each substance.

• milk, with a pH of 6.6

Calculate the hydrogen ion concentration of each substance.

• an egg, with a pH of 7.8

Calculate the hydrogen ion concentration of each substance.

• oven cleaner, with a pH of 13

Calculate to two decimal places the pH of a solution with each concentration of H^+.

(a) concentration of H^+ = 0.000 32

(b) concentration of H^+ = 0.000 3

(c) concentration of H^+ = 0. 000 045

(d) concentration of H^+ = 0.005

Distilled water has an H^+ concentration of 10^{-7} mol/L. Calculate the pH of distilled water.

Drinking water from a particular tap has a pH between 6.3 and 6.6. Is this tap water more or less acidic than distilled water? Explain your answer.

The sound level of a moving power lawn mower is 109 dB. The noise level in front of the amplifiers at a concert is about 118 dB. How many times louder is the noise at the front of the amplifiers than the noise of a moving power lawn mower?

The intensity, I, of light passing through water can be modelled by the equation I= 10^{1-0.13x}, where x is the depth of the water in metres. Most aquatic plants require a light intensity of 4.2 units for strong growth. Determine the depth of water at which most aquatic plants receive the required light.

Dry cleaners use a cleaning fluid that is purified by evaporation and condensation after each cleaning cycle. Every time the fluid is purified, 2.1% of it is lost. The fluid has to be topped up when half of the original build remains. After how many cycles will the fluid need to be topped up?

How long will it take for $2500 to accumulate to $4000 if it is invested at an interest rate of 6.5%/a, compounded annually?

A wound, initially with an area of 80 cm^2, heals according to the formula A(t)= 80(10^{-0.023t}), where A(t) is the area of the wound in square centimetres after t days of healing. In how many days will 75% of the wound be healed?

A new car has an interior sound level of 80dB at 50 km/h. A second car, at the same speed, has an interior sound level that is two times more intense than that of the new car. Calculate the sound level inside the second car.