Skip to main content
Ch.13 - Solutions & Their Properties
Chapter 13, Problem 68

The ozone layer in the Earth's stratosphere has an average total pressure of 10 mm Hg 11.3 * 10-2 atm2. The partial pressure of ozone in the layer is about 1.2 * 10-6 mm Hg11.6 * 10-9 atm2. What is the concentration of ozone inparts per million, assuming that the average molar mass ofair is 29 g/mol?

Verified step by step guidance
1
Convert the partial pressure of ozone from mm Hg to atm using the conversion factor (1 atm = 760 mm Hg).
Calculate the mole fraction of ozone by dividing the partial pressure of ozone (in atm) by the total pressure of the atmosphere (in atm).
Use the ideal gas law to find the molar concentration of air in the atmosphere. Assume standard temperature and pressure conditions where R (gas constant) = 0.0821 L atm / K mol and T (temperature) = 273 K.
Multiply the mole fraction of ozone by the molar concentration of air to find the molar concentration of ozone.
Convert the molar concentration of ozone to parts per million (ppm) by multiplying it by 10^6.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
5m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Partial Pressure

Partial pressure refers to the pressure exerted by a single component of a gas mixture. In the context of the ozone layer, it helps determine the contribution of ozone to the total atmospheric pressure. Understanding partial pressure is crucial for calculating the concentration of gases in a mixture, as it allows us to isolate the behavior of individual gases.
Recommended video:
Guided course
00:48
Partial Pressure Calculation

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). For air, the average molar mass is approximately 29 g/mol, which is essential for converting between mass and moles in gas calculations. This concept is vital when determining the concentration of a gas in a mixture, as it relates the mass of the gas to its volume and number of moles.
Recommended video:
Guided course
02:11
Molar Mass Concept

Parts Per Million (PPM)

Parts per million (PPM) is a unit of measurement used to describe the concentration of a substance in a solution or mixture. It indicates how many parts of a substance are present in one million parts of the total mixture. In the context of the ozone concentration, converting the partial pressure of ozone to PPM allows for a standardized way to express its abundance in the atmosphere, facilitating comparisons and assessments of air quality.
Recommended video:
Guided course
01:38
Parts per Million (ppm)