The estimated average concentration of NO₂ in air in the United States in 2006 was 0.016 ppm. (a) Calculate the partial pressure of the NO₂ in a sample of this air when the atmospheric pressure is 755 torr (99.1 kPa).

Key Concepts

Partial Pressure

Partial pressure refers to the pressure exerted by a single component of a gas mixture. It can be calculated using Dalton's Law, which states that the total pressure of a gas mixture is equal to the sum of the partial pressures of its individual gases. In this context, the partial pressure of NO2 can be determined by multiplying its concentration (in ppm) by the total atmospheric pressure.

Concentration Units

Concentration can be expressed in various units, including parts per million (ppm), which indicates the number of parts of a substance in one million parts of the total solution or mixture. To convert ppm to a more usable form for calculations, it is often necessary to relate it to the total pressure of the gas mixture, allowing for the determination of the partial pressure of the specific gas.

Gas Laws

Gas laws describe the behavior of gases under various conditions of temperature, volume, and pressure. The ideal gas law (PV=nRT) is particularly relevant, as it relates pressure (P), volume (V), and temperature (T) to the number of moles (n) of gas. Understanding these laws is essential for calculating the behavior of gases in different scenarios, including determining partial pressures from concentrations.