Air is about 78.0% nitrogen molecules and 21.0% oxygen molecules. Several other gases make up the remaining 1% of air molecules.What is the partial pressure of nitrogen in air at atmospheric pressure (1 atm)? Assume ideal behavior.
78% of 1 atm, or 0.78 atm
To find the partial pressure of nitrogen in air at atmospheric pressure (1 atm), we can use the concept of partial pressure and the ideal gas law.
The ideal gas law states:
PV = nRT
Where:
P = pressure
V = volume
n = number of moles
R = ideal gas constant
T = temperature
In our case, we are interested in finding the partial pressure of nitrogen in air. We know that air is composed of 78.0% nitrogen molecules, so we can assume that 78.0% of the air molecules are nitrogen molecules.
Step 1: Calculate the mole fraction of nitrogen in air.
Mole fraction is the ratio of the moles of a particular gas to the total moles of all the gases present.
Mole fraction of nitrogen (X_nitrogen) = (number of moles of nitrogen) / (total number of moles of all gases)
Since air is composed of 78.0% nitrogen, we can assume that 78.0% of the air molecules are nitrogen molecules. So, the mole fraction of nitrogen can be calculated as follows:
X_nitrogen = 0.780
Step 2: Calculate the total moles of all gases.
Since air is composed of 78.0% nitrogen, 21.0% oxygen, and the remaining 1% of other gases, we can assume that the mole fractions of oxygen (X_oxygen) and the other gases (X_other) are:
X_oxygen = 0.210
X_other = 0.010
The total moles of all gases can be represented as:
Total moles of all gases = n_nitrogen + n_oxygen + n_other
Step 3: Convert moles to partial pressures.
The mole fraction of a gas can be related to its partial pressure by the following equation:
X_gas = (partial pressure of gas) / (total pressure)
Rearranging the equation:
(partial pressure of gas) = X_gas * (total pressure)
Since we are interested in finding the partial pressure of nitrogen (P_nitrogen), we can rearrange the equation as follows:
P_nitrogen = X_nitrogen * (total pressure)
Since the total pressure is given as 1 atm, the partial pressure of nitrogen can be calculated as:
P_nitrogen = 0.780 * 1 atm
Therefore, the partial pressure of nitrogen in air at atmospheric pressure (1 atm) is 0.780 atm.