CHEM: The ideal gas law, PV = nRT is independent of the kind of gas. In other wo
ID: 537668 • Letter: C
Question
CHEM:
The ideal gas law, PV = nRT is independent of the kind of gas. In other words, the pressure exerted by a given number of ideal particles is the same whether the sample consists of all one type of particle or a mixture of different kinds of particles. Therefore, the pressure exerted by a mixture of gases can be expressed as follows: P_total = (n_1 + n_2 + n_3 + ..)RT/V = n_total RT/V A partial pressure is the pressure exerted by just one type of gas in a mixture. A partial pressure is calculated using only the number of moles of that particular gas, instead of the total number of moles: P_1 = n_1RT/V, P_2 = n_2RT/V, P_3 = n_3RT/V, etc. The sum of the partial pressures is equal to the total pressure in the mixture: P_total = P_1 + P_2 + P_3 + .. What is the partial pressure of nitrogen in air at atmospheric pressure (1 atm)? Assume ideal behavior. Express your answer to three significant figures and include the appropriate units. What is the partial pressure of oxygen in air at atmospheric pressure (1 atm)? Assume ideal behavior. Express your answer to two decimal places and include the appropriate units.Explanation / Answer
Part A) The air contains 78.0% of N2 in the atmosphere. Suppose if we consider 1mole of air, the percentage of N2 is 0.78%
The molefraction of N2 = moles of N2/total moles = 0.78 mole/1mol = 0.78
The partial pressure of N2 = molefraction*total pressure = 0.78*1 atm = 0.78 atm
Part B) The air contains 21.0% of O2 in the atmosphere. Suppose if we consider 1mole of air, the percentage of O2 is 0.21%
The molefraction of O2 = moles of O2/total moles = 0.21 mole/1mol = 0.21
The partial pressure of O2 = molefraction*total pressure = 0.21*1 atm = 0.21 atm