Question

Enter your answer in the provided box. On a certain winter day in Utah, the average atmospheric pressure is 718 torr. What is the molar density (in mol/L) of the air if the temperature is −29°C?

Answer 1

Answer:

The correct answer is 0.047 mol/L

Explanation:

The atmospheric air is a mixture of gases. We can assume an ideal behavior of the gas and use the ideal gas equation:

PV= nRT

where P is the pressure, V is the volume, n is the number of moles, R is a constant (0.082 L.atm/K.mol) and T is the temperature in K.

We have to first convert the pressure from Torr to atm:

760 Torr= 1 atm

⇒ 718 Torr x 1 atm/760 Torr = 0.945 atm

Then, we convert the temperature from ºC to K:

0ºC = 273 K

⇒ -29ºC+273= 244 K

Finally, we introduce the data in the equation and calculate de densitiy, which is the moles per liters of gas (n/V):

PV = nRT

n/V= P/RT

n/V = (0.945 atm)/(0.082 L.atm/K.mol x 244 K) = 0.047 mol/L