Question

At this point Ron is slightly confused, this isn’t surprising. However, Hermione is doing rather well with them. This also isn’t surprising since she studies every day, as should all students. She feels she can help him understand these problems by working with him though another: A 1.00 L sample of dry air contains 0.0319 mol N2, 0.00856 mol O2, and 0.000381 mol Ar. If temperature is 25.0◦C what is the partial pressure of N2? Express your answer in atmospheres.

Answer 1

Answer:

$\boxed{\text{0.780 atm}}$

Explanation:

Hermione is pretty smart. She realizes that, according to Dalton's Law of Partial Pressures, each gas exerts its pressure independently of the others, as if the others weren't even there.

She shows Ron how to use the Ideal Gas Law to solve the problem.

pV = nRT

She collects the data:

V = 1.00 L; n = 0.0319 mol; T = 25.0 °C

She reminds him to convert the temperature to kelvins

T = (25.0 +273.15) K = 298.15 K

Then she shows him how to do the calculation.

$p \times \text{1.00 L} = \text{0.0319 mol} \times \text{L}\cdot\text{atm}\cdot\text{0.082 06 K}^{-1}\text{mol}^{-1} \times \text{298.15 K}\\\\1.00p = \text{0.7805 atm}\\\\p = \textbf{0.780 atm}\\\\\text{The partial pressure of the nitrogen is } \boxed{\textbf{0.780 atm}}$

Isn't she smart?