Question 73 - Review - Chapter 1

Problem:

Given is 1 $m^2$ lucht.

Density of air = 1.3 $kg/m^3$

We assume that the air contains only nitrogen gas $N_{2}$.

Question:

How many molecules are there in $cm^2$ of air?

Solution:

The formula of nitrogen gas is $N_{2}$

So we have two nitrogen atoms per molecule of gas.

# Berekeningen
import scipy.constants as physics
from mendeleev import N

N_A = physics.value('Avogadro constant')
Density = 1.3
Volume = 1

Weight = Density * Volume * 1000 / 100**3
print(f'The weight of 1 cm3 gas is Density * Volume = {Density} * {Volume} * 1000(1000g = 1kg) / 100^3(cm3)= {Weight} g')

print(f'The atomic mass of {N.name} is {N.atomic_weight}.')
N2_ag = 2 * N.atomic_weight
print(f'So the molecular weight of nitrogen gas is 2 * {N.atomic_weight} = {N2_ag}')
print('')
number_molecules = (N_A * Weight ) / N2_ag
print(f'The number of molecules in 1 cm3 of gas is Avogadro / MolecularMass times Weight of 1 cm3 gas')
print('')
print(f'- Number of molecules: {N_A} * {Weight} / {N2_ag}) = {number_molecules:5.3g}')

The weight of 1 cm3 gas is Density * Volume = 1.3 * 1 * 1000(1000g = 1kg) / 100^3(cm3)= 0.0013 g
The atomic mass of Nitrogen is 14.007.
So the molecular weight of nitrogen gas is 2 * 14.007 = 28.014

The number of molecules in 1 cm3 of gas is Avogadro / MolecularMass times Weight of 1 cm3 gas

- Number of molecules: 6.022140857e+23 * 0.0013 / 28.014) = 2.79e+19