 ON7AMI Amateur Radio, Meteology and Astronomy website. JO10UX # 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.

In :
# 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


 سُوۡرَةُ حٰمٓ السجدة / فُصّلَت ثُمَّ اسْتَوَىٰ إِلَى السَّمَاءِ وَهِيَ دُخَانٌ فَقَالَ لَهَا وَلِلْأَرْضِ ائْتِيَا طَوْعًا أَوْ كَرْهًا قَالَتَا أَتَيْنَا طَائِعِينَ ﴿١١ فَقَضَاهُنَّ سَبْعَ سَمَاوَاتٍ فِي يَوْمَيْنِ وَأَوْحَىٰ فِي كُلِّ سَمَاءٍ أَمْرَهَا ۚ وَزَيَّنَّا السَّمَاءَ الدُّنْيَا بِمَصَابِيحَ وَحِفْظًا ۚ ذَٰلِكَ تَقْدِيرُ الْعَزِيزِ الْعَلِيمِ ﴿١٢ Surah Fussilat: Thereafter turned He to the heaven and it was as smoke, and said Unto it and Unto the earth: come ye twain, willingly or loth. They said: we come willingly. (11) Then He decreed them as seven heavens in two days, and revealed Unto each heaven the command thereof; and We bedecked the nether heaven with lamps and placed therein a guard. That is the ordinance of the Mighty, the Knower. (12) De hemelen en aarde (waren) een samenhangende massa. Wij hebben ze toen van elkaar gescheiden… Wij hebben de hemel tot een beschermend dak gemaakt … en de dag en de nacht, de zon en de maan geschapen. (Koran 41 11:12) Copyright (c) 2000-2020 - Jean Paul Mertens - ON7AMI - formal ON1AMI - Grote Steenweg 86 - 9840 Zevergem - Belgium - Europe