[Thermodynamics] Density of Air

2021-09-27 16:36 作者:AoiSTZ23 0人读过 | 我要投稿

By: Tao Steven Zheng (郑涛)

【Problem】

The composition of air is roughly 80% nitrogen and 20% and oxygen. Calculate the density of air under normal temperature and pressure conditions (NTP).

NTP is defined as the condition when temperature is 20 degrees Celsius and the pressure is 1 atmosphere.

【Solution】

Step 1: Calculate Mass
Nitrogen and oxygen gas are diatomic, so the molar mass is

$%200.80%20%5Cleft(2%20%5Ccdot%2014.01%20%5C%2C%20%5Cfrac%7Bg%7D%7Bmol%7D%20%5Cright)%20%2B%200.20%20%5Cleft(2%20%5Ccdot%2016.00%20%5C%2C%20%5Cfrac%7Bg%7D%7Bmol%7D%20%5Cright)%20%3D%2028.80%20%5C%2C%20%5Cfrac%7Bg%7D%7Bmol%7D%20$

To calculate the mass of 1 mole of air is

$%20%5Cleft(1%20%5C%2C%20mol%20%5Cright)%20%5Cleft(28.80%20%5C%2C%20%5Cfrac%7Bg%7D%7Bmol%7D%20%5Ctimes%20%5Cfrac%7B1%20%5C%2C%20kg%7D%7B1000%20%5C%2C%20g%7D%20%5Cright)%20%3D%200.02880%20%5C%2C%20kg%20$