Bio-Chem Notes 5/8/2013 12:44:00 PM
Chemistry – is the study of matters and its changes
Matter – is anything that has mass and volume
History of matter – Thales to Aristotle … Four types of matter, joined by 4
principles. Thomas Jefferson and everyone for 2 thousand years subscribed
to this idea.
Hot Air moist
Dry Earth cold
Chapter 1 – The Air we breathe
Clean Air – The composition of Our air
Nitrogen 78 percent
Oxygen 21 Percent
Other Gasses 1 Percent
- Even though air might smell different, it will still only be less than one
percent ambient air
- To be considered air, we have to be able to breathe it.
Pure Substance Mixture
Air is a mixture
So what is a pure substance? – Only one type of item. So a mixture is
comprised of pure substances.
Comprised of molecular oxygen
Mollecular Nitrogen, etc.
- 78 percent really just means 78 parts per hundred.
-Is nitrogen (molecular)
21 percent / pph – is molecular oxygen
1 pph others
o Nitrogen remains unchanged when we breathe, because our
bodies don’t have the ability to change molecular nitrogen –
we get our nitrogen from food.
o Nitrogen is neccesarily as a basic building block for amino
acids. Required to make us “who we are” is the presence of
nitrogen. o Typical composition of inhaled and exhaled air
substance Inhaled Air Exhaled air
Nitrogen 78 78
Oxygen 21 16
Argon 0.9 0.9
Carbon Dioxide 0.04 4.0
Water Vapor Variable Variable
- Concentration Terms 1.2
Parts per Hundred (Percent)
o Atmosphere is 21 % oxygen = 21 oxygen molecules per 100
molecules and atoms in air
Parts per million (ppm)
Midday ozone levels reach about 0.4 ppm
0.4 ozone molecules
1 x 10^6 molecules and atomos in air
- So our units are not appropriate to describe
the concentration of this pollutant
- So we have to look in terms of billions of
0.0390 pph -- so pph doesn’t work well for gasses that are
below one percent.
0.0390 – parts per thousand -- 0.390 ppthousand
3.90pp ten thousand
??? in ppb?
Parts per billion (ppb)
o Sulfur dioxide in the air should not exceed 30 ppb
o 30 sulfur dioxide molecules
o 1x10^9 molecules and atoms in air Basically like working wi