Chemistry 101 - H
Arithmetic of Chemistry
Chapter 9 - Arithmetic of
Chemistry
This presentation was created by
Professor Carl H. Snyder
Chemistry Department
University of Miami
Coral Gables, FL 33124
[email protected]
Copyright 2004 by Carl H. Snyder,
University of Miami. All rights
reserved.
Quantities of Everyday Things
2 Socks = 1 pair of
socks
6 Cans of soda = 1
six-pack of soda
12 Eggs = 1 dozen
eggs
100 Paper clips = 1
box of paper clips
Balanced Equations
The Chemistry of a Charcoal
Grill
As the carbon of the charcoal briquettes in a
backyard grill burns:
One atom of carbon and one diatomic
molecule of oxygen combine to form one
molecule of carbon dioxide:
1C + 1O2 ---> 1CO2
or more simply
C + O2 ---> CO2
The reaction releases heat.
Counting Atoms and
Molecules: Part I
Carbon dioxide formation:
C + O2 ---> CO2
C + O=O ---> O=C=O
Carbon monoxide formation:
2 C + O2 ---> 2 CO
C, C, O=O ---> CO, CO
How much oxygen reacts with one 36 g
charcoal briquette to produce CO2?
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Counting Atoms and
Molecules by Weight Ratios
The Mole
For C + O2 ---> CO2
32 amu (1 molecule) of O2 will react with 12
amu (1 atom) of C, and . . .
32 g of O2 will react with 12 g of C.
The Mole and Avogadro’s Number
The Mole - Atoms and Molecules
A mole is simply a number of
chemical particles, just as a
dozen is a number of eggs.
One mole of:
lead atoms
carbon atoms
water molecules
sulfur atoms
Each contains 6.02 x 1023
atoms or molecules.
The Mole - Atoms and Molecules
In the can there are
3.68 x 1023 atoms of
aluminum.
In the coin there are
1.58 x 1023 atoms of
silver.
In the glass there are
79 x 1023 molecules of
water.
Avogadro’s Number of
Pennies - Part 1
Stacked in columns of 400 pennies each, 6.02 x
1023 pennies would fill all the space within the
moon’s orbit around the earth.
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Avogadro’s Number of
Pennies - Part 2
Counting Atoms and
Molecules: Part II
Distributed equally to everyone in the
earth's population of about 6 billion
people, a mole of pennies would give
each of us a trillion dollars.
A Dozen Paperclips, A Mole of
Carbon Atoms
A dozen paperclips weighs 12 g
You have 36g of paperclips.
How many dozen paperclips do you have?
A mole of carbon weighs 12 g
You have 36 g of carbon.
How many moles of carbon do you have?
How many carbon atoms do you have?
Molarity
Molarity = moles / liter
The Concentration of
Solutions
Solute - the lesser
substance
Solvent - the greater
substance
Solution - a mixture of
a solute and a solvent
Concentration - the
quantity of solute per
unit (volume or weight)
of solution.
Other Measures of Concentration
Percentage Concentration
Percentage
concentration amount of solute per
100 g (weight) or 100
mL (volume) of
solution.
Vinegar contains
acetic acid at a
concentration of 5
percent by weight.
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Percentage Concentrations of
Some Ordinary Solutions
Other Measures of Concentration
Parts Per Million (ppm)
Ppm is equivalent to milligrams of solute per
kilogram of solution (mg / kg)
Bottled Water
Legal Limits of Impurities in
Our Drinking Water
Concentrations of cations in bottled water
The Glass Where Pollution
Begins
End - Chapter 9
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