Physical Properties Demonstration

1
Physical Properties Demonstration

• Why is there a difference in the behavior of the
  two cans of soda? (Hint think about what is
  contained in each can.)

2
Density Demonstration
Density mass/volume Assume the density of H2O
1g/mL Estimate what is the density of diet
soda? What is the density of regular soda? Which
can weighs more? How do you know?
3
The early Earth

• Density of Elements and Compounds has, in a large
  part determined their distribution on the planet
• Volcanic gases include H2, O2, H2O, CO2 (carbon
  dioxide), N2, CO (carbon monoxide),

4
Given these densities, which gases in the early
earth do you think stayed close to the planet and
which escaped into space? Why?


Density (g/mL)
Hydrogen (H2) 8.988 x 10-5
Nitrogen (N2) 1.25 x 10-3
Carbon Monoxide (CO) 1.25 x 10-3
Carbon Dioxide (CO2) 1.977 x 10-3
Hydrochloric Acid (HCl) 1.00045 x 10-3
Which important gas present on earth today is
missing from this list?
5
Carbon Cycle

• Carbon is exchanged between the atmosphere and
  the land and water reservoirs on Earth. The
  existing cycles remove about as much carbon as
  they add, but human activity is currently
  increasing atmospheric carbon by about 3 bmt per
  year

6
Chemical Reactions

• Photosynthesis
• Carbon dioxide in the atmosphere is converted
  into sugar.
• Solar energy 6CO2 6H2O ? C6H12O6
  6O2
• Carbon Dioxide Water Sugar Oxygen
• The solar energy is converted into stored
  chemical energy in the form of sugar

7
Chemical Reactions continued

• Chemical reactions involve a rearrangement of
  atoms as they change from one substance to
  another
• Use formulas rather than names
• Starting materials on left, products on right
• ? means yields
• means reacts with
• Atoms on left must equal atoms on right

8
Photosynthesis a chemical reaction

• 6CO2 6H2O ? C6H12O6 6O2
• Balanced?

9
Reaction of Mg and HCl

• Where did the Mg go?
• What evidence do you have that a reaction took
  place?
• Reaction

10
Balancing Reactions

• Balance
• Na Cl2 ? NaCl
• NO2 H2O ? HNO3 NO
• KI Pb(NO3)2