Chem 106 Practical Everyday Chemistry ENERGY Dr. Ron Rusay Diablo Valley College Spring 2003

Energy  Energy can be defined as the capacity to do work.  Can you name other types of energy?  Chemical Energy is defined as heat.

Temperature v. Energy  Temperature reflects random motions of particles; i.e. the kinetic energy of a system.  Heat involves a transfer of energy between 2 objects due to different energies and temperature differences. Always: HOT -> cold

Heat Transfer  Have you ever burned the roof of your mouth?

Heat Capacities

Greenhouse Gases

What is a greenhouse gas? The sun’s energy & the molecule’s shape decide. Our atmosphere (air) is 78% nitrogen and 21% oxygen.Our atmosphere (air) is 78% nitrogen and 21% oxygen. Neither are greenhouse gases. They do not absorb infrared radiation (heat).Neither are greenhouse gases. They do not absorb infrared radiation (heat). However, H 2 O and CO 2 can absorb infrared energy. Without them earth would be very chilly.However, H 2 O and CO 2 can absorb infrared energy. Without them earth would be very chilly.

What does a molecule’s shape have to do with heat absorbance? …How can and a TV remote be used to show the difference?

Infrared Absorbance Remote TV

Infrared Absorbance Sample TV Remote

Infrared Absorbance & Molecular Vibrations Stretching & Bending

Infrared Absorbances: Molecular Shapes & Vibrations Stretching & Bending in Water Antisymmetric Stretching Bending Symmetric Stretching Molecules & Science are NOT passive!

Measuring Infrared Absorbance An Infrared Spectrophotomer

Infrared Spectra: Nitrogen & Oxygen produce flat lines: 100% Transmission, 0 Absorbance

Combustion  Energy = Carbon Why has CO 2 been increasing?

2 C 8 H 18(l) + 25 O 2(g) -----> 16 CO 2(g) +18 H 2 O (l) Combustion of Octane: + HEAT

Using the Energy from Burning Gasoline

Human factors: Atmospheric Changes in CO 2 Correlating Mauna Loa, Hawaii with 8 other global sites Direct atmospheric CO 2 measurements and reconstructions from measurements of air bubbles trapped in ice.

Human factors: Atmospheric Changes in CO 2 and Temperature Temperature CO 2 concentration

Heats of Combustion  Combustion of octane releases 5,470 kJ per mole of octane (  H comb = -5,470 kJ/mol)  How many pounds of CO 2 are added to atmosphere from burning 1 gallon of gasoline?

2 C 8 H 18(l) + 25 O 2(g) -----> 16 CO 2(g) +18 H 2 O (l) 1 Gallon Octane  ~ 2.6 kg (~ ? lbs) + ~ 9.2 kg Oxygen (~ 20 lbs) CO 2  ~8.1 kg CO 2 (~18 lbs) + ~ 3.7 kg Water (H 2 O) (~8 lbs) Combustion of Octane: + HEAT

What can be done to reduce the rate of increase of CO 2 ? What do you drive?

What can be done to reduce the rate of increase of CO 2 ? Cutting back on driving? How many pounds of CO 2 do you produce each year from driving? Estimated driving miles / week? ____ mi/week Your vehicle’s gas mileage___ mi/gal (national avg = 25 mi/gal) 18 lbs/gal x 52 weeks/yr x ___ mi/week ÷ ___ mi/gal = ____ lbs CO 2

What can be done to reduce the rate of increase of CO 2 ? Estimated driving miles / week? _200_ mi/week Vehicle’s gas mileage_25_ mi/gal (national avg) 18 lbs/gal x 52 weeks/yr x _200_ mi/week ÷ _25 _ mi/gal = _ 7488 _ lbs About 3.5 tons of CO 2 per student per year!About 3.5 tons of CO 2 per student per year! 75% of the electricity generated in California comes from burning carbon fuels. When finished turn off lights & electrical devices….. Including Computers! The average miles driven per week by a DVC student is about 200 mi/week.

Does Oil play a role in public policy?