1. Chapter 4 (CIC) and Chapter 5, 8 (CTCS) Read in CTCS Chapter 5.1,3-4, 8.9 Problems in CTCS: 5.3, 13, 15, 22, 23, 29, 35, 90, and 8.63, 65, 67, 69

2. Global Warming (CO 2 )  Fuel Fuel’s are typically fossil fuels (crude oil, coal) Gasohol is a mixture of ethanol and gasoline  CH 2 =CH 2 + H 2 O  CH 3 CH 2 OH  C 6 H 12 O 6  CH 3 CH 2 OH + CO 2 Does EtOH give same performance as gasoline? Does EtOH give the same amount of energy per gram? 1 st Law – If we have Conservation of Energy, why are worried about depleting our resources?

3. Annual US Energy Consumption From Various Sources

4. Combustion All but two of those energy sources were based on combustion giving CO 2 as a byproduct Energies can be obtained from a calorimeter Q: Determine the heat of combustion for a gram of natural gas (CH 4 ) compared to a gram of butane (C 4 H 10 ) if their heats of combustion are –802.3 and –2658.4 kJ/mol respectively. A:-50.01 kJ/g and –45.74kJ/g

5. Energy Diagram Reactants Products Enthalpy Reaction Progress  H rxn

6. Where does the exothermic energy come from? When bonds are broken, energy is required When bonds are made, energy is released Compare the bond strengths in the equation above (See Table 8.4 - pg 289) The products are: –More stable –Lower in Energy –Have stronger bonds

7. CO 2 and H 2 O are too stable (have bonds that are too strong) to decompose and give off more energy Q: Could you use ozone as a fuel? How much energy is released/g of ozone? (Use bond energies to calculate) A: -2.11 J/g (-2.96 kJ/g according to  Hº f ) Bond Energies are averages of gas molecules  Hº f – enthalpy of formation in standard state (º)

8. Q: Using bond energies, calculate the heat of reaction for the combustion of molecular hydrogen and 1 mol of oxygen to form gaseous products A: -485 kJ (actual = -483.6 kJ) Q: Would you expect a more endo- or exo-thermic reaction if the products were liquid?

9. H 2 O (g)  H 2 O (l)  H = negative,WHY? 2 H 2 (g) + O 2 (g)  2 H 2 O (l) Can’t use bond energies!  Hº rxn = -571.7 kJ Spontaneity (  G) –If you have a large negative  H, you can assume spontaneity Q: What are some of the strongest bonds?

10. Triple: N  N, C  O; Double: C=O; Single: O-H, Si-O This suggests that these bonds would have trouble reacting 2 C  O + O=O  2 O=C=O  Hº rxn = -566 kJ Explosives –Should have many weak bonds –Ideally have all atoms of reaction self contained –Need to be stable enough to work with –Should create gaseous molecules

11. Nitroglycerin What are the products of decomposition? Q: What is the  H rxn /mol of nitro? (why not  Hº rxn ?) A: -1782 kJ