1. Chapter 16!!! start with some basic terms- 1st law of thermodynamics spontaneous processes explain figure 16.2 entropy positional probabililtly second law of thermodynamics and the equation that goes with it!

3. This chapter is all about energy. Where it comes from, where it goes, how it gets there and changes. The 1st LTHERMO says energy can't be created or destroyed, only changed. THat is great, but where does it go and why?

4. Spontaneous process- something that happens all by itself. you can look at all the things that effect a reactions, the temperature, (the catalyst the activation energy, the concentrations,) or you can look at the beginning and end only we will start with beginning and end only

5. entropy- the measure of disorder. All reactions proceed towards entropy naturally it is the idea of what is most likely to occur, or what gives the greatest options tied to positional probability cause it gives the highest available positions for the molecules

6. H H H H H H H H H H H H HHHHH what? p.p means what is most probable, or likely. which of the following arrangements is most likely? that the atoms would line up neatly? that the atoms would be close? or just that the atoms would be in the jar? yep, just that they would be there. most probable, highest p.p., most entropy

7. 2nd L oT ΔS universe = ΔS of system +Δ S surr the universe is always headed to disorder, so to know if something is spontaneous, you look at the reaction ( whatever you are wanting to happen) and the surrounds ( the air/stuff around the reaction ClCl ClCl ClCl ClCl ClCl ClCl ClCl ClCl ClCl ClCl

8. which of these has the most positional entropy, and why- 1 mol CO2 gas, 1 mol CO2 solid 2 mol gas at 1 atm, 2 mol gas at.001 atm

9. gases have more entropy than liquids, which have more entropy than solids. greater entropy is noted with a positive sign ( +S) and less with a negative ( -S) Exothermic reactions are +S surrounding endothermic reactions are -S surrounding

10. in endothermic reactions- heat flows from surroundings to system in exothermic, heat goes from system to surroundings ΔS surr is neg What are the signs for ΔS? ΔS system is pos ΔS surr is positive ΔS system is negative

11. so, lets look at signs for system... water turning to steam chocolate melting freezing soda in your car in winter ice melting? bike rusting balloon exploding burning gummy bears roasting marshmallow loading a city bus w/ grownups making coffee?? wreck your car fixing your car + -

12. 2nd L oT ΔS universe = ΔS of system +Δ S surr want ΔS univ. to be positive, that denotes spontaneous processes ΔS of system Δ S surrΔS universe spontaneous? + _ + ++ + __ _ _ ? ? Yes no, proceed other way yes, if sys is larger than surr yes if surr larger than sys

13. Using tables of entropy of formation you can figure out mathmatically how likely a reaction is to occur use the tables on page a19- a21. find the entropy of each part, and add them up! Numbers are figured in joules per Kelvin ΔS reaction = ΣnS products -ΣnSreactants

14. lets try one! predict the sign of S then calculate the sign of S for the following reaction 2H 2 S g + SO 2 g = 3S rombic s + 2 H 2 O g you would predict ____ cause of the states of matter ΔS reaction = ΣnS products -ΣnSreactants

15. 2H 2 S g + SO 2 g = 3S rombic s + 2 H 2 O g heats of formation are as follows (see pg a19) 2H 2 S g = 206 ( 2) SO 2 g = (248) 3S rombic s = ( 32 ) 3 2 H 2 O g =(189) 2

16. 2H 2 S g + SO 2 g = 3S rombic s + 2 H 2 O g heats of formation are as follows (see pg a19) 2H 2 S g = 206 ( 2) SO 2 g = (248) 3S rombic s = ( 32 ) 3 2 H 2 O g =(189) 2 so ΣS products is 96 + 378=474 and ΣS reactants is 412 + 248 =660 so your total is 474 - 660 = -186, which is what we expect. a negative number.

17. But more importantly is something called free energy G = H - TS want G to be negative, so that the free energy of the universe increases, this is a spontaneous reaction - - + = spontaneous

18. G = H - TS - - + = spontaneous - + = spontaneous at high temp - = spontaneous at low temp - + = not!spontaneous + check pg 761 + - + click me

19. so... if the reaction is exothermic, giving off - 45 kj heat and the temperature is 290 K, the entropy is + 3.0, what is the free energy, and is the reaction spontaneous?

20. so... if the reaction is exothermic, giving off - 45 kj heat and the temperature is 290 K, the entropy is + 3.0, what is the free energy, and is the reaction spontaneous? G = H - TS H T S want it to be negative

21. so... if the reaction is exothermic, giving off - 45 kj heat and the temperature is 290 K, the entropy is + 3.0, what is the free energy, and is the reaction spontaneous? G = H - TS H T S want it to be negative G = -45 - ( 290 * 3.0) G = -45 - (870) G = -915, so this is spontaneous!

22. free energy and work hypothetically work = change in free energy that means that the free energy of the universe is available to do work w max = ΔG

23. In reality, all real processes lose energy as they occur. free energy = some work all real processes are irreversible. Useful energy is lost along the way examples? explain the following food web sunlight car engine. the amount of fossil fuel we have/can get work is changed into heat, and entropy of the universe increases.

24. The 1st Law of Thermodynamics says energy can't be created or destroyed, only changed. the thermodynamist Henry Bent says 1st law You can't win, only break even 2nd law you can't break even 2nd Law of Thermodynamics For any spontaneous process there is always an increase in entropy