Thermodynamics

Total Flash Cards » 41
 
1. 

1st law of thermodynamics

 

the total energy of the universe is constant

 
2. 

2nd law of thermodynamics

 

the total entropy of the universe is always incresing

 
3. 

3rd law of thermodynamics

 

the entropy of every pure perfectly formed crystalline substance at absolute zero is zero

 
4. 

a negative delta H is what kind of reaction?

 

exothermic

 
5. 

a positive delta H is what kind of reaction?

 

endothermic

 
6. 

definition of entropy

 

measure of disorder

 
7. 

4 rules of entropy

 

1. gases have greater entropy than liquids
2. liquids have greater entropy than solids
3. entropy of a system increases as temp increases
4. in a chemical reaction the side with more mols has greater entropy

 
8. 

thermochemistry

 

the heat changes that occur during chemical reactions

 
9. 

energy

 

the capacity for doing work or supplying heat

 
10. 

what is the energy stored in chemical bonds called?

 

chemical potential energy

 
11. 

heat

 

energy that transfers from one object to another becuase of a temperature difference between them.

 
12. 

calorie

 

the quantity of heat needed to raise the temp of 1g of pure water 1 degree C

 
13. 

kilocalorie

 

equal to 1000 calories

 
14. 

joule

 

the SI unit of heat and energy named after the English physicist James Prescott Joule

 
15. 

how many joules in 1 calorie?

 

4.184 Joules

 
16. 

Heat capacity

 

the amount of heat needed to increase the temp of an object exactly 1 degree C

 
17. 

Specific heat capacity

 

the amount of heat it takes to raise the temp of 1g of the substance 1 degree C

 
18. 

calorimeter

 

a device for measuring heat changes

 
19. 

enthalpy

 

the heat content of a system at constant pressure

 
20. 

what does delta H stand for?

 

heat of reaction or enthaply of reaction

 
21. 

Hess's law

 

if you add two or more thermochemical equations to get the final equation, then you can also add the heat of reaction to five the final heat reaction.

 
22. 

standard heat of formation

 

the change in enthaply that accompanies the formation of one mol of a compound from its elements with all substances in their standard states at 25 degrees C

 
23. 

free energy

 

energy that is available to do work

 
24. 

spontaneous reactions

 

reactions that occur naturally and that facor the formation of products at the specified conditions

 
25. 

nonspontaneous reactions

 

reactions that do not facor the formation of products at the specified conditions

 
26. 

standard entropy

 

the entropy of a substance in its stable state at 25 degrees C

 
27. 

Gibb's free energy

 

the maximum amount of energy that can be coupled to another provess to do useful work

 
28. 

CaCO3(s) + 176kJ ----> CaO(s) + CO2(g)
a. caculate the energy required to decompose 5.20 mol of CaCO3

b. how many kcal are required?

 

a. 915 kJ

b. 219 kcal

 
29. 

SO3 + H2O -----> H2SO4 + 129.6 kJ

how much heat in kJ and kcal is released when 583 grams of SO3 reacts with water?

 

a.

 
30. 

2CO2 + 43.9 kJ ----> 2CO + O2

how many molecules of CO2 can be decomposed by the addition of 22.2 kJ of heat?

 

6.09x10^23 molecules

 
31. 

2C2H6(g) + 7O2(g) ---> 4CO2(g) + 6H2O(l)

calculate delta H, delta S, and delta G

 

a. H= -3119.6 kJ/mol

b. S= -620.7 J/kmol

c. G= -2934.57 kJ/mol

 
32. 

2NO2(g) ---> N2O4(g)

calculate delta H,S and G

 

 
33. 

2Fe + 3CO2 + 26.3kJ ---> Fe2O3 + 3CO

a. calculate kJ for 7.3 mols of Fe

b. is this a positive or negative enthalpy change?

 

a. 96 kJ

b. positive

 
34. 

2Mg + O2 ----> 2MgO + 288kcal

a. calculate kcal for 0.12 mols of Mg

b. calculate kJ

 

a. -17kcal

b. -71kJ

 
35. 

C2H4 + 3O2 ----> 2CO2 + 2H2O + 1.39x10^3

calculate the heat for 1.87g of C2H4

 

-92.7kJ

 
36. 

I2(s) ----> I2(g)

calculate delta H,S and G

 

H=62.438 kJ/mol

S=144.56 J/kmol

G=19.327 kJ/mol

 
37. 

3CO(g) + Fe2O3(s) ----> 2Fe(s) + 3CO2(g)

calculate delta H,S and G

 

H= -24.7 kJ/mol

S= 16.36 J/kmol

G= -29.4 kJ/mol

 
38. 

2NO2(g) ---> 2NO(g) + 2H2O(g)

calculate delta H,S and G

 

H= -369.5 kJ/mol

S= 319.05 J/kmol

 
39. 

2NO(g) + O2(g) ----> 2NO2(g)

calculate delta H,S and G

 

H= -144.1 kJ/mol

S= -146.54 J/kmol

 
40. 

2HF(g) ---> H2(g) + F2(g) at 1030. C

calculate delta H,S and G

 

H= 542.2 kJ/mol

S= -14.10 J/kmol

G= 560.6 kJ/mol

 
41. 

NaOH(s) + HCl(aq) ---> NaCl(aq) + H2O(l)

at 85.0 C

calculate delta H,S and G

 

H= 100.33 kJ/mol

S= 64.4 J/kmol

G= -123.4 kJ/mol