Name:  ______________________                                        date:  _______________

Ch.  10 & 14 thermodynamics            test  [70 points]           Chemistry

For problems involving calculations, show your work in an organized manner, includes any relevant formula / equation, the proper units in your work / answer, and the proper number of significant figures in your answer.

 

1.  Ethanol, C2 H5 OH, has the following properties


Melting point = - 114C
Boiling point = 78 C

∆Hfusion = 5.02 kJ /mole                           specific heat of solid = 0.97 J / g K
∆Hvaporization = 38.56 kJ / mole                specific heat of liquid = 2.3 J / g K

How much heat is needed to completely vaporize 25 grams of ethanol at – 130 ◦C ?  [20 points]


2.  fill-in the below table:  +, -; specify any conditions.  [12 points]

∆G

∆H

∆S

 

+

+

 

-

-

 

+

-

 

-

+

 

3.  The combustion of 1.0 grams of peanut raised the temperature of 50. mL water from 22 C to 33 C.  What is the ∆Hreaction (in kJ / mole) of the combustion of peanut ?  Assume that peanut contains a single chemical and its molar mass is 30. g/mole.  [15 points]


4.  Based on the following chemical reaction, answer the below questions:  [25 points]

2 CH3 OH (g)   +  3 O2 (g)   ->  2 CO2 (g)   +  4 H2 O (g)                   ∆H = - 1453 kJ

a.  How much heat would be generated by the combustion of 10.0 grams of CH3OH ?

b.  What is ∆Sreaction (positive, negative, or ambiguous) ?  Justify / rationalize your answer.

c.  What is ∆Greaction (positive, negative, zero, or ambiguous) ?   Justify / rationalize your answer.

d.  Is the reaction spontaneous ?  Justify / rationalize your answer.