Ch. 10, 14.2, 14.3 thermodynamics                 test                   70 points                                  honors chemistry

Show your work in an organized manner, include (i) any relevant equation (or formula), (ii) conversion factor(s), (iii) put the proper units in your calculations and answer, and (iv) have the proper number of significant figures in your answer.

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

                                                                                                Signature:  ___________________

1. How much heat would be needed for 10.0 g of Ethanol, C2H5OH, at – 35 ºC goes to 85 ºC ? [20 points]

melting point = - 114 ºC
boiling point = 78 ºC

ΔHfusion = 5.02 kJ / mol
ΔHvaporization = 38.6 kJ / mol

specific heat (J / (g ºC))
solid = 0.97
liquid = 2.3
gas = 1.88

2. 50.0 g of a metal in a 95 ºC water bath is transferred to 45 mL water at 21 ºC ; what is the final temperature of the metal ?  Assume that the metal’s specific heat is 0.35 J / (g ºC).  [10 points]

3. What is the ΔS of the below reactions ?  That is, it’s positive, negative, zero, or ambiguous.  Justify / rationalize your answer. [15 points]

a.  Mixing aqueous solutions of silver nitrate and sodium bromide ?

b.  C2H5OH(g)  +  O2(g)  →  CO2(g)  H2O(g)

c.  Condensation of a chemical

4. How much heat would be generated in the combustion of 5.0 g of butane, C4H10 ?  Assume all chemicals in the reaction are gases.  [15 points]

5. Would the below reactions be spontaneous ?    If it depends on the temperature, specify when it would be spontaneous – at a high or low temperature.  Justify / rationalize your answer using concepts of thermodynamics.  [10 points]

a.  The combustion of butane [hint:  see question 4]

b. Dissolve solid ammonium nitrate in water.  [hint:  enthalpy lab]