CHEM 1515 Spring 2015 ACA3

Last modified: Wed 12/31/1969 06:00:00 pm CHEM 1515 Spring 2015 ACA3

Oklahoma State University

This is ACA # 3. It is OK to use your textbook or lecture notes from class, but if you can answers the questions without it that is OK too.

Do not press the RETURN or ENTER key while you are answering these questions. Your browser will interpret either the same as clicking on the Submit key.

Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.

The ACA should be completed by Monday, January 27, 2014 at 11:59 pm.

First Name:

Last Name:

Laboratory Section:

1. For each of the following reactions predict the sign of S.

a. CS₂(l) + 3O₂(g) ---> CO₂(g) + 2SO₂(g)

b. NH₄NO₂(s) --heat--> N₂(g) + 2H₂O(g)

c. KNO₃(s) --H₂O(l)--> K⁺(aq) + NO₃^-(aq)

2. Calculate G°_rxn for the following reaction. (Here is a table that includes thermodynamic values.) (Note: Use the mathematical relationship )

C₂H₅OH(l) + 3O₂(g) ---> 2CO₂(g) + 3H₂O(l)

kJ mol^-1

3a. For the reaction

H₂O(g) ---> H₂(g) + 1/2O₂(g)

H° is +242 kJ mol^-1 and S° is 45 J mol^-1 K ^-1.

Calculate G° for this reaction at 298 K. (Note: Use the mathematical equation G° = H° - TS°)

kJ mol^-1

b) Is the reaction spontaneous at 298 K? (Yes/No)

c) Is the reaction spontaneous at 1000 K? (Yes/No)

d) Calculate the temperature at which the reaction becomes spontaneous. K

4. Complete the following table

H° (kJ mol^-1)	S° (J mol^-1 K ^-1)	G° (kJ mol^-1)	Temperature (K)
-	+	-	all temperatures
-	-	- +	low temperature high temperature
+	+
+	-

5. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

6. If there is one question you would like to have answered in lecture, what would that question be?