1) Predict the sign, (+) or (-), for∆H and ∆S for the following reactions.

2 C(s) + O (g)         2CO(g)                             ∆H: _____                ∆S: _____

CO₂ (s)      CO₂ (g)                                         ∆H: _____                ∆S: _____

N₂(g) + 3H₂(g)     2NH₃(g)                              ∆H: _____                ∆S: _____

2) Use the standard entropy valuesbelow to calculate the entropy change(∆S^o_rxn) for the following balanced equation.N₂ (g) + 2 O₂ (g) --> 2 NO₂(g)

Species        S^{o ,(J/K*mol)}   

N₂(g)           191.5                             

O₂(g)           205.0                                                 

NO₂(g)        240.0

3) A reaction for which ∆H and ∆Sare both negative will be:     

a. spontaneous at hightemperatures.

b. spontaneous at low temperatures.

c. spontaneous at all temperatures.

d. never be spontaneous

e. more information is needed to determine spontaneity.

Answers I got: 1) - + , + - , + - 2) -121.5 3) I think itsA.

Thanks