Chem 220   CC #7   5 points      Name _________________________________lab ____

A)    What will the sign on DS be for each of the following:

2 CH₃OH_(l)  + 3 O_{2 (g)}  à 2 CO_{2 (g)}  +  4 H₂O_(g)     _______

CaCO_{3 (s)} à CaO _(s) + O_{2 (g)                                                     __________}

      H₂O _(l) à H₂O _(s)                                                    _______

B)     The heat of vaporization of freon is 17.2 kJ/mole at 25 ^oC. What is the change in entropy for one mole of liquid freon when it vaporizes at 25 ^oC ?

C)    Calculate the temperature that a reaction would become spontaneous if  DH = 176 kJ and DS = 99 J/K ?

What is the driving force for this reaction?

D)    What does DG equal if the change in enthalpy is  - 110.5 kJ  and the change is entropy is 73 J/K at 35 ^oC ?

Is this reaction spontaneous at this temperature?

E)     Calculate DG for the following reaction.

2 HCN_(g)  +  5/2 O_{2 (g)} à  H₂O_(l)  + 2 CO_{2 (g)} +  N_2(g)

DG_f (kJ/mol)    121                   0               - 273.2        -394.4       0