Which of the following compounds has the lowest entropy at 25 oC?
Which of the following substances has the greatest entropy per mole?
Without consulting entropy tables, predict the sign of DS for the following process: Pb(s) + Cl2(g) ----> PbCl2(s).
|A)||DS < 0|
|B)||DS > 0|
|C)||DS = 0|
|D)||More information is needed to make a reasonable prediction.|
Using the data below, calculate DSorxn for the following reaction: 4 Cr(s) + 3 O2(g) ----> 2 Cr2O3(s).
|Substance||D S, J/K·mol|
|E)||None of the above.|
In 1774 Joseph Priestly prepared oxygen by heating mercury(II) oxide according to the reaction HgO(l) ----> Hg(l) + ½O2(g), for which DHo = 90.84 kJ/mol and DSo = 108 J/K.mol. Which of the following statements is true for this reaction?
|A)||The reaction is spontaneous only at low temperatures.|
|B)||The reaction is spontaneous at all temperatures.|
|C)||DGo becomes less favorable as temperature increases.|
|D)||The reaction is spontaneous only at high temperatures.|
|E)||The reaction is at equilibrium at 25 oC and 1 atm pressure.|
Is H2O2(g) stable? For the reaction H2O2(g) -----> H2O(l) + 1/2 O2(g),
DHo = -106 kJ/mol; DSo = 58 J/K.
|B)||Yes, if the temperature is low enough.|
|C)||Yes, if the rate of decomposition is low.|
|D)||Yes, if the O-O bond energy is greater than the O-H bond energy.|
|E)||Yes, under all conditions.|
The signs of DHo, DSo,
DGo for the vaporization of water at 50 oC are
|A)||positive, positive, and positive.|
|B)||negative, negative, and negative.|
|C)||positive, negative, and positive.|
|D)||positive, positive, and negative.|
|E)||More information would have to be given to answer the question.|
Use the following data to calculate
DGo at 298 K for the combustion of propane:
C3H8(g) + 5 O2(g)
----> 3 CO2(g) + 4 H2O(l)
|Substance||D Gof, kJ/mol|
|E)||None of the above.|
The heat of vaporization of 1-pentanol is 55.5 kJ/mol, and its entropy of vaporization is 148 J/K•mol. What is the approximate boiling point of 1-pentanol?
Calculate DGo for the dissociation of HF in H2O at 25 oC. [Ka of HF = 6.9 x 10-4 at 25 oC].
Spontaneous reactions occur in one direction only and are not spontaneously reversable in the opposite direction.
What is the best way to predict whether a reaction will be spontaneous?
|A)||Energy changes in a system|
|C)||Both entropy and change in enthalpy|
|D)||none of the above|
The greater the number of microstates the less likely the possibility of a spontaneous reaction.
Which statement is true concerning entropy?
|A)||An exothermic process results in a decrease in the entropy of the surroundings.|
|B)||An exothermic process transfers heat from system to surroundings.|
|C)||An endothermic process absorbs heat from within the system.|
|D)||An endothermic process increases the entropy of the surroundings.|
If the change in free energy is less than zero then
|A)||the reaction is spontaneous in the forward direction.|
|B)||the reaction is non-spontaneous or spontaneous in the opposite direction.|
|C)||the system is in equilibrium.|
|D)||none of the above.|