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Home  arrow Chapter 19: Chemical Thermodynamics  arrow Homework 5

Homework 5



This activity contains 12 questions.

Question 1.

Calculate G° for the reaction below at 25°C.

2SO2(g) + O2(g) --> 2SO3(g)

SubstanceHf°(kJ/mol)S°(J/mol·K)
SO2(g)-297249
O2(g)0205
SO3(g)-395256
 
End of Question 1


Question 2.
Calculate G° in kJ for the following reaction at 25°C if the value of Keq is 6.1 x 10-58.

3O2(g) --> 2O3(g)

 
End of Question 2


Question 3.
For each of the following pairs, choose the substance with the higher entropy per mole at a given temperature:

(i) O2(g) at 5 atm or O2(g) at 0.5 atm, (ii) Br2(l) or Br2(g)

 
End of Question 3


Question 4.
For which of the following processes will S° system be the most positive?

 
End of Question 4


Question 5.
For which one of the following substances is Gf° zero?

 
End of Question 5


Question 6.

Given the following standard molar entropies, calculate S in J/K° for the reaction

C(s)+O2(g) -->CO2(g)

S° J/mol·K5.74205.0213.6
 
End of Question 6


Question 7.
The molar heat of vaporization for ethanol is 37.4 kJ/mol. If the boiling point of ethanol is 78.0°C, calculate S in J/K for the vaporization of 0.500 mol ethanol.

 
End of Question 7


Question 8.
Use data from Appendix C to calculate Kp at 298 K for the reaction

H2(g) + I2(g) 2HI(g).

 
End of Question 8


Question 9.

Use the following data to calculate G° in kJ at 155°C for the reaction

2O3(g)--> 3O2(g)

Hf°kJ/mol142.70

S°J/mol·K238.8205.0
 
End of Question 9


Question 10.

Which of the following conditions are true for a reaction that is spontaneous at low temperatures and becomes nonspontaneous at a higher temperature? (Assume that H and S do not change with temperature.)
 
End of Question 10


Question 11.
Which one of the following has the greatest entropy?

 
End of Question 11


Question 12.
Without consulting a table of values, predict the relative trend of entropy per mole for molecular oxygen, ozone, and monatomic oxygen gases under identical conditions.
c17ukc05.jpg

 
End of Question 12





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