Content Frame
Note for screen reader users: There is text between the form elements on this page. To be sure that you do not miss any text, use item by item navigation methods, rather than tabbing from form element to form element.
Skip Breadcrumb Navigation
Home  arrow Chapter 19  arrow Problem Solving Center  arrow Practice Exercises

Practice Exercises



This activity contains 32 questions.

Question 1.

Which of the following processes are spontaneous and which are nonspontaneous: (i) separation of N2 and O2 molecules in air from each other, (ii) the reaction of sodium metal with chlorine gas to form sodium chloride, (iii) the dissolution of HCl(g) in water to form concentrated hydrochloric acid?

Online Text


Open Hint for Question 1 in a new window.
 
End of Question 1


Question 2.
The normal boiling point of ethanol is 78.5°C. Is the vaporization of ethanol an endothermic or exothermic process? In what temperature range is the vaporization of ethanol a spontaneous process?

Online Text


Open Hint for Question 2 in a new window.
 
End of Question 2


Question 3.
Consider the thermodynamic quantities E, q, and w. Which of these quantities are state functions?

Online Text


Open Hint for Question 3 in a new window.
 
End of Question 3


Question 4.
How does the entropy of the system change when each of the following occurs (i) a solid is melted, (ii) a liquid vaporizes, (iii) a gas liquefies?

Online Text


Open Hint for Question 4 in a new window.
 
End of Question 4


Question 5.

Mercury freezes at -38.9°C, and its enthalpy of fusion is 2.33 kJ/mol. Calculate the value of S for the freezing of 1.00 mol of Hg(l) at -38.9°C.

Online Text


Open Hint for Question 5 in a new window.
 
End of Question 5


Question 6.
Calculate the entropy change when 1.50 mol of an ideal gas expands at a constant temperature from an initial volume of 20.0 L to a final volume of 90.0 L.

Online Text


Open Hint for Question 6 in a new window.
 
End of Question 6


Question 7.

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)

Online Text


Open Hint for Question 7 in a new window.
 
End of Question 7


Question 8.

For each of the following processes, predict whether Ssys is positive or negative: (i) 2K(s) + Br2(l) --> 2KBr(s), (ii) 2MnO2(s) --> 2MnO(s) + O2(g)

Online Text


Open Hint for Question 8 in a new window.
 
End of Question 8


Question 9.

Using the tabulated values of S° in Appendix C, calculate the value ofS° for the reaction

C2H4(g) + H2(g) C2H6(g)

Online Text


Open Hint for Question 9 in a new window.
 
End of Question 9


Question 10.

Using the tabulated values of S° in Appendix C, calculate the value of S° for the reaction

2CH3OH(g) + 3O2(g) 2CO2(g) + 4H2O(g)

Online Text


Open Hint for Question 10 in a new window.
 
End of Question 10


Question 11.

Using data from Appendix C, calculate G° at 298.15 K for the following process:

H2(g) + Cl2(g) 2HCl(g)

Online Text


Open Hint for Question 11 in a new window.
 
End of Question 11


Question 12.

Using data from Appendix C, calculate G° for the following process:

2NOCl(g) 2NO(g) + Cl2(g)

Online Text


Open Hint for Question 12 in a new window.
 
End of Question 12


Question 13.

For a certain reaction, H = 45 kJ and S = 125 J/K. Assume that H and S do not vary with temperature. At what temperature will the reaction have G = 0?

Online Text


Open Hint for Question 13 in a new window.
 
End of Question 13


Question 14.

Methanol, CH3OH, can be made by the reaction of CO with H2:

CO(g) + 2H2(g) CH3OH(g)

H° = -90.7 kJ/mol and S° = -90.88 J mol-1 K-1 for this reaction. How is G° for the reaction expected to vary with increasing temperature? Under standard conditions is the reaction spontaneous at 298 K? Explain.

Online Text


Open Hint for Question 14 in a new window.
 
End of Question 14


Question 15.

Explain qualitatively how G and Q change for the following reaction as the partial pressure of N2 is increased.

N2(g) + 3F2(g) 2NF3(g)

Online Text


Open Hint for Question 15 in a new window.
 
End of Question 15


Question 16.

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

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

Online Text


Open Hint for Question 16 in a new window.
 
End of Question 16


Question 17.

Which of the following processes are spontaneous?

(i) separation of CO2 from air to make dry ice

(ii) the reaction of hydrogen with oxygen to form water

(iii) making a sugar solution by dissolving sugar in water

(iv) filling a tire with air at high pressure

Online Text


Open Hint for Question 17 in a new window.
 
End of Question 17


Question 18.
Ice liquefies at 0°C. Is liquefication exothermic or endothermic? In what temperature range is the process spontaneous?

Online Text


Open Hint for Question 18 in a new window.
 
End of Question 18


Question 19.
Which one of the following processes is irreversible?

Online Text


Open Hint for Question 19 in a new window.
 
End of Question 19


Question 20.

In which of the following cases does the entropy increase?

(i) gas escaping from a filled tire

(ii) solid melting

(iii) salt precipitating from solution

(iv) calcium carbonate decomposing to form carbon dioxide and calcium oxide

Online Text


Open Hint for Question 20 in a new window.
 
End of Question 20


Question 21.
The heat of vaporization of diethyl ether is 26.0 kJ/mol at 34.51°C while the heat of fusion is 7.27 kJ/mol at -116.3°C. Calculate the entropies of vaporization and fusion.

Online Text


Open Hint for Question 21 in a new window.
 
End of Question 21


Question 22.
Calculate the entropy change when a gas with a volume of 30.0 L is compressed to fill a tire with a volume of 10.0 L at constant temperature. Assume there are 1.20 mol of gas and that the gas is ideal.

Online Text


Open Hint for Question 22 in a new window.
 
End of Question 22


Question 23.
In which case does the entropy of the system decrease significantly?

Online Text


Open Hint for Question 23 in a new window.
 
End of Question 23


Question 24.

In which case(s) below is the entropy of the first substance greater than the entropy of the second?

(i) 1 mol of H2(g) vs 0.5 mol of H2(g) at 400 K

(ii) 1 mol of CH4(g) vs 1 mol of HCl(g) at 300 K

(iii) 1 mol of CaCO3(s) vs 1 mol of F2(g) at 300 K

(iv) 1 mol of CH4(g) at 200 K vs 1 mol of CH4(g) at 400 K

(v) 1 mol of H2O(l) at 300 K vs 1 mol of H2O(g) at 300 K

Online Text


Open Hint for Question 24 in a new window.
 
End of Question 24


Question 25.

Using the tabulated values of S° in Appendix C, calculate the value of S° for the reaction

CaCO3(s) --> CaO(s) + CO2(g)

Online Text


Open Hint for Question 25 in a new window.
 
End of Question 25


Question 26.

Using the tabulated values of S° in Appendix C, calculate the value of S° for the reaction

2H2(g) + O2(g) --> 2H2O(g)

Online Text


Open Hint for Question 26 in a new window.
 
End of Question 26


Question 27.

Using data from Appendix C, calculate G° for the reaction

Fe2O3(s) + 3C(s, graphite) --> 2Fe(s) + 3CO(g)

Online Text


Open Hint for Question 27 in a new window.
 
End of Question 27


Question 28.

Using data from Appendix C, calculate G° for the reaction

2NO2(g) --> N2O4(g)

Online Text


Open Hint for Question 28 in a new window.
 
End of Question 28


Question 29.

An endothermic reaction has H = 60 kJ and an entropy change of -120 J/K. Assuming that H and S do not vary with temperature, at what temperature will the system be at equilibrium?

Online Text


Open Hint for Question 29 in a new window.
 
End of Question 29


Question 30.

If a reaction is not spontaneous at room temperature but becomes spontaneous as the temperature is increased (as, for example, the dissociation of calcium carbonate to carbon dioxide and calcium oxide), what can you say about the signs of the enthalpy and entropy changes?

Online Text


Open Hint for Question 30 in a new window.
 
End of Question 30


Question 31.
Calculate the equilibrium constant at 298 K for the reaction

CaCO3(s) --> CaO(s) + CO2(g)

Online Text


Open Hint for Question 31 in a new window.
 
End of Question 31


Question 32.

In the synthesis of ammonia,

N2(g) + 3H2(g) --> 2NH3(g),

what happens to G and Q if the partial pressure of NH3 is increased?

Online Text


Open Hint for Question 32 in a new window.
 
End of Question 32





Pearson Copyright © 1995 - 2010 Pearson Education . All rights reserved. Pearson Prentice Hall is an imprint of Pearson .
Legal Notice | Privacy Policy | Permissions

Return to the Top of this Page