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Review Chapter 23

1.    What are the symbols for the following and what would their signs (+,-) be if they were spontaneous and not spontaneous?  Then write the equation for them. (DH = Hp-Hr)

  spontaneous not spontaneous formula
enthalpy      
entropy      
Gibbs free energy      

2.    How does the equilibrium constant of a reaction determine the amount of products and reactants?

3.    What is the study of thermodynamics tell chemists about reactions?

4.    What would Keq be relative to 1 for the following situations?

    a.    products are greatly favored

    b.    reactants are greatly favored

    c.    the forward reaction is favored

    d.    the reverse reaction is favored

5.    What is a spontaneous reaction?

6.    In an exothermic reaction, compare the energies of the reactants and products.

7.    What are the standard conditions for measuring enthalpy changes?

8.    Define the following terms.

    a.    entropy

    b.    enthalpy

9.    What was Gibbs' contribution to the idea of free energy and spontaneous reactions?

10.    At what stage of a reaction is c = 0?

11.    Copy the enthalpy diagram on page 754.  Label the y-axis as follows.

    Hreactants = 400kJ

    Ea = 500kJ

    Hproducts = 100kJ

    Answer the following questions

    a.    What is the activation energy required for the forward reaction?

    b.    What is the total enthalpy (DH) for the forward reaction?

    c.    What would you expect the sign of entropy (DS) to be for the forward and reverse reaction?

    d.  Which reaction, forward or reverse, would most likely be spontaneous?

    e.    What is the activation energy required for the reverse reaction?

    f.    What is the total enthalpy (DH) for the reverse reaction?

    g.    Can you be completely sure, by the information given in the diagram, whether the reaction is spontaneous or not?  Why?

12.     Interpret the following diagrams 23-8 & 23-9 on pages 756 and 757 and answer the following questions.

    a.    What happens to the sign of entropy (DS) as you move from a solid to a liquid?

    b.    What happens to the sign of entropy (DS) as you move from a gas to a liquid?

    c.    What happens to the sign of entropy (DS) as you move from an ionic solid to an electrolyte solution?

    d.    If the solution in figure 23-9 becomes warmer, what is the sign of entropy (DS), enthalpy (DH), & Gibbs (DG)?

13.    List the 4 rules for determining entropy. (pg 757)

 

 

 

14.    List the 3 rules for determining Gibbs free energy?

    

 

Last modified: May 28, 2003