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Homework Help: Spontaneous Reactions and Molar Entropy

  1. Apr 7, 2006 #1
    The reaction A(g) --> B(g) is spontaneous under standard conditions. Which of the following statements must be true?

    I. B(g) --> A(g) is nonspontaneous under standard conditions.
    II. A(g) will be completely converted to B(g) if sufficient time is allowed.
    III. A(g) will be completely converted to B(g) rapidly.

    a. none of these
    b. I
    c. I and II
    d. I, II, and III

    The speed of the reaction, or kinetics, is not used to define a spontaneous reaction, so III doesn't fit. It is I because
    I is the reverse reaction, but I am not fully certain of II.

    Which substance will have the highest standard molar entropy at 25 C ?
    a. C(graphite)
    b. C2H4(g)
    c. CH3OH(l)
    d. MgCO3(s)

    Is it the only one in gas form since it has the most disorder?

    Thank you.
  2. jcsd
  3. Apr 9, 2006 #2


    User Avatar
    Science Advisor
    Homework Helper

    1) II is also not true, can you tell me why? Think about the equilibrium Gibb's equation.

    2)If it's a gas in standard conditions, yes.
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