Please Explain Why. Which one of the following statements is false? (a) A sponta
ID: 872796 • Letter: P
Question
Please Explain Why.
Which one of the following statements is false?
(a) A spontaneous reaction always proceeds towards equilibrium. (b) A nonspontaneous reaction cannot be made to occur.
(c) A highly spontaneous reaction does not always proceed rapidly. (d) The reverse of a spontaneous reaction is always nonspontaneous. (e) A spontaneous reaction always has a negative value of ?G.
Which one of the following descriptions must indicate a reaction that is spontaneous in the forward direction?
(a) ?H = positive value, ?S = positive value
(b) An exothermic reaction in which the entropy of the products is greater than that of the reactants.
(c) ?H = positive value, ?S = negative value
(d) An exothermic reaction in which the entropy of the reactants is greater than that of the products.
(e) ?H = negative value, ?S = negative value
Explanation / Answer
Finding the value of ?G: don't bother!
This might seem strange, given the key importance ?G in determining whether or not a reaction will take place in a given direction. It turns out, however, that it is almost never necessary to explicitly evaluate ?G. As we will show in the lesson that follows this one, it is far more convenient to work with the equilibrium constant of a reaction, within which ?G is "hidden". This is just as well, because for most reactions (those that take place in solutions or gas mixtures) the value of ?G depends on the proportions of the various reaction components in the mixture; it is not a simple sum of the "products minus reactants" type, as is the case with ?H.
?G = ?H