A reaction in which the entropy of the system increases can be spontaneous only

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False Think about it in terms of the Gibbs free energy equation, G = H - TS. (keep in mind that these would actually be delta G, delta H, and delta S for the reaction). For a reaction to be spontaneous, G must be negative. Either a negative H (an exothermic reaction) or a positive value of S (the entropy of the system increases) will move the reaction closer to being spontaneous; a positive H or a negative S will move the reaction farther from being spontaneous. For any reaction, you can have 1 of 4 cases: 1) H is negative and S is positive. Since G will be a negative number minus a positive number, it will always be negative, so the reaction will always be spontaneous. 2) H is positive and S is negative. Since G will be a positive number minus a negative number (i.e. a positive # + a positive #), G will always be positive, and the reaction will never be spontaneous. 3) Both H and S are negative. G is a negative number minus a negative number (i.e. a negative plus a positive), so G will be negative and the reaction will be spontaneous whenever H > TS (at lower temperatures); at higher temperatures, TS > H, and the reaction will not be spontaneous. 4) Both H and S are positive. G is a positive # minus a positive #, so it will be negative (the reaction will be spontaneous) only when TS > G (at higher temperatures). Looking at the three statements: If the entropy of the system increases, you are looking at cases 1 and 4. The reaction can be spontaneous in either of those cases (endothermic or exothermic), so neither of the first two statements is correct.

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