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Question 16.1: CONCEPTUAL Predict whether ΔS is positive or negative for ea...

CONCEPTUAL

Predict whether ΔS is positive or negative for each of the following processes:

(a) taking dry ice from a freezer where its temperature is -80°C and allowing it to warm to room temperature.

(b) dissolving bromine in hexane.

(c) condensing gaseous bromine to liquid bromine.

STRATEGY

1. Consider the relative disorder of final and intial states.
2. Recall that entropy increases from solid to liquid to gas.

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Increase in temperature and a phase change; ΔS > 0 (a) Dry ice warming
A solution with two different molecules is more random than a solution with only one
kind of molecule; ΔS > 0		 (b) Dissolving bromine
A phase change from gas to liquid; ΔS < 0 (c) Br_{2}(g)  →  Br_{2}(l)

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