Lecture_05

# Problem 536 5 non ideal solutions non ideal solutions

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Unformatted text preview: , and solve for the mole fraction of methane. We should verify that this indeed is a small number so that the assumption made regarding the partial pressure of benzene is valid. Problem 5.36. 5 Non-ideal solutions: Non-ideal solutions are those that deviate from Raoult’s law. Positive deviation from Raoult’s law: P &gt; xAPA* + (1 – xA)PB*. Negative deviation from Raoult’s law: P &lt; xAPA* + (1 – xA)PB*. In many solutions, both components show the same type of deviation (positive or negative) from Raoult’s law so that we have either PA &gt; xAPA* and PB &gt; xBPB* or PA &lt; xAPA* and PB &lt; xBPB*. However, there are exceptions to this behavior, as seen in Fig. 5.9 (ethanol). When dealing with non-ideal solutions, it is convenient to define activity of a component as P (5.75) a A = PA .  A Obviously, for an ideal solution, Raoult’s Law is obeyed and, therefore, a A = x A . However, for a non-ideal solution, the activity will not be equal to the mole fraction. In such cases, the activity can be related to the mol...
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## This document was uploaded on 02/28/2014 for the course CHEM 311 at LA Tech.

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