This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
Unformatted text preview: Experiment 3: How Can Solubility be used to Determine Thermodynamic Values of KNO 3 ? PRELABORATORY QUESTIONS 1. Describe the major features of the van’t Hoff plot you will construct. For the dissolution of a salt, do you expect the yintercept of the bestfit line to be positive or negative? Explain your predictions. Explain the physical implications of the sign of the slope of the line and of the yintercept. The data should give a straight line with slope =  Δ H°/R and yintercept = Δ S°/R for the reaction. When a salt dissolves, the ions are no longer constrained in a crystal lattice. Therefore the Δ S° should be positive, and the yintercept of the line should be positive. An exothermic dissolution will exhibit a positive slope (negative Δ H , while an endothermic reaction will show a negative slope (positive Δ H°). 2. Figure 1 illustrates fictitious van’t Hoff plots for unspecified reactions. Indicate all the possible types of reaction (from the following choices) that each van’t Hoff plot could characterize: vaporization, dissolution of a salt, dissolution of a concentrated acid, precipitation, metathesis, the collision of several gaseous molecules to produce a smaller number of molecules. Explain your choices. (A) Δ H° positive, Δ S° positive: vaporization, dissolution of a salt (B) Δ H° negative,...
View
Full
Document
This note was uploaded on 11/05/2011 for the course CHEM 0330 taught by Professor Rosepetruck during the Fall '08 term at Brown.
 Fall '08
 ROSEPETRUCK
 Solubility

Click to edit the document details