CHM 2045 Lecture 3: 3

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byzantiumjackal692

1 Mar 2014

School

University of Florida

Department

Chemistry

Course

CHM 2045

Professor

chu

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Document Summary

Ideal solutions: solutions made from compounds with similar properties: b. That is, the compounds can be interchanged without changing: spatial arrangement of molecules, intermolecular attractions. Ideally dilute solutions: solute molecules are completely separated from one another by solvent molecules so they have no interactions: b. mcat: you can assume it is ideally dilute, but you cannot automatically assume its ideal. Solutions: nonideal solutions: a. nonideal solutions: violate the tenets of both ideal solutions and ideally dilute solutions, colloids: definition and properties, a. Aside from gas-gas [edit: problem 439 says it can be. Solutions: solvation: a. solvation: when ionic compounds break into their respective ions, polar molecules use their dipole moments to attract the ions. Solvation: hydration: a. hydration: when several solvent molecules surround an ion, b. aqueous phase: something that is hydrated, c. hydration number. 27: number of water molecules needed to surround an ion, varies with size and charge of the ion, usually has values between 4 and 6.

Related Questions

I need help on this chemistry work. Thanks.

DATA ANALYSIS

Using the example, calculate the Gibbs free energy for the process of dissolving ammonium nitrate and the process of dissolving sodium hydroxide (equation: ÎG = ÎH â TÎS).

Use the standard temperature 298 K.

Use the experimental data to calculate enthalpy of dissolving (ÎH).

Use the following data to calculate the entropy change (ÎS):

	S (J/K mol)
NH₄NO₃(s)	151
NH₄⁺(aq)	113.4
NO₃^-(aq)	146.4
NaOH(s)	64.46
Na⁺(aq)	59.0
OH^-(aq)	- 10.7

After completing the calculations answer the following questions separately for each experiment:

Is the dissolving exothermic or endothermic?

Does the entropy decreases or increases during dissolving?

Is the Gibbs free energy positive or negative? Is the process of dissolving spontaneous?

Using data in the appendix in your textbook, calculate Gibbs free energy for the reaction of dissolving

lithium phosphate, Li₃PO₄, in water at 25 Â°C. Do the calculations in two ways:

1) Use standard enthalpy of formation (ÎH) and entropy (S) from the appendix in your textbook, and use the same formula as you did in the lab experiments: ÎG = ÎH â TÎS. Remember that both ÎH and ÎS has to include three lithium ions.

2) Use standard free energies of formation from Appendix 6 (ÎG) and equation

ÎG = âÎG _products â âÎG _reactants

Are the results similar in both calculations?

CHM 2045 Lecture 3: 3

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