Experiment 15 ：
Vapor Pressure and the Heat of Vaporization

Zhouhao fan
01/28/2015

Chemistry 1220

T.A. - Drew Adkins

Purpose:
Use laboratory techniques to explore two factors that affect solubility: temperature and solute-solvent interactions.
Quantify the solubility and use graphing techniques to study the solubility trends as a function of temperature.
Compare the presentation of solubility data by using different units.

Procedure:
Refer to pages 20 to 23 of General Chemistry 1220 laboratory Manual, Volume 1 by Department of Chemistry The Ohio State University, Hayden-McNeil Publishing, 2014-2015.

Data and Result:
See the attachments.

Sample Calculation:
Part B solubility: Mass of sample / mass of water *100g
1. 1.7336g / (10ml*0.9975g/ml)*100g = 17.4g
2. 1.7336g / (15ml*0.9975g/ml)*100g = 11.6g
3. 1.7336g / (20ml*0.9975g/ml)*100g = 8.7g
Part C solubility: Mass of sample / mass of water *100g
1. 6.8991g / (10ml*0.9975g/ml)*100g = 69.2g
2. 6.8991g / (20ml*0.9975g/ml)*100g = 34.6g
3. 6.8991g / (30ml*0.9975g/ml)*100g = 23.1g
4. 6.8991g / (40ml*0.9975g/ml)*100g = 17.3g
Part B mole fraction: mole solute / (mole solute + mole solvent)
1. (1.7336g / 126.07g/mole)/((1.7336g / 126.07g/mole)+(10ml*0.9975g/ml) / 18g/mole) = 0.024
2. (1.7336g / 126.07g/mole)/((1.7336g / 126.07g/mole)+(15ml*0.9975g/ml) / 18g/mole) = 0.016
3. (1.7336g / 126.07g/mole)/((1.7336g / 126.07g/mole)+(20ml*0.9975g/ml) / 18g/mole) = 0.012

Graphs:

Discussion:
In this experiment, our object is to figure out the effects of temperature to solubility and solute-solvent interactions. Keeping the mass of solute fixed, adding water and cooling the temperature, the concentration and mole fraction for the different temperature of the saturated solution can be calculated. About the solute-solvent interactions, follow the same method and use 70:30 water:dioxane as solvent to calculate the concentration of the saturated solution.

For part A, weigh 6.3g to 6.7g solid and dissolve in 10 ml water. Then, heat the solution until all of the solid is dissolved. Next, cool the tube down until there crystal formed and record the temperature. Repeat the last step 3 times with 5 more ml to the tube every time.
For part B, weigh 1.7g to 1.9g solid, and repeat the steps in part A. (note: the temperature will be lower than part A and just do 3 times)
For part C, weigh 6.5g to 7.0g solid, and use 70:30 water:dioxane as solvent. Then repeat steps in part. (note: add 10 ml water every time.)

After the lab, use the equation
“solubility=Mass of