Dominican University student project

01/27/09 Kristen Ufheil

Solute: Riboflavin
SMILES: OC2/NC\1/N(c3cc(c(cc3/N C/1C(=O)N2)C)C)CC(O)C(O)C(O)CO
InChI: 1/C17H20N4O6/c1-7-3-9-10(4-8(7)2)21(5-11(23)14(25)12(24)6-22)15-13(18-9)16(26)20-17(27)19-15/h3-4,11-12,14,22-25H,5-6H2,1-2H3,(H,20,26,27)
Chemspider Link: http://www.chemspider.com/Chemical-Structure.1043.html
Solute Type: Diketone
Solvent: Methanol
SMILES: CO
Average Solubility g/100g = 0.2112 g/100g
Average Concentration moles/L = 0.004249 moles/L

Procedure
1. A solute is chosen (Riboflavin)
2. An appropriate solvent is chosen (Methanol)
3. Mixing Vessel is chosen - 50mL Pyrex Erlenmeyer flask
4. Solvent + solute mixing - Manual swirling/stirring - X amount of solute will be added to the solvent. Manual swirling and stirring will be administered accordingly until no more solute can be dissolved, indicating that saturation has been achieved.
5. Clarifying saturated solution - Into 3 centrifuge tubes transfer approximately 4-6 mL of solution by means of 5 mL pipettes. Tubes are then centrifuged for 60 seconds and the clear solution is transferred to a 10 mL graduated cylinder so the volume can be recorded
6. Evaporation by hot water bath - The clear saturated solution will be transferred to the pre-weighed glass vials. The vials will then be placed in a hot water bath. Once the solution has evaporated the mass of the vessel + solute can be recorded.

Start Time – 2:25 P.M.
Trial 1
About 45 mL of methanol is poured into 50 mL Erlenmeyer flask
Riboflavin is added shortly after – creates cloudy yellow solution
2:29 pm – solution is added to centrifuge tubes via 5mL pipettes and centrifuged for 30 seconds
2:31 pm – volume of saturated solution recorded using 10 mL graduated cylinder = 6.9 mL
2:32 pm – glass vial is weighed = 12.802 grams; solution is then transferred to vial and weighed = 17.823
2:34 pm – glass vial + solution is placed in hot water bath
2:38 – vial still in hot water bath; bubbling occurs
2:45 solution seems to have evaporated; vial + solute is weighed = 12.782g
Trial 2
2:42 pm – second tube is centrifuged for 30 seconds
2:43 pm – volume is measure = 6.2 mL
2:44 pm – glass vial is weighed = 12.817 g; solution poured into vial and weighed = 17.892
2:47 pm – vial placed in hot water bath
2:54 pm – solution finished evaporating; vial + solute is weighed again = 12.828g
Trial 3
2:50 – third tube is centrifuged for 30 seconds
2:51 – volume is measured = 6.9 mL
2:52 – vial is weighed = 12.888g; solution added and weighed = 17.892g
2:57 – vial enters hot water bath
3:02 – evaporation is finished; vial + solute weighed = 12.899g
End Time 3:08 P.M.


Results

Trial 1
Trial 2
Trial 3
Solute
Riboflavin
Riboflavin
Riboflavin
Solvent
Methanol
Methanol
Methanol
Solvent D
0.7918 g/cm³
0.7918 g/cm³
0.7918 g/cm³
Empty Evap. Vessel (g)
12.802
12.817
12.888
Vol of Solution
6.9 mL
6.2 mL
6.9 mL
Evap Vessel + Solution (g)
17.823
17.892
17.94
Evap Vessel + Solute (g)
12.812
12.828
12.899
Solubility g/mL
.001442 g/mL
.001774 g/mL
.001593 g/mL
Concentration M (moles/L)
.003823 mole/L
.00470 mole/L
.004225 mole/L
Molality (moles/kg)
.004866 mole/kg
.005953 mole/kg
.005343 mole/kg
Solubility g/100g solvent
.1991 g/100g
.2167 g/100g
.2177 g/100g