Modeling Lab

The purpose of this lab was to be able to better understand and recognize molecular structures and polarity.


HF



H2O2



CH3NH2



C3H8
























CH4


PROCEDURES:

1) build a model for each of the molecules listed on the data table on the back of this page.

2) Draw the tree-dimensional structure of each molecule table 1. Use solid lines to represent bonds in the plane of the paper, dashed lines for bonds that point back form the plane of the paper, and wedged lines for bonds that point out from the plane of the paper toward viewer.

3) Note the shape of each molecule in the third column of table 1, the bond angles in column 4, whether or not they will be polar in column 5, and whether or not they exhibit resonance structure in column 6.

From our experiment, we have observed and learned that there is much more to molecular shape than meets the eye. Some have double bonds or even triple bonds or many more pairs of electrons than you would have thought.

Chromatography and Pigments

The mobile phase of the experiments are the solvents which include H₂O, C_H3OH, C₃H₇OH, and C₆H_{14. The stationary phase is the paper strips we used during the lab. Retention time was how long the solvent held onto the pigment. The farther the pigments went, the longer retention time. A polar molecule will be better at carrying the pigments because it is stickier than a non polar molecule. Our prediction was that} C₃H₇OH would be the best solvent.



In part 1, our first step was to fill four of the wells in the well tray half full of different solvents. We then took chromatography paper and put 3 or 4 dots using black ink. The paper had a right angle bend 1.5 cm from the end. Then we placed the strips in the solvents. After about a half an hour, we observed what had happened to the pigments of the ink





Our observations from part one were that water was the most affective solvent at carrying pigments. Followed by methanol, escpropy, and hexane.

The next day we repeated the experiment using H2O because it was the best solution at spreading the pigments.

Safety Procedures: Apron, goggles, hair tied back, keeping solvents under the fume hood to avoid headaches, closed shoes and no bulky clothing.