Polarity and Molecular Shape Lab

Title:

Polarity and Molecular Shape LAB

Statement of the Problem:

1. Construct models of molecules

2. Determine molecular shapes

3. Predict polarity of molecules

Materials:

Molecular model Kit

Procedure:

In this lab we built a 3-dimensional model for every molecule , after constructing the models we drew a 3D representation, using different lines to represent the different directions of the bonds and types of bonds.

Results:

This is a table of the molecular formula, shape of molecule, bond angle, whether or not it has polarity, and if it is a resonance structure.

Analysis Questions:

1) Explain how water's shape causes it to be polar.

The electrons are pulled toward the more electronegative atom in the molecule. In water's case it is oxygen that is the most electronegative and since the bonds with the two hydrogen atoms form an angular molecule it leaves the side with oxygen's full valence orbitals exposed so hydrogen's exposes positive nucleus and oxygen's exposed electrons makes it a very polar molecule.

2) Describe how water's properties would be different if the molecules were linear instead of bent.

If water was linear there would be no exposed sides (thus symmetrical) and the electrons wouldn't accumulate toward any one side.

3) Based on the results of this experiment. List the molecules from the expirement that would be water-soluble.

C3H8, Si2H6, HF, H2O2, IF3, SF6, SO32-

Lab Chromatography Lab Report

Statement of the Problem:

Which solvent of the four we are using (C6H14, CH3OH, C3H7OH, H2O) is best pulling pigments from ink?

Paper chromatography is an important separation technique that depends on differences in both absorption and solubility. Each component of the mixture will move a definite distance on the paper in proportion to the distance that the solvent moves. This ratio can be calculates for each component, to aid in identification. Retention factor values are dependent upon the paper, devoling solution, and sample size.

(retention factor) Rf = distance component moves / distance solution moves

Hypothesis:

Water will separate the different pigments from the ink.

Materials:

H2O, CH3OH, C3H7OH, C6H14

Mixtures to separate: Water-soluble overhead pens (black, red, green, black, red, yellow, blue)

Solid Phase: Chromatography paper strips (10) - 1cm x 8cm

Procedure:

First we gathered the materials we needed for Part 1 of this lab ( four 1cm x 8cm paper strips, a black marker, a small sample of each of the the solvents to fill up half a 24 well plate

Results (Data):

* The separation of the dyes within the marker where affected by the type of chemicals they were soaked in.
* Different markers had different dyes which were shown as the chemicals separated the dyes.

Conclusions:

Our hypothesis was highly supported.
It was supported because during the lap water best separated the dyes within the markers color .
Water separated the dyes most effectively, CH3OH separated the dyes less effectively then the water but more effectively the the C6H14 which had a better separation then C3H7OH which separated the least amount of dyes (but gave headaches).
Water is a highly effective solvent and this is why it is the international solvent.
The amounts of the solvents if they weren't the same, the ink being dipped to deep into the solvent , amount of ink used, and the amount of paper dipped into the solvents