Polarity and Molecular Shape Lab

Objectives

• Construct models of molecules
  
• Determine molecular shapes
• Predict polarity of molecules

Materials

• Molecular model kit

Procedure

• We built a model for each of the listed molecules on the back of our given paper.

CH4	BF3	C3H8	H2O
Si2H6	HF	CH3NH2	H2O2
N2	SeF4	C2H4	SiH2O
IF3	SF6	CO2	SO32

• Drew the three-dimensional structure for each of these molecules
• Then determine each of the molecules; shape, bond angle, polarity, and resonance

Results
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Molecular Formula	Lewis Structure	3-Dimensional Model	Shape	Bond Angle	Polarity	Resonance
CH4		row 1, cell 3	tetrahedral	109°	no	no
BF3		row 2, cell 3	triagular planar	120°	yes	no
C3H8			linear	120°	no	no
H2O			angular	109.5°		yes	no
Si2H6				108.9°	no	no
HF			linear	180°	yes	no
CH3NH2		row 7, cell 3	tetrahedral	120°	yes	no
H2O2		row 8, cell		row 8, cell 4	row 8, cell 5	no	no
N2		row 9, cell 3	linear	180°	no	no
SeF4			seesaw	row 10, cell 5	no	no
C2H4			planar	120°	no	no
SiH2O		row 12, cell 3	trigonal planar	120°	yes	no
IF3			T-shaped	180°	yes	no
SF6			tetrahedral	180°	yes	no
CO2			linear	180°	no	no
SO32-			trigonal planar	104.5°	row 16, cell 6	yes

Chromatography Lab

Paper Chromatography Lab

• We were trying to figure out which solvent out of the four chosen (H₂O, CH₃OH, C₃H₇OH, and C₆H₁₄) would best work to mobilize the components (water-based markers).
  

Hypothesis

• We hypothesized that the C₃H₇OH would be the best solution and move the component farther due to the amount of Hydrogen atoms.

Materials

• H₂O
  
• CH₃OH
  
• C₃H₇OH
  
• C₆H₁₄
  
• Black, Red, Green, Purple, and Blue Overhead Pens
  
• Chromatography Paper (Cut into 1 cm by 8 cm strips)

Safety Precautions

• Goggles
  
• Aprons
  
• To avoid contact with the Hexane we prepped our station before hand and made sure to keep the goggles and aprons fully covering their designated areas. We made extra sure to keep the Hexane in use under the fume hood and to keep our heads away from the fumes.

Procedure

• In Part I of the Chromatography Lab we took four pieces of the Chromatography paper and dotted them three times with a black overhead pen. We then took our well pan to the chemical dispensary fume hood to retrieve the different solvents to use in our experiment. With the caution of the Hexane in mind we took the well pan directly back to our stations' fume hood. We separately labeled the chromatography papers for which solvents they would be placed into and then we put the papers into the separate solvents. After waiting a half an hour we observed the papers with the following results. In order from left to right is H₂O, CH₃OH, C₃H₇OH, and C₆H₁₄.

• In Part II of the Chromatography Lab we choose a solvent which worked best determined in Part I of the lab. (H₂O!) We then took various colors of overhead pens such as Red, Green, Purple, and Blue. Dotted separate chromatography papers for each pen color, then set them in the well plate, already filled with H₂O. We got the following results in the following order; Blue, Purple, Red, and Green

Conclusion

• The results of our experiment show that our hypothesis that C₃H₇OH would work best due to the amount of Hydrogen atoms was incorrect and therefore thrown out.
• H₂O worked the best out of the four given solvents, because of it's polarity.
  
• CH₃OH worked second best
• C₃H₇OH came in third
• And C₆H₁₄ worked the worst.

Learning Experience

• Through this experimental lab we learned that safety precautions are very important when dealing with toxic chemicals. Thus keeping a pair of goggles and an apron on was necessary at all times.

Technical Difficulties

• Any experiment could face difficulties. Our experiment could have been better with a wider range of colors and solvents. We could have compared different solvents to see if we could find one more polar then H₂O. This could have immensely improved our experiment.