Lab 22 3n1d25

Richard Brison Period 4 12/17/13 Jon Costello Lab 22: Models of Molecular Compounds Purpose: To construct models of covalent molecules and predict the geometry and polarity of each molecule. Procedure:   

Construct ball and stick models of the compound listed on the data table. As you are doing this, fill out the data table with all of the information needed. When completed, pack up the ball and stick models and clean up the laboratory.

Data: I have stapled the Data Table as the final sheet of this lab. It has all the data collected for this lab. Calculations: 1. HBr : 2.8 -2.1 = 0.7 = Polar 2. H2O : 3.5 – 2.1 = 1.4 = Polar 3. PH3 : 2.1 - 2.1 = 0 = Non – Polar 4. CH4 : 2.5 – 2.1 = 0.4 = Non – Polar 5. HClO : 3.5 – 2.1 = 1.4 = Polar / 3.5 - 3.0 = 0.5 = Polar 6. N2 : 3.0 – 3.0 = 0 = Non – Polar 7. CH3NH2 : 2.5 -2.1 = 0.4 = Non - Polar / 3.0 – 2.5 = 0.5 = Polar / 3.0 – 2.1 = 0.9 = Polar 8. H2CO : 2.5 – 2.1 = 0.4 = Non – Polar / 3.5 – 2.5 = 1.0 = Polar 9. C2H2 : 2.5 – 2.1 = 0.4 = Non – Polar / 2.5 – 2.5 = 0 = Non – Polar 10. CH3Cl : 2.5 – 2.1 = 0.4 = Non - Polar / 3.0 – 2.5 = 0.5 = Polar 11. HCOOH : 3.5 – 2.5 = 1.0 = Polar / 3.5 – 2.1 = 1.4 = Polar / 2.5 – 2.1 = 0.4 = Non – Polar 12. HCN : 3.0 – 2.5 = 0.5 = Polar / 2.5 – 2.1 = 0.4 = Non – Polar 13. H2O2 : 3.5 – 2.1 = 1.4 = Polar / 3.5 – 3.5 = 0 = Non – Polar Conclusion: In this lab, we conducted several experiments in which we constructed models of covalent molecules to predict the geometry and polarity of each molecule, which we then collected the data from and placed them on our data table.

Critical Questions: 1. In this lab, I used molecular shapes to predict the molecular polarity of many compounds. I did this by first drawing up the Lewis Structure of the given compound. With this, I would then find the bonds that were present, find their electronegativites, and calculate their differences. Once this was done, I could combine this information and easily find the polarity of the entire molecule. Once all of this work was done, then I could easily write a very good prediction of the molecular polarity of the compound that was given to me. To find examples of how I did this, you can refer to the Data and Calculations sections of this lab report. 2. The ball and stick models that we used in this lab have many advantages and disadvantages to their use in the lab. Some advantages are that you can get a 3D view of the molecule and bond angles. Also, you can see other things that are quite difficult to visualize on the 2D paper surface. Finally, a disadvantage of the ball and stick models is that you cannot properly get a view of the actual size of different atoms and the bonds holding them together that are present in reality. 3. A. I believe that HI is a polar molecule. B. I believe that SH2 is a polar molecule. C. I believe that NH3 is a non – polar molecule. D. I believe that CO2 is a polar molecule.

4. Knowing this general rule, I can easily tell that alcohol and water are the same molecular polarity, which is polar. Also, I believe that water is not used to get rid of stains and such at the dry cleaners because it is not the same polarity of these stains and therefore will not properly dissolve and get rid of the stain present on the garment. Sources of Error: Improper calculations, false information on the data table, wrong Lewis Structures, bad ball and stick models.