Ester Synthesis Lab Report

Introduction:
In this experiment, when vinyl strip and acetate strip is rubbed by tissue, it will charge the vinyl strip negatively and acetate strip positively caused by the transfer of electron between the strip and tissue. If molecules have non zero bond dipole, because polar molecule must have a non-zero molecular dipole where electron spend more of their time closer to one atomic nucleus than the other and make one end partially positive or negative than the other end. Different charge will attract the opposite charge which will bend the stream of liquid if it’s polar which cause the bend of the stream. Therefore proofing the shape of molecule of the liquid is not symmetric and it’s a polar molecule because of their attraction or repulsion.
The reason why polar molecule have polarity and partially charged ends can be explained by Linus Pauling’s electronegativity property, the rule of VSEPR and Lewis structure.
A polar molecule is molecule bond dipoles that do not cancel out and doesn’t equal to zero. Instead they give a non-zero molecular dipole. To see if a molecule is polar, it will depends on their shape and different in electronegativity.

Electronegativity property was produced by Pauling’s calculations proofing different in the attraction of nuclei for covalent bond.
He calculated different elements electronegativity and give them a value through calculation, where fluorine have the highest electronegativity of 4.0. He used electronegativity to explain the polarity of a chemical bond. He stated that a very polar bond will be an ionic bond with a different electronegativity larger than 1.7; not too polar will be polar covalent bond with a different electronegativity smaller than 1.7 and larger than 0.5; nonpolar bond will be a pure covalent bond with a different electronegativity smaller than 0.5. Since they have different in electronegativity where one side attraction force is stronger, electron spend more of their time closer to one atomic nucleus than the other and make one end partially positive or negative than the other end. But sometime a polar molecule may also be non-polar even the bond is polar. This is where VSEPR and Lewis structure comes into place and can be well explained with the use of carbon dioxide as an
example.

Base on the VSEPR theory and Lewis structure diagram, carbon dioxide form a linear molecular shape with two lone pairs of electron.
Using electronegativity property, their different in electronegativity equals 3.5-2.5=1.0, showing that they have polar covalent bond and it’s a polar molecule. But the reality is that it’s not. Although it contains polar covalent bond, it’s not a polar molecule. Using electronegativity and representing it as bond dipole in a vector arrow, carbon dioxide produces a zero total. The reason why carbon dioxide doesn’t have polarity is because the bond dipole cancels each other and made all polarity to become zero for the whole molecule and cause carbon dioxide to be a nonpolar molecule. Although carbon dioxide have polar bond, it’s not a polar molecule because of it bond dipole and shape. Which explain polarity of molecule also depends on the shape of
molecule.

Procedure: 1. Fill the dropper/burets with one of the liquid or solution 2. Rub majority of the acetate stripe back and forth with tissue paper several times. 3. Allow liquid to drops or run in a thin stream into the waste beaker 4. Hold the rubbed acetate stripe close to the liquid stream or drops and observe any effect on the stream or drops of liquid. 5. Repeat steps 1 to 4 with the charged vinyl strip. 6. Repeat steps 1 to 6 for different liquid.
Materials:
* * Lab apron * Safety glasses * Medicine dropper * 50-mL burets * Clamp and stand * Burets funnel * 400-mL beaker * Fur * Plastic * Paper towel * Unknown liquid