11.18.10

Announcements:

1. Tomorrow is Chem-day in the Lyceum.

2. On Tuesday, the day before break, we will have our lab test for this unit.

AFTER BREAK

3. On Monday 11/29/10, we will have a quiz.

4. On Tuesday we will have another quiz.

5. On Wednesday, December 1, we will have our unit test.

Homework: none.

Today in class we first got pages 25 through 30. Then we officially begin the class by going over the worksheet that we worked on Wednesday with the substitute. There were two major problems that we worked on which were C2H2 and C2H6O. For C2H2, the correct Lewis structure was: H-C=-H. (The double bond is suppose to have another line on top, so after the C is three lines.) The second problem that students were confused about was C2H60. The Lewis Structure for this molecule is a bit too complicated, but it not something you should worry about so much.

Next we went over polar and non polar. As a reminder, polar means unequal or different, and non polar means equal or same. Make sure that you understand those two terms completely so that the future will be easy for you. After we reviewed a little bit about non polar and polar, we did page 25. Then we started a lab.

This lab starts on page 27 and is called "Polarity Olympics: The Trials". First on the page, we decided what the charge of each molecule was in H2O. The two Hs' have an electronegativity charge of 2.1 The oxygen molecule has a charge of 3.5 and because it has a higher electronegativity, it has a negative charge. The two hydrogen atoms have a positive charge. After doing the first page together as a class, we then finally began our lab.

(Page 27)

In the lab, we used a penny, water, hexane,watch glasses, capillary tubes, markers, and two cotton swabs. For the first part of the lab, we put many drops of water onto a penny until it overflowed. We recorded the number of drops and then drew a side view of the penny. We did the same procedure twice a second time, but instead of water we used a liquid called hexane. From our results, water had the most drops than hexane. We observed that hexane evaporated a lot faster than water did when it touched the table.

For the second part of the lab, we used capillary tubes and watch glasses. We put 10 drops of water onto one watch glass and hexane onto another. The we took the capillary tubes and touched them with each liquid separately. The capillary tube that held the most liquid was hexane.

The third part was easy just like the previous two parts. The point of this trial was to clean two types of marker from the glass. On one watch glass we drew a line with permanent marker and on the other, we drew on it with a transparency marker. Then we put water on a cotton swab and wiped the transparency marker. The transparency mark went away and the cotton swab turned green. With the same swab, we wiped the permanent marker, but it didn't go away. Next we put five drops of hexane onto a new cotton swab and wiped the transparency mark, but it didn't erase. When we wiped the permanent mark with the hexane filled swab, the mark went away. From our data, we concluded that water erased the transparency mark, but not the permanent mark and hexane erased the permanent mark , but not the transparency mark. The water and hexane were opposites.

This was the lab we did today and it was pretty easy. We ended the class by cleaning up our mess. Also our lab test is most likely going to be somewhat similar to this one! If you have any questions about anything, be sure to ask Mr. Paek for help!

Next Scriber: Petrina Z.