Wednesday, Dec 1, 2010

Collect remaining safety contracts.

Collect Questions and Hypotheses.

Hand back and answer questions on Safety Quiz. If students didn't score at least 26/30, they had to retake.
While students were retaking safety quiz, other students did book work, Section 2.3, read, do density problems 1-9 on page 56, and do end of section problems 1-6 on page 60.

Hand back and go over any questions on the Waves Test.

Go over procedure for Wood Lab Day 1. Didn't get to safety.
Handed out green sheet for lab. Students were antsy so didn't go over green sheet. Told students to read it on their own.

Procedure for Wood Lab Part 1.
1. Measure mass of popsicle sticks (by measuring mass of burning test tube, and then mass of test tube plus popsicle sticks, and then subtracting. Also measure mass of collection test tube plus solid rubber stopper.
2. Set up apparatus as shown in the diagram.
a. Don't overstuff the test tube
b. Make sure the clamp is over the rubber stopper so you don't move the flame under the rubber stopper and melt it
c. The glass L coming from the burning test tube goes deep into the collection test tube. The glass L leaving the collection test tube is shallow in the collection test tube.
d. Make sure the stopper is firmly in the burning test tube. If not, it can come off during the experiment and fill the room with foul gas.
e. The Erlenmeyer flask is filled with ice water
f. Only fill the buck high enough to fill the Mason Jar with water. If you fill the bucket too high, the Mason Jar will start to float and tip when it fills with gas. This will release the foul gas into the room. Don't let the Mason Jar tip as it fills with gas.
g. Make sure you remove the rubber tubing from the water BEFORE shutting off the alcohol lamp.
3. Call teacher over to inspect the set up and then light the alcohol lamp.
4. Move the alcohol lamp along the brick to burn different parts of the popsicle sticks.
5. When the popsicle sticks are burned, or you no longer see any smoke going through the glass L, or no longer any bubbles in the collection jar, or the collection jar is full, then remove the rubber tubing from the water and then shut off the burner.
6. Slide the rubber band to the level of the gas in the Mason Jar. This will allow you to measure how much gas you collected.
7. Call instructor, when he tells you, slowly lift the Mason jar straight up to let the water fall out, and then, when he tells you, turn it mouth up towards him. He will throw in a lighted match so you can observe the big flames.
8. Measure the mass of the collected liquid by measuring the mass of the collection test tube + stopper + collected liquid and then subtracting the mass of the collection test tube + stopper.
SAVE THE COLLECTED LIQUID!! You will need it for part 2 of the lab. Put a piece of masking tape on the test tube with your names on it and put in in the designated test tube rack. Make sure it has the solid rubber stopper on it.
9. Measure the mass of the charred remains by measuring the mass of the the burning test tube + charred remains and subtracting out the mass of the burning test tube.
10. Dispose of charred sticks in the designated container.
11. If you have time, do another run.
12. Take apart the equipment and put it where it belongs.
13. Wipe off lab bench and wash hands.
What would you add to the procedure to test for conservation of mass?

Talk about the data table to check for conservation of mass.
How would you show the results graphically (bar graph)?

Calculations for volume of gas collected.