Today we began class by going over quiz 1.2 (measurements and sig figs) which we took yesterday. Mr. Lieberman is a grading machine and was able to grade them in one night! (even with parent night which was described as "wild")We then began the Density of Pennies Lab. Together we did the Pre-Lab questions. The first question dealt with the estimated uncertainty in a 100 mL graduated cylinder. We found the answer to be one-tenth of a mL. The second question was about calculating the average volume of a metal cylinder. To do this, we subtracted the initial volume from the final volume. We answered this question together in our groups.
Before beginning the lab, we all put on our fashionable safety goggles, because, well, when dealing with pennies...you just never know! The purpose of the lab was to plot mass and volume data for a set of pennies, both pre and post 1982. The data would then be analyzed to identify the identity of the metal that makes up the penny.
We started out by counting out 25 pre-1982 pennies. Then we recorded the masses of 5, 10, 15, 20, and 25 pennies. We filled a graduated cylinder with water to a start value around 50.0 mL. We gently dropped five pennies into the graduated cylinder and recorded the new volume of the water. We continued this process with the rest of the pennies by adding five at a time after recording each volume. To calculate the volume of the pennies, we subtracted the start value from the new volumes. We repeated these steps with the 25 post-1982 pennies. There are Post-Lab questions which are due with the rest of the lab on Monday. Mr. Lieberman said not to worry about the graph because we are doing that in class tomorrow!
And...drum roll please...the scribe for tomorrow is Deena M.!
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