I had a busy week, especially in my Chemistry class. We're studying valences, Lewis charges and formal charges of atoms and molecules.
Each new unit scares the hell out of me, but at the end of each of them, I somehow have managed to grasp the material. As the semester is drawing to a close, I've got a streak of A's going on quizzes and labs. If I can pull a good grade on the last test, in a couple of weeks, I might pull an A in a class I was nervous I couldn't even get a B in.
On Monday, we had a lab. In that lab, we were given an unknown metal, which we were to ascertain the atomic weight, and consequently its identity. How were going to do that, you're asking yourself right now? Well, we had to figure out the unknown metal's specific heat.
By the look and the weight, I was pretty certain that the unknown metal I had been given was lead.
Every metal has a unique specific heat-- how many joules of heat energy it takes to raise one gram of the metal one degree Celsius. The way we figured this out was to raise the temperature of the metal to a known temperature-- in this case 100 degrees Celcius, the boiling temperature of water. We did this by putting the metal, which we had weighed, into a test tube and put that into a bath of boiling water. Then you set up a makeshift calorimeter-- a styrofoam cup full of a measured amount of water with thermometer in it. You dump the heated metal into it and measure the increase of temperature of the water. Assuming all of the increase comes from the metal, you can determine how much heat the metal held, and calculate the specific heat of the unknown metal. Then, using the odd fact that 25 divided by the specific heat is the atomic mass of most metals, I determined that the atomic mass of my unknown metal was 207. I looked up at the period table of elements that is on the wall of the lab, and saw that the atomic mass of lead is 207.2. Hot damn!
I realized afterward that I was just a little too excited about getting the atomic mass nearly exactly right-- I'm slowly sliding toward science nerddom.