Monday, March 16, 2009 - Block 4B

Handed out pink sheet for dry lab for Distillation of Wood for those who did not hand it in. This is due by Friday of this week. It is a reduced write-up that will be graded at 80% of the available score and should allow students to recover some credit for the lab write-up.

Reviewed last Wednesday's class:
Phases of matter: solid, liquid, gas
Solids have a definite shape and a definite volume
Liquids have a definite volume but take the shape of their container
Gases take the shape of their container and fill the container.

It takes energy to go from solid--> liquid --> gas

In today's lab we are going to add heat using a hot plate to a mixture of ice water, melt the water, heat the water, and boil the water.

Hypothesis: In your lab notebooks, sketch your prediction for the heating curve for this experiment, Temperature on the y-axis and adding energy or time on the x-axis.
We will assume the hot plate adds heat at a constant rate.

Explained how to set up the lab and how to use the computers.
Two groups used the old fashioned thermometers.

In this lab you need to wear goggles so long as the hot plates are on and you need to use the stirring rod to constantly stir the water so it has a uniform temperature throughout.

It took so long to set up the lab that many students only finished at the bell. I ended up having to take down the equipment after class.

Students printed out their heating curves. We will discuss them next time.