Tuesday, Nov 30, 2010

Collected safety contracts.

Show how to insert glass tubing into rubber stopper using a rag and glycerin.

Safety quiz.

We have studied Physics which deals with motion and forces. Now we are going to study chemistry which deals with matter and how it changes. There are two main types of changes - physical and chemical.
In physical changes, the atoms do NOT get rearranged to form new substances. Examples of Physical changes are phase changes, such as melting ice, or smashing a rock into smaller pieces. In the first, you still have water but in liquid form instead of solid. In the second, you still have the rock but in smaller pieces.

Went over physical properties - how a substance looks or what you can measure. If the property doesn't depend on the amount of the substance, it is a "characteristic physical property".
Examples of characteristic physical properties are: density, color, magnetism, electric or heat conductivity, hardness.

In chemical changes, the atoms are rearranged to form new substances. An example is hydrogen gas reacting with oxygen gas to form liquid water. Both hydrogen and oxygen gas are highly flammable, but water is not. The properties of the product can be very different from the properties of the reactants.

We show how the atoms are arranged using symbols for each element, subscripts to show how many of each atom, and coefficients to show how many of each molecule. For the reaction above, the chemical equation is: 2H2 + O2 -> 2H2O

In the Wood Lab, you are going to have to identify which changes are physical and which are chemical.

Wood Lab:

Day 1: Question: What happens when you burn popsicle sticks in a test tube?

Hypotheses: Make predictions based on your background knowledge and explain why you made that prediction.
I asked that students list 4 or 5 predictions backed up with reasoning.

Students will type up and hand in their Question and Hypotheses for Day 1 - due tomorrow.

Showed diagram of setup for day 1 of Wood Lab.
Students will make a neatly drawn, full page labeled diagram of the setup - due tomorrow. From this diagram, students will also type up the equipment list for Day 1.

Students practiced lighting alcohol lamps.

Students listed their top 4 choices for lab partners for the Wood Lab. I will go through them and assign partners trying to honor their preferences.

Instead of just going over the equipment, I drew the setup for the Wood Lab Day 1.


Students with signed safety contracts practice lighting alcohol lamps.

Wood lab:
Question: What happens when you burn wood in a test tube?
Student Hypotheses:

Show set up for Wood Lab day 1
Equipment list
Procedure