Hnrs Chem P1 Lieberman-October 9, 2012

Homework

• due today was the Chemthink on chemical reactions
• chemical reactions worksheet due tomorrow
• chapter 3.4 reading and web assign due the day of the test

We started off class talking about the Nobel prizes being awarded this week. If you want to check it out, go to www.nobelprize.org.  

Balancing Equations

•    Reactants-what goes in to the equation
•    Products-what comes out of the equation
•  Law of Conservation of Mass-what goes in must come out.
•  The equation is unbalanced if when written, the products contain atoms that didn't exist in the reactants or one/some of the atoms in the reactants are lost. This is when we need to balance the equation

Some Examples...

N₂+O₂àNO

Al+CuSO₄àCu+Al₂(SO₄)₃

These are unbalanced because the atoms in the reactants don't equal the atoms in the products.

If we balance them, they are...

N₂+O₂à2NO

2Al+3CuSO₄à3Cu+Al₂(SO₄)₃

_{Notice how the reactants and products now have the same number of each type of atom.} 

_{Here's a picture detailing the balanced equation of} 2H₂+O₂à2H₂O

Synthesis reactions-chemical reaction where two or more substances combine to form a compound. 

Reactant+Reactant-->1 Product

C+O₂àCO₂

Decomposition Reactions-Chemical reaction where a compound is broken to form two or more substances

1 Reactant-->Product+Product

2HgO-->2Hg+O2

We will go over the rest of the notes tomorrow

Mr. Lieberman also did a demonstration involving an exploding paint can today. He had a paint can with a small hole on the side of the can. there was also a hole in the lid. He filled the can with methane from the side hole, and lit it with a lighter from the top. it burned the methane slowly for a short time, then, unexpectedly, the can exploded. The explosion couldn't occur at first because there wasn't enough oxygen in the can (it was unbalanced). When the oxygen filled in (balanced the equation) the can exploded.

Next scribe...Jeremy E.