Balancing Equations and Chemical Reactions

Today we began our discussion on the balancing of equations. One of the most important things to remember as you balance a chemical equation is the Law of Conservation of Mass, or in other words, what you start with you have to end up with. When dealing with an equation, you may only change the coefficients, NOT the subscripts. Two things you can do when balancing an equation is first: to start simplifying the atoms that only appear once in the formula, and second: to always balance and oxygen last.

There are five types of chemical reactions. The two we began discussing in class today were:

1. Synthesis reactions. These types of reactions occur when two substances (generally elements) combine and form a compound. Reactant + Reactant --> 1 product or A + B --> AB. An example of a synthesis reaction is 2 H2 + O2 --> 2 H2O

2. Decomposition reactions. This kind of reaction occurs when a compound breaks up into the elements or in a few to simpler compounds. 1 reactant --> product + product or AB --> A + B. An example of this type of reaction is 2 H2O --> 2 H2 + O2

In order to further explain these two reactions, Mr. Lieberman showed us two demonstrations.
http://www.youtube.com/watch?v=8ncN7AdROrY

The first video demonstrates a synthesis reaction. Liebs used a balloon filled with hydrogen gas and a candle as the two reactants. When the open flame touched the candle, it reacted violently with the hydrogen inside the balloon, causing the balloon to pop (although it was more of an explosion) and the product of the reaction was water.

The second video shows an example of a decomposition reaction. A large graduated cylinder was filled with hydrogen peroxide and some dish soap. When Liebs added the catalyst, the hydrogen peroxide reacted and foamed over the top of the graduated cylinder. Liebs calls this demonstration "elephant toothpaste."
http://www.youtube.com/watch?v=f_ftXxCwvDw

So that pretty much sums up what we learned in class today. Sorry everybody, my computer won't let me upload/embed the videos, so I just posted the web addresses to each of the videos. Hopefully they work.
Also, the next scribe is................. Nirali P.