Stoichiometry

Today we started chapter 6 - stoichiometry.
Stoichi-what?
"stoichio" is Greek for element.
"metry" means measurement.
Stoichiometry is measuring the amounts of chemicals involved in a reaction.

Proportional relationships are the specific amounts of each compound in a reaction.

2Cu + 1O2 -> 2CuO

Suppose you double the amounts of copper and oxygen used.

4Cu + 2O2 -> 4CuO

In a balanced equation, you can continue to increase the amounts of the compounds as long as the proportions are kept the same.
-link to PHET website

This website explains all about proportional relationships and gives you an opportunity to try it out. There's even a game!

The balanced equation describes the ratio in which the substances combine. The ratio is obtained from the coefficients of the balanced equation. This combining ratio is the mole ratio of the combining substances. It can be used to predict what would happen if the amount of one substance is changed.

Now back to stoichiometry. Stoichiometry involves measuring or calculating the amounts of elements or compounds involved in a chemical change.
Coefficients in a balanced equation tell us the numbers of moles reacted or produced. They can also be used as conversion factors.

3X + Y -> 2Z

To find the ratios you just take what you need/what you have OR where you're going/where you started.