# Unit 7: Stoichiometry

## 7a - Using Molar Relationships

A chemical reaction equation tells us about the relationship between atoms and molecules in a reaction. It tells us how many of each reactant particle is used up, and it tells us how many product particles are made.

Likewise, a chemical reaction equation can also tell us about moles of reactants used and moles of products formed. And so we can apply a chemical reaction equation to quantities of atoms and molecules that are actually measurable.

Using a reaction equation as a set of molar relationships so that we can do real-world chemistry is what we call stoichiometry.

## 7a - Using Molar Relationships

A chemical reaction equation tells us about the relationship between atoms and molecules in a reaction. It tells us how many of each reactant particle is used up, and it tells us how many product particles are made.

Likewise, a chemical reaction equation can also tell us about moles of reactants used and moles of products formed. And so we can apply a chemical reaction equation to quantities of atoms and molecules that are actually measurable.

Using a reaction equation as a set of molar relationships so that we can do real-world chemistry is what we call stoichiometry.

Video Playlist for 7a

## 7a Redux

These videos should be a little better in helping you figure out how to work with reactions in stoichiometry.

Being able to work through gram-gram stoichiometry questions would ensure that you're at least at the student level of understanding.

New Mole Ratios Playlist

Other Worksheets for 7a

You are expected to be able to:

• Use a balanced chemical equation as a relationship between the moles of two species in a chemical reaction
• Use molar mass as a relationship between grams and moles for any product or reactant in a reaction

## 7b - Percent Yield

Percent yield is one of the methods we have for determining how well a laboratory experiment went. It helps us to know if, how, and possibly why mistakes or errors may have been introduced in our lab work.

Percent yield is the comparison between how much of a reaction product we made in the lab and how much we expected to make based on what we had to begin with.