StoichiometryDevon Bateman

Essential Question• Why is a foot…a foot?

–King Henry I had a foot 12 inches long.

Unit Questions• What are measurements?

• What do we measure?

• How do we measure?

• Why do we measure?

• How do chemists measure molecules?

Overview• Measurement

– List examples of measurement

– Define purpose of measurement

– Explain chemist’s use of the mole

• Stoichiometry

– Relate stoichiometry to a recipe

– Demonstrate mole ratios in balanced equations

WHAT DO WE MEASURE AND HOW?

• Measurements allow us compare or analyze data.

• Therefore, measurements must be reasonable.

• How do chemists count molecules?

• Can chemists count by measuring?

Chemists count using the mole.

• Mole: the unit used to measure the amount of a substance

• 1 mole = 6.02x1023 particles

• Stoichiometry- the study of mole and mass relationships in a chemical reaction

http://www.lsua.us/chem1001/stoichiometry/stoichiometry.html

• The mass of the reactants must equal the mass of the products.

H2 + Cl2 2 HCl

• A balanced chemical equation is very similar to a recipe.

• Coefficients represent the mole ratio between substances.

6 O2 + C6H12O6 6 CO2 + 6 H2O

Example

4 Fe + 3 O2 2 Fe2O3

• It takes 4 moles iron & 3 moles oxygen to produce 2 moles iron (III) oxide.

Conclusion

• The mole allows chemists to analyze chemical reactions.

• Balanced equations can be treated like recipes.

• Amount of ingredients determines the amount of product