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Author:
Jack Bauer

Student Exploration: Stoichiometry

Vocabulary: Avogadro’s number, balanced equation, cancel, coefficient, dimensional analysis, molar mass, mole, molecular mass, stoichiometry

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

A 250 mL glass of orange juice contains 22 grams of sugar. How much sugar is in a two-liter (2,000 mL) bottle of orange juice? ___________________________________________

It requires two sticks of butter to make a batch of 20 cookies. How much butter will it take to make 150 cookies? ______________________________________________________

Gizmo Warm-up

Just as a cook follows a recipe to decide how much of each ingredient to add, a chemist uses stoichiometry to determine the amounts of substances involved in chemical reactions. The Stoichiometry Gizmo™ allows you to try your hand at figuring out the amounts of reactants and products that take part in a chemical reaction.

To begin, check that this equation is shown:

Fe2O3 + 3CO à 2Fe + 3CO2

Look at the coefficients (such as the “3” in 3CO) in front of each substance in the equation. The coefficients tell you how many molecules or atoms take part in a chemical reaction. In the spaces below, list the number of each molecule or atom in the equation:

Fe2O3 ____ CO ____ Fe ____ CO2 ____

In a balanced equation, the same number of each kind of atom is shown on each side of the equation. Calculate the number of iron (Fe), oxygen (O), and carbon atoms (C).

Reactants Iron: ____ Oxygen: ____ Carbon: ____

Products Iron: ____ Oxygen: ____ Carbon: ____

Based on these values, is the equation balanced? __ ____________________________

Activity A:

Moles

Get the Gizmo ready:

Check that the equation is still:

Fe2O3 + 3CO à 2Fe + 3CO2

If not, click New equation until it reappears.

Introduction: A mole is:

A) A mammal known for digging up gardens.

B) A small, dark spot on the skin.

C) A spy embedded within an enemy government.

D) 6.02 × 1023 particles of a substance.

E) All of the above.

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