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Limiting Reactants using Particulate Diagrams (12 Favorites)

ACTIVITY in Balancing Equations, Stoichiometry, Conservation of Mass, Limiting Reactant. Last updated July 17, 2019.


Summary

In this activity, students will gain practice drawing particulate diagrams. This is important because it is a big focus on the newly revised AP exam. Many teachers need more examples of what this looks like.

Grade Level

High school

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS1-7: Use mathematical representation to support the claim that atoms, and therefore mass, are conserved during a chemical reaction.
  • Scientific and Engineering Practices:
    • Developing and Using Models

AP Chemistry Curriculum Framework

This activity supports the following unit, topics and learning objectives:

  • Unit 4: Chemical Reactions
    • Topic 4.3: Representations of Reactions
      • TRA-1.C: Represent a given chemical reaction or physical process with a consistent particulate model.
    • Topic 4.5: Stoichiometry
      • SPQ-4.A: Explain changes in the amounts of reactants and products based on the balanced reaction equation for a chemical process.

Objectives

By the end of this activity, students should be able to visualize what is occurring in a chemical reaction in terms of limiting and excess reactants using particulate diagrams.

Chemistry Topics

This activity supports students’ understanding of

  • Chemical Reactions
  • Stoichiometry
  • Limiting Reactant
  • Excess reactant
  • Balancing Equations
  • Conservation of Matter
  • Particle Diagrams

Time

Teacher Preparation: None

Lesson: 30–45 minutes

Materials

  • Student activity sheet

Safety

  • No specific safety precautions need to be observed for this activity.

Teacher Notes

  • Remind students that each problem has the same instructions at the top of the handout.
  • You can include state of matter in the chemical sentences so students also need to consider this in their particle pictures or, tell students to assume that all are in the gaseous state of matter.
  • Students can whiteboard and present their particle pictures for the equations.
  • Also, consider having different equations at different temperatures so students must show particle movement in their diagrams as well.
  • This is appropriate for all levels of chemistry.

For the Student

Lesson

Directions

For each word equation:

  • Write a balanced chemical equation.
  • Draw particulate representations of the reaction. Make sure you include the correct number of each particle based on the information provided.
  • Determine which reactant is limiting and which is in excess.

1. Three molecules of oxygen react with four molecules of hydrogen to produce water molecules.

a. Write the balanced chemical equation:

b. Draw the particulate representations of the reaction:

c. Which reactant is limiting?

d. Excess?

2. Two sodium atoms react with three water molecules to produce sodium hydroxide and hydrogen gas.

a. Write the balanced chemical equation:

b. Draw the particulate representations of the reaction:

c. Which reactant is limiting?

d. Excess?

3. Four Aluminum atoms combine with three chlorine molecules to produce solid aluminum chloride.

a. Write the balanced chemical equation:

b. Draw the particulate representations of the reaction:

c. Which reactant is limiting?

d. Excess?

4. Four Aluminum atoms combine with three chlorine molecules to produce solid aluminum chloride.

a. Write the balanced Chemical equation:

b. Draw the particulate representations of the reaction:

c. Which reactant is limiting?

d. Excess?

5. Assuming the reaction goes to completion, draw the product particles in the box on the right.

c. Which reactant is limiting?

d. Excess?