Summary

In this activity, students will use candy to investigate stoichiometry and mole-gram relationships in chemical equations. It could also be used to introduce the concept of limiting reactants.

Grade Level

High school

NGSS Alignment 

This activity will help prepare your students to meet the following scientific and engineering practices: 

• Scientific and Engineering Practices:
  • Using Mathematics and Computational Thinking
  • Developing and Using Models

Objectives

By the end of this activity, students should be able to:

• Write balanced equations given the formulas of reactants and products.
• Perform stoichiometric calculations (mole-to-mole and gram-to-mole) using balanced equations.

Chemistry Topics

This activity supports students’ understanding of

• Balanced equations
• Molar mass
• Stoichiometry
• Dimensional analysis

Time

Teacher Preparation: 15-20 minutes

Lesson: 50 minutes

Materials

For each group:

• Balance
• Bag with the following food items (at least):
  • Butterscotch pieces (2)
  • Peppermints (1)
  • Animal crackers (6)
  • Smarties (4)
  • Skittles (2)
  • Starbursts (2)
  • M&Ms (10)
  • Jelly beans (30)
• Student handout

Safety

• Do not consume lab materials, even if they’re otherwise edible products.
• Food in the lab should be considered a chemical not for consumption.

Teacher Notes

• Students should have been exposed to chemical symbols/formulas (including polyatomic elements), balanced equations, and dimensional analysis prior to completing this activity.
• A plastic bag of candy items should be prepared ahead of time. Suggested quantities are listed in the materials section. The quantities listed are enough candy for no excess chemical in each reaction and match the exact ratios of the coefficients of each balanced equation. If you want to add in a limiting reactant component to this activity, you can add additional pieces of candy to the bag so that there are extras of some “elements,” representing excess reagents.
• Each piece of candy represents one mole of that “element”.
• When asked how many moles of polyatomic elements (ex: S₄, Sk₂, Mm₅, Jb₂) are used, it is referring to how many moles of the molecule/unit, not the individual atoms. Just like if you were to use the equation 2 H₂ + O₂ → 2 H₂O and you asked “How many moles of hydrogen were used in this reaction?” the ideal answer would be 2 moles of hydrogen (H₂) since elemental hydrogen is understood to be diatomic, even though four moles of hydrogen atoms were used. Be sure this is clear to students as they work on those problems. Alternatively, you could rewrite the questions using the formula rather than the name (“St₄” rather than “smarties”), but it is good for them to learn the distinction.
• Molar masses are determined by finding the mass of one unit of candy formula (ex: Bs → molar mass = mass of 1 butterscotch piece; S₄ → molar mass = mass of 4 smarties).
• There is nothing sacred about the types of candies used in this activity – you can always sub out a different type of candy if you can’t find one. Or make it seasonal – candy hearts for Valentine’s Day, candy corn for Halloween, candy canes for Christmas, etc.
• If you want to have candy available for students to eat after the lab (but not in the lab!), have a separate stash of candy that hasn’t come into contact with the balance.