Summary

In this activity, students will use dimensional analysis to complete calculations and conversions for the number of moles, atoms, and molecules in several everyday household items using collected data.

Grade Level

High School

NGSS Alignment

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

• MS-PS1-1: Develop models to describe atomic composition of simple molecules and extended structures.
• HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.

Objectives

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

• Identify the value of Avogadro’s number.
• Determine the molar mass of chemicals when their chemical formula is given.
• Calculate the number of moles present of a substance using the mass of the substance and the molar mass.
• Complete conversions between the number of particles of a material and the mass of the material using Avogadro’s number correctly.

Chemistry Topics

This activity supports students’ understanding of

• Quantitative Chemistry
• Mole Concept
• Dimensional Analysis
• Avogadro’s Number
• Molar Mass
• Molecular Formula

Time

Teacher Preparation: 45 minutes

Lesson: 45 minutes

Materials (per group)

• 1 Sugar packet
• 1 piece of Chalk
• 1 Nickel
• Water (~30 ml)
• Small Beaker/container for water
• 50mL Graduated cylinder
• *Balance (this can be shared between groups)
• Periodic table
• Calculator

Safety

• Always wear safety goggles when handling chemicals in the lab.
• Students should wash their hands thoroughly before leaving the lab.
• When students complete the lab, instruct them how to clean up their materials and dispose of any chemicals.
• Do not consume lab solutions, even if they’re otherwise edible products.
• Food in the lab should be considered a chemical not for consumption.

Teacher Notes

• In advance of using this activity with student, teachers should gather materials, perform measurements and calculations to create an answer key using the specific samples that will be given to students.
• Avogadro’s number = 6.02 x 10²³ = the number of atoms in 12.000 grams of carbon-12.
• Molar mass = the mass of one mole of a chemical. It is calculated using the molar mass of each atom that makes the chemical, obtained from the periodic table. Ex H₂O = 18.0 g/mole (H = 1.0 x 2 atoms + O = 16.0 g x 1 atom)
• Number of moles of a chemical = mass of that chemical / molar mass of that chemical
• Number of particles present = mass of sample / molar mass * Avogadro’s number
• This activity is best after students have some general information on calculating molar mass and what a mole is. The student page assumes knowledge of calculating molar mass.
• Suggested group size = 2 students
• Have 1 empty sugar packet on hand to measure. This way each group doesn’t have to open (and waste) a whole sugar packet.
• You could easily walk students through each calculation or leave it more inquiry based. I have had luck walking them through one sample calculation and letting them try the rest on their own.