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Calculating Moles in Daily Life (39 Favorites)
ACTIVITY in Molecular Formula, Mole Concept, Dimensional Analysis, Molar Mass. Last updated September 19, 2019.
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 10^{23} = 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 H_{2}O = 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.
For the Student
Lesson
Background
Now that we have discussed Avogadro’s number and molar mass, we are going to use these quantities to do some analysis of common items in your life. We’re going to look at a nickel, water, chalk and sugar and determine the number of particles within a given sample.Prelab Questions
- Define Avogadro’s number:
- Define molar mass:
Objective
In this activity you will make a series of mass measurements. You will then convert these measurements to moles and molecules.
Safety
- Always wear safety goggles when handling chemicals in the lab.
- Wash your hands thoroughly before leaving the lab.
- Follow the teacher’s instructions for cleanup of materials and disposal of chemicals.
- Do not consume lab solutions, even if they’re otherwise edible products.
Procedure & Data Collection
- Make the following measurements and calculations:
Mass of Nickel | |
Mass of a nickel | g |
Mass of 30 mL of Water: this is about how much water is in one gulp | |
Mass of cup and water (before pouring 30mL) | g |
Mass of cup and water (after pouring 30mL) | g |
Mass of 30 mL water | g |
Mass of Sugar: Don’t open the sugar packet, see teacher for empty mass | |
Mass of Sugar in packet | g |
Mass of empty packet (from teacher) | g |
Mass of sugar | g |
Mass of Signature | |
Mass of chalk (before writing your name 3 times) | g |
Mass of chalk (after writing your name 3 times) | g |
Mass of chalk used in 3 signatures | g |
Mass of chalk used in 1 signature | g |
Calculations
Use information that you have collected above to help complete the following calculations. Please show your work with proper dimensional analysis and significant figures.
- A nickel is composed of 25.0% nickel and 75.0% copper.
- Calculate the mass of nickel in the coin.
- Calculate the number of moles of nickel in the coin.
- Calculate the number of atoms of nickel in the coin.
- Calculate the mass of copper in the coin.
- Calculate the number of moles of copper in the coin.
- Calculate the number of atoms of copper in the coin.
- Water
- Calculate the molar mass of water
- Calculate the number of moles of water swallowed
- Calculate the number of molecules of water swallowed
- Table
sugar
(sucrose, C_{12}H_{22}O_{11})
- Calculate the molar mass of sucrose
- Calculate the number of moles of sugar in the packet
- Calculate the number of molecules of sugar in the packet
- Calculate the number of atoms on carbon in the packet
- Assume the chalk was 100% calcium carbonate.
- Using what we learned about naming chemicals, write the formula for calcium carbonate
- Calculate the molar mass of calcium carbonate
- Calculate the number of moles of calcium carbonate used in a single signature
- Calculate the number of oxygen atoms in your signature
Analysis
- What is the difference between calculations made for the nickel and the other materials? (hint: consider the composition of each material)
- What other household items do you think we could perform similar calculations with? Make several suggestions and explain if necessary.
- What household item wouldn’t work for such simple calculations and why not?
- Why might a person be interested in this type of calculation?
- Write a brief summary of what you learned in this lab that includes how the objective was met.