In this activity, students determine how many moles of paraffin are used when they color a piece of paper. They also determine how many molecules and moles of wax are in one crayon.
By the end of this lesson, students should be able to
- calculate the number of moles in a given mass of a substance.
- calculate the number of molecules in a given mass of a substance.
This lesson supports students’ understanding of
- Mole concept
- Significant figures
Teacher Preparation: 5 minutes
Lesson: 20-40 minutes
- One crayon
There are no special safety considerations for this activity.
- This is an open-ended activity, so students may come up with different methods for collecting data.
- Prior to this activity, students should be familiar with the concept of the mole.
- For grading purposes, it is recommended that 20% of the grade be assigned to correctly collecting the necessary data, 20% for correctly answering each question, and 60% of the grade for correctly showing calculations.
- Have students use correct significant figures in this activity.
For the Student
Crayons are primarily paraffin wax and colorant. For this activity, the mass of the colorant can be ignored because it is extremely small compared to the mass of the paraffin. The molecular composition of paraffin is C25H52.
To devise an experiment to answer the following questions:
- If you color the picture on the back of this page, will you use up a mole of wax?
- How many molecules of wax did you put onto the picture?
- How many moles of wax are in one crayon?
- Determine what pieces of data you will need to collect in order to answer the questions listed above.
- Create an organized data table to hold your data.
- Get a crayon, gather the data you will need, and answer the questions posed above. Be sure to show all calculations. Answer each question in a compete sentence.
- Double check to make sure that your data and calculations are neat, organized, and clearly labeled.
Picture for students to color that is on back of Student Activity sheet: