IIT/FIELD MUSEUM – High School Transformation Project
Lesson: Introduction to the Mole
Glencoe Chemistry: Matter and Change
Unit 4 The Mole and Stoichiometric
Chapter 11 The Mole
Section 11.1 Measuring Matter
Section 11.2 Mass and the Mole
- Context of Lesson
Taught near the end of the first unit, this lesson teaches students to classify matter as mixtures, compounds and elements through an analogy. The class should already have talked through the definitions of matter, elements, compounds, and mixtures.
- Main Goals/ Objectives:
Students will do activities about the size of a mole and the relationship between moles and mass. In performing these activities, students will:
· Describe how a mole is used in chemistry.
· Relate a mole to common counting units.
· Relate the mass of an atom to the mass of a mole of atoms.
- Nature of Science: Integrated Theme
· Distinguish observations from inferences, explain that inferences should be based on observations, and explain that the development of scientific knowledge involves both observations and inferences so scientific knowledge is partially inferential.
· Explain that scientists’ creativity influence their doing inquiry so they may have different observations and interpretations of the same phenomena.
· Explain that scientists’ background knowledge influence their doing inquiry so they may have different observations and interpretations of the same phenomena.
· Explain that scientific knowledge should be based on empirical data.
- Scientific Inquiry: Integrated Theme
· Explain that scientific investigations all begin with a question, but do not necessarily test a hypothesis.
· Explain that there is no single scientific method and provide at least two different methods.
· Explain that inquiry procedures are guided by the question asked.
· Explain that all scientists performing the same procedures may not get the same results.
· Explain that inquiry procedures can influence the results of an investigation.
· Explain that research conclusions must be consistent with the data collected.
· Explain that scientific data are not the same as scientific evidence.
· Explain that explanations are developed from a combination of collected data and what is already known.
- General Alignment to Standards
State Goal 11: Understand the processes of scientific inquiry and technological design to investigate questions, conduct experiments, and solve problems.
A. Know and apply the concepts, principles and processes of scientific inquiry.
Ø ILS 11.A.4a Formulate hypothesis referencing prior research and knowledge
Ø ILS 11.A.5b Design procedures to test the selected hypotheses.
Ø ILS 11.A.4c Collect, organize and analyze data accurately and precisely
Ø 11.A.4e Formulate alternative hypotheses to explain unexpected results
State Goal 12: Understand the fundamental concepts, principles and interconnections of the life, physical and earth/space sciences.
C. Know and apply the concepts that describe properties of matter and energy and the interactions between them.
Ø ILS 12.C.3b Model and describe the chemical and physical characteristics of matter.
- Materials
For each group of 2 students:
· “How Big is a Mole?” worksheet
· Pencil
· Highlighter or fine-tip marker
Per class:
· One-mole samples of at least ten elements and four compounds (see note)
· Electronic balances
- Preparation
Measure the mass of fourteen identical transparent containers—zip-top sandwich bags, plastic vials, etc.—and write the mass of each container on the outside of it. Then measure out exactly one mole (by mass) of ten different elements and four compounds. (Choose substances that have molar masses within the range of the student balances’ capacity.) Place one sample in each container, and write the name and formula on the outside of the container. An example is given below:
Potassium ChlorideKCl
bag mass: 4.03 g
- Note
Mole Song: Mike Offutt’s CD of chemistry songs, including “A Mole is a Unit,” is available at http://www.artistsofnote.com/mike/tapes.html
The following is a list of suggested materials, one mole samples of at least ten elements and four compounds.
Element/ Compound / Mass1 / Aluminum (Al) / 27.0g
2 / Carbon (C) / 12.0g
3 / Copper (Cu) / 63.5 g
4 / Iron (Fe) / 55.9g
5 / Lead (Pb) / 207.2g
6 / Magnesium (Mg) / 24.3 g
7 / Nickel (Ni) / 58.7g
8 / Sulfur (S) / 32.1g
9 / Zinc (Zn) / 65.4g
10 / Ammonium Chloride (NH4Cl) / 53.5g
11 / Calcium Chloride (CaCl2) / 147.0g
12 / Calcium Sulfate (CaSO4) / 145.2g
13 / Magnesium Sulfate
(Epsom Salt) (MgSO4 · 7H2O) / 246.4g
14 / Olaxic Acid (H2C2O4 · 2H2O) / 126.0g
15 / Sodium Bicarbonate (NaHCO3) / 84.0g
16 / Sodium Carbonate (NaCO3) / 128.0g
17 / Sodium Chloride (NaCl) / 58.5g
18 / Sucrose (C12H22O11) / 342.0g
19 / Water (H2O) / 18.0g
The Lesson
- Bell Ringer
Write on the chalkboard or overhead: “What do the words pair, dozen, and gross have in common? Write what links these words as well as an example of how each one is used.” Allow students time to think, pair, and share their responses.
- Activity
Discuss briefly with students the fact that the words pair, dozen, and gross all convey a distinct number. You know that there are 12 items in a dozen. No matter what the item, a dozen is equal to 12. A gross is another unit of grouping. There are 144 items in a gross. A score, another set group, is equal to 20 items. You can have a score of years or a score of rocks, but it will always be 20 items. There is a word we use in chemistry that similarly means a particular number: that word is mole and the number it represents is 6.02 x 1023. This number is known as Avogadro's number. Written in standard notation, that’s 602 000 000 000 000 000 000 000! To give students a sense of how very large this number is, tell them that a mole of sheets of paper, stacked up, would reach to the moon eighty billion times! (If you have a recording of a mole song such as Mike Offutt’s “A Mole is a Unit,” this is a good time to play it for the class!)
Pass out the “How Big is a Mole?” worksheets. Instruct students to make as many dots as they can in the box on the front during the one minute you will give them to do so. When they have their pencils ready, tell them to start, then allow one minute for making dots before telling students to stop. Instruct students to count the number of dots in the box and write down their dots/minute measurement. To facilitate/speed up the counting process, suggest that students mark each dot with a highlighter as they count it. Then instruct students to work with their seat neighbors (in groups of four or so) to find out how long it would take the whole class to make a mole of dots. (Sample calculations are below.)
If a student can make 303 dots per minute, it will take 3.78 x 1015 years to make a mole of dots!
1 mole / 6.02 x 1023 dots / minute / 1 hour / 1 day / 1 year / 3.78 x 1015 years1 mole / 303 dots / 60 minutes / 24 hours / 365 days
Even if 25 students in the class worked at this rate, it would take the class 1.51 x 1014 years, making dots 24-7, to make a mole of dots!
1 mole / 6.02 x 1023 dots / minute / 1 hour / 1 day / 1 year / 1.51 x 1014 years1 mole / 7 575 dots / 60 minutes / 24 hours / 365 days
After students have made the calculations and you have reinforced the immensity of Avogadro’s number, tell them that you have samples of one mole of several elements. Show them the containers and explain that the mass on the label represents the mass of the empty container, so they can determine the mass of the contents alone. Do not tell students how you measured a mole of each element or what the connection is between moles and mass—let them wonder, for a few minutes, how you counted out all those atoms! Instruct students to work with a partner and measure the mass of each mole sample and record their data in a data table. Students are responsible for determining how you counted out a mole of atoms (or formula units, in the case of the compounds) of each substance. Circulate among students as they work, asking questions to get a sense of their thought processes. Ask what patterns they are finding among the masses of the elements, and once they have determined that the mass of a mole of an element is the same number as the element’s atomic mass, challenge them to determine what this means about the mass of a mole of a compound.
Once students have finished their measurements, gather the class again at their desks for a brief discussion of their findings. Allow students to share their discovery that a mole of atoms of an element has a mass in grams equal to the atomic mass in amu of that element and the corresponding relationship for compounds. Also, ask students what data from this experience are based on observations and which are inferences. The numerical data—masses of the samples—are observations, while the pattern and the relationship between moles and atoms are inferences. Discuss the importance of both types of data.
- Homework
Read Sections 11.1 and 11.2; do practice problems #1-3, 11, 13, and 15
- Modifications/Accommodations
· To save a bit of time dotting and counting, allow students just thirty seconds for making dots, then have them double the number of dots in the box for a dots/minute measurement.
· Assign the calculation of how many minutes/mole of dots for homework. Alternatively, do the calculation on the board as a demonstration/reminder of factor-label conversions.
- Assessment
Students’ responses to the bell ringer, their calculations during the dots activity, their conclusions during the mass activity, and their discussions with their partners will be observed by the teacher and contribute to the teacher’s assessment of students’ learning. Their activity sheets and responses to the section review will also contribute to the assessment.
Introduction to the Mole Model Lesson
Pre Lab Activity: How Big is a Mole?
A mole is 6.02 x 1023 of anything. A mole of donuts is 6.02 x 1023 donuts, and a mole of basketballs is 6.02 x 1023 basketballs—and that’s a lot of basketballs! A mole of basketballs would just about fit into a ball bag the size of the Earth! So just how big is a mole? That’s what we’re going to find out.
When your teacher instructs you to do so (and not before!), spend exactly one minute making dots in the box below, as many dots as you can make in a minute.
Now, count the dots. (A highlighter or differently-colored pen may be useful.) What is your dot making rate in dots/minute? ______
Working at this rate, how many dots could you make in an hour? ______
___ dots / 60 minute / ____ dots/hrminute / 1 hour
In a year? ______
____ dots / 24 hours / 365 days / _____ dots/yrhour / 1 day / 1 year
So how long would it take you to make a mole of dots? That’s 6.02 x 1023 dots!
____ dots / 1 mole / _____ mole/hourhour / 6.02 x 1023 dots
How long would it take to make a mole of dots if your whole class worked constantly at this rate? ______
____ dotshour
Avogadro’s number (6.02 x 1023) is an ENORMOUS number, but it has to be! A mole of copper atoms would fit nicely in the palm of your hand—about 20 copper pennies. Atoms are so tiny that we need a huge number of them to work with.
Introduction to the Mole Model Lesson
In the lab, you have the opportunity to measure a mole of several elements. Record the chemical formula for each element, along with the mass you measure, in a data table below.
Write down any patterns or generalizations you notice about the masses of the mole samples of elements.
Write any patterns you notice for the compounds.
Write your guess about how your teacher counted out a mole of atoms of each element.
Introduction to the Mole Laboratory Activity
Data Table
Sample / Chemical Formula / Mass of Sample with bag (g) / Mass of bag (g) / Mass of Sample (g)1 / Aluminum
2 / Carbon
3 / Copper
4 / Iron
5 / Lead
6 / Magnesium
7 / Nickel
8 / Sulfur
9 / Zinc
10 / Ammonium Chloride
11 / Calcium Chloride
12 / Calcium Sulfate
13 / Magnesium Sulfate
(Epsom Salt)
14 / Olaxic Acid
15 / Sodium Bicarbonate
16 / Sodium Carbonate
17 / Sodium Chloride
18 / Sucrose
19 / Water
Introduction to the Mole Laboratory Activity
Data Table
Sample / Chemical Formula / Mass of Sample with bag (g) / Mass of bag (g) / Mass of Sample (g)1 / Aluminum / Al / 31.8 g / 4.8 g / ~ 27.0 g
2 / Carbon / C / 16.8 g / 4.8 g / ~12.0 g
3 / Copper / Cu / 68.3 g / 4.8 g / ~ 63.5 g
4 / Iron / Fe / 60.7 g / 4.8 g / ~ 55.9 g
5 / Lead / Pb / 212.0 g / 4.8 g / ~ 207.2 g
6 / Magnesium / Mg / 9.1 g / 4.8 g / ~ 4.3 g
7 / Nickel / Ni / 63.5 g / 4.8 g / ~ 58.7 g