Lab preliminaries the day before:

Students are informed that they must be on time to class. At the bell, the door will be locked and not opened until the end of the period. Furthermore, students will be shrunk in size so that may explore atoms individually rather than in huge masses. They are then told a horror story of a former student who left the lab to go the bathroom and has never returned. A little calculation indicates that this 400A unit person still has not reached the bathroom even though he left class years ago. This is a dangerous lab! Students are cautioned not to be fooled by the fact that people outside the room look to be normal height. The glass on the windows and doors has been deformed by the shrinking agent to create this illusion… and so forth.

Lab Instructions:

The lights are turned out, the fan is turned on, and students are informed that they are shrinking. They are instructed to breathe normally. Meanwhile, they are informed that our balances are being shrunk precisely so that they will soon measure in atomic mass units rather than in grams. After a minute or two, the lights are turned on and they are given a molecular model kit composed of 3 Swedish fish, 8 gummy bears, and 10 m & m’s. They are assured that while these look like candy they are atoms. The Swedish fish are G atoms, the gummy bears are M atoms, and the m&m’s are S atoms. They are then given the assignment.

---

Fortunately and unfortunately, since you have just been exposed to the atmosphere of this room, you have shrunk to a height of approximately 400 Angstroms- fortunately, because you are now small enough to perceive the world of atoms and molecules directly; unfortunately, because you are now perilously small and exposure to the outside world (even a bacterium, is now 1000000 times larger than you) could lead to catastrophe. In order to leave this time-space warp, you must present this results’ sheet to the doorkeeper. You will be given a bag of atoms to work with. Please follow directions carefully or you risk being trapped here forever. This is an Individual Project although you may seek help from anyone in the class during the lab event.

Given the reaction: G₃M₈ + S₂ => GS₂ + M₂S

For all students:

1. In one G₃M₈ molecule, there arehow manyG atoms andow manyM atoms.

2. Balance the equation:

3. Using all of the atoms of a given type in your kit, determine the average atomic mass of each atom. You do not have to mass each atom individually. (Our balances have also shrunk today, so they now weigh in atomic mass units instead of grams.) All masses must have units.

G:

M:

S:

4. Calculate the mass of 1 dozen (12) of each type of atom.

G:

M:

S:

5. Calculate the mass of 1 mole of each type of atom. 1 mole = 6.022 x 1023. Pay particular attention to significant figures here.

G:

M:

S:

6. Convert your answers in problem number 5 to grams. 1 gram = 6.022 x 1023 AMU.

G:

M:

S:

For chemistry 2, 3, and 4 students only:

7. Compare the mass of 1 atom (3) with the mass of a mole of atoms (6). Attach explanation.

8. Calculate what the molecular masses of each of the reactants and products should be (from problem 3)

G3M8

S2

GS2

M2S

For chemistry 3 and 4 students only:

9. Determine the actual molecular masses of the reactants and products by massing them.

G3M8

S2

GS2

M2S

10. Show, on the back of this paper, using the molecular masses (8), and the coefficients of the balanced equation (2), that mass is conserved in the reaction.

For chemistry 4 students only:

11. Estimate the mass of (be sure to include units)

3 G3M8 molecules	4 dozen GS2 molecules	2.5 moles of M2S molecules

12. What per cent of the mass of a G₃M₈ molecule comes from G atoms?

13. How many grams of M are in 250 g of G₃M₈?

14. How many grams of S₂ will react with 17.3 g of G₃M₈?

15. How many grams of GS₂ and M₂S should be formed from the reaction in 14?

16. How many GS₂ molecules can be made from 5. g of G₃M₈ and 5. g of S₂?

---

This is a very early lab, after students have studied balancing equations but before they have studied the mole, per cent composition, stoichiometry, reactant in shortest supply, etc. Most of this is extra credit. For example, there is no level 4 chemistry in this school.

Problems 3-6 are intended to have the students discover that if the atomic mass of an atom is # AMU, then the mass of a mole of atoms is # g.

Related posts:

1. The Mole Lecture Notes Earlier, we saw how the mass spectrometer could be used to determine the relative masses of atoms. We determined, for example, that Li had an...
2. The Mole Lecture Lab 1. Select a kit containing six rubber stoppers, three small and three large. Do not mix your kit with stoppers from other kits. 2. Determine...
3. Computer Graded Repeatable Chemistry Quizzes This section describes a technique used in generating 36 computer graded quizzes, each with three variables: x, y, z Working in the background all second...
4. Balancing Equations Using Algebraic Methods Health hazard alert: The following technique is difficult and involves the creative use of algebra. It is recommended only for students who are attempting the...
5. Balancing Equations by the Method of Oxidation-Reduction Preliminaries: You might wish to review oxidation numbers before continuing An oxidation-reduction reaction is a reaction in which some atoms oxidation numbers change. Reaction...