Unit 3 Part 2: The Mole and Stoichiometry

Essential Questions:

1. What is a mole and how does it relate to Avogadro’s number?
2. How is the molar mass of a compound determined?
3. How is the concept of the mole and Avogadro’s number used to conceptualize and calculate: empirical and molecular formula; mass to mole to molecule relationships; and molar volumes of gases?
4. What is Stoichiometry?
5. How are stoichiometric problems solved, specifically mole to mole, mole to mass, and mass to mass?
6. What are the steps in solving stoichiometric problems?
7. What is a limiting reactant?
8. How are the limiting reactants and percent yield determined?
9. What is percent yield and how does it describe the efficiency of a chemical reaction?

GSE:

SC3. Obtain, evaluate, and communicate information about how the Law of Conservation of Matter is used to determine chemical composition in compounds and chemical reactions.

a. Use mathematics and computational thinking to balance chemical reactions (i.e., synthesis, decomposition, single replacement, double replacement, and combustion) and construct an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

b. Plan and carry out an investigation to determine that a new chemical has been formed by identifying indicators of a chemical reaction (e.g., precipitate formation, gas evolution, color change, water production, and changes in energy to the system).

c. Use mathematics and computational thinking to apply concepts of the mole and Avogadro’s number to conceptualize and calculate • percent composition • empirical/molecular formulas • mass, moles, and molecules relationships • molar volumes of gases

d. Use mathematics and computational thinking to identify and solve different types of reaction stoichiometry problems (i.e., mass to moles, mass to mass, moles to moles, and percent yield) using significant figures. (Clarification statement: For elements c and d emphasis is on use of mole ratios to compare quantities of reactants or products and on assessing students’ use of mathematical thinking and not on memorization and rote application of problem-solving techniques.)

e. Plan and carry out an investigation to demonstrate the conceptual principle of limiting reactants.

Vocabulary:

1. mole
2. Avogadro’s number
3. molar mass
4. percent by mass
5. empirical formula
6. molecular formula
7. hydrate
8. stoichiometry
9. mole ratio
10. limiting reactant
11. excess reactant
12. actual (experimental) yield
13. theoretical (calculated) yield
14. percent yield

Recommended Reading: (These textbook pages will supplement the information covered in class)

Chapter 10 - (page 304) Chemical Quantities

Chapter 12 - (page 382) Stoichiometry

Mole links:

http://ths.sad44.org/ourpages/auto/2016/8/30/46345068/Mole%20fun%20facts%20_1_.pdf *(Mole fun facts)

http://www.ed.mtu.edu/esmis/id61.htm

http://www.visionlearning.com/library/module_viewer.php?mid=53

https://www.youtube.com/watch?v=XnfATaoubzA (Stoichiometry tutorial video)

http://chemcollective.org/activities/tutorials/stoich/reaction_stoi (Stoichiometry tutorial)

http://www.chemtutor.com/mols.htm (Mole and Stoichiometry tutorial and notes)

https://www.khanacademy.org/test-prep/mcat/physical-processes/stoichiometry/v/stoichiometry-limiting-reagent (Limiting reactant tutorial)

https://www.chem.tamu.edu/class/majors/tutorialnotefiles/limiting.htm (Limiting reactant tutorial)

http://ed.ted.com/lessons/daniel-dulek-how-big-is-a-mole-not-the-animal-the-other-one (TED talks - the mole concept)

https://www.quora.com/How-was-the-Avogadro-number-derived (The mole and Avogadro's number - where did it come from?)

Flexible Grouping Activity

Differentiated Instructional Techniques

If you got questions 1, 2, or 3 incorrect:

· Option 1: Collaborative pairs – Get with someone else in the class and collaborate on how to solve stoichiometry problems (all 4 types). You need your notes, periodic table, the graphic organizer, your solved sample problems, and the 2 stoichiometry worksheets.

· Option 2: Web resources – Visit on of the following links on your phone or on a classroom PC and work through the video or tutorial online:

o https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome/stoichiometry-ideal/v/stoichiometry

o https://www.youtube.com/watch?v=XnfATaoubzA

o https://www.sophia.org/tutorials/chemical-reactions-stoichiometry

· Option 3: Personalized instruction/small group instruction – Get with Mr. E and go through some of the problems that you are having with these calculations

If you got question 4 incorrect (limiting Reactant Problems):

· Option 1: Collaborative Pairs - Get with someone else in the class and collaborate on how to solve limiting reactant problems. You will need your limiting reactant worksheet, your outline, periodic table, and models (solved problems).

· Option 2: Web resources - Visit on of the following links on your phone or on a classroom PC and work through the video or tutorial online:

o https://www.chem.tamu.edu/class/majors/tutorialnotefiles/limiting.htm

o https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome/limiting-reagent-stoichiometry/v/stoichiometry-limiting-reagent

o http://www.ausetute.com.au/exceslim.html

o https://www.youtube.com/watch?v=krioEzlRegc

· Option 3: Personalized instruction/small group instruction – Get with Mr. E and go through some of the problems that you are having with these calculations

If you got all 4 of the problems incorrect you can choose from the above options but it is highly recommended that you choose Option 3…

If you got all 4 problems correct:

· Task 1: Complete the mole conversion extension activity in the lab.

· Task 2: Get a copy of the limiting reactant worksheet #2 and complete.