Class with Mrs. Glassel: July 2025

Tuesday, July 22, 2025

Fall 2025 Courses

Tchaikovsky’s 1812 Overture - A Musical Journey (self-paced)

Monday, July 21, 2025

Summer 2025 Courses

Saturday, July 19, 2025

Books and Other Educational Items for Sale

Items are marked with individual prices. Local pickup can be arranged in the western and southern suburbs of Minneapolis. If you're interested, please contact me at the contact form here.

The Old Curiosity Shop by Charles Dickens: $8

The House of Seven Gables by Nathaniel Hawthorne: $9

Mutiny on the Bounty by Charles Nordhoff and James Norman Hall (hardcover): $7

The Red Pony by John Steinbeck: $7

Julie of the Wolves by Jean Craighead George: $6

Essential ACT flashcards: $5 or best offer

5 Steps To A 5 AP World History Flashcards: $5 or best offer

Numbers & Math Symbols stamps: $5 or best offer

(Please note that the number 1 is missing and will not be sold with the set.)

Tuesday, July 15, 2025

Science Zine Topic

Please submit your science zine topic in this form.

Monday, July 14, 2025

Science Zine Project

You can find all the details about your zine project here.

Thursday, July 10, 2025

Think of stoichiometry as the "recipe math" of chemistry. Just as a cookie recipe tells you that you need exactly two cups of flour and one cup of sugar to make a specific number of cookies, a balanced chemical equation tells you the exact ratio of reactants needed to create a specific amount of product. Stoichiometry is simply the set of calculations chemists use to measure these amounts. It allows you to predict the future of a reaction: if you know how much of one ingredient you have, stoichiometry gives you the mathematical tools to figure out exactly how much of the other ingredients you need or how much "stuff" you will end up with when the reaction is over.

In practice, stoichiometry relies heavily on the "mole," which serves as the bridge between the atomic world and the grams we measure on a scale in the lab. By using the coefficients (the big numbers in front of formulas) from a balanced equation, you create "mole ratios." These ratios are the heart of stoichiometry; they let you convert from moles of one substance to moles of another. Whether you are figuring out which chemical will run out first (the limiting reactant) or calculating the maximum amount of product you can produce (theoretical yield), stoichiometry ensures that matter is accounted for and that you aren't wasting chemicals by guessing.

Here are two examples of stoichiometry: one using a real-world analogy to visualize the concept, and one using a chemical reaction to show how it is used in the lab.

Example 1: The S'mores Analogy (Conceptual)

Stoichiometry essentially follows a recipe to ensure you don't waste ingredients.

The Balanced Equation:

2 Graham Crackers + 1 Marshmallow + 1 Chocolate Piece -> 1 S'more

The Scenario:

Imagine you have 10 Graham Crackers, 10 Marshmallows, and 10 Chocolate Pieces. How many S'mores can you make?

The Stoichiometry:

Even though you have plenty of marshmallows and chocolate, the stoichiometry (the ratio) says you need 2 crackers for every 1 S'more.

10 Crackers / 2 Crackers per S'more = 5 S'mores.

The Result:

You can only make 5 S'mores. The graham crackers are your "limiting reactant"—once they run out, the reaction stops, leaving you with leftover marshmallows and chocolate ("excess reactants").

Example 2: Airbag Safety (Chemical Application)

In the real world, engineers use stoichiometry to save lives. An airbag needs to inflate with a specific volume of nitrogen gas (N2) in milliseconds during a crash.

The Balanced Equation:

2NaN3 (s) -> 2Na (s) + 3N2 (g)

The Scenario:

An engineer needs exactly 60 Liters of Nitrogen gas to fill the driver's side airbag. If they use too little, the bag won't cushion the driver. If they use too much, the bag could explode or be too hard.

The Stoichiometry:

The engineer uses the mole ratio (2 moles of NaN3 produce 3 moles of N2) to calculate the precise mass of Sodium Azide powder to put inside the steering wheel. They calculate backwards from the gas needed (N2) to the solid required (NaN3) to ensure the reaction is perfect every time.

Wednesday, July 9, 2025

Grams to Moles and Moles to Grams Practice Problems (with answer key)

Part 1: Moles to Grams (Elements)

Convert the given amount of moles into grams.

2.00 mol of Helium
0.75 mol of Copper
10.0 mol of Sulfur
0.15 mol of Silver
5.2 mol of Calcium

Part 2: Grams to Moles (Elements)

Convert the given mass in grams into moles.

24.31 g of Magnesium
100.0 g of Iron
5.00 g of Lithium
250.0 g of Gold
15.5 g of Potassium

Part 3: Moles to Grams (Compounds)

Calculate the molar mass of the compound, then convert moles to grams.

3.00 mol of water
0.50 mol of sodium chloride
1.20 mol of carbon dioxide
2.50 mol of CH4
0.10 mol of H2SO4

Part 4: Grams to Moles (Compounds)

Calculate the molar mass of the compound, then convert grams to moles.

100.0 g of calcium carbonate
36.0 g of C6H12O6
50.0 g of NH3
117.0 g of sodium chloride
22.0 g of carbon dioxide

Answer Key

Part 1: Moles to Grams (Elements)

8.00 g
47.66 g
320.60 g
16.18 g
208.42 g

Part 2: Grams to Moles (Elements)

1.00 mol
1.79 mol
0.72 mol
1.27 mol
0.40 mol

Part 3: Moles to Grams (Compounds)

54.05 g
29.22 g
52.81 g
40.11 g
9.81 g

Part 4: Grams to Moles (Compounds)

1.00 mol
0.20 mol
2.94 mol
2.00 mol
0.50 mol

Tuesday, July 8, 2025

Predicting the Products of a Chemical Reaction

Part I: Formation Reactions

Predict the chemical formula of the product formed, then balance the entire equation.

(General Pattern: A + B -> AB)

Na + Cl2 -> ______________________
Mg + O2 -> ______________________
Al + Br2 -> ______________________
K + S -> ______________________
Li + N2 -> ______________________
H2 + O2 -> ______________________

Part II: Decomposition Reactions

Predict the products formed (break them into elements), then balance the entire equation. Remember your homonuclear diatomic elements!

(General Pattern: AB -> A + B)

H2O -> ______________________
HgO -> ______________________
MgCl2 -> ______________________
NI3 -> ______________________
Al2O3 -> ______________________
Ag2O -> ______________________

Part III: Combustion Reactions

Predict the products for the complete combustion of the following compounds, then balance the equation.

(General Pattern: carbohydrate + O2 -> CO2 + H2O)

CH4 + O2 -> ______________________ (Methane)
C3H8 + O2 -> ______________________ (Propane)
C6H12O6 + O2 -> ______________________ (Glucose)
C2H5OH + O2 -> ______________________ (Ethanol)
C4H10 + O2 -> ______________________ (Butane)

Part IV: Mixed Practice

Identify the reaction type (Synthesis, Decomposition, or Combustion), predict the products, and balance.

Ca + N2 -> ______________________
Type: ______________________
FeS -> ______________________
Type: ______________________
C8H18 + O2 -> ______________________
Type: ______________________

ANSWER KEY

Part I: Synthesis

2Na + Cl2 -> 2NaCl
2Mg + O2 -> 2MgO
2Al + 3Br2 -> 2AlBr3
2K + S -> K2S
6Li + N2 -> 2Li3N
2H2 + O2 -> 2H2O

Part II: Decomposition

7. 2H2O -> 2H2 + O2

8. 2HgO -> 2Hg + O2

9. MgCl2 -> Mg + Cl2

10. 2NI3 -> N2 + 3I2

11. 2Al2O3 -> 4Al + 3O2

12. 2Ag2O -> 4Ag + O2

Part III: Combustion

13. CH4 + 2O2 -> CO2 + 2H2O

14. C3H8 + 5O2 -> 3CO2 + 4H2O

15. C6H12O6 + 6O2 -> 6CO2 + 6H2O

16. C2H5OH + 3O2 -> 2CO2 + 3H2O

17. 2C4H10 + 13O2 -> 8CO2 + 10H2O

Part IV: Mixed Practice

18. Synthesis: 3Ca + N2 -> Ca3N2

19. Decomposition: 8FeS -> 8Fe + S8 (or Fe + S)

20. Combustion: 2C8H18 + 25O2 -> 16CO2 + 18H2O