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.

Sunday, July 6, 2025

Worksheet: Writing Chemical Formulas for Binary Ionic Compounds

Instructions

For each of the following pairs of elements or ions, write the correct chemical formula for the binary ionic compound that they would form. Remember that the overall charge of the compound must be neutral.

1. Sodium and Chlorine

2. Potassium and Iodine

3. Magnesium and Bromine

4. Calcium and Oxygen

5. Barium and Sulfur

6. Aluminum and Fluorine

7. Lithium and Nitrogen

8. Aluminum and Oxygen

9. Gallium and Phosphorus

10. Strontium and Chlorine

11. Cesium and Sulfur

12. Beryllium and Nitrogen

13. Iron (II) and Oxygen

14. Iron (III) and Chlorine

15. Copper (I) and Bromine

16. Copper (II) and Sulfur

17. Lead (IV) and Oxygen

18. Tin (II) and Fluorine

19. Zinc and Iodine

20. Silver and Phosphorus

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Answer Key

1. NaCl

2. KI

3. MgBr₂

4. CaO

5. BaS

6. AlF₃

7. Li₃N

8. Al₂O₃

9. GaP

10. SrCl₂

11. Cs₂S

12. Be₃N₂

13. FeO

14. FeCl₃

15. CuBr

16. CuS

17. PbO₂

18. SnF₂

19. ZnI₂

20. Ag₃P

Tuesday, June 24, 2025

An Introduction to Chemical Reactions

A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances into another. At the heart of chemistry is understanding how and why these reactions occur. We can classify most chemical reactions into one of five main types.

1. Synthesis (or Combination) Reaction

In a synthesis reaction, two or more simple substances combine to form a more complex product. Think of it as building something bigger from smaller pieces.

General Formula: A + B ⟶ AB

Example: The reaction between sodium and chlorine gas to produce sodium chloride (table salt).

2Na + Cl₂ ⟶ 2NaCl

2. Decomposition Reaction

A decomposition reaction is the opposite of a synthesis reaction. A complex substance breaks down into two or more simpler substances.

General Formula: AB ⟶ A + B

Example: The decomposition of hydrogen peroxide into water and oxygen gas.

2H₂O₂ ⟶ 2H₂O + O₂

3. Single-Displacement (or Single-Replacement) Reaction

In this type of reaction, a single uncombined element replaces another element in a compound. Essentially, one element "kicks out" another.

General Formula: A + BC ⟶ AC + B

Example: Zinc metal reacts with copper(II) chloride. The zinc replaces the copper.

Zn + CuCl₂ ⟶ ZnCl₂ + Cu

4. Double-Displacement (or Double-Replacement) Reaction

In a double-displacement reaction, the positive and negative ions of two ionic compounds exchange places to form two new compounds. It's like the compounds "swap partners."

General Formula: AB + CD ⟶ AD + CB

Example: When silver nitrate reacts with sodium chloride, they form silver chloride and sodium nitrate.

AgNO₃ + NaCl ⟶ AgCl + NaNO₃

5. Combustion Reaction

A combustion reaction is a rapid reaction between a substance with an oxidant, usually oxygen, to produce heat and light. When the substance is a hydrocarbon (made of carbon and hydrogen), the products are always carbon dioxide and water.

General Formula (for hydrocarbons): Hydrocarbon + O₂ ⟶ CO₂ + H₂O

Example: The combustion of methane (natural gas).

CH₄ + 2O₂ ⟶ CO₂ + 2H₂O

Practice Problems

Instructions: For each of the following reactions, identify which of the five types of chemical reactions it is.

H₂ + O₂ ⟶ H₂O

Type of Reaction: _________________________

Mg + 2HCl ⟶ MgCl₂ + H₂

Type of Reaction: _________________________

CaCO₃ ⟶ CaO + CO₂

Type of Reaction: _________________________

C₃H₈ + 5O₂ ⟶ 3CO₂ + 4H₂O

Type of Reaction: _________________________

2KOH + H₂SO₄ ⟶ K₂SO₄ + 2H₂O

Type of Reaction: _________________________

Chemical Reactions - ANSWER KEY

1. 2H₂ + O₂ ⟶ 2H₂O

Type of Reaction: Synthesis

Explanation: Two simple substances (hydrogen and oxygen) combine to form a more complex one (water).

2. Mg + 2HCl ⟶ MgCl₂ + H₂

Type of Reaction: Single-Displacement

Explanation: Magnesium (a single element) replaces the hydrogen in hydrochloric acid (HCl).

3. CaCO₃ ⟶ CaO + CO₂

Type of Reaction: Decomposition

Explanation: A complex substance (calcium carbonate) breaks down into two simpler substances (calcium oxide and carbon dioxide).

4. C₃H₈ + 5O₂ ⟶ 3CO₂ + 4H₂O

Type of Reaction: Combustion

Explanation: A hydrocarbon (propane, C₃H₈) reacts with oxygen to produce carbon dioxide and water.

5. 2KOH + H₂SO₄ ⟶ K₂SO₄ + 2H₂O

Type of Reaction: Double-Displacement

Explanation: The potassium (K⁺) from KOH swaps with the hydrogen (H⁺) from H₂SO₄. The positive ions have "swapped partners."