Worksheet 1: What Is a Reaction?
Theory: Understanding Chemical Reactions
A chemical reaction is a process in which starting substances called reactants change into new substances called products, while matter is conserved and atoms are only rearranged. For example, when wood burns, carbon in the wood reacts with oxygen to form ash, carbon dioxide, and release heat and light energy.
- Reactants: The substances you start with (left side of the arrow).
- Products: The new substances formed (right side of the arrow).
- Law of Conservation of Mass: Matter cannot be created or destroyed in a chemical reaction. Atoms are simply rearranged.
Activity 1: Real-Life Chemistry
Look at the situations below. Check the box if you think a Chemical Reaction is happening.
You have 3 attempts left.
| Situation | Reaction? |
|---|---|
| 🧊 Ice melting into water | |
| 🕯️ Burning a candle | |
| 🔩 Rust forming on iron | |
| 🍬 Sugar dissolving in water | |
| 🧪 Baking soda + Vinegar fizzing |
Visual Demonstration
Let's verify the last one. Mix baking soda and vinegar:
Activity 2: Evidence of a Reaction
Theory: Observing Chemical Change
How do you know a reaction happened? You can't always see atoms moving, but you can see the evidence they leave behind.
- Color Change: A rusting nail turns reddish-brown.
- Temperature Change: Heat (Exothermic) or Cold (Endothermic) is released or absorbed.
- Gas Formation: Bubbles appear (like fizz), or an odor is produced.
- Precipitate: A solid forms when two clear liquids are mixed.
Click on ALL the signs that indicate a chemical reaction:
You have 3 attempts left.
Visualizing Rearrangement
Let's look at Synthesis: Two Hydrogen molecules and one Oxygen molecule combining to make water.
Worksheet 2: Types of Reactions
Theory: Classifying Reactions
Chemists group reactions based on patterns:
- Synthesis (A + B → AB): Building. Two simple things combine to make one complex thing. (e.g., 2H2 + O2 → 2H2O)
- Decomposition (AB → A + B): Breaking. A complex thing breaks down into simpler parts. (e.g., Water splitting)
- Combustion: Burning. A substance (usually hydrocarbon) reacts rapidly with Oxygen to release energy (Heat/Light). (e.g., Methane burning)
- Single Replacement (A + BC → AC + B): Swapping. One lonely element kicks another element out of a compound to take its place.
Activity 4 & 5: Match & Identify
Match the Type (Left) to the Description (Right) and Identify the equations.
You have 3 attempts left.
Equation: 2H₂ 2H₂O
Equation: CaCO₃ CaO + CO₂
Worksheet 3: Writing Chemical Equations
Theory: Chemical Formulas vs. Word Equations
Chemists use symbols to save space and communicate universally.
- Symbols: H = Hydrogen, O = Oxygen, Na = Sodium, Cl = Chlorine.
- Subscripts (little numbers): Tell you how many atoms are in a molecule.
H₂O= 2 Hydrogens, 1 Oxygen. - Coefficients (big numbers): Tell you how many molecules you have.
2H₂O= 2 Water molecules.
Activity 6: Word Equations → Chemical Equations
Convert the following word equations into chemical formulas.
You have 3 attempts left.
+
+
Activity 7: Balance the Equations
The Law of Conservation of Mass means we must have same number of atoms on both sides.
You have 3 attempts left for EACH problem.
Worksheet 4: Think Like a Chemist
1. Iron reacts with oxygen over time.
2. A hydrocarbon burns in oxygen.
👨🔬 Professor's Analysis: Think Like a Chemist
Virtual Lab: Lava Lamp Model
Simulate a reaction that changes density. Gas bubbles attach to oil, making it float.
Activity 9: Reflection & Exit Questions
Reflection
What part of today's lesson helped you understand chemical reactions the most?
👨🏫 Professor's Analysis
Design: Mr Maurice Nkusi
Production: ADS-TLT