Mass Matters
What does the Law of Conservation of Mass say about chemical reactions?
Mass is not created or destroyed in a chemical reaction.
What are the starting substances in a reaction called?
Reactants
Why do we need to balance chemical equations?
To follow the Law of Conservation of Mass — the atoms must be equal on both sides.
What do the Smarties represent in our balancing activity?
Atoms/molecules
Which color Smartie represented hydrogen in our class?
Red
If 20g of baking soda reacts with 50g of vinegar, how much product should you end up with?
70g (20+50)
What are the substances formed at the end of a reaction called?
What are the substances formed at the end of a reaction called?
Balance: H₂ + O₂ → H₂O
2H₂ + O₂ → 2H₂O
True
Name an atom that always exists as a pair in their natural form?
Any of these: H₂, O₂, N₂, Cl₂, F₂, Br₂, I₂
In the open baking soda + vinegar experiment, why does it look like mass is lost?
Because gas escapes into the air.
In the reaction Na + Cl₂ → NaCl, name the reactants and the product.
Reactants: Na and Cl₂. Product: NaCl.
Balance: Na + Cl₂ → NaCl
2Na + Cl₂ → 2NaCl
Why did we need more than one H Smartie when building H₂O?
Because each water molecule has 2 hydrogen atoms.
Which of these is a real element symbol:
Nf, Cz, So, Br?
Br is a real element symbol - the rest are made up!
True or False: Mass can be created in a chemical reaction.
False
What does the arrow in a chemical reaction represent/ what did I compare it to?
It separates reactants from products. I compared it to the middle of a seesaw.
Balance: Fe + HCl → FeCl₂ + H₂
Fe + 2HCl → FeCl₂ + H₂
In the reaction 2Na + Cl₂ → 2NaCl, how many Smarties do you need total?
4 Na and 4 Cl = 8 Smarties total
What color did we use to represent sulfur AND what is the symbol (letter) for sulfur?
Purple, and the symbol is S
Explain why mass stays the same when burning wood, even if it looks smaller afterward.
Because the lost mass becomes gases like smoke and carbon dioxide.
Create your own reaction using real-world items and identify the reactants and products.
Open-ended: e.g., Cake Batter + Heat → Cake
Balance: Fe + O₂ → Fe₂O₃
4Fe + 3O₂ → 2Fe₂O₃
What happens if you don’t have the same number of atoms on both sides?
The equation is unbalanced and breaks the Law of Conservation of Mass.
Why did we use Cl₂ instead of Cl in our balancing equations?
Because chlorine is a pair in its natural form.