1. Law of Conservation of Mass

2. Law of Conservation of Mass
Coal is completely burned
100 g
100 g
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What do you observe?
Write down your observations.

3. Law of Conservation of Mass Conservation means to be kept the same
Coal is completely burned
100 g
100 g
A: Mass of the jar & its contents remains the same. Mass is conserved.
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In a chemical reaction, matter is neither created nor destroyed, it is transformed into something else.

4. Mass of Reactants  Mass of Products
Since matter can not be created or destroyed, the mass of the chemical reactions must be balanced
The amount of mass you start with (reactants) must be equal to the mass of what you end with (products).
Mass of Reactants  Mass of Products
100g total =
100g total

5. The mass on both sides of the arrow must be equal.
According to the law of conservation of mass, how much zinc was present in the zinc carbonate? + = +
256g
256g
REMEMBER !!!
The mass on both sides of the arrow must be equal.
A 40 g B 88 g C 104 g D 256 g
ANSWER: = 104g of Zn

6. CuCO3(s)  CuO(s) + CO2(g) 123.6 g 79.6 g ? g 44.0 g
According to the law of conservation of mass, how much carbon dioxide was present in the copper (II) carbonate?
CuCO3(s)  CuO(s) + CO2(g)
123.6 g
79.6 g
? g +
44.0 g
123.6g
123.6g
What are the reactants?
CuCO3
123.6 g
What is the mass of reactants?
CuO & CO2
What are the products?
Mass?
What is the mass of products?
79.6 g + CO2
Answer: – 79.6 = 44.0g of CO2

7. Solve the follow problem in your IAN Notebook.
Practice #1
Solve the follow problem in your IAN Notebook.
If 50 grams of sodium (Na) react with chlorine (Cl2) to form 125 grams of salt (NaCl), how many grams of chlorine reacted?
2Na + Cl2  2NaCl

8. Solve the follow problem in your IAN Notebook.
Practice #2
Solve the follow problem in your IAN Notebook.
From a laboratory process, a student collects g of hydrogen (H2) and g of oxygen (O2). How much water was originally involved in the process?
H2O  H2 + O2