Copy of Copy of The Law of Conservation of Mass
Chemical Equations and Mass Conservation
Modeling Mass Conservation
Use chemical equations to illustrate mass conservation during chemical changes.
Key standard: PS-MS-PS1-5, which emphasizes understanding that the total number of atoms remains constant in a reaction, thus ensuring mass is conserved.
Reactants and Products
Identifying Reactants and Products
Example reaction: Methane + Oxygen → Carbon Dioxide + Water
Reactants: Methane and Oxygen
Products: Carbon Dioxide and Water
Recognition Method: Analyzing the chemical equation allows the identification of reactants and products.
Indicators of a Chemical Reaction
Signs of Reactions
Indicators:
Color change
Formation of a new substance
Example of a Common Reaction: Rust formation
Sources of Fe (Iron) include: Metal surface of the car
Source of Oxygen: Air
Chemical Equation Coefficients:
Coefficient of Fe atoms: 4
Coefficient of O molecules: 3
Chemical Equation Coefficients
Understanding Coefficients Within Reactions
Example Equation: 4Fe + 3O2 → 2Fe2O3
Coefficients indicate the quantity of each reactant and product, serving to balance the reaction.
Law of Conservation of Mass
Historical Context
Antoine Lavoisier's experiments in the 1770s demonstrated that mass remains constant in chemical reactions
Law of Conservation of Mass: Matter is neither created nor destroyed during chemical or physical changes; atoms are simply rearranged.
Mass lost or gained is accounted for by atomic movement rather than loss.
Models in Chemistry
Role of Models
Models serve as tools for understanding processes that cannot be directly observed.
Example: Model of Iron Sulfide (FeS):
Mass of FeS: 24.0g
Demonstrates conservation of mass by showing that the mass of reactants equals the mass of products.
Conservation of Matter in Models
Number of Atoms in a Reaction
Through modeling, it is clear that although atoms are rearranged, the total amount of matter remains unchanged throughout the reaction.