Compare the total mass of the reactants to the total mass of the products. What choice demonstrates the Law of Conservation of Mass?
[tex]$60 g N _2+130 g O _2 \rightarrow 220 g N _2 O _5$[/tex]
[tex]$210 g Ag +80 g Cl _2 \rightarrow 240 g AgCl$[/tex]
[tex]$41 gN _2+9 gH _2 \rightarrow 50 gNH _3$[/tex]
[tex]$40 g Mn +30 g O _2 \rightarrow 90 g MnO _2$[/tex]
Answer (1)
Calculate the total mass of reactants for each reaction.
Calculate the total mass of products for each reaction.
Compare the total mass of reactants and products for each reaction.
Identify the reaction where the total mass of reactants equals the total mass of products: 41 g N 2 + 9 g H 2 → 50 g N H 3 .
The reaction that demonstrates the Law of Conservation of Mass is: 41 g N 2 + 9 g H 2 → 50 g N H 3 .
Explanation
Understanding the Law of Conservation of Mass The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. We need to compare the total mass of the reactants to the total mass of the products for each given reaction to see which one obeys this law.
Calculating Total Masses Let's calculate the total mass of reactants and products for each reaction:
Reaction 1: 60 g N 2 + 130 g O 2 → 220 g N 2 O 5 Total mass of reactants: 60 g + 130 g = 190 g Total mass of products: 220 g
Reaction 2: 210 g A g + 80 g C l 2 → 240 g A g Cl Total mass of reactants: 210 g + 80 g = 290 g Total mass of products: 240 g
Reaction 3: 41 g N 2 + 9 g H 2 → 50 g N H 3 Total mass of reactants: 41 g + 9 g = 50 g Total mass of products: 50 g
Reaction 4: 40 g M n + 30 g O 2 → 90 g M n O 2 Total mass of reactants: 40 g + 30 g = 70 g Total mass of products: 90 g
Comparing Masses Now, let's compare the total masses of reactants and products for each reaction:
Reaction 1: Reactants (190 g) = Products (220 g) Reaction 2: Reactants (290 g) = Products (240 g) Reaction 3: Reactants (50 g) = Products (50 g) Reaction 4: Reactants (70 g) = Products (90 g)
Only Reaction 3 has the same total mass of reactants and products.
Identifying the Correct Reaction Therefore, the reaction that demonstrates the Law of Conservation of Mass is: 41 g N 2 + 9 g H 2 → 50 g N H 3
Examples
The Law of Conservation of Mass is a fundamental principle in chemistry and has practical applications in various fields. For example, in pharmaceutical manufacturing, it's crucial to ensure that the total mass of reactants used in a drug synthesis equals the total mass of the products, accounting for any byproducts. This ensures that the chemical reaction is efficient and that the final product is pure and safe. Similarly, in environmental science, understanding mass conservation helps track pollutants in ecosystems, ensuring that the total amount of a pollutant remains constant, even as it transforms or moves through different environmental compartments.
