Compare the total mass of the reactants to the total mass of the products. What choice demonstrates the Law of Conservation of Mass?
A. [tex]$100 g Na _3 N \rightarrow 70 g Na +14 g N _2$[/tex]
B. [tex]$40 g Ca +35 g O _2 \rightarrow 79 g CaO$[/tex]
C. [tex]$115 g Sr ( OH )_2 \rightarrow 103 g SrO +18 g H _2 O$[/tex]
D. [tex]$161 g ZnSO _4 \rightarrow 81 g ZnO ^{-80} g SO _3$[/tex]
Answer (2)
Calculate the total mass of reactants and products for each reaction.
Compare the total mass of reactants and products.
Reaction 1: 100 g = 84 g
Reaction 2: 75 g = 79 g
Reaction 3: 115 g = 121 g
Reaction 4: 161 g = 161 g
The reaction that demonstrates the Law of Conservation of Mass is: 161 g Z n S O 4 → 81 g Z n O + 80 g S O 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. This means that in a closed system, the total mass of the reactants must equal the total mass of the products. We are given four chemical reactions, and we need to determine which one demonstrates this law.
Analyzing Reaction 1 Let's analyze each reaction:
Reaction 1: 100 g N a 3 N → 70 g N a + 14 g N 2 Total mass of reactants: 100 g Total mass of products: 70 g + 14 g = 84 g Since 100 g = 84 g , this reaction does not demonstrate the Law of Conservation of Mass.
Analyzing Reaction 2 Reaction 2: 40 g C a + 35 g O 2 → 79 g C a O Total mass of reactants: 40 g + 35 g = 75 g Total mass of products: 79 g Since 75 g = 79 g , this reaction does not demonstrate the Law of Conservation of Mass.
Analyzing Reaction 3 Reaction 3: 115 g S r ( O H ) 2 → 103 g S r O + 18 g H 2 O Total mass of reactants: 115 g Total mass of products: 103 g + 18 g = 121 g Since 115 g = 121 g , this reaction does not demonstrate the Law of Conservation of Mass.
Analyzing Reaction 4 Reaction 4: 161 g Z n S O 4 → 81 g Z n O + 80 g S O 3 Total mass of reactants: 161 g Total mass of products: 81 g + 80 g = 161 g Since 161 g = 161 g , this reaction demonstrates the Law of Conservation of Mass.
Conclusion Therefore, the reaction that demonstrates the Law of Conservation of Mass is: 161 g Z n S O 4 → 81 g Z n O + 80 g S O 3
Examples
The Law of Conservation of Mass is crucial in various real-world applications. For instance, in pharmaceutical manufacturing, ensuring that the total mass of reactants equals the total mass of products is essential for quality control and safety. If a chemical reaction doesn't adhere to this law, it could indicate errors in the process, contamination, or the presence of unwanted side reactions. This principle also applies in environmental science when tracking pollutants in a closed ecosystem, helping scientists understand how pollutants transform and distribute without any loss or gain of mass.
The reaction that demonstrates the Law of Conservation of Mass is Reaction D, where the total mass of reactants (161 g) equals the total mass of products (161 g). The other reactions do not satisfy this law. Therefore, the answer is D .
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