To determine which reaction demonstrates the Law of Conservation of Mass, we need to compare the total mass of the reactants to the total mass of the products for each choice. According to the Law of Conservation of Mass, the mass of the reactants must equal the mass of the products.
Let's analyze each choice:
Choice A:
- Reactants: [tex]\(78 \text{ g K} + 71 \text{ g Cl}_2 = 149 \text{ g}\)[/tex]
- Products: [tex]\(149 \text{ g KCl}\)[/tex]
- Comparison: [tex]\(149 \text{ g (reactants)} = 149 \text{ g (products)}\)[/tex]
Choice B:
- Reactants: [tex]\(56 \text{ g Fe} + 16 \text{ g O}_2 = 72 \text{ g}\)[/tex]
- Products: [tex]\(88 \text{ g FeO}\)[/tex]
- Comparison: [tex]\(72 \text{ g (reactants)} \neq 88 \text{ g (products)}\)[/tex]
Choice C:
- Reactants: [tex]\(55 \text{ g Mn} + 32 \text{ g O}_2 = 87 \text{ g}\)[/tex]
- Products: [tex]\(85 \text{ g MnO}\)[/tex]
- Comparison: [tex]\(87 \text{ g (reactants)} \neq 85 \text{ g (products)}\)[/tex]
Choice D:
- Reactants: [tex]\(23 \text{ g Na}_2\text{CO}_3 + 1 \text{ g H}_2\text{O} + 28 \text{ g CO}_2 = 52 \text{ g}\)[/tex]
- Products: [tex]\(84 \text{ g NaHCO}_3\)[/tex]
- Comparison: [tex]\(52 \text{ g (reactants)} \neq 84 \text{ g (products)}\)[/tex]
Based on these comparisons, we can see that only Choice A demonstrates the Law of Conservation of Mass, where the total mass of the reactants is equal to the total mass of the products.
Conclusion: The correct answer is Choice A.
