Students X and Y, both prepared an oxide of copper by combining copper and oxygen in the ratios of 4:1 and 8:2, respectively. Do their results justify the Law of Constant Proportions? Explain.
Yes, their results justify the Law of Constant Proportions. According to this law, in any compound formed by two or more elements, the elements combine in a fixed ratio by mass. Student X prepared copper oxide with copper and oxygen in the ratio 4:1, while Student Y prepared it in the ratio 8:2. When we simplify Student Y's ratio of 8:2, it reduces to 4:1, which is exactly the same as Student X's ratio.
Since both students obtained the same mass ratio of copper to oxygen in the compound, their results confirm that a chemical compound always contains elements in definite proportions by mass, irrespective of how it is prepared. This is consistent with Proust's Law, which states that chemical compounds always contain elements in fixed ratios by mass.
Explanation
The question tests understanding of the Law of Constant Proportions (Proust's Law). The key insight is that the ratios 4:1 and 8:2 are equivalent - when 8:2 is simplified by dividing both numbers by 2, it equals 4:1. This demonstrates that regardless of the amount of compound prepared, the mass ratio of constituent elements remains constant, which is exactly what the Law of Constant Proportions states. The textbook context confirms this law states that 'elements in a compound have definite proportions irrespective of its source.'
Solution Steps
Step 1: Identify the ratio prepared by Student X = 4:1 (copper:oxygen)
Step 2: Identify the ratio prepared by Student Y = 8:2 (copper:oxygen)
Step 3: Simplify Student Y's ratio: 8:2 = 4:1
Step 4: Compare both ratios - they are identical (4:1 = 4:1)
Step 5: Conclude that since both ratios are the same, the results justify the Law of Constant Proportions