2.75g of cupric oxide was reduced by heating in a current of hydrogen ...
Law of constant proportion means whatever be the method of preparation of a compoundthe compoisition remains the same.
I method
Weight of copper oxide = 2.75 g
Weight of copper = 2.196 g
2.75 g of the copper oxide contained 2.196 g of the metal
100 g of the copper oxide contained = 2.196/2.75 x 100 = 79.86 %
II method
2.952 g of copper oxide contains 2.358 g of copper
100 g of the copper oxide contained = 2.358/2.952 x 100 = 79.87 %
For the law of constant proportion, the % obtained should be same in both the methods.
This question is part of UPSC exam. View all NEET courses
2.75g of cupric oxide was reduced by heating in a current of hydrogen ...
Introduction:
The law of constant composition, also known as the law of definite proportions, states that a chemical compound always contains the same elements in the same proportions by mass. This law is a fundamental principle in chemistry and provides a basis for understanding the composition and behavior of compounds. In this case, we will analyze the results of two experiments involving the compound cupric oxide (CuO) to determine if they illustrate the law of constant composition.
Experiment 1: Reduction of Cupric Oxide:
- Mass of cupric oxide before reduction: 2.75g
- Mass of copper remaining after reduction: 2.196g
Experiment 2: Conversion of Copper Nitrate to Cupric Oxide:
- Mass of copper used: 2.358g
- Mass of cupric oxide formed: 2.952g
Analysis:
To determine if the results of these experiments illustrate the law of constant composition, we need to compare the ratios of copper to oxygen in cupric oxide in both experiments.
Calculations:
Experiment 1:
- Mass of copper in cupric oxide before reduction = 2.75g - 2.196g = 0.554g
- Mass of oxygen in cupric oxide = 2.75g - 0.554g = 2.196g
- Ratio of copper to oxygen = (0.554g / 2.196g) ≈ 0.252
Experiment 2:
- Mass of oxygen in cupric oxide = 2.952g - 2.358g = 0.594g
- Ratio of copper to oxygen = (2.358g / 0.594g) ≈ 3.973
Comparison:
If the results of the experiments illustrate the law of constant composition, the ratio of copper to oxygen in cupric oxide should be the same. However, in this case, the ratio in Experiment 1 is approximately 0.252, while the ratio in Experiment 2 is approximately 3.973. These ratios are significantly different, indicating that the law of constant composition is not observed in this example.
Explanation:
The discrepancy in the ratios of copper to oxygen in cupric oxide between the two experiments suggests that the composition of cupric oxide is not consistent. This could be due to experimental errors, variations in the reaction conditions, or impurities in the starting materials. The law of constant composition holds true for pure substances under specific conditions, but in practical scenarios, deviations can occur.
Conclusion:
Based on the analysis of the experimental results, it can be concluded that the law of constant composition is not illustrated in this case. The ratios of copper to oxygen in cupric oxide obtained from the two experiments are significantly different, indicating a lack of consistency in the composition of the compound. It is important to recognize that while the law of constant composition is a fundamental principle in chemistry, there can be exceptions and variations in real-world scenarios.
To make sure you are not studying endlessly, EduRev has designed NEET study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in NEET.