7. A 100.00g sample of the gaseous hydrocarbon ethane is a gaseous hydrocarbon, with 79.89g of carbon and 20.11g of hydrogen. Ethylene is a different gas phase hydrocarbon. A 100.00g sample of ethylene has 85.63g of carbon with 14.37 of hydrogen. A sample of a hydrocarbon has 64.580g of carbon has 5.420g of hydrogen.
a. Use the mass percents and the law of constant composition to prove that all three compounds are different.
b. Prove that ethane and ethylene obey the law of multiple proportions.
I didn't address the problem because the third gas doesn't add to 100 g so it must have something else besides C and H and makes it a non-hydrocarbon. I suggest you proof the problem and repost.
a. To prove that all three compounds are different using the mass percents and the law of constant composition, we need to compare the ratios of carbon to hydrogen in each compound.
For ethane:
Mass of carbon = 79.89g
Mass of hydrogen = 20.11g
Ratio of carbon to hydrogen = 79.89g / 20.11g = 3.971
For ethylene:
Mass of carbon = 85.63g
Mass of hydrogen = 14.37g
Ratio of carbon to hydrogen = 85.63g / 14.37g = 5.971
For the hydrocarbon with unknown identity:
Mass of carbon = 64.580g
Mass of hydrogen = 5.420g
Ratio of carbon to hydrogen = 64.580g / 5.420g = 11.914
Since the ratios of carbon to hydrogen in each compound are different, we can conclude that all three compounds are different.
b. To prove that ethane and ethylene obey the law of multiple proportions, we need to compare the ratios of carbon to hydrogen in different samples of the same compound.
For ethane:
Mass of carbon = 79.89g
Mass of hydrogen = 20.11g
Ratio of carbon to hydrogen = 79.89g / 20.11g = 3.971
For ethylene:
Mass of carbon = 85.63g
Mass of hydrogen = 14.37g
Ratio of carbon to hydrogen = 85.63g / 14.37g = 5.971
The ratio of carbon to hydrogen in ethane is approximately 1:4, while in ethylene, the ratio is approximately 6:1. These ratios are in simple whole number ratios, indicating that ethane and ethylene follow the law of multiple proportions.