Which of the following compounds have the same empirical formula?
- (1) But-2-ene
- (2) Propane
- (3) Ethene
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3)
The correct answer and explanation is :
To determine which of the compounds have the same empirical formula, we need to first write out their molecular formulas and then calculate their empirical formulas.
1. But-2-ene:
- Molecular formula of But-2-ene: C₄H₈
- But-2-ene is a four-carbon alkene, with a double bond between the second and third carbon atoms.
- Empirical formula: C₂H₄ (simplified ratio of carbon to hydrogen is 2:4, or 1:2)
2. Propane:
- Molecular formula of Propane: C₃H₈
- Propane is a three-carbon alkane.
- Empirical formula: C₃H₈ (the ratio of carbon to hydrogen in propane is already in its simplest form)
3. Ethene:
- Molecular formula of Ethene: C₂H₄
- Ethene is a two-carbon alkene with a double bond between the two carbon atoms.
- Empirical formula: C₂H₄ (the ratio of carbon to hydrogen is already in its simplest form)
Comparison of Empirical Formulas:
- But-2-ene: C₄H₈ → Empirical formula: C₂H₄
- Propane: C₃H₈ → Empirical formula: C₃H₈
- Ethene: C₂H₄ → Empirical formula: C₂H₄
Analysis:
- But-2-ene and Ethene both have the empirical formula C₂H₄.
- Propane has the empirical formula C₃H₈, which is different from both but-2-ene and ethene.
Conclusion:
The compounds that have the same empirical formula are But-2-ene and Ethene.
Thus, the correct answer is:
B. (1) and (3) only