Mole Concept
A hydrocarbon sample contains 75% carbon by mass and remainder hydrogen. Its empirical formula is (Atomic masses: C=12, H=1)
Select the correct option:
Solution
CH4
- Define Mass Percentages:
- Carbon (C) = 75%
- Hydrogen (H) = 100%−75%=25%.
- Convert to Moles (assume 100g sample):
- Moles of C=12 g/mol75 g=6.25 mol.
- Moles of H=1 g/mol25 g=25 mol.
- Determine Atomic Ratio:
- Ratio (H:C)=6.2525=4.
- Formulate Empirical Formula:
- Since the ratio is 1:4, the empirical formula is CH4.
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About This Question
- Subject
- chemistry
- Chapter
- some basic concepts in chemistry
- Topic
- mole concept
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
CH4
- Define Mass Percentages:
- Carbon (C) = 75%
- Hydrogen (H) = 100%−75%=25%.
- Convert to Moles (assume 100g sample):
- Moles of C=12 g/mol75 g=6.25 mol.
- Moles of H=1 g/mol25 g=25 mol.
- Determine Atomic Ratio:
- Ratio (H:C)=6.2525=4.
- Formulate Empirical Formula:
- Since the ratio is 1:4, the empirical formula is CH4.
This easy difficulty chemistry question is from the chapter some basic concepts in chemistry, covering the topic of mole concept. It appeared in the 2025 exam.
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