MCAT Chem Question — Empirical Formula
- Jan 21, 2017
- MCAT Question of the Day
- Reviewed By: Liz Flagge
One mole of a compound consists of approximately 72g carbon and 6g hydrogen. What is its empirical formula?
Click for Explanation
The empirical formula expresses the smallest number of atoms making up a molecule in the correct integer ratio. In this question, converting to moles gives us six moles of carbon and six moles of hydrogen in one mole of the entire compound. This gives us our molecular formula, C6H6. However, remember that empirical formulas must consist of the smallest ratio of all atoms involved! This ratio is CH, which is our answer.
A. C6H6, incorrect. This represents the molecular, rather than the empirical, formula.
B. CHO, incorrect. There is no oxygen present.
C. CH, correct. The empirical formula is the smallest whole-number ratio of the elements making up a molecule.
D. C6H12, incorrect. This does not reflect the correct molar ratio of the elements.
Want more MCAT practice?
We’ve got options for every schedule and learning style!
From the best online MCAT course created by top instructors with 524+ MCAT scores to the most representative full-length practice exams and private tutoring, we can custom tailor your MCAT prep to your goals!
Not sure which option is right for you? Schedule a free MCAT consultation with an MCAT expert using the form below. No obligation, just expert advice.
Search the Blog
Free ConsultationSchedule Now
Free MCAT Practice AccountNeed great MCAT practice?
Get the most representative MCAT practice possible when you sign up for our free MCAT Account, which includes a half-length diagnostic exam and one of our full-length MCAT practice exams.Learn More