AP Chemistrymediummcq1 pt
An oxide of iron analyzes as 69.9% iron and 30.1% oxygen by mass. What is its empirical formula?
A.Fe2O3
B.FeO
C.Fe3O4
D.FeO3
Explanation
Core Concept
Taking a 100 g basis: 69.9 g of iron is 1.25 mol and 30.1 g of oxygen is 1.88 mol. Dividing both mole amounts by 1.25 leaves a 1 to 1.5 ratio, and multiplying by 2 clears the fraction, giving Fe₂O₃. Never round 1.5 away; scale up until both subscripts are whole numbers.
Correct Answer
AFe2O3
More Unit 1: Atomic Structure and Properties practice questions
- mediumWhy does atomic radius decrease across a period from Li to F?
- easyWhich element has the largest atomic radius: S, Se, or Te?
- easyWhich orbital diagram for carbon's 2p subshell is correct (arrows represent electrons)?
- mediumA 34.0 g sample of NH₃ contains how many moles of hydrogen atoms?
- mediumHow many atoms are in 9.0 g of water (molar mass 18.0 g/mol)?
Practice more AP Chemistry questions with full explanations
Practice Unit 1: Atomic Structure and Properties Questions →