Empirical and molecular formula calculations and quantitative analysis basics - Question Bank
1. If a compound's molecular formula is three times its empirical formula, the ratio of their molecular weights is:
2. A compound contains 30.43% nitrogen and 69.57% oxygen by mass. What is its empirical formula? (Atomic masses: N=14, O=16)
3. What is the percentage composition of phosphorus in phosphoric acid (H3PO4)? (Atomic masses: H=1, P=31, O=16)
4. The combustion of 0.1 mol of an organic compound yields 0.3 mol of CO2 and 0.4 mol of H2O. What is the empirical formula of the compound?
5. A compound has an empirical formula C5H12. If its molecular weight is 72 g/mol, what is its molecular formula?
6. What is the percentage of hydrogen in ethane (C2H6)? (Atomic masses: C=12, H=1)
7. If the molecular formula of a compound is C4H10, what is its empirical formula?
8. What is the empirical formula of a compound containing 60% carbon, 8% hydrogen, and 32% oxygen by mass? (Atomic masses: C=12, H=1, O=16)
9. A compound has the empirical formula C4H8O2 and a molecular weight of 144 g/mol. What is its molecular formula?
10. What is the percentage of nitrogen in ammonium nitrate (NH4NO3)? (Atomic masses: N=14, H=1, O=16)
11. In the determination of the empirical formula, if the mole ratios are 0.5 : 1 : 0.25, what is the simplest whole-number ratio?
12. The empirical formula of a compound is C3H4O2. If its molecular weight is 72 g/mol, what is its molecular formula?
13. A compound contains 75% carbon and 25% hydrogen by mass. What is its empirical formula? (Atomic masses: C=12, H=1)
14. What is the percentage composition of oxygen in ozone (O3)? (Atomic mass: O=16)
15. If the empirical formula is CH2 and the molecular formula is C3H6, what is the factor 'n' in the molecular formula (Empirical Formula)n?
16. A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. Its molecular weight is 180 g/mol. What is its molecular formula?
17. What is the percentage of sulfur in sulfuric acid (H2SO4)? (Atomic masses: H=1, S=32, O=16)
18. A compound has the empirical formula C2H6O and a molecular weight of 46 g/mol. What is its molecular formula?
19. What is the empirical formula of a compound with the molecular formula C6H6?
20. A compound contains 88.8% carbon and 11.2% hydrogen by mass. What is its empirical formula? (Atomic masses: C=12, H=1)
21. In the combustion analysis of an organic compound, what is typically collected and measured to determine the amount of carbon?
22. A compound has an empirical formula CH. If its molecular weight is 26 g/mol, what is its molecular formula?
23. What is the percentage of potassium in potassium permanganate (KMnO4)? (Atomic masses: K=39, Mn=55, O=16)
24. A sample of a compound contains 0.5 mol of carbon, 1.0 mol of hydrogen, and 0.25 mol of oxygen. What is its empirical formula?
25. If a compound has a molecular formula that is three times its empirical formula, the ratio of their molecular weights is:
26. A compound has an empirical formula C5H10O and a molecular weight of 86 g/mol. What is its molecular formula?
27. What is the percentage by mass of chlorine in carbon tetrachloride (CCl4)? (Atomic masses: C=12, Cl=35.5)
28. The molecular formula of a compound is C3H6. What is its empirical formula?
29. A compound contains 3.2 g of sulfur and 4.8 g of oxygen. What is its empirical formula? (Atomic masses: S=32, O=16)
30. Which of the following is NOT a step in determining the empirical formula from percentage composition?
31. A compound has an empirical formula C4H4O. If its molecular weight is 136 g/mol, what is its molecular formula?
32. What is the percentage composition of hydrogen in water (H2O)? (Atomic masses: H=1, O=16)
33. If the molecular formula of a compound is (CH2O)n, and its molecular weight is 180 g/mol, what is the value of n? (Atomic masses: C=12, H=1, O=16)
34. A compound contains 50% sulfur and 50% oxygen by mass. What is its empirical formula? (Atomic masses: S=32, O=16)
35. In quantitative analysis, what is the primary goal of determining the empirical formula?
36. A compound has the empirical formula C2H5. If its molecular weight is 58 g/mol, what is its molecular formula?
37. What is the percentage of nitrogen in ammonia (NH3)? (Atomic masses: N=14, H=1)
38. A substance has an empirical formula CCl2 and a molecular weight of 147 g/mol. What is its molecular formula? (Atomic masses: C=12, Cl=35.5)
39. If the molecular formula of a compound is twice its empirical formula, what is the ratio of their molecular weights?
40. A compound contains 2.4 g of carbon, 0.4 g of hydrogen, and 3.2 g of oxygen. What is its empirical formula?
41. What is the percentage of oxygen by mass in carbon dioxide (CO2)? (Atomic masses: C=12, O=16)
42. A compound with the empirical formula C3H8 has a molecular weight of 44 g/mol. What is its molecular formula?
43. The empirical formula of glucose is CH2O. What is the ratio of carbon atoms to hydrogen atoms in a glucose molecule?
44. A compound contains 80% carbon and 20% hydrogen by mass. If its empirical formula is CH3, what is its molecular formula?
45. What is the percentage composition of carbon in methane (CH4)? (Atomic masses: C=12, H=1)
46. A sample of an organic compound has a molar mass of 78 g/mol. If its empirical formula is C2H2, what is its molecular formula?
47. If a compound contains 40% carbon, 6.67% hydrogen, and 53.33% oxygen by mass, what is its empirical formula?
48. Which of the following represents the simplest whole-number ratio of atoms of each element present in a compound?
49. A compound has an empirical formula CH2O and a molecular weight of 60 g/mol. What is its molecular formula?
50. What is the empirical formula of a compound that has the molecular formula C6H12O6?