Mass %, Emp and Mol Formulas
1. What is the mass % of calcium in calcium nitrate?
2. What is the mass % of calcium in 2.5 g of calcium nitrate?
3. A mixture contains 20.0% Al. What is the mass of the mixture if it contains 20.0 g Al?
4. A mixture contains 20.0% Al. What is the mass of the mixture if it contains 5.00 g Al?
5. Determine the empirical formula of a compound with the following mass percentage:
C: 72.58 %, H: 6.09 %, O: 11.37 %
T. Chen
CHEM099 Montgomery College T. Chen Chemistry, Rockville
6. A long chain organic compound X contains three elements: carbon, hydrogen and oxygen. It has a formula mass of 380.48 amu.
a) Use the given mass percentages to calculate the empirical formula of compound X: C: 56.82 %, H: 9.54 %
b) What is the molecular formula of compound X?
7. A compound has empirical formula of CH3and molar mass ~ 60 g/mole. Find its molecular formula.
8. A compound has formula mass of 192.1 amu has the following composition: 37.51 % C, 4.20% H and the remaining O. Find its molecular formula.