MOLES/ % COMPOSITION/ EMPIRICAL & MOLECULAR FORMULA
TEST REVIEW
1. Calculate the molar mass of iron (II) sulfate.
2. Calculate the mass of 6 moles of chromium (VI) oxide
3. How many carbon atoms contain the same amount of mass as one molybdenum atom?
4. How many sulfur atoms are in one mole of sulfur?
5. How many formula units are there in one mole of silver (I) cyanide formula units?
6. How many atoms are in a copper penny if the penny has a mass of 2.5g?
7. How many atoms are in 28 g of sodium? .
8. Dioxin, C1211404O2i is a powerful poison. How many moles of dioxin are there in 700 g of dioxin?
How many molecules?
9. Calculate the percent by mass of each element in limestone, CaCO3.
10. A sample of the oxide of sodium has a mass of 4.55 g. Of this mass, 1.17g is oxygen and the rest is
sodium. Find the percent composition of each element in sodium oxide and determine the empirical
formula.
11. The compound benzene has two formulas, CH and C6H6. Which is the empirical formula and which
is the molecular formula?
12. A compound is composed of 7.20g of carbon, 1.20 g of hydrogen,-and 9.60 g of oxygen. The molar
mass of the compound is 180 g. Find the empirical and molecular formulas for this compound.
13. Oxalic acid is a compound used in cosmetics and paints. A 0.725 g sample of oxalic acid was found
to contain 0.194 g of carbon, 0.016 g of hydrogen, and 0.516 g of oxygen. If the molar mass of oxalic
acid is 90.04 g/mol, what is the molecular formula?
14. Calculate the mass of carbon that would have the same number of atoms as 7.75 g of chlorine.
15.Determine the empirical formula for a compound containing 79.9% copper and 20.1% sulfur.
16. The compound borazine consists of 40.29% boron, 7.51 % hydrogen, and 52.20% nitrogen, and its
molar mass is 80.50 g/mol. Calculate the empirical and molecular formula for borazine.
17. The composition of silver oxalate is 71.02% silver, 7.91 % carbon and 21.07% oxygen. If the molar
mass of silver oxalate is 303.8 g/mol, determine silver oxalates empirical and molecular formula.
18. A compound of phosphorus and sulfur contains 27.876 % phosphorus and 72.13% sulfur. The molar
mass of the compound is 222.3 g/mol. Calculate the empirical and molecular formula.
19. Cerium (III) iodide, (CeI3) occurs as a hydrate with the composition 76.3% CeI3 and 23.7% H2O.
Calculate the formula for the hydrate.
20. Cobalt (II) nitrate, is used in ceramic glazes and produces a blue color when the ceramic is fired. This
compound exists as a hydrate whose composition is 37.1 % water and 62.9% cobalt (II) nitrate by
mass. Write the formula for this hydrate.
21. Determine the mass in grams of 3.57 mol Al.
22. Determine the number of moles in 125 g Zn.
23. What is the mass in grams of 1.50 X 1015 atoms of Nitrogen.
24. Determine the molar mass of strontium(II) nitrate.
25. What is the mass of 3.25 moles of sulfuric acid?
26. How many grams of potassium permanganate are in 2.55 moles?
2
27. What is the mass of 4.35 X 10" moles of zinc(II) chloride?
28. Calculate the mass in grams of a sample containing six atoms of Polonium.
29. What is the percent composition of phosphate in phosphoric acid?
30. When an oxide of potassium is decomposed, 19.55 g K and 4.00 g O are obtained. What is the
empirical formula for the compound?
31. An oxide of aluminum contains 0.545 g Al and 0.485 g O. Find the empirical formula for the oxide.
32. What mass of silver, Ag, contains the same number of atoms as 9.0 g of platinum, Pt?
33. A mass of 2.50 g of blue, hydrated copper sulfate (CuSO4•XH2O) is placed in a crucible and heated.
After heating, 1.59 g white anhydrous copper sulfate remains. What is the formula for the hydrate?
Name the hydrate.
34. A hydrate is found to have the following percent composition: 48.8% MgSO4 and 51.2% H2O. What
is the formula and the name for this hydrate.
35. Triethylenemelamine is used in the plastics industry and as an anticancer drug. Its analysis is 52.93%
C, 5.92% H, and 41.15% N. The molar mass of triethylenemelamine is 204.2 g/mol. Determine the
empirical and molecular formula of triethylenemelamine
36. Calculate the molar mass of Aluminum bromide hexahydrate. Write the formula also.
61
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