CP Chem Review: The Mole!
Molar Mass: Calculate the molar mass of the following compounds:
A) Ca3(PO4)2
B) C5H12
C) Cu2SO4
D) CoCl2
E) Lithium Nitrate
F) Lead(IV) Oxide
The Mole:
2. How many atoms of Phosphorus are in 128.35 grams of Phosphorous?
3. How many moles of Radon are in 7.98x1024 atoms of Radon?
4. How many atoms of Mercury are in 765.34g of Mercury?
5. How many grams does 9.78x1023 molecules of Barium Cyanide weigh?
6. How many molecules are in 253.89 grams of Sodium Sulfide?
7. How many ATOMS are in 309.95 grams of water?
8. The chemical formula for ibuprofen (Advil) is C13H18O2. If you buy 3 bottles of Advil, how
many molecules of ibuprofen do you have? (1 bottle = 60 pills, 1 pill = 3.45 grams)
Percent Composition
Determine the percent composition of each element for the following compounds
9. A) CuI2
B) C4H10O
C) C10H14N2
D) Ca(HCO3)2
E) Nickel (III) Carbonate
F) Beryllium Phosphite
Empirical and Molecular Formula
10. Rubbing alcohol was found to contain 60.0 % carbon, 13.4 % hydrogen, and the
remaining mass was due to oxygen. What is the empirical formula of rubbing alcohol?
11. Phenyl magnesium bromide is used as an important organic reagent. Determine its
empirical formula if it contains 39.75% C, 2.78% H, 13.41% Mg, and 44.06% Br.
12. An unknown compound was found to have a percent composition as follows:
47.0 % potassium, 14.5 % carbon, and 38.5 % oxygen. What is its empirical formula?
If the true molar mass of the compound is 166.22 g/mol, what is its molecular formula?
13. A compound is analyzed and found to have a mass of 289.9 g/mole and contain 49.67%
carbon, 48.92% chlorine and 1.39% hydrogen. What is the molecular AND empirical
formula of the compound?
14. Determine the molecular formula of a compound with an empirical formula of NH2 and
a molar mass of 32.06g/mol.
Hydrates
15. MgSO4 ∙7H2O is a common hydrate. A chemist decides to burn off the water in the
hydrate to obtain pure MgSO4. If he measures 350.75 grams of MgSO4 ∙7H2O, what can
he/she expect the new mass of the product to be?
16. A chemist needs to know the chemical formula for an unlabeled hydrate found in lab.
The label reads Na2SO4 ∙__H2O, so she wants to know the coefficient for water.141.8 180
She weighs 532 grams of the hydrate, and after burning off the water, re weighs her
product at 234.42g. Complete the chemical formula for the hydrate.