EMPIRICAL FORMULAS AND FORMULA STOICHIOMETRY
1. CONVERT TO GRAMS:
A. 1.50 MOL OF BROMINE
B. .00258 MOLES OF ALUMINUM HYDROXIDE
M = MOLAR MASS =G/MOL
THEREFORE: G = M X MOL
AND: MOL = G/M
C. 132 MOL OF CARBON TETRACHLORIDE
2. CONVERT TO MOLES:
A. 125.00 GRAMS OF NITRIC ACID
B. .0357 GRAMS OF MAGNESIUM
C. 5.656 GRAMS OF HYDROGEN GAS
3. . A COMPOUND IS FOUND TO BE 82.7 % CARBON AND 17.3 % HYDROGEN BY MASS. IN A SEPARATE
EXPERIMENT THE COMPOUND IS FOUND TO HAVE A MOLAR MASS OF 58.0 G/MOL.
A. WHAT IS THE EMPIRICAL FORMULA OF THE COMPOUND?
B. WHAT IS THE MOLECULAR FORMULA?
4. WHAT IS THE PERCENT BY MASS OF OXYGEN IS CALCIUM HYDROXIDE?
5. THE % HYDROGEN IN A COMPOUND THAT CONTAINS 16 HYDROGENS / MOLECULE IS 14.40%.
A. WHAT IS THE MOLAR MASS OF THE COMPOUND.
B. IF THE ONLY OTHER ELEMENT IN THE COMPOUND IS CARB0N, HOW MANY CARBON ATOMS ARE PRESENT
IN THE MOLECULE? WHAT IS THE MOLECULAR FORMULA?
6. . A COMPOUND WHOSE FORMULA IS X2O5 (X IS AN UNKNOWN ELEMENT) IS FOUND TO BE 44.0 % OXYGEN
BY MASS.
A. WHAT IS THE MOLAR MASS OF THE COMPOUND?
B. WHAT IS THE ATOMIC MASS OF ELEMENT “X”? IDENTIFY “X”
7. PYROLUSITE IS AN ORE (A HETEROGENOUS MIXTURE CONTAINING MINERALS) CONTAINING MANGANESE.
TO ANAZLYZE THE ORE FOR PERCENT MANGANESE, THE MANGANESE IS REMOVED FROM A .750 G SAMPLE
OF THE ORE AND IS CONVERTED INTO
1.000 G PF Mn2P2O7.
A. HOW MUCH MANGANESE IS IN THE Mn2P2O7?
B. HOW MUCH MANGANESE WAS IN THE ORIGINAL SAMPLE OF THE ORE?
C. WHAT IS THE PERCENT BY MASS OF MANGANESE IN THE ORE?
8. Write the formula for calcium sulfate dIhydrate:_________________
What is the percent water by mass in the hydrate:
9. A 5.650 g sample hydrocarbon containing only carbon, hydrogen, and oxygen is burned
producing 10.792 g of carbon dioxide and 6.628 g of water. What is the empirical formula of
the hydrocarbon that was burned?