SHOW ALL WORK, ALL EQUATIONS, and ALL UNITS Name: _____________________________________
Empirical Formula, Molecular Formula, and Hydrates:
DETERMINE Empirical and Molecular Formula for the compound.
1. The compound benzene has two formulas, CH and C6H6. Which is the empirical formula and which is the molecular formula?
CH is the empirical formula (smallest whole-number ratio) and C6H6 is the
molecular formula (because it is NOT the smallest whole number ratio)…
Whole-Number ratio refers to the “Mole Ratio” – Subscripts within formula
2. Rust, or iron oxide can exist as either iron(II)oxide or as iron(III)oxide. If you analyzed the sample by isolating the iron from the
oxygen and found that you had 272.1 grams of iron – which type of iron oxide are you looking at if you started with 350 grams
of rust?
3. A form of phosphorus called red phosphorus is used in match heads. When 0.062 grams of red phosphorus burns, 0.142 grams
of phosphorus oxide is formed. What is the empirical formula of this oxide?
0.142 grams ( P?O? ) - 0.062 grams Phosphorus = 0.08 grams of Oxygen
P:
mol
grams
Pmolgrams 3
100.2
97.30
1062.0
;
220.1
100.2
100.2
3
3
mol
mol
O:
mol
grams
Omolgrams 3
100.5
00.16
108.0
;
52
2
1
2
100.2
100.5
3
3
mol
mol
P2O5, phosphorus pentoxide
