The Mole Concept Worksheet
1. . Calculate the molar mass of each of the following:
a. (NH4)2Cr2O7
__________ g/mol (252.06 g/mol)
b. CoCl2 . 6 H2O
__________ g/mol (237.93 g/mol)
2. Determine the mass in grams of the following:
b. 3.00 x 1020 N2 molecules (0.0140 g)
b. 2.35 moles of NaHCO3 (197 g)
3. The molecular formula of acetylsalicylic acid (aspirin), one of the most commonly used pain
relievers, is C9H8O4.
a. Calculate the molar mass of aspirin. (180 g/mol)
b. A typical aspirin tablet contains 325 mg of C9H8O4. How many molecules of
acetylsalicylic acid is in a tablet? (1.09 x 1021)
4. Manganese metal can be prepared by a thermite reaction.
4 Al(s) + 3 MnO2(s) → 3 Mn(s) + 2 Al2O3(s)
a. What mass of manganese metal (in g) can be produced from the reaction of 2.935 g of
aluminum with an excess of manganese(IV)oxide? (4.479 g)
b. If, in the reaction, only 2.386 g of manganese was produced, what is the percentage
yield? (53.27 %)
Ans. = ______ g Mn
Ans. = ______ %
5. Calcium nitrate and ammonium fluoride react to form calcium fluoride, nitrogen monoxide,
and water vapor. What mass of calcium fluoride is formed after 15.0 g calcium nitrate and
17.5 g ammonium fluoride are reacted? (7.14 g)
Ans. = _______ g CaF2
6. The percentage composition of acetic acid is found to be 39.9% C, 6.7% H, and 53.4% O.
Determine the empirical formula of acetic acid. (CH2 O) The molar mass was determined by
experiment to be 60.0 g/mol. What is the molecular formula? (C2H4 O2)
7. Aniline, a starting material for urethane plastic foams, consists of C, H, and N. Combustion
of such compounds yields CO2, H2O, and N2 as products. If the combustion of 9.71 g of
aniline yields 6.63 g H2O and 1.46 g N2, what is its empirical formula? (C6H7 N) The molar
mass of aniline is 93 g/mol. What is its molecular formula? (C6H7 N)