Name: ______________________________Class: _________________ Date: _________________
Molar Mass and Mole Calculations Worksheet
1. Calculate the molar mass for each of the following compounds:
a. NaCl = 58.44 g/mol
e. (NH4)3PO4 = 149.12 g/mol
b. Fe2O3 = 159.7 g/mol
f. Ca3(PO4)2 =310.18 g/mol
c. MgCO3 = 84.32 g/mol
g. C6H12O6 = 180.18 g/mol
d. Ba(OH)2 = 171.35 g/mol
h. C5H5N = 79.11 g/mol
2.Calculate the number of moles in each of the following masses:
a. 45.0 g of acetic acid, CH3COOH = 0.75 mol
b. 7.04 g of lead (II) nitrate = 0.03 mol
3. Calculate the mass in grams of each of the following amounts:
a. 3.00 mol of selenium oxybromide, SeOBr2 = 764.31 g
M=78.97+ 16+2(79.9)= 254.77 g/mol 254.77 x 3=
b. 488 mol of calcium carbonate = 48,843.92 g
M=40.08+12.01+3(16)= 100.09 g/mol 100.09 x 488=
4. Calculate the number of molecules or formula units in each of the following
amounts:
a. 4.27 mol of tungsten(VI) oxide, WO3 = 2.57 x 1024
4.27 x 6.02x1023=
b. 0.989 mol of nitrobenzene C6H5NO2 = 5.95 x 1023
0.989 x 6.02x1023=
5. Calculate the mass of each of the following quantities:
a. 8.39  1023 molecules of fluorine = 52.96 g
8.39x1923/6.02x1023= 1.39 mol 1.39 x 38=
M= 2(19) = 38 g/mol
b. 6.82  1024 formula units of beryllium sulfate = 1,190.33 g
M= 9.01+ 32.06+ 4(16) = 105.07
6.82 x 1024/6.02x1023= 11.33
105.07 x 11.33=
Name: ______________________________Class: _________________ Date: _________________
6.A chemist needs 22.0 g of phenol, C6H5OH, for an experiment. How many
moles of phenol is this?
(6 carbon 6 hydrogen 1 oxygen)
m= 22.0 g
mol= mass/Molar mass
M= 6(12.01) + 6 (1.01) + 16 =
mol= 22 g/ 94.12=
94.12 g/mol
mol= 0.23 mol
7. A student needs 0.015 mol of iodine crystals, I2, for an experiment. What mass
of iodine crystals should the student obtain? (2 iodine)
mol= 0.015 mol
mass= mol x Molar mass
M= 2(126.9) = 253.8 g/mol
m= 0.015 x 253.8
m= 3.81 g
8. An Avogadro’s number (1 mol) of sugar molecules has a mass of 342 g, but an
Avogadro’s number (1 mol) of water molecules has a mass of only 18 g.
Explain why there is such a difference between the mass of 1 mol of sugar and
the mass of 1 mol of water.
Mass is dependent on the “weight” of each element/molecule. A sugar
molecule (doesn’t specify in question) but glucose C6H12O6 has a Molar
Mass= 180.18 g/mol while water H2O has a Molar Mass= 18.02 g/mol. Even
though the amount of molecules is the same, the mass is different because
sugar is a heavier molecule
9. A chemist weighs a steel cylinder of compressed oxygen, O2, and finds that it
has a mass of 1027.8 g. After some of the oxygen is used in an experiment, the
cylinder has a mass of 1023.2 g. how many moles of oxygen gas are used in
the experiment? (2 oxygen)
∆m= mass beginning – mass ending
mol= mass ÷ Molar mass
1027.8 g – 1023.2 g =
mol= 4.6 g ÷ 32 g/mol
mass of amount used = 4.6 g
mol = 0.14 mol
M= 2(16) = 32 g/mol