11 • The Mole
Unit Study Guide
Things to Remember:
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Molar mass is in grams; formula mass is in amu
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Particles are the same as atoms, molecules, and formula units
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Create your own “toolbox” as soon as your receive your test
Section 1: Concepts to Know
1. 1 mole of anything contains how many things?
2. What chemist is credited with determining the mole?
3. What is the temperature and pressure at STP?
4. 1 mole of gas at STP occupies what volume?
5. What is the difference between an empirical formula and molecular formula?
Section 2: Moles and Molar Mass
1. Find the molar mass of the following gaseous compounds. Put it in the form
of “1 mole of X = ___ g of X.”
a. SF4
b. H2O
c. F2
d. P4O6
e. Ammonia (NH3)
2. Find the following quantities.
a. How many moles of SF4 are in a 53.5 g sample?
b. A sample containing 3.50 x 1024 molecules of H2O contains how many
moles of the compound?
c. A 92.5 L sample of F2 at STP contains how many moles of F2?
d. What is the mass of a 0.325 mole sample of P4O6?
e. How many molecules of NH3 are in a 0.0150 mole sample?
f. What is the volume of a 2.50 mole sample of SF4 at STP?
g. A 72.7 g sample of H2O contains how many molecules?
h. What is the mass of 5.9 x 1023 molecules of F2?
i.
What is the volume of a 190.5 g sample of P4O6 at STP?
j.
What is the mass of a 15.8 L sample of NH3?
k. How many liters are occupied by 4.22 x 1023 molecules of SF4 at STP?
l.
How many molecules of H2O are in a 1.44 L sample at STP?
3. For each of the following unknown compounds, find its molar mass. Match
each compound with one of the compounds in question 1.
a. A 0.240 mole sample of an unknown gas has a mass of 4.09 g.
b. A 3.29 g sample of an unknown gas occupies 0.336 L at STP.
c. A 37.4 g sample of an unknown gas contains 5.11 x 10 23 molecules.
Section 3: Empirical and Molecular Formula
1. Find the percent composition of all elements in the following
neurotransmitters.
a. GABA: C4H9NO2
b. Ephinedrine: C9H13NO3
c. Dopamine: C8H11NO2
d. Seratonin: C10H12N2O
2. A sample of lysine contains 0.895 g carbon, 0.170 g hydrogen, 0.335 g
nitrogen, and 0.385 oxygen. The molar mass of lysine is 146 g/mol.
a. Find the empirical formula for lysine.
b. Find the molecular formula for lysine.
3. Glutamine is 41.1% carbon, 6.9% hydrogen, 19.2% nitrogen, and 32.8%
oxygen by mass. The molar mass of glutamine is 146 g/mol.
a. Find the empirical formula for glutamine.
b. Find the molecular formula for glutamine.
4. A 36.4 g sample of a gaseous compound containing only nitrogen and oxygen
is 30.5% nitrogen by mass and occupies 8.85 L at STP.
a. Find the molar mass of this compound.
b. Find the empirical formula for this compound.
c. Find the molecular formula for this compound.
d.