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Version B
Chapter 10 The MOLE
Moletiple Choice: Place the correct answer in the space provided and on the attached answer
sheet. (2 points each)
1. The simplest whole-number ratio of the atoms of the elements in a compound is given by the
a. empirical formula
b. molecular formula
c. molar mass
d. formula mass
2. The actual number of atoms of each element in a molecular compound is given by the
a. empirical formula
b. molecular formula
c. formula mass
d. molar mass
3. A mole of this atom would have a mass of 32.06g:
a.
b.
c.
d.
sulfur
sodium
chlorine
neon
4. What is the molar volume of a gas at standard temperature and pressure?
a. 1 L / mol
b. 22.4 mL / mol
c. 22.4 L / mol
d. depends on the gas
5. The mole is a unit of:
a. volume
b. temperature
c. count
d. mass
6. What is the empirical formula of the compound whose molecular formula is P4O10?
a.
b.
c.
d.
PO
PO2
P2O5
P8O20
7. The mass of one mole of any substance
a.
b.
c.
d.
8.
depends on the substance
equals 6.02 x 1023
depends on the number of moles
equals 1
How many total atoms are in a formula unit of Al2(SO4)3?
a. 17
b. 15
c. 12
d. 3
Review Questions: (6 points)
1. Element X has three isotopes. The atomic mass and abundance of each is listed below.
Find the average atomic mass of Element X.
2.
Isotope 1
mass = 52.8amu
abundance = 43%
Isotope 2
mass = 50.1amu
abundance = 38%
Isotope 3
mass = 54.5amu
abundance = 19%
The half-life of an element is 22 years. What mass of a 640g sample of the element will remain
undecayed after 66 years?
Problem Section: Show ALL WORK! No work = No credit.
1. Complete the chart.
COMPOUND
FORMULA
MOLAR MASS
potassium sulfide
calcium phosphate
tetracarbon decahydride
2. How many moles are in 27.7 g of potassium sulfide?
(3 points)
3. How many formula units are in 27.7 g potassium sulfide? (3 points)
4. What is the mass of 4.5 x 1024 formula units of calcium phosphate. (3 points)
5. How many molecules are in 650 liters of tetracarbon decahydride gas at STP? (3 points)
6. What volume will 38 grams of tetracarbon decahydride spread out to at STP? (3 points)
7. Find the molecular formula of a compound that has a molar mass of 56 g/mol, and has an empirical formula
of CH2. (3 points)
8a. Find the percentage composition of MgCO3 (4 points)
% Sr =
%C =
%O =
8b. Use your answer above to find the mass of strontium in 75g of magnesium carbonate. (2 points)
9. a Find the percentage composition of nickel(III) nitrate. (6 points)
% Ni =
%N =
%O =
9b. What mass of nickel(III) nitrate contains 50g of nickel? (2 points)
Optional Question: (2 points)
A balloon is filled with 18.6 Liters of tricarbon hexahydride and is at STP. How many carbon atoms are in
the balloon?