Name ____________________________________
Chemistry
Mr. Harper
CH 7: Formula Packet
Bookwork
1.
2.
3.
4.
5.
p.238 #1; p.239 #2; p.244 #1-2 (practice) and #5 (section review)
p.239 #1; p.242 #1-3
p.247 #1-3
p.249 #1-2 (practice); p.249 #4 (section review)
Extra practice: p.252 #28-33, 36-40
Percent Composition Practice
1. Find the percent composition of iron (III) phosphate.
2. Find the percent composition of silver acetate.
3. If water is 11.21% hydrogen by mass, how many grams of hydrogen can be obtained by
separating the hydrogen and oxygen in 368 g of water?
4. How many grams of oxygen can you obtain from 80.0 g of water?
5. A 24.00 g sample of an oxide of iron contains 6.63 g of oxygen. Calculate the percent of iron in
the compound.
6. A 1.61 g sample of an oxide of chromium contains 1.10 g of chromium. Calculate the percent
of oxygen in the compound.
7. If 3.90 g of an oxide of mercury is decomposed by heat, 0.15 g of oxygen is liberated. Find the
percent of mercury in the compound.
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Mole Conversion Map
Molecules
of
compound
Grams of
compound
6.022 x 1023
Molar Mass
(Periodic Table)
# of atoms or ions
per molecule
Ions
or
Atoms
Moles of
compound
# of atoms
per molecule
1 mole = molar mass in grams
1 mole = 6.022 x 1023 molecules
Moles of
element
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Steps to Solving Mole Conversion Problems
1. Write down the given amount – grams, moles, or molecules.
2. Determine what you are trying to find – grams, moles, molecules, atoms, or ions.
3. Next to the given amount construct your “picket fence.”
4. Put the given unit on the bottom of the picket fence (underneath the line in the denominator), and put
the desired unit on top of the picket fence (the unit you are looking for goes in the numerator).
5. Create the conversion factors you will need to fill in the picket fence with the correct numbers.
a. The general conversion factor looks like this:
1 mole of particles = 6.022 x 1023 particles = molar mass of the particle in grams
b. Particles could be atoms, molecules, ions, or any other object for that matter.
c. Here are examples with water and sulfuric acid.
1 mole of H2O = 6.022 x 1023 molecules of H2O = 18.02 grams of H2O
1 mole of H2SO4 = 6.022 x 1023 molecules of H2SO4 = 98.09 grams of H2SO4
d. There are other conversion factors specific to a given compound. Water and sulfuric acid are
used as examples.
1 mole of H2O = 2 moles of H = 1 mole of O
1 molecule of H2O = 2 atoms of H = 1 atom of O
1 mole of H2SO4 = 2 moles of H = 1 mole of S = 4 moles of O
1 molecule of H2SO4 = 2 H+1 ions and 1 (SO4)-2 ion = 3 total ions
e. You will need to create one or more of these conversion factors for the given compound in the
problem.
6. Place the number from the conversion factor that goes with the desired unit on top and the number that
goes with the given unit on bottom.
7. If you cannot convert to the desired unit with one conversion factor, then write another multiplication
sign with a line to use a second conversion factor. For instance, there is no conversion factor to go from
grams of H2O to atoms of H. You first need to convert from grams of H2O to molecules of H2O then from
molecules of H2O to atoms of H.
8. Once all the numbers are in place, multiply across the top and the bottom and divide those two
numbers. Make sure to carry your units through so the right units cancel out and the correct unit is left.
Also, make sure to use correct significant figures.
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Chemistry
Mr. Harper
Mole Conversions: Worksheet A
1. Convert 5.00 moles of sodium bromide to grams.
2. Convert 78.59 grams of sulfur dioxide to moles.
3. Convert 3.42 x 1024 molecules of tetraphosphorus decoxide to moles.
4. Convert 3.67 moles of magnesium oxide to molecules.
5. Convert 44.52 grams of water to molecules.
6. Convert 2.28 x 1023 molecules of silver nitrate to grams.
7. How many moles of chlorine are in 6.25 moles of carbon tetrachloride?
8. How many atoms of oxygen are in 5.44 moles of sulfuric acid?
9. How many moles of copper are in 61.44 grams of copper (II) nitride?
10. How many atoms of nitrogen are in 61.44 grams of copper (II) nitride?
11. How many total ions are in 235.0 grams of nickel (III) carbonate?
Mole Conversions: Worksheet B
1. Convert 76.52 grams of silicon dioxide to moles.
2. How many atoms of hydrogen are in 3.55 moles of sulfuric acid?
3. Convert 1.12 x 1024 molecules of dinitrogen tetroxide to moles.
4. How many atoms of nitrogen are in 72.99 grams of ammonium nitrate?
5. Convert 41.32 grams of sodium oxide to molecules.
6. How many ions are in 5.25 moles of potassium phosphide?
7. Convert 1.58 x 1023 molecules of ammonium nitrate to grams.
8. How many moles of oxygen are in 3.00 moles of strontium phosphate?
9. Convert 4.65 moles of magnesium chloride to molecules.
10. How many moles of hydrogen are in 72.99 grams of ammonium nitrate?
11. Convert 4.00 moles of potassium bromide to grams.
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Name __________________________
Pd _____
Chemistry
Mr. Harper
Mole Conversions Practice Quiz
1. What is the molar mass of calcium carbonate?
2. What is the percent composition of calcium carbonate?
3. How many moles of calcium carbonate are in 343.0 g of the compound?
4. How many moles of oxygen are in 343.0 g of calcium carbonate?
5. How many molecules of calcium carbonate are in 343.0 g?
6. How many total ions are in 343.0 g of calcium carbonate?
5
Chemistry
Mr. Harper
Empirical Formula Practice
1. Find the empirical formula of a compound with the following percent composition: 69.94% Fe,
30.06% O. Name the compound.
2. Find the empirical formula of a compound with the following percent composition: 27.05%
Na, 56.47% O, & 16.48% N. Name the compound.
3. Find the empirical formula of a compound with the following percent composition: 69.19% Ag,
20.52% O, & 10.28% S. Name the compound.
4. A 24.00 g sample of an oxide of iron contains 6.63 g of oxygen. Find the empirical formula of
the compound, and name the compound. (Hint: You are already given an amount in grams.
Start with that and convert to moles to find the empirical formula.)
5. If 3.90 g of an oxide of mercury is decomposed by heat, 0.15 g of oxygen is liberated. Find the
empirical formula of the compound, and name the compound.
6. A 1.61 g sample of an oxide of chromium contains 1.10 g of chromium. Find the empirical
formula of the compound, and name the compound.
7. Find the empirical formula of a compound with the following percent composition: 37.03% Fe,
42.43% O, & 20.53% P. Name the compound.
8. Find the empirical formula of a compound with the following percent composition: 52.55% Ba,
36.73% O, & 10.72% N. Name the compound.
Molecular Formula Practice
1. Find the empirical formula of a compound with the following percent composition: 92.3% C,
7.7 % H.
2. The molar mass of the compound in the previous problem was found to be 78.1 g/mol. What
is the molecular formula? (Hint: Look at page 248 and sample problem N.)
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Name _____________________
Pd _____
Chemistry
Mr. Harper
CH 7 Sample Test: Chemical Compounds
Directions: Complete the following problems. Be sure to show all work, use correct units and sig figs,
and circle your answers.
Useful relationships: 1 mole = 6.022 x 1023 particles = molar mass (g)
1. How many moles are in 33.5 g of aluminum oxide?
2. What is the mass of 3.573 moles of chloric acid?
3. How many total ions are in 88.1 g of calcium bisulfite?
4. How many moles of oxygen are in 5.00 moles of lead (IV) carbonate?
5. Find the percent composition of chromium (II) chlorite.
6. What is the formula mass of aluminum sulfate and what percent of it is sulfate?
7. What is the empirical formula of a compound that has 49.41% potassium,
20.26% sulfur, and 30.33% oxygen by mass? What is the name of the
compound?
8. An oxide of mercury is heated in a crucible releasing the oxygen. Use the
following data to determine the empirical formula and name of the oxide of
mercury?
Mass of crucible + lid = 19.31 g
Mass of crucible + lid + oxide of mercury = 23.22 g
Final mass, after heating, of crucible + lid + mercury = 22.93 g
9. A compound has an empirical formula of HO and its molar mass is 34.01 g/mol.
What is the molecular formula and name of the compound?
10. A compound has an empirical formula of CH2 and its molar mass is 42.08 g/mol.
What is the molecular formula and name of the compound?
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Answers to Sample Exam
1. 0.329 mol Al2O3
2. 301.8 g HClO3
3. Ca(HSO3)2; 7.87 x 1023 ions
4. Pb(CO3)2; 30.0 mol O
5. Cr(ClO2)2; 27.82% Cr, 37.93% Cl, 34.24% O
6. Al2(SO4)3; 342.17 amu; 84.230% SO4
7. K2SO3, potassium sulfite
8. HgO, mercury (II) oxide
9. H2O2, hydrogen peroxide
10. C3H6, propene or (tricarbon hexahydride)
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