Mole Conversions
Name
Period
Unit 5 – HW 1 Worksheet (Goals 1 – 4)
1. Identify the representative particle in each of the following: (atom, molecule, formula unit)
a. CuSO4
b. H2O
c. NaCl
d. Zn
e. Cu
f. CO2
2. How many atoms are present in the following compounds?
a. BaS
b. O3
c. Cl2
d. Ag3PO4
e. Fe(NO3)3
f. PCl5
3. Consider the following samples: 1.00 mol H2O2, 1.00 mol C2H6, or 1.00 mol CO
a. Which sample contains more molecules?
b. Which sample contains more atoms?
4. Write the relationship between the mole and Avogadro’s number.
5. Calculate the number of representative particles (molecules, formula units, atoms) or moles for each of
the following using Avogadro’s number:
a. 8.2 mol CuSO4
b. 8.67 x 1018 atoms Zn
c. 343.67 mol H2O
d. 328 formula units H3PO4
6. Calculate the molar mass of each of the following using the periodic table:
a. CO2
b. C6H12O6
c. CCl4
d. HNO3
e. Fe
f. CuOH
7. Write the relationship between the mole and molar mass.
8. Calculate the number of grams or moles for each of the following using molar mass:
a. 142.7 g NaHCO3
b. 13.87 mol CuCl2
c. 3.14 x 103 mol HCl
d. 8.63 x 10-3 g CaCO3
9. Write the relationship between the mole and molar volume at STP.
10. Calculate the volume in liters or moles for each of the following at STP using molar volume:
a. 27 L NO2
b. 3.5 mol H2
c. 2.30 x 101 L HCN
d. 0.250 mol O2
11. Calculate the required information for each problem:
a. Molecules in 87.6 grams of CO2
b. Volume in liters of 100.0 grams of gaseous O2 at STP
c. Mass in grams of 9.2 x 1021 NaCl formula units
d. Volume in liters of 1.33 x 1024 N2 molecules
e. Mass in grams of 300 molecules of H2O
f. Number of H atoms in 6.047 x 1023 molecules of H2
g. Number of O atoms in 13.7 grams of SO2.
Percent Composition and Empirical Formula
Name
Period
Unit 5 – HW 2 Worksheet (Goal 4 - 5)
1. Define percent composition.
2. Briefly describe how to determine percent composition given a chemical formula.
Percent Composition Calculations
Determine the percent composition by mass of each element in the following compounds.
3. Magnesium carbonate
MgCO3
4. Sulfuric Acid H2SO4
5. Sodium Nitrate NaNO3
6. A hydrated salt (a salt with water loosely bound to it) has a mass of 12.33 g. The salt is heated in a crucible to
remove the water. After heating, the anhydrous salt (a salt without water attached to it) has a mass of 9.25 g.
What is the percent composition of water in the hydrated salt?
7. Define empirical formula.
8. Is the empirical formula of a compound the same as the molecular formula? Explain.
9. Circle the empirical formulas in the following list of compounds.
NaCl
Pb2(SO4)4
H2O2
H2O
MgCl2
MgO
Empirical Formula Calculations
Show your work. Remember to first convert values to moles and then determine the lowest whole number mole ratio.
10. Find the empirical formula for a compound which contains 32.8% chromium and 67.2% chlorine.
11. What is the empirical formula for a compound which contains 80.1 % zinc and 19.3% oxygen?
12. The characteristic odor of pineapple is due to ethyl butyrate, an organic compound which contains only carbon,
hydrogen and oxygen. If a sample of ethyl butyrate is known to contain 0.62069 g of carbon, 0.103448 g of
hydrogen and 0.275862 g of oxygen, what is the empirical formula for ethyl butyrate? What is the molecular
formula of ethyl butyrate if the molar mass is 116.16 g/mol?
Writing and Balancing Chemical Equations
Name
Period
Unit 5 – HW 3 Worksheet (Goals 6 – 8)
1. Describe the following word equation with a statement or sentence: Iron + Oxygen iron (III) oxide
2. In a chemical equation, what is the purpose of the arrow?
3. How are the symbols (s), (l), (g) and (aq) used in an equation?
4. What is a catalyst and where is it shown in a chemical equation?
3. Describe a Combination Reaction:
4. Describe a Decomposition Reaction:
5. Describe a Single Replacement Reaction:
6. Describe a Double Replacement Reaction:
7. Describe a Combustion Reaction:
8. When a “hydrocarbon” is a reactant in a combustion reaction, _________________ and ___________________
are the products.
9. An element like magnesium can also react with oxygen. Give an example of a combustion reaction involving an
element as one of the reactants.
10. Match the generic equations given with their reaction type:
a. RS R + S
_________________________________
b. R+S- + T+U- R+U- + T+S-
_________________________________
c. CxHy + ?O2 ?CO2 + ?H2O
_________________________________
d. R + S RS
_________________________________
e. T + RS TS + R
_________________________________
11. Write the Law of Conservation of Mass –
12. Balance the following equations:
KNO3
KNO2 +
Al
+
HCl
CO
+
O2 C4H10
+
Th(NO3)4
H2O2
Pb(NO3)2
+
K3PO4
H2O
PBr3
+
H2O
Na
+
H2O
CO2
H2
H2O
Th3(PO4)4
+
KNO3
PbCl2
NaNO3
+
H2O
O2
NaCl
+
+
+
O2
+
CO2
+
O2
AlCl3
O2
CH4
Classify reaction type:
CO2
H3PO3
NaOH
+
+
+
HBr
H2
13. Complete each of the following descriptions by writing the balanced chemical equation with chemical formulas
and symbols. Refer to the text for help with symbols and formulas.
When metallic iron is dropped into a solution of hydrochloric acid, bubbles of hydrogen gas and an iron (II)
chloride solution are produced.
Lithium metal burns in the presence of oxygen gas to generate solid lithium oxide.
Solid calcium carbonate will react with sulfuric acid (H2SO4) to form solid calcium sulfate, carbon dioxide, and
water.
Solid copper (II) chloride will react with a phosphoric acid (H3PO4) solution to form copper (II) phosphate and
hydrogen chloride, both in solution.
Hydrogen peroxide solution will react in the presence of a manganese dioxide catalyst to generate water and
oxygen gas.
Stoichiometry
Name
Period
Unit 5– HW 4 Worksheet (Goal 10 - 11)
1. For each of the following reactions, solve the problem:
a. How many moles of KClO3 are needed to produce 0.366 moles of O2?
2 KClO3 2 KCl + 3 O2
b. How many moles of H2O are produced from 9.45 moles of NH4NO3?
NH4NO3 N2O + 2 H2O
2. Aluminum sulfate, Al2(SO4)3 is used in fireproofing fabrics and the manufacture of antiperspirants.
Al2O3(s) + 3 H2SO4(aq) Al2(SO4)3(aq) + 3 H2O(l)
a. How many moles of Al2(SO4)3 would be produced if 6 mol of H2SO4 reacted with excess Al2O3?
b. How many moles of Al2O3 are required to make 2 mol of H2O?
3. Copper (II) nitrate, Cu(NO3)2, is used to give a dark finish to items made o f copper metal, making them appear
antique. Using the balanced equation, complete the following table:
3 Cu(s) + 8 HNO3(aq) 3 Cu(NO3)2(aq) + 4 H2O(l) + 2 NO(g)
Equation
Cu
HNO3
Cu(NO3)2
# of moles
Molar
Mass
Total
Mass
State of
Matter
What is the total mass of the reactants?
What is the total mass of the products?
What law does the comparison of the mass of the reactants and products follow?
H2O
NO
Make sure each equation is BALANCED before working on the Stoichiometry problem!
1. “Baking Powder” consists of a mixture of “Baking Soda” (sodium bicarbonate, NaHCO3) and some solid acid so
that the moistened mixture will react to form CO2 gas. When sodium dihydrogen phosphate, NaH2PO4, is used in
this reaction, the following reaction occurs,
NaHCO3
+
NaH2PO4
Na2HPO4
+
H2O
+
CO2
What mass of sodium dihydrogen phosphate (NaH2PO4) must be used to completely react with 0.65 mole of
“baking soda.”
2. Calcium cyanide powder is used by beekeepers to destroy a colony of diseased bees. This powder must be
stored in a closed container, since moist air decomposes it, according to the equation:
Ca(CN)2
+ H2O Ca(OH)2 +
HCN
Determine the number of moles of water needed to liberate 94.5g of HCN gas.
3. Stannous flouride is a common toothpaste additive as a source of flourideion for retarding tooth decay. It may
be manufactured from tin and dry hydrogen flouride gas:
Sn + HF SnF2 + H2
If 31.4g of SnF2 are to be produced what mass of hydrogen gas will be liberated?
4. “Fools gold” is pyrite ore, and it contains beautiful crystals of FeS2. This is also a source of iron metal, and so is
somewhat valuable although it isn’t gold. How many grams of this ore must be used to obtain 255 kg of pure
iron?
FeS2 Fe + S8
5. How many moles of oxygen are required to produce 242 grams of MgO, magnesium oxide?
Mg + O2 MgO
6. Welders use the reaction of Acetylene (C2H2) and Oxygen (O2) to provide energy for their welds. The equation
for the reaction is:
C2H2 + O2 CO2 + H2O
What volume of Oxygen (O2) will be required to burn 52 grams of Acetylene (C2H2)?
7. Silicon Carbide is one of the hardest substances known to man. It is used extensively in sharpening stones and
other tools. Silicon Carbide (SiC) is made by the following reaction.
SiO2 + C SiC + CO
What mass of carbon C is required to produce 5.0 grams of Silicon Carbide?
8. The odorous compound Dimethyl Mercapitan (C2H6S) is burned to Sulfur Dioxide (SO2).
C2H6S + O2 CO2 + H2O + SO2
What volume of Sulfur Dioxide (SO2) is produced by each 1.000 kg of Dimethyl Mercapitan (C2H6S) burned?
9. An astronaut on the moon missions consumes 1.000 kg units of carbohydrates (C6H12O6) per day. These react in
his body as follows:
C6H12O6 + O2 CO2 + H2O
How many grams of Oxygen are required to sustain the astronaut each day?
Use the following equation to solve the next three stoichiometry problems:
Li3N + 3 H2O NH3 + 3 LiOH
10. What mass of water is needed to react with 7.30 x 1024 molecules of Li3N?
11. When 13.3 ml of NH3 are produced how many formula units of LiOH are also produced?
12. When 4.0 x 1012 molecules of water are used, how many grams of NH3 are produced?
Limiting Reagent and Percent Yield
Name
Period
Unit 5 – HW 5 Worksheet (Goals 12 – 14)
1. What is a Limiting Reagent?
2. What is an Excess Reagent?
3. When solving for an amount of a product formed by stoichiometry, which reagent should be used?
4. Actual Yield -
5. Theoretical Yield -
6. Percent Yield -
Identify and use the limiting reagent in a reaction to calculate the maximum amount of product(s) produced and the
amount of excess reagent.
7. Aluminum (Al) reacts with bromine (Br2) in a combination reaction to form Aluminum bromide (AlBr3).
a. Write the balanced equation for this reaction.
b. Identify the limiting reagent and calculate how many grams of product can be made from 2.2 x 1024
atoms of aluminum reacting with 500 grams of bromine?
8. C3H7O completely combusts. (remember: H2O and CO2?)
a. Write the balanced equation for this reaction.
b. If 87 Liters of oxygen reacts with 87 grams of C3H7O find the limiting reagent. Then calculate the volume
of carbon dioxide that can be produced (assume STP)?
c. How many moles of excess reagent are left over, unused?
Calculate the theoretical yield, actual yield, or percent yield given appropriate information.
9. Silicon dioxide reacts with carbon to produce silicon carbide (SiC) and carbon monoxide.
a. Write the balanced equation for this reaction.
b. If 75 grams of silicon dioxide is heated with excess of carbon, 31.9 grams of silicon carbide is produced.
What is the percent yield of this reaction?
10. A solution of rubidium carbonate reacts with aqueous magnesium sulfate in a double replacement reaction.
Magnesium carbonate is not soluble.
a. Write the balanced equation for this reaction.
b. If the reaction proceeds with an 87% yield, how many grams of precipitate are collected when 12 grams
of magnesium sulfate reacts with excess rubidium carbonate?
c. How many formula units of rubidium carbonate are consumed when the reaction from part b.
proceeds?
Calculate the % yield from experimental data after identifying the limiting reagent.
11. Write the complete balanced equation for the single replacement reaction between a solution of copper (II)
sulfate, CuSO4 and the element aluminum, Al.
a. You dissolve 25.0 grams of copper (II) sulfate, then react it with 5.0 grams of aluminum. Upon collecting the
copper produced, you dry it and determine the collected copper’s mass to be 9.0 grams.
b.
Show your work, and also explain how you know which reactant was the limiting reagent and which was in
excess.
c. Show your work for calculating the % yield of this experiment.
d. How many grams of copper (II) sulfate went unreacted?