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AP Stoichiometry Class Packet Unit 1
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AP Stoichiometry Class Packet Unit 1
SIGNIFICANT FIGURES REVIEW SHEET
Count the number of Significant figures:
Round to three significant figures:
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AP Stoichiometry Class Packet Unit 1
SIGNIFICANT FIGURES CALCULATIONS
Unrounded Answer
Rounded Answer
1. 1.2m + 2.35m
2. 2.6358cm * 2.1cm
3. 5.681mm - 2.mm
4. 3845.2L / 25.2354L
5. 25cm + 3cm
6. 1.2m * 2m
7. 859678.2354cm –
568426.1cm
8. 5.3cm * 5.2398m * 2m
9. 45.25252nm + 45.8563nm
10. 68.23m / 38.255m
11. 10000g / 10.0g
12. 1L * 1.0L
13. 1254.1cm / 100cm
14. 0.000456m + 0.00524m
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AP Stoichiometry Class Packet Unit 1
MOLES AND MOLAR MASS
Students should be able to demonstrate an understanding of the following essential knowledge:
1.A.3 The mole is the fundamental unit for counting numbers of particles on the macroscopic level and
allows quantitative connections to be drawn between laboratory experiments; which occur at the
macroscopic level, and chemical processes, which occur at the atomic level.
Find the gram formula mass of the following: (Show all work)
1. CO2
10. ZnCl2
2. FeS
11. Ca(OH)2
3. NaCl
12. CH4
4. Al2(CO3)3
13. NH3
5. SiO2
14. H2O2
6. H2SO4
15. NaHCO3
7. Al2(SO3)3
16. C6H12O6
8. C12H22O4
17. MgO
9. Fe2O3
18. SrSO4.3H2O
Find the number of moles in the following measurements: (Show your work)
1. 900. grams C6H12O6
3. 192 grams SiO2
2. 24.5 grams H2SO4
4. 450. grams of ZnCl2
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AP Stoichiometry Class Packet Unit 1
5. 22 grams of CO2
7. 3.40 grams of H2O2
6. 20. grams of Fe2O3
8. 840. grams of NaHCO3
Now solve for the mass given the moles. (Show your work)
1. 2.00 moles of C6H12O6
2. 5.00 moles of SrSO4.H2O
3. 0.250 moles of CH4
4. 0.100 moles of NH3
5. 12.0 moles of SiO2
6. 0.330 moles of FeS
7. 1.50 moles of MgO
8. 0.500 moles of ZnCl2
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AP Stoichiometry Class Packet Unit 1
MOLAR VOLUME AND AVOGADRO’S NUMBER
Students should be able to demonstrate an understanding of the following essential knowledge:
o 1.A.3 The mole is the fundamental unit for counting numbers of particles on the macroscopic level
and allows quantitative connections to be drawn between laboratory experiments; which occur at the
macroscopic level, and chemical processes, which occur at the atomic level.
Use dimensional analysis to convert the following:
1. A volume of 2.34L of oxygen gas to moles at STP.
2. A volume of 55.67L of carbon dioxide gas to moles at STP.
3. A 0.365 mole sample of sulfur hexafluoride gas to liters at STP.
4. A 3.98 mole sample of nitrogen gas to liters at STP.
5. A sample of 5.67x1025 atoms of carbon to moles.
6. A sample of 1.09x1021 molecules of water to moles.
7. A sample of 2.73 moles of nitrogen dioxide to molecules.
8. A sample of 0.0876 moles of bromine to atoms.
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AP Stoichiometry Class Packet Unit 1
MULTI-STEP DIMENSIONAL ANALYSIS AND STOICHIOMETRY
Students should be able to demonstrate an understanding of the following essential knowledge:
o 1.A.3 The mole is the fundamental unit for counting numbers of particles on the macroscopic level
and allows quantitative connections to be drawn between laboratory experiments; which occur at the
macroscopic level, and chemical processes, which occur at the atomic level.
Use dimensional analysis and your understanding of the mole road map to convert the following:
1. A sample of 2.34L of argon gas to atoms at STP.
2. A sample of 67.8L of krypton gas at STP to grams.
3. A sample of 45.67grams of CCl4 to liters at STP.
4. A sample of 0.00798 grams of iron to atoms.
5. A sample of 4.58x1024 atoms of zinc to grams.
6. A sample of 1.54x1021 molecules of O2 to liters at STP.
7. A sample of 4.587 grams of PCl5 to atoms.
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AP Stoichiometry Class Packet Unit 1
Use the following reaction to answer questions 8-10.
N2 + 3H2  2NH3
8. Convert 5.68 grams of nitrogen to liters of ammonia gas at STP.
9. How many grams of hydrogen are formed from 45.67L of ammonia gas at STP?
10. How many molecules of hydrogen will react with 4.56x1024 molecules of nitrogen?
Use the following reaction to answer questions 11-14.
2H20  2H2 + O2
11. How many grams of oxygen can be formed from 56.0 grams of water?
12. If 3.87x1025 molecules of water are used, how many liters of hydrogen gas form at STP?
13. If 34.5L of gaseous water are used, how many liters of hydrogen gas are formed at STP?
14. There is a short cut for conversions of volume to volume or molecules to molecules under the
same conditions. Can you see it? Why isn’t there a similar short cut for mass to mass?
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AP Stoichiometry Class Packet Unit 1
BALANCING REACTIONS
Students should be able to demonstrate an understanding of the following essential knowledge:
o 1.E.1 Physical and chemical processes can be depicted symbolically; when it is done, the illustration
must conserve all atoms of all types.
o 1.E.2 Conservation of atoms makes it possible to compute the masses of substances involved in
physical and chemical processes. Chemical processes result in the formation of new substances, and the
amount of these depends on the number and the types and masses of elements in the reactants, as well as
the efficiency of the transformations.
o 3.B.1 Synthesis reactions are those in which atoms and/or molecules combine to form a new
compound. Decomposition is the reverse of synthesis’ a process whereby molecules are decomposed,
often by the use of heat.
Type of
reaction
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AP Stoichiometry Class Packet Unit 1
LIMITING REACTANTS
Students should be able to demonstrate an understanding of the following essential knowledge:
o 3.A.2 Quantitative information can be derived from stoichiometric calculations that utilize the mole
ratios from the balanced chemical equations. The role of stoichiometry in real-world applications is
important to note, so that it does not seem to be simply an exercise done by only chemists.
Reactants are not always present in the exact amounts required by the balances chemical equation. In
planning any cost effective production process, it is necessary to produce and use only what is
needed, not have too much of any reactant left over, and to recognize which component limits the
amount of material that can be produced.
Model:
A cake recipe calls for:
2 cups of water
4 cups of flour
8 squares of chocolate
4 cups of sugar
8 oz of butter
4 eggs
Ingredients you have:
lots of water
5 cups of flour
12 square of chocolate
4 cups of sugar
16 oz of butter
6 eggs
Key Questions:
1. According to the model, how much of each ingredient will you have left over after baking the cake?
Water
Flour
Chocolate
Sugar
Butter
Eggs
2. Which ingredients were in excess?
3. Which ingredient was completely consumed?
4. What would be a good definition for the term limiting reactant?
5. Provide a good method for determining the limiting reactant and the final amount of the product
before execution of the procedure.
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AP Stoichiometry Class Packet Unit 1
Exercises:
6. You have 100 bolts, 150 nuts and 150 washers. You assemble a nut/bolt/washer set using the
following equation: 2 washers + 1 bolt + 1 nut = 1 shell.
a. How many shells can you assemble from your supply?
b. What is the limiting component?
7. You react 150 H2 molecules with 100 O2 molecules to produce water.
a. Write the balance reaction for the synthesis of water.
b. Using your balanced equation, calculate which element is the limiter.
c. How many water molecules can be produced based on this supply?
d. If you had 1.73 moles of hydrogen and 0.89 moles of Oxygen, which is the limiter? How
many moles of water can be produced?
e. If you had 17.3g of hydrogen and 8.91 g of oxygen, what is the limiting reactant and how
many moles of water can be synthesized?
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AP Stoichiometry Class Packet Unit 1
MORE LIMITERS AND PERCENT YIELD
Students should be able to demonstrate an understanding of the following essential knowledge:
o 3.A.2 Quantitative information can be derived from stoichiometric calculations that utilize the mole
ratios from the balanced chemical equations. The role of stoichiometry in real-world applications is
important to note, so that it does not seem to be simply an exercise done by only chemists.
1. In the following unbalanced combustion equation, how many grams of heptane (C7H16) will react with
exactly 0.4782 g of O2 gas?
C7H16 + O2  CO2 + H2O
2. Consider the following reaction:
3 Si + 2 N2 → Si3N4
(a) When 21.44 moles of Si reacts with 17.62 moles of N2, how many moles of Si3N4 are formed?
(b) What is the limiting reactant?
(c) For the reactant in excess, how many moles are left over at the end of the reaction?
3. Consider the following reaction:
2 CuCl2 + 4 KI → 2 CuI + 4 KCl + I2
(a) When 0.56 moles of CuCl2 reacts with 0.64 moles of KI, how many moles of I2 are formed?
(b) What is the limiting reactant?
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AP Stoichiometry Class Packet Unit 1
(c) For the reactant in excess, how many moles are left over at the end of the reaction?
4. Consider the following reaction:
4 FeS2 + 11 O2 → 2 Fe2O3 + 8 SO2
(a) When 26.62 moles of FeS2 reacts with 5.44 moles of O2, how many moles of SO2 are formed?
(b) What is the limiting reactant?
(c) For the reactant in excess, how many moles are left over at the end of the reaction?
5. This unbalanced chemical equation is relevant to both parts (a) and (b) of this question
Fe3O4 +H2  Fe + H2O
(a) Iron ore, in the form of the mixed iron oxide shown, can be reduced by the addition of
hydrogen gas. How many grams of Iron metal will be produced in the process, if 411 g of Fe3O4 are
reacted completely with hydrogen gas?
(b) Determine the amount of water produced in this reaction in moles, if 1201 g of iron ore are
reacted with sufficient hydrogen to convert it to products, in such a way that the reaction has a
48.22 % yield.
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AP Stoichiometry Class Packet Unit 1
6. Using the general equation below to help answer the questions that follow.
ACID + CARBONATE  A SALT + CARBON DIOXIDE + WATER
(a) Write a word equation for copper(II) carbonate reacting with hydrochloric acid.
(b) Write a balanced symbol equation for the reaction. (Include state symbols and assume the
product salt to be soluble in water, i.e. it is aqueous).
(c) In such a reaction 25.00 mL of hydrochloric acid solution is found to react completely with
20.70 g of copper(II) carbonate. Calculate the concentration (molarity) of the acid.
(d) The reaction in (c) was repeated and it was found that on this occasion 12.00 g of the product
salt were produced. Calculate the percentage yield in this reaction.
(e) In another experiment, 35.00 mL of the acid of the same concentration as in (c) is reacted with
40.00 g of copper(II) carbonate. Determine which reagent is limiting and which is in excess.
EXPLAIN your reasoning.
7. Consider the following reaction:
2 Al + 6 HBr → 2 AlBr3 + 3 H2
(a)When 3.22 moles of Al reacts with 4.96 moles of HBr, how many moles of H2 are formed?
(b) What is the limiting reactant?
(c)For the reactant in excess, how many moles are left over at the end of the reaction?
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AP Stoichiometry Class Packet Unit 1
CHEMICAL FORMULAS
Students should be able to demonstrate an understanding of the following essential knowledge:
o 1.A.1 Molecules are composed of specific combinations of atoms; different molecules are
composed of combinations of different elements and of combinations of the same element in
differing amounts and properties.
Chemical formulas can be determined by measuring the mass of each element present in a sample of a
compound. The conversion of microscopic quantities (grams) to microscopic quantities (atoms) is used
by chemists, biochemists, pharmacologists and others who work in the production of new materials for
research and industrial purposes. You will need to do such calculations to determine the amount of
elements and compounds present in samples or needed to produce various materials. Acetic acid is an
active ingredient in vinegar. A chemical analysis of 157.5g of acetic acid is provided:
Key Questions:
1. Show how the mass percent was calculated from the mass
of each element.
Element
Mass
(g)
Carbon
63.00
Oxygen
83.93
Hydrogen 10.57
Mass
Percent
40.00
53.29
6.714
Moles
5.246
5.246
10.486
2. Show how the moles of the element were calculated for each element.
3. What is the empirical formula of this compound? Explain.
4. What information does the empirical formula provide?
5. Why is the atomic mass percent composition of an unknown chemical compound an important
quantity to determine in a chemical analysis?
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AP Stoichiometry Class Packet Unit 1
6. Sodium carbonate (baking powder) has the formula Na2CO3. Calculate the molar mass of the
compound, the percent composition by mass of each element, and the mass of each element in
73.6g of the sample.
EMPIRICAL AND MOLECULAR FORMULAS
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AP Stoichiometry Class Packet Unit 1
EMPIRICAL FORMULA FRQ
1. A common oxide of nitrogen contains 25.93% N. Deduce the empirical formula of the oxide.
2. A compound that is usually used as a fertilizer can also be used as a powerful explosive. The compound
has the composition 35.00% nitrogen, 59.96% oxygen and the remainder being hydrogen. What is its
empirical formula? Given it is ionic, suggest a name for the compound.
3. What are the empirical formulae for these compounds, that both contain five carbon atoms?
(a) C5H10
(b) C5H12
4. A substance has an empirical formula of CH2Br and a molar mass of 188 g mol-1. What is the molecular
formula of the compound?
5. The common pain medicine, Advil, contains the active ingredient Ibuprofen that has a molar mass of
206 g mol-1. Ibuprofen contains 75.73% C, 8.74% H, the remainder being oxygen. What are the empirical
and molecular formulae for Ibuprofen?
6. The molar mass of the common antibiotic oxytetracycline is found to be 460 g mol-1 and a 2.000 g
sample contains 1.1478 g of carbon, 0.10435 g of H, 0.62609 g of oxygen and the remainder being
nitrogen. What is the molecular formula of the oxytetracycline?
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AP Stoichiometry Class Packet Unit 1
MOLARITY
Students should be able to demonstrate an understanding of the following essential knowledge:
o 3.A.2 Quantitative information can be derived from stoichiometric calculations that utilize the mole
ratios from the balanced chemical equations. The role of stoichiometry in real-world applications is
important to note, so that it does not seem to be simply an exercise done by only chemists.
1. Calculate the molarity of each of the following solutions:
(a) 2.5 mol of NaOH in 0.500 L of solution
(b) 1.8L of solution containing 3.3 mol KNO3
(c) 30. g of NaOH in 0.500 L of solution
(d) 522 g of K2SO4 in 1.5 L of solution
(e) 12 g of HCl in 250 mL of solution
2. Calculate the total moles of solute in each of the following solutions:
(a) 1.7 L of 0.35M NaOH
(b) 50 mL of 3.3-molar KNO3
(c) 5.0 L of 1.25 M NaOH
(d) 116 mL of 1.5 M K2SO4
3. Calculate the total grams of solute in each of the following solutions:
(a) 1.0 L of 0.5 M CaCl2
(b) 500 mL of 3.3-molar KNO3
(c) 0.25 L of 1.0 M NaOH
(d) 42 mL of 1.7 M K2SO4
4. Find the Molarity of the following solutions:
a.) 0.50 moles of sodium chloride in 0.50 liters.
b.) 2.00 moles of ammonia in 0.50L solution.
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AP Stoichiometry Class Packet Unit 1
c.) 0.50 moles of sucrose dissolved in 2.00L.
d.) 80.0 grams of NaOH in one liter of solution.
e.) 101 grams of KNO3 in 500. ml of solution.
f.) 202.5 grams of CuCl2 dissolved in 2L of water.
g.) 74 grams of Ca(OH)2 in 500. mL of water.
5. Find the mass needed for each solution:
a.) A solution of 1.00L of 2.00M NaCl
b.) A solution of 0.500L of 3.00M NaOH
c.) A solution of 6.00L of 0.50M CaCl2
d.) A solution of 4.00L of 0.25M CuSO4.5H2O
e.) A solution of 3.00L of 1.50M NaF
f.) A solution of 1.50L of 1.50M Mg(NO3)2
g.) A solution of 4.50L of 6.00M HCl
h.) A solution of 5.00L of 2.50M H2SO4
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AP Stoichiometry Class Packet Unit 1
DILUTIONS
1. Calculate the volume of 3.00 M nitric acid that must be diluted with water to produce 1.50 L of 0.750 M
nitric acid.
2. Calculate the volume of 6.00 M hydrochloric acid that must be diluted with water to produce 2.00 L of
1.75 M hydrochloric acid.
3. Calculate the volume of 5.00 M KOH that must be diluted with water to produce 355 mL of 0.250 M
KOH.
4. Calculate the final volume of 3.00 M sulfuric acid when 1.50L of 6.00M sulfuric acid is diluted.
5. A student is given 2.00L of 5.00M NaOH and must dilute to create a 1.25M solution of NaOH. Calculate
the amount of water that must be added to the original solution.
6. Outline the correct laboratory procedure for diluting a stock solution of 18.4 M sulfuric acid to produce
1.0 L of 1.84 M sulfuric acid. Take care to include any calculations; safety procedures and how you would
use appropriate glassware in your answer.
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AP Stoichiometry Class Packet Unit 1
FORMULAS OF IONIC COMPOUNDS
Students should be able to demonstrate an understanding of the following essential knowledge:
o 1.A.1 Molecules are composed of specific combinations of atoms; different molecules are
composed of combinations of different elements and o combinations of the same element in
differing amounts and properties.
Ionic Compounds require two types of ions: cations, which are positive and anions, which are negative.
All metals (on the left side of the periodic table) form cations and nonmetals (on the left side of the
periodic table) form anions primarily. In order to determine the formula of the compound they create you
must make sure their ions sum to zero. For example, table salt is sodium chloride. Using the periodic
table’s first set of ions, sodium forms +1 ions and chlorine forms -1 ions. Therefore their ions cancel out
and the formula is NaCl. It is not always that easy. Calcium chloride is the salt we put on roads to melt ice.
Calcium forms +2 ions and Chloride forms -1 ions. We need two chloride ions to balance the charges. The
formula is CaCl2. Notice the metal, or positive cation is always written first! Try the following
examples:
1. Cesium fluoride:
______________ 4. Barium sulfide:
______________
2. Potassium oxide:
______________ 5. Aluminum chloride:
______________
3. Magnesium iodide:
______________ 6. Calcium phosphide:
______________
There is a short cut called the drop and swap rule. Simply “drop” the charges from superscripts to
subscripts and switch their order. In example 6, calcium phosphide had charges +2 and -3 respectively.
Drop the charges to form uncharged subscripts 2 and 3 and reverse to form Ca3P2. Try the drop and swap
rule to find the formula:
Chloride
Sulfide
Fluoride
Phosphide
Lithium
Aluminum
Magnesium
Potassium
Now we know how to write formulas from their names but we also need to know how to write names
from formulas. The rule is: write the whole name of the first element and the second element drop the
ending and replace with “ide.” For example: H2S is hydrogen sulfide. In this case, the amount of each
element doesn’t affect the name of the compound. to name the following examples:
1. NaF
__________________________
6. NaH
______________________________
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AP Stoichiometry Class Packet Unit 1
2. MgCl2
__________________________
7. K3P
______________________________
3. Al2O3
__________________________
8. MgO
______________________________
4. MgI2
__________________________
9. Li2Te
______________________________
5. H2O
__________________________
10. AlCl3
______________________________
Transition metals refer to the metals in groups 3-12 of the period
table (elements Sc through Zn and down). These metals form
various positive ions. It is important to identify which ion is used
when naming the compound. We will work backwards to do this,
meaning, we will look at the charge for the second ion in the formula
to find that charge of the first. We will report the charge of the first
ion in roman numerals (the numerals you need to memorize are
listed to the right) in parenthesis after that ion. For example:
One I
Two II
Three III
Four IV
CuO
O is -2 so Cu needs to be +2
Copper (II) oxide
Cu2O
O is -2 so each Cu must be +1
Copper (I) oxide
Five V
Six
VI
Seven VII
These two compounds have different structures and properties and must have different names. Try to
name the following compounds with transition metals:
1. FeBr2
________________________
6. NiF3
________________________
2. FeBr3
________________________
7. CuCl
________________________
3. PbS
________________________
8. CuCl2
________________________
4. PbS2
________________________
9. CuS
________________________
5. NiO
________________________
10. Cu2S
________________________
Formula writing may seem easier. You can still use the drop and swap rule. Remember the number in
roman numerals refers to the charge of the first ion. Try to give the formula of the following compounds:
1. Chromium (VI) oxide
_____________
6. Zinc (II) oxide
_____________
2. Manganese (VII) chloride_____________
7. Iron (II) oxide
_____________
3. Lead (IV) iodide
_____________
8. Iron(III) oxide
_____________
4. Silver (I) sulfide
_____________
9. Gold (III) phosphide
_____________
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AP Stoichiometry Class Packet Unit 1
5. Nickel (II) fluoride
_____________
10. Titanium (IV) sulfide
_____________
POLYATOMIC IONS
Binary compounds have only two elements in their formula, as we saw in exercises above. Tertiary
compounds have three or more elements in their formula and have a new system of naming. These
compounds have a polyatomic ion, which is an ion that has a few elements grouped together with only
one charge between them. A common example is OH-, which shows two elements with an overall charge
of -1. As before, name the first element completely and then name the polyatomic ion. Make sure you use
the right one; some are very similar!
1. KHCO3
_________________________
4. LiNO2
______________________________
2. CaSO4
_________________________
5. Cu(ClO4)2 ______________________________
3. NaNO3
__________________________
6. Al2(SO3)2 ______________________________
To write the formula of a tertiary compound you can still use the drop and swap rule, however, you must
be sure to only drop the superscripts and leave the subscripts alone. For example, aluminum carbonate:
Al+3 and CO3-2
Leave the 3 alone! Swap the 3 and 2
Al2(CO3)3
Formulas don’t show any charges. You can see that we use parenthesis around the polyatomic ion
because the entire ion charge was -2 and must swap with aluminum so the entire ion gets aluminum’s +3.
Hydroxide
Nitrate
Carbonate
Phosphate
Acetate
Sodium
Calcium
Ammonium
Iron (II)
Aluminum
1. Zinc Hydroxide: ________________________
4. Magnesium oxalate:______________________
2. Calcium chlorate: ________________________
5. Lead (IV) chromate:_______________________
3. Hydrogen acetate: ________________________
6. Stronium cyanide:________________________
Write the name of each of the following. To help get the correct name, use the periodic table to determine
which elements are metals, which are non-metals and which compounds should include Roman numerals
in their names.
(a) NBr5
(b) P2S5
(c) Ge2O3
(d) N2O5
(e) SiO2
(f) AlH3
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AP Stoichiometry Class Packet Unit 1
(g) FeO
(i) OCl2
(h) CuCl2
(j) XeF6
NAMING COVALENT COMPOUNDS
Recall, covalent compounds contain nonmetals only. They can be named using the stock system described
above or a prefix system:
1- mono
6-hexa
2-di
7-hepta
3-tri
8-octa
4-tetra
9-nona
5-penta
10-deca
Write the prefix before the element. Mono is dropped for the first element only.
Name the following:
1. P2O5
_____________________________
4. SF6
_____________________________________
2. NO3
_____________________________
5. PCl5
______________________________________
3. CO
_____________________________
6. N2O4
______________________________________
Give the formula:
1. Xenon octafluoride
______________________________________
2. Carbon tetrachloride
______________________________________
Acids are derived from singular anions and polyatomic anions reacting with hydrogen ions in solution.
Follow the following rules:
If the acid is binary add the prefix “hydro” and end the acid name in “ic”
If the acid is ternary:
“ite” anions become “ous”
“ate” anions become “ic
Name the following acids:
1. HCl
_____________________________
4. H2SO4
_____________________________
2. HNO3
_____________________________
5. HF
_____________________________
3. H2SO3
_____________________________
6. H3PO4
_____________________________
Give the formula:
1. hydroiodic acid
_____________________________
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AP Stoichiometry Class Packet Unit 1
2. nitrous acid
_____________________________
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