Unit 4 STOICHIOMETRY Interactive Notebook Table of Contents
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Learning Goal
Homework
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Effort
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Learning Goal
Homework
Mastery/
Effort
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Learning Goal
Homework
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Effort
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Unit 4 Exam
12/18/13
12/19/13
TRUSD Fall Semester Final EXAM
12/20/13
TRUSD Fall Semester Final EXAM
California Standard Stoichiometry
3. The conservation of atoms in chemical reactions leads to the principle of conservation of matter and the ability to
calculate the mass of products and reactants.
a. Students know how to describe chemical reactions by writing balanced equations.
b. Students know the quantity one mole is set by defining one mole of carbon-12 atoms to have a mass of exactly 12
grams.
c. Students know one mole equals 6.02 × 1023 particles (atoms or molecules). This number, called Avogadro’s number,
is known to a high degree of accuracy.
d. Students know how to determine the molar mass of a molecule from its chemical formula and a table of atomic
masses and how to convert the mass of a molecular substance to moles, number of particles, or volume of gas at
standard temperature and pressure. The molar mass of a compound, which is also called either the molecular mass
or molecular weight for covalent compounds or formula mass for ionic compounds, is the sum of the atomic masses
of the constituent atoms of each element in the molecule. Molar mass is expressed in units of grams per mole. The
number of particles in the sample is determined by multiplying the number of moles by Avogadro’s number. The
volume of an ideal or a nearly ideal gas at a fixed temperature and pressure is proportional to the number of moles.
Students should be able to calculate the number of moles of a gas from its volume by using the relationship that at
standard temperature and pressure (0°C and 1 atmosphere), one mole of gas occupies a volume of 22.4 L.
e. Students know how to calculate the masses of reactants and products in a chemical reaction from the mass of one of
the reactants or products, when the chemical reaction is written as a balanced expression. Atoms are neither
created nor destroyed in a chemical reaction.
f.* Students know how to calculate percent yield in a chemical reaction.
3
Interactive Notebook Score Sheet
Quizzes/Formatives
Date
Score/Max
Score
Retake Needed
(yes or no)
Peer
Initial
Parent Initial
Peer
Initials
Level of
Effort
Formative 15 Molar
Conversions
Formative 16 Percent
Composition
Formative 17 Balancing
Reaction Equations
Formative 18
Stoichiometry
Formative 19 Limiting
Reactants
Formative 20 Hydrates
Unit 4 Test
District Final Exam
Name of Scored Assignment
Date Due
Histogram – graphic representation of discrete data.
Score/Max
Date (x axis) and progress on standards mastery with
5 advanced, 4 proficient, 3 basic, 2 below basis, and 1 incomplete (y axis)
4
Unit 4 Stoichiometry Study Guide
California Chemistry Standard Set 3
Key Vocabulary Terms
Mole (Avogadro’s Number)
Percent Composition
Molecular Formula
Empirical Formula
Coefficient
Subscript
Reactants
Products
Molar Mass
Atomic Mass
Limiting Reactant
Excess Reactant
Mole Ratio
Particles
Law of Conservation of Matter
Synthesis Reaction
Decomposition Reaction
Single Replacement (Displacement) Reaction
Double Replacement (Displacement) Reaction
Combustion Reaction
5
Concepts
1. The Law of conservation of matter: In any physical or chemical change, matter is neither created nor
destroyed but merely changed from one form to another. Explain the Law of Conservation of Matter
when balancing chemical reactions
2. Describe 5 types of Chemical Reactions
a. Synthesis Reaction
b. Decomposition Reaction
c. Combustion Reaction
d. Single Displacement Reaction
e. Double Displacement Reaction
Items for Memorization - Avogadro’s Number: 6.02 x 1023
1. Determine the molar mass of a formula e.g., H2O, O2, Ca(OH)2, Fe3(PO4)2
2. Determine percent composition of all of the elements in a formula e.g., H2O, O2, Ca(OH)2,
Fe3(PO4)2
3. Determine Empirical and Molecular Formula from percent composition data
4. Perform the following conversions:
Mole to Mole
Grams to Mole
Moles to Particles
Grams to Particles
Grams A to Grams B
Mole to Volume
Volume to Mole
6
1. Given mass of compounds in words be able to do the following adding energy where appropriate:
a. Balance the chemical reaction
i. Subscripts and Coefficients
___R1 + ___R2  ___P1 + ___P2
b. Perform 3 step conversions to evaluate reactant to maximize yield given one of the reactants,
then compare to actual reactants to determine limiting and excess reactants.
Mass to Mole then Mole ratio then Mole to Mass
i. Find the limiting (least: LR) and excess (larger: ER) reactants
1. Grams R1  Grams R2
Grams R2  R1
ii. Find the amount of product
1. Grams LR  P1
Grams LR  P2
2. Mass Balance: Grams reactant = Grams product
a. ___R1 + ___R2  ___P1 + ___P2 + Energy
http://chemcollective.org/home
7
THE MOLE & Chemical Formulas: Review Practice 1
A mole (also known as Avogadro's Number) is the number that is used in making calculations
involving atoms and molecules. Given the relatively microscopic size of the particles, it would
be rather difficult (read: utterly pointless) to calculate amounts in terms of numbers of atoms.
So, we use the mole.
A mole, (mol for short) is equal to (all together now) 6.022 x 1023 atoms or molecules.
The atomic mass given for an element on the periodic table measured out in grams is equal
to one mole of atoms of that element.
Thus, the Molar Mass (MM) of elements and compounds is the mass, in grams, equal to the atomic and
formula masses of those elements and compounds. The unit of Molar Mass is grams/mole.
Quick Write
In your own words describe what a mole of something means
___________________________________________________________________________________
___________________________________________________________________________________
___________________________________________________________________________________
1 step: particles, grams, or L of gas at STP to moles and moles to particles, grams or L of gas at STP
1) How many moles are in 15 grams of lithium?
2) How many atoms are in 2.4 moles of sulfur?
3) How many moles are in 5.6 L of argon gas at STP?
4) How many moles are in 12.16 g of magnesium?
8
What are the molecular weights of the following compound (inventory and sum)?
5) NaOH
6) H3PO4
7) CuSO4
8) (NH4)2SO4
9. Written Explanation of Molar Conversion Problem: Convert 3.5 moles CuSO4 into grams.
Part 1: Identification
What is your known? _____________________________
What are you looking for? __________________________
What conversion factor will you use?_______________________________________________________
Part 2: Math… Solve the problem
Part 3: Explanation Use the following content words to explain how you solved the problem:
Known, unknown, convert, units, cancel, calculate, conversion factor, multiply, divide, setup
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
10) How many moles are in 21g of sodium fluoride, NaF?
9
Unit 4 – Benchmark Gram/Mole/Volume Conversions – Practice!
You may use a periodic table, but NOT a calculator. SHOW YOUR WORK!
Problems 1
Assume that you have an 11 gram sample of carbon dioxide gas, CO2 at standard conditions (STP)
How many moles of CO2 do you have?
How many molecules of CO2 do you have?
What volume (in liters) should the sample occupy?
Problems 2
Assume that you have a sample of propane gas, C3H8 that occupies 11.2 liters at standard conditions.
How many moles of propane are contained in the sample?
What is the mass in grams of the sample?
How many molecules of propane are in the sample?
10
Problems 3
You have a sample of calcium that contains 0.25 moles of calcium atoms.
What is the mass, in grams, of the sample of calcium?
How many atoms of calcium does the sample contain?
Problems 4
You have a sample of aluminum that contains 2 x 1023 atoms of aluminum.
How many moles of aluminum atoms do you have?
What is the mass, in grams, of your sample of aluminum?
Problems 5
You have a 5.6 liter sample of nitrogen gas, NH3, at standard conditions.
How many moles of nitrogen are contained in the sample?
What is the mass, in grams, of the sample?
Problem 6
How many moles are in 54 grams of water, H2O?
How many L do 54 grams of water, H2O occupy at STP
11
2-step Molar Conversion and 1 step Molar Conversion Practice
Particles, grams, or L of gas at STP to moles and then to particles, grams or L of gas at STP
How many particles are in 39 grams of aluminum hydroxide, Al(OH)3?
1) How many grams and formula units are in 0.02 moles of beryllium iodide, BeI2?
2) How many formula units are in 32.5 grams of copper (II) hydroxide, Cu(OH)2?
3) How many grams are in 3.3 moles of potassium sulfide, K2S?
4) How many molecules are in 1.704 x 103 grams of ammonia, NH3?
5) How many grams are in 2.3 x 10-3 moles of calcium phosphate, Ca3(PO4)2?
12
6) What is the mass of 1 mole of lithium hydroxide?
7) A saltshaker filled with 29.22 grams of sodium chloride contains how many moles of sodium chloride?
8) Which of the following has the greatest mass? Hint convert all to grams first!
4.2 mol of carbon or 1.2 x1024 atoms of CaCO3 or 12.6 g of Al2(NO3)3
9) In 60 g of N2O there are how many molecules (grams to moles and then to molecules)?
10) Find the number of atoms in each of the following:
a. 0.25 mole Ni
b. 2.0 mole S
11) Find the volume of each of the following amounts of gas at STP:
a. 0.75 mole of O2
b. 2.5 moles N2
12) How many moles are in each of the following volumes of gas at STP?
a. 67.2 L CO2
b. 56 L He
13
Percent Composition and Chemical Formulas
Percent Composition By Mass
Part divided by the whole!
Inventory STEP 1
a. CH4
41.30%
b. Mg(MnO4)2
38.70%
20.00%
c. Al2(SO3)3
Molar Mass STEP 2
a.CH4
b. MgF2
c. C3H8
Determine the percent composition of each element STEP 3
Example: Find the % comp of calcium phosphate: Ca3(PO4)2
3Ca = 3(40) = 120 g Ca
2P = 2(31) = 62 g P
8O = 8(16) = 128 g O
molar mass
 310 g Ca3(PO4)2
Percent composition = Mass of the component X 100
Mass of the whole
% Ca = 120/310 x 100 = 38.7 %
% P = 62/310 x 100 = 20.0 %
% O = 128/310 x 100 = 41.3 %
100 % add up to check your work
Ca % = 38.7%
P % = 20.0 %
O % = 41.3 %
Quickwrite: Explain how to solve percent composition problems
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
a.CH4
14
b. MgF2
c. C3H8
 Practice Percent Composition Find the percent compositions of all of the elements in the following compounds:
1)
CuBr2
2)
NaOH
3)
(NH4)2S
4)
N2S2
5) copper II sulfide
6) iron III oxide
7) sucrose (C12H22O11)
15
Practice with calculator
1. Identify all the steps to find the correct formula for your hydrate. Using the correct formula,
calculate the percent of H2O in your hydrate
Na2CO3 • ____H20
a.
Mass of Crucible and Cover………………………………………49.5g
b.
Mass of Crucible, Cover & Hydrate
……………………… 53.81
c.
Mass of Crucible, Cover, and Anhydrous Salt……… 52.72
2. Write the correct formula for your hydrate. Using the correct formula, calculate the percent of
H2O.
MgNO3• ____H20
a.
Mass of Crucible and Cover ……………………………………………… 152 g
b.
Mass of Crucible, Cover & Hydrate ………………………………… 157.82g
c.
Mass of Crucible, Cover, and Anhydrous Salt…………………154.58g
16
Water of Hydration
Many ionic compounds incorporate a fixed number of water molecules into their crystal structures. A compound
that contains water of hydration is called a hydrate. When expressing the formula for a hydrate, it is necessary
to notate the fixed number of H2O molecules following the anhydrous formula for the ionic compound. A large
dot is placed between the formula and the H 2O molecules. For example: CuSO4 • 5H2O is the correct formula
for the hydrated form of copper (II) sulfate pentahydrate. The water of hydration can be removed by heating
the sample. Once heat is applied the H2O molecules are removed as steam to produce an anhydrous salt which
often will appear different than its hydrate. Most often a hydrated crystal is of different color than its
anhydrous crystal. For this example the anyhydrous salt is CuSO4.
1.
The first step to finding the formula for a hydrate is to
record the mass of the hydrate.
2. After heating the hydrate, the mass is determined for the
anhydrate that remains.
3. The mass of the water that was present is calculated by
finding the difference between the mass of the hydrate and
the mass of the anhydrate.
4. The mass of the water and the mass of the anhydrate are
each converted to moles using their respective molar masses.
5. From this a whole number ratio can be determined
Mass of
Mass of
Mass of
Mass of
the empty crucible
the crucible plus hydrate sample
the system after heating
the system after a second heating
4.00g
4.50 g
4.32g
4.32g
hydrate sample mass = 0.50 g
anhydrous sample mass = 0.32 g
hydration water mass = 0.18 g
The second heating is to verify that in fact all of the water of hydration was removed.
a. Determine the percent water of hydration in the original sample
% water of hydration:
𝑚𝑎𝑠𝑠 𝑜𝑓 𝑤𝑎𝑡𝑒𝑟
𝑚𝑎𝑠𝑠 𝑜𝑓 ℎ𝑦𝑑𝑟𝑎𝑡𝑒
b. the compounds has the formula CuSO4
× 100 =
0.18 𝑔
0.50 𝑔
𝑥 100 = 36%
∙ ?H2O. Determine how many moles of water per mole of anhydrate.
CuSO4 molar mass = 159.6g ; moles of CuSO4 = 0.32g/159.6g = 0.0020 moles
H2O molar mass = 18.0; moles of H2O = 0.18 g / 18.0g = 0.010 moles
c. divide both mole values by the smallestCuSO4: 0.0020 / 0.0020 = 1
H2O: 0.010 / 0.0020 = 5
5 moles of hydration water for every mole of CuSO4
CuSO4.5H2O
What is the molar mass of CuSO4.5H2O and is the copper percent by mass
17
Hydrate Practice 2
1. A hydrate of magnesium sulfate has a mass of 13.52 g. This sample is heated until no water
remains. The MgSO4 anhydrate has a mass of 6.60 g. Find the formula and name of the hydrate.
2. A sample of copper (II) sulfate hydrate has a mass of 3.97 g. After heating, the CuSO 4 that
remains has a mass of 2.54 g. Determine the correct formula and name of the hydrate.
3. When 5.00 g of FeCl3 · xH2O are heated, 2.00 g of H2O are driven off. Find the chemical formula
and the name of the hydrate.
18
4. A sample of the hydrate of sodium carbonate has a mass of 8.85 g. It loses 1.28 g when heated.
Find the formula and the name of the hydrate.
5. A 16.4 g sample of hydrated calcium sulfate is heated until all the water is driven off. The
calcium sulfate that remains has a mass of 13.0 g. Find the formula and the chemical name of the
hydrate.
6. When 8.00 g of Pb(C2H3O2)2 · xH2O are heated, 1.14 g of H2O are driven off. Find the chemical
formula and the name of the hydrate.
7. A hydrate is determined to be 45.43% water and 54.57% CoCl2. Find the chemical formula and
name for this hydrate. (*Hint – assume that there is 100 g total of hydrate compound.)
19
Empirical and Molecular Formulas
Believe it or not, there is more than one kind of chemical formula (insert a sharp gasp of surprise
here). Judging from the heading of this section, they would be empirical and molecular formulas.
Empirical formulas give the lowest whole number ratio of the atoms in a compound, whereas the
molecular formula gives the exact composition of one molecule.
Empirical
Molecular
HO
H2O2
CH
C2H2
CH
C6H6
NO
NO
NO2
N2O4
Determine the empirical formula from the molecular formula:
a) C6H6
h) C2H2
b) C2H6
i) Na2SO4
c) C3H8
j) C6H4N2
d) Fe3(CO)9
k) P4O10
e) C2H4O2
l) Re2Cl6
f) N2H4
Empirical formulas can be calculated using
experimental
data:
g) CaBr
2
m) Se3O9
n) LiCl
Definition: The symbols for the elements combined in a compound, with subscripts showing the
smallest whole-number ratio of the different atoms in the compound
Given that a certain compound is 69.58% Ba, 6.090% C and 24.32% O, calculate the empirical formula
of this compound.
Assume that you have 100.00 g of the compound:
69.58% Ba = 69.58 g Ba
6.090% C = 6.090 g C
24.32% O = 24.32 g O
Convert the mass of each element to moles of that element:
Ba = (69.58 g Ba)(1 mol Ba/137.3 g Ba) = 0.5068 mol Ba
C = (6.090 g C)(1 mol C/12.01 g C) = 0.5071 mol C
O = (24.32 g O)(1 mol O/16.00 g O) = 1.520 mol O
Divide through each value by the smallest number of moles (0.5068)to get a
1 : 1.001 : 2.999 ratio, which rounds of nicely to give the formula BaCO3
Molecular formulas can be calculated using empirical formulas:
A. Definition: A formula for a molecular compound that represents ALL of the atoms found in a single molecule of that
compound.
The molecular formula is either the same as the empirical formula, or it is a whole number multiple of the empirical formula
Example 2 : Given that the empirical formula of a compound is CH and the molar mass is 104 g/mol, calculate the molecular
formula.
mass of C = 12.01 g/mol
mass of H = 1.01 g/mol
empirical formula mass = 13.0 g/mol
to find the number of CH units in the compound:
# CH units =
104 𝑔
𝑚𝑜𝑙𝑒
1 𝑚𝑜𝑙𝑒
× 13.0 𝑔 = 8.00
The nearest whole number is 8 so the Molecular formula = 8(CH) or C8H8
Example 2 : empirical formula = HO and molecular wt. = 34.02
20
Worksheet: Empirical Formulas and Molecular Formula
Part 1: Empirical Formulas
Work each of the following problems. SHOW ALL WORK.
1. A compound is found to contain 63.52 % iron and 36.48 % sulfur. Find its empirical formula.
2. Determine the empirical formula of a compound containing 63.50 % silver, 8.25 % nitrogen, and the remainder
oxygen.
Part 2: Molecular Formulas
Work each of the following problems. SHOW ALL WORK.
1. The empirical formula of a compound is NO2. Its molecular mass is 92 g/mol. What is its molecular formula?
2. The empirical formula of a compound is CH2. Its molecular mass is 70 g/mol. What is its molecular formula?.
3. A compound is found to be 40% Carbon, 6.7% hydrogen and 53.5 % oxygen. Its molecular mass is 60 g/mol. What
is its molecular formula?
21
Chemistry: Balancing Equations
The information in a chemical equation can be looked at in several ways.
On this worksheet you will represent particles of the substances involved in a chemical reaction before and after it
takes place.
The unbalanced equation for the reaction of chlorine gas with hydrogen gas is
Cl2(g) + H2(g)
HCl(g)
Each picture shows the same bottle after something happened. The circles show a unit
volume of the gas in the jar. Draw the particles for the third picture.
A certain number of
Cl2 molecules are
put into the jar.
The same number of
H2 molecules are
added to the jar.
The mixture is ignited.
Assume that all the
Cl2 and H2 are used up.
2. Show the same reaction using the fewest possible molecules. Draw the molecules in these circles.
+
Cl2
H2
HCl
3. Balance the equation using the smallest possible whole number coefficients.
________ Cl2(g) + ________ H2(g)
________ HCl(g)
4. Suppose you start with different amounts of the reactants. In the empty circle, show the
particles after the reaction. (Be sure you account for all the particles.) On the line below
the circle, describe what is in the circle.
+
Cl2(g)
22
+
H2(g)
________
23
Chemical Reactions
Read Section 10.1 in textbook (pg 277-283) Describe how you might know a chemical reaction has occurred
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________________
Chemical Equations and Reactions Introduction (277-383 textbook)
When a piece of magnesium is added to dilute hydrochloric acid, fizzing occurs and hydrogen gas is released from the
mixture. The fizzing is evidence that a(n) (1)__________________ has occurred between magnesium and
hydrochloric acid. The name given to either magnesium or hydrochloric acid in this case is
(2)______________________ , and the hydrogen gas that is released is called a(n) (3)___________________ of the
reaction. Some other indications that reactions have occurred might be change of color or (4)_________________ ,
or formation of a solid (5)____________________ . If a thermometer is placed into a mixture undergoing chemical
reaction, you might observed that the temperature has gone up or down, indicating that (6)_________________ was
being released or absorbed. The short hand form by which a reaction is represented is called a(n) (7) ____________ .
In using this method of representation, you must satisfy the (8)____________________ , a principle that states that
matter is neither created nor destroyed. In order to satisfy this principle, you normally select the proper numerical
(9)________________ to indicate the number of units of each substance taking part in the chemical change.
Explain in words each of the symbols
Mg (s) + 2HCl (aq)  MgCl2 (aq) + H2
10.
Mg
_______________
15.
(aq)
_______________
11.
(s)
_______________
16.

_______________
12.
+
_______________
17.
MgCl2 _______________
13
2
_______________
18.
H2
_______________
14
HCl
______________
19
(g)
_______________
24
Balancing Equations Practice
Part A: Identify the following parts of each chemical formula by circling the subscripts and drawing a
square around the coefficients.
H2
2 HCl
4 O2
CH4
3 CO2
2 NaOH
Part B: List the symbols for the atoms in each formula and give the number of each element.
C2H6 ________________________________________________________________________
2Mg(OH)2____________________________________________________________________
4Li2O____________________________________________________________________
4P4O10________________________________________________________________________________________________________________
3Al(OH)3 ____________________________________________________________________
Part C: Balance each of the following equations following the procedure described in class. Be sure to
show your work.
__P + __O2 → P4O10
___Mg + ___O2 → __MgO
___ Al2O3 → ___Al + ___O2
=P =
=Mg =
=Al =
=O =
=O =
= O=
Part D: Practice Problems – Balance each equation using the process from Part C. Name Products
___Na + ___Br2  ___NaBr
___C + ___H2 ___CH4
__Cl2 + ___NaBr  ___NaCl + ___Br2
__H2 + __N2  ___NH3
__CuCl2 + __H2S ___CuS + __HCl
__C2H6 + ___O2 ___CO2 + ___H2O
25
TO REACT OR NOT TO REACT? THAT IS THE QUESTION!
Chemical changes are a result of chemical reactions. All chemical reactions involve a change in substances and a
change in energy. Neither matter nor energy is created or destroyed in a chemical reaction---only changed. There are
so many chemical reactions that it is helpful to classify them into 5 general types including Combustion Reactions:
SYNTHESIS REACTION
In a synthesis reaction two or more simple substances combine to form a more complex substance. Two or more reactants yielding
one product is another way to identify a synthesis reaction.
For example, simple hydrogen gas combined with simple oxygen gas can produce a more complex substance-----water!
The chemical equation for this synthesis reaction looks like: reactant + reactant →product
To visualize a synthesis reaction look at the following cartoon:
In the cartoon, the skinny bird (reactant) and the worm (reactant) combine to make
one product, a fat bird.
DECOMPOSITION REACTION
In a decomposition reaction a more complex substance breaks down into its more simple parts. One reactant yields 2 or more
products. Basically, synthesis and decomposition reactions are opposites.
For example, water can be broken down into hydrogen gas and oxygen gas. The chemical equation for this decomposition reaction
looks like: reactant → product + product
To visualize a decomposition reaction look at the following cartoon:
In this cartoon the egg (the reactant), which contained the turtle at one time,
now has opened and the turtle (product) and egg shell (product) are now two
separate substances.
SINGLE REPLACEMENT REACTION In a single replacement reaction a single uncombined element replaces another in
a compound. Two reactants yield two products. For example when zinc combines with hydrochloric acid, the zinc replaces
hydrogen. The chemical equation for this single replacement reaction looks like: reactant + reactant → product + product
To visualize a single replacement reaction look at the following cartoon:
Notice, the guy in the orange shirt steals the date of the other guy. So, a part of one of the reactants
trades places and is in a different place among the products.
DOUBLE REPLACEMENT REACTION In a double replacement reaction parts of two
compounds switch places to form two new compounds. Two reactants yield two products. For example when silver nitrate
combines with sodium chloride, two new compounds--silver chloride and sodium nitrate are
formed because the sodium and silver switched places. The chemical equation for this double
replacement reaction looks like: reactant + reactant -→ product + product
To visualize a double replacement reaction look at the cartoon showing the hat and people
changes.
ENERGY OF CHEMICAL REACTIONS
Chemical reactions always involve a change in energy. Energy is neither created or destroyed. Energy is absorbed or released in
chemical reactions. Chemical reactions can be described as endothermic or exothermic reactions.
Endothermic Reactions
Chemical reactions in which energy is absorbed are endothermic. Energy is required for the reaction to occur. The energy absorbed
is often heat energy or electrical energy. Adding electrical energy to metal oxides can separate them into the pure metal and
oxygen. Adding electrical energy to sodium chloride can cause the table salt to break into its original sodium and chlorine parts.
Exothermic Reactions
Chemical reactions in which energy is released are exothermic. The energy that is released was originally stored in the chemical
bonds of the reactants. Often the heat given off causes the product(s) to feel hot. Any reaction that involves combustion (burning)
is an exothermic chemical reaction.
26
Handy Checklist for figuring out what type of reaction is taking place:
Follow this series of questions. When you can answer "yes" to a question, then stop!
1) Does your reaction have oxygen as one of it's reactants and carbon dioxide and water as products? If
yes, then it's a combustion reaction
2) Does your reaction have two (or more) chemicals combining to form one chemical? If yes, then it's a
synthesis reaction
3) Does your reaction have one large molecule falling apart to make several small ones? If yes, then it's a
decomposition reaction
4) Does your reaction have any molecules that contain only one element? If yes, then it's a single
displacement reaction
5) If you haven't answered "yes" to any of the questions above, then you've got a double displacement
reaction
Types of Reactions
Choose the correct symbol for the type of reaction. Place that answer in the blank at the beginning of each
equation and then balance each equation correctly and write the coefficient set.
S = synthesis
D = decomposition
C = combustion
SD = single displacement
DD = double displacement
H2O (l)  NaOH (aq) + H2 (g)
1. _____
Na (s) +
2. _____
CO (g) +
O2 (g) 
3. _____
FeS (s) +
HCl (aq) 
4. _____
NaNO3 (s) 
CO2 (g)
FeCl2 (aq) +
NaNO2 (s) +
H2S (g)
O2 (g)
27
O2 (g) 
5. _____
CH4 (g) +
6. _____
Fe (s) +
7. _____
KI (aq) +
8. _____
Al (s) +
9. _____
KClO3 (s) 
10. _____
C4H10 (g) +
28
CO2 (g) +
CuNO3 (aq) 
Cl2 (g) 
S (s) 
Cu (s) +
KCl (aq) +
H2O (g)
Fe(NO3)2 (aq)
I2 (aq)
Al2S3 (s)
KCl (s) +
O2 (g) 
O2 (g)
CO2 (g) +
H2O
Types of Reactions Worksheet
Balance the following equations and indicate the type of reaction taking place:
1)
____ NaBr + ____ H3PO4  ____ Na3PO4 + ____ HBr
Type of reaction: ____________________
2)
____ Ca(OH)2 + ____ Al2(SO4)3  ____ CaSO4 + ____ Al(OH)3
Type of reaction: ____________________
3)
____ Mg + ____ Fe2O3  ____ Fe + ____ MgO
Type of reaction: ____________________
4)
____ C2H4 + ____ O2  ____ CO2 + ____ H2O
Type of reaction: ____________________
5)
____ PbSO4  ____ PbSO3 + ____ O2
Type of reaction: ____________________
6)
____ NH3 + ____ I2  ____ N2I6 + ____ H2
Type of reaction: ____________________
7)
____ H2O + ____ SO3  ____ H2SO4
Type of reaction: ____________________
29
Word Equations Worksheet Write the formula for each and balance the reactions:
1)
When dissolved beryllium chloride reacts with dissolved silver (I) nitrate in water, aqueous beryllium nitrate
and silver (I) chloride powder are made.
2)
When isopropanol (C3H8O) burns in oxygen, carbon dioxide, water, and heat are produced.
3) When dissolved sodium hydroxide reacts with sulfuric acid (H2SO4), aqueous sodium sulfate, water, and heat are
formed.
4)
When fluorine gas is put into contact with calcium metal at high temperatures, calcium fluoride powder is
created in an exothermic reaction.
5)
30
When sodium metal reacts with iron (II) chloride, iron metal and sodium chloride are formed.
Combination (Synthesis) Reactions
Two or more elements or compounds may combine to form a more complex compound.
Basic form: A + X → AX
Examples of synthesis reactions:
Metal + oxygen → metal oxide
EX. 2Mg(s) + O2(g) → 2MgO(s)
Nonmetal + oxygen → nonmetallic oxide
EX. C(s) + O2(g) → CO2(g)
Metal oxide + water → metallic hydroxide
EX. MgO(s) + H2O(l) → Mg(OH)2(s)
Nonmetallic oxide + water → acid
EX. CO2(g) + H2O(l) → ; H2CO3(aq)
Metal + nonmetal → salt
EX. 2 Na(s) + Cl2(g) → 2NaCl(s)
A few nonmetals combine with each other.
EX. 2P(s) + 3Cl2(g) → 2PCl3(g)
Write the reactant formula, predict the product in words then write the product formula, then balance.
calcium + oxygen 
copper + sulfur  copper(II) sulfide
calcium oxide + water 
aluminum + bromine 
31
Decomposition Reaction
A single compound breaks down into its component parts or simpler compounds.
Basic form: AX → A + X
Examples of decomposition reactions:
Metallic carbonates, when heated, form metallic oxides and CO2(g). EX. CaCO3(s) → CaO(s) + CO2(g)
Most metallic hydroxides, when heated, decompose into metallic oxides and water.
EX. Ca(OH)2(s) → CaO(s) + H2O(g)
Metallic chlorates, when heated, decompose into metallic chlorides and oxygen.
EX. 2KClO3(s) → 2KCl(s) + 3O2(g)
Some acids, when heated, decompose into nonmetallic oxides and water.
EX. H2SO4 → H2O(l) + SO3(g)
Some oxides, when heated, decompose.
EX. 2HgO(s) → 2Hg(l) + O2(g)
Some decomposition reactions are produced by electricity.
EX. 2H2O(l) → 2H2(g) + O2(g)
EX. 2NaCl(l) → 2Na(s) + Cl2(g)
Write the reactant formula, predict the product in words and write the product formula, then balance.
______NaCl  ____Na + _____Cl2
___ CaBr  ___ Ca + ___ Br2
____NCl3  ___N2 + ___ Cl2
___CCl4  ___C + ___ Cl2
___P4O10  ___P4 + ___O2
___KI  ___K + ___I2
32
Single displacement
This is when one element trades places with another element in a compound. These reactions come in
the general form of: A + BC ---> AC + B
One example of a single displacement reaction is when magnesium replaces hydrogen in water to make
magnesium hydroxide and hydrogen gas:
Mg + 2 H2O ---> Mg(OH)2 + H2
Write the reactant formula, predict the product in words and write the product formula, then balance.
1. K + AgNO3 →
2. Al + H2SO4 →
3. Cl2 + KI →
4. Li + H2O →
Quickwrite: Using one the four examples, explain how you predicted the product and how you
balanced the reaction.
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33
Double displacement
This is when the anions and cations of two different molecules switch places, forming two entirely
different compounds. These reactions are in the general form:
AB + CD ---> AD + CB
One example of a double displacement reaction is the reaction of lead (II) nitrate with potassium iodide
to form lead (II) iodide and potassium nitrate:
Pb(NO3)2 + 2 KI ---> PbI2 + 2 KNO3
Write the reactant formula, predict the product formula, then balance.
1) Ca(OH)2 + H3PO4 
6) Al2(SO4)3 + Ca3(PO4)2 
2) K2CO3 + BaCl2 
7) FeBr2 + K2CO3 
3) Cd3(PO4)2 + (NH4)2S 
8) Ag2S + CuCl2 
4) Co(OH)3 + HNO3 
9) Pb(NO3)2 + HI 
5) AgNO3 + KCl 
10) CuS + KCl 
34
Combustion Reactions
Octane (C8H18) is a major component of gasoline. The burning of octane produce carbon
dioxide (CO2) as shown in the equation below:
2 C8H18 + 25 O2 → 16 CO2 + 18 H20
A) Calculate the molar masses of octane and carbon dioxide. Show your calculations and
include units in your answer.
b) Calculate the amount of carbon dioxide, in grams, produced by the combustion of 100
grams of octane. Show your calucations and include units in your answer.
Many people think it is important to reduce the amount of CO2 being released by fuel
combustion because CO2 is a greenhouse gas. Propane (C3H8) is another hydrocarbon fuel
used to power some motor vehicles. THE combustion of propane is shown in the equation
below.
C3H8 + 5 O2 → 3 CO2 + 4 H20
The combustion of 100 g of propane produces 299.4 g of carbon dioxide. Assume the
combustion of propane produces the same amount of energy per gram as the combustion of
octane.
c. Based on this information and your calculations, identify which fuel, octane or propane, is
less harmful to the environment. Justify your answer.
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35
Worksheet: Writing and Identifying Equations
CHEMISTRY: A Study of Matter
Directions: a) Write balanced equations for the following word equations.
b) In the blank to the left of the equation, tell if the equation is synthesis (S), decomposition (D), combustion
(C), single replacement (SR), or double replacement (DR).
_____ potassium chloride + silver (I)nitrate yields potassium nitrate + silver (I) chloride
_____ iron metal + copper (II) sulfate yields iron (II) sulfate + copper metal
_____ beryllium fluoride + magnesium yields magnesium fluoride + beryllium
_____ aluminum sulfate + barium chloride yields aluminum chloride + barium sulfate
_____ zinc metal + oxygen gas yields zinc (II) oxide
36
_____ Ethane (C2H6) + oxygen gas yields carbon dioxide and water
_____Aluminum metal reacts with aqueous zinc (II) chloride to produce Zn metal and aqueous AlCl3.
_____ Iron and sulfur combine and form iron (II) sulfide.
_____ Solid diphosphorus pentoxide can be produced from the elements oxygen and phosphorus. (Note: Solid
elemental phosphorus contains 4 atoms per molecule; it is written P4.)
_____ When hydrogen sulfide (H 2S)gas is passed over solid hot iron (III) hydroxide, it reacts to form solid
iron (III) sulfide and water vapor.
37
Balancing Formative Practice
1.
a.
b.
In every balanced chemical equation, each side of the equation has the same number of ____.
atoms of each element
c.
moles
molecules
d.
coefficients
2.
What are the coefficients that will balance the skeleton equation below?
AlCl3 + NaOH → Al(OH)3 + NaCl
a.
b.
1, 3, 1, 3
3, 1, 3, 1
3.
When the equation Fe + Cl2 → FeCl3 is balanced, what is the coefficient for Cl2 ?
a.
b.
1
2
c.
d.
c.
d.
1, 1, 1, 3
1, 3, 3, 1
3
4
4.
When potassium hydroxide and barium chloride react, potassium chloride and barium hydroxide
are formed. The balanced equation for this reaction is ____.
a.
b.
KH + BaCl → KCl + BaH
KOH + BaCl → KCl + BaOH
5.
When the following equation is balanced, what is the coefficient for HCl?
Mg(s) + HCl(aq) → MgCl (aq) + H2 (g)
a. 6
38
b. 3.
c. 1
c.
d.
d. 2
2KOH + BaCl2 → 2KCl + Ba(OH)2
KOH + BaCl2 → KCl2 + BaOH
6.
What are the coefficients that will balance the skeleton equation below?
N2 + H2 → NH3
a.
b.
1, 1, 2
1, 3, 3
c.
d.
3, 1, 2
1, 3, 2
7. Which of the following is a balanced equation representing the decomposition of lead(IV) oxide?
a.
b.
PbO2 → Pb + 2O
PbO2 → Pb + O2
c.
d.
Pb2O → 2Pb + O
PbO → Pb + O2
8.
What are the missing coefficients for the skeleton equation below?
Cr(s) + Fe(NO3)2 (aq) → Fe(s) + Cr(NO3)3 (aq)
a.
b.
4, 6, 6, 2
2, 3, 2, 3
c.
d.
2, 3, 3, 2
1, 3, 3, 1
9.
What are the missing coefficients for the skeleton equation below?
Al2(SO4)3 (aq) + KOH(aq) → Al(OH)3 (aq) + K2SO4 (aq)
a.
b.
1, 3, 2, 3
2, 12, 4, 6
c.
d.
4, 6, 2, 3
1, 6, 2, 3
10.
What is the balanced chemical equation for the reaction that takes place between bromine and
sodium iodide?
a.
b.
Br2 + NaI → NaBr2 + I
Br2 + 2NaI → 2NaBr + I2
c.
d.
Br + NaI2 → NaBrI2
Br + NaI2 → NaBr + I2
39
Law of Conservation of Mass In any physical change or chemical reaction, mass is neither created
nor destroyed. Therefore, the sum of the masses of the reactants is equal to the sum of the masses of
the products.
Reactants are written in the left hand side of the arrow while the products are in the right hand side.
massreactants = massproducts
mercury(II) oxide decomposes to yield mercury metal and oxygen gas
2HgO  2Hg
+ O2
216 g
= 200 g + 16 g
massreactants
=
massproducts
Sample Problem:
a. In an experiment, 10.00 g of red mercury (II) oxide powder is placed in an open flask and heated until it is
converted to liquid mercury and oxygen gas. The liquid mercury has a mass of 9.26 g. What is the mass of
oxygen formed in the reaction?
2HgO

2Hg
+
O2
b. A student carefully placed 15.6 g of sodium in a reactor supplied with an excess quantity of chlorine gas. When
the reaction was complete, the student obtained 39.7 g of sodium chloride. How many grams of chlorine gas
reacted? How many grams of sodium reacted?
1.
Practice Problems: Solve the following problems. Write the reactants and products. CIRCLE YOUR ANSWERS.
In the complete reaction of 22.99 g of sodium with 35.45 g of chlorine, what mass of sodium chloride is
formed?
3. In a flask, 10.3 grams of aluminum reacted with 100.0 g of liquid bromine to form aluminum bromide. After the
reaction, no aluminum remained, and 8.5 grams of bromine remained unreacted. How many grams of bromine
reacted? How many grams of compound were formed?
40
4. A 10.0-g sample of magnesium reacts with oxygen to form 16.6 g of magnesium oxide. How many grams of
oxygen reacted?
5. From a laboratory process designed to separate water into hydrogen and oxygen gases, a student collected 10.0
g of hydrogen and 79.4 g of oxygen. How much water was originally involved in the process?
6. A 12.2-g sample of X reacts with a sample of Y to form 78.9 g of XY. What is the mass of Y that reacted?
7. A 28.0-g sample of nitrogen combines completely with 6.0 g of hydrogen gas to form ammonia. What is the
mass of ammonia formed?
8. A substance breaks down into its component elements when it is heated. If 68.0 g of the substance is present
before it is heated, what is the combined mass of the component elements after heating?
9. A 13.0-g sample of X combines with a 34.0-g sample of Y to form the compound XY2. What is the mass of the
reactants?
10. Sodium chloride can be formed by the reaction of sodium metal and chlorine gas. If 45.96 grams of sodium
combines with an excess of chlorine gas to form 116.89 g of sodium chloride, what mass of chlorine gas is used
in the reaction?
41
S’more Stoichiometry
Definitions: ‘Stoichio’ means element and ‘metry’ means the process of measuring. The mass and
quantity relationships among reactants and products in a reaction are found using the process of
stoichiometry.
Problem:
1) If you are given one bag of large marshmallows, what is the maximum number of S’mores that
can be made?
2) How many boxes of graham crackers and how many chocolate bars are needed to make this
many S’mores?
Solutions:
1st Step: Write a chemical equation using the following symbols:
Substance
Symbol
Unit Mass
Graham Cracker
S
7.00 g
Marshmallow
Mm
7.10 g
Chocolate Pieces
Or
3.30 g
S’more
S2MmOr3
________ g
2nd Step: Balance the equation: What does the equation tell us? What do the coefficients
represent?
They represent the ratio of the ___________ or the ______________.
3rd Step: Calculate the unit mass of the S’more (S2MmOr3)below:
42
4rth Step: Calculating the number of units (or moles) given:
Determine the number of unit marshmallows that are available in the bag.
If there are 454 g marshmallows in one bag, how many marshmallows do you have?
5th Step: Finding the units of other substances in the reaction:
Now, determine how many units of graham crackers and chocolate segments are needed to
make the maximum number of s’mores available.
5th Step: Convert your number of graham crackers and chocolate segments into mass (gram):
When you go to the store, you cannot quickly determine the exact number of graham crackers or
chocolate segments there are in a box or bar. The mass is easy to read, however. Using mass
values, you can quickly determine how much you need to buy.
6th Step: Finally-convert the masses into your needed units.
In this case, if a box of graham crackers has a mass of 254 g, how many boxes do you
need? Also, if one chocolate bar has a mass of 49.5 g, how many bars do I need?
43
Now we will transfer this process into the language of chemical reactions. When you complete
this problem, get it checked by your teacher and you will be rewarded with the necessary items to
make your S’more!
If we were to add a piece of solid Cu to an aqueous solution of silver nitrate, the Silver would be
replaced in a single replacement reaction forming aqueous copper (II) nitrate and solid silver.
How much silver is produced is 15.00 grams of Cu is added to the solution of excess silver nitrate?
Show all work and don’t forget to use significant figures.
Steps 1 and 2: Write and balance the chemical equation:
Step 3: Convert g Cu to moles Cu:
Step 4: Convert moles of Cu to moles of Ag produced:
Step 5: Convert moles Ag to grams of Ag produced:
Step 6: If silver metal sells for %4.50/ounce, could you get rich from this lab? (How much would it
be worth?) Conversion factor: (1 gram = 0.0353 oz)
Extra: Try writing this entire stoichiometric process on one line. Remember to cancel out all
necessary units!
44
Mass A
(in grams)
(in grams)
Liters gas A
(at STP)
Mass B
(in grams)
Mole
A
Moles
B
Liters gas A
(at STP)
Particles A
(atoms/molecules)
s
Particles B
(atoms/molecules)
45
Interpretation of Equations
Silicon nitride is used in the manufacturing of high-temperature thermal insulation for heat engines
and turbines. It is produced by the following reaction.
3Si(s) + 2N2(g) → Si3N4(s)
Interpret the equation in terms of particles, moles, and masses.
How many moles
Si______________________________________________________________________
N2_____________________________________________________________________
Si3N4__________________________________________________________________________________________________________
How many particles
Si______________________________________________________________________
N2_____________________________________________________________________
Si3N4__________________________________________________________________________________________________________
How many grams
Si______________________________________________________________________
N2_____________________________________________________________________
Si3N4__________________________________________________________________________________________________________
Show using the grams calculated above that mass is conserved in the reaction.
Finding and Using Molar Ratios
The coefficients in a balanced chemical equation can be used to determine the relative number of
molecules, formula units, or moles of a compound involved in a chemical reaction.
Example:
N2 (g) + 3 H2 (g) --> 2 NH3 (g)
1 molecule of N2 reacts with 3 molecules of H2 to form 2 molecules of NH3 OR
1 mole of nitrogen (N2) reacts with 3 moles of hydrogen (H2) to form 2 moles of ammonia (NH3)
The coefficients in a balanced equation can be used to write a molar ratio. Molar ratios are conversion
factors that can be used to relate: moles of product formed from a certain number of moles of
reactant moles of reactant needed to form a certain number of moles of a product. The number of
moles of a particular reactant needed to completely react with a certain number of moles of a second
reactant. For the following reaction:
4 NH3 (g) + 5 O2 (g) --> 4 NO (g) + 6 H2O (g) the following molar ratios can be written:
4 moles NH3; 4 moles NH3; 4 moles NH3; 5 moles O2 ;
5 moles O2 ; 4 moles NO
5 moles O2
4 moles NO 6 moles H2O 4 moles NO
6 moles H2O 6 moles H2O
The inverses of each of these molar ratios can also be written.
46
Practice Using Mole Ratios
What is the molar ratio between Li and N2 in the following reaction:
6 Li (s) + N2 (g) --> 2 Li3N (s)
2. The heat from a welder’s torch is produced by the burning (combustion) of acetylene gas. The
reaction is represented by the following balanced chemical equation.
2C2H2(g) + 5O2(g) → 4CO2(g) + 2H2O(g)
Write the mole ratios from the balanced equation. There are 6.
3. Limestone (CaCO3) is treated with hydrochloric acid and water to manufacture calcium chloride
hexahydrate. This compound is used to melt ice and snow on pavements and roads. The following
balanced chemical equation represents the reaction.
CaCO3(s) + 2HCl(aq) + 5H2O(l) →
CaCl2∙6H2O(s) + CO2(g)
How many moles of calcium chloride hexahydrate will be produced from 4.00 mol calcium carbonate?
How many moles of hydrogen chloride will be needed to produce 1.25 mol of the hydrate?
c. If 15 mol water is available for the reaction, how many moles of carbon dioxide will be released?
47
Mole/Mole Practice1
CHEMISTRY: A Study of Matter
1. ___NO + ___O2 → ___NO2
a. 2 moles of NO will react with ______ mole(s) of O2 to produce ______ mole(s) of NO2.
b. if 3.6 moles of O2 react with unlimited NO how many mole NO2 will be produced?
c. How many moles of NO must react to form 4.67 moles of NO2?
2. ___NH3 + ___O2 → ___N2 + ___H2O
a. 20 moles of NH3 are needed to produce ______ moles of H2O.
b. How many moles of N2 will be produced if 3.5 moles of O2 react?
3. ___AlF3 + ___O2 → ___Al2O3 + ___F2
a. 20 moles of AlF3 will produce ______ moles of F2.
b. ______ moles of AlF3 will react with 0.6 moles of O2.
1
© 2004, GPB
48
8.6
4. ___C3H8 + ___O2 → ___CO2 + ___H2O
a. How many moles of oxygen react with 11 moles of C3H8?
b. How many moles of CO2 are produced if 3.5 moles of water are produced?
5. ___O2 + ___Fe → ___Fe2O3
a. Fill in the following word equation--______ moles of oxygen gas react with ______ moles of iron to
produce _____ moles of iron (III) oxide.
b. ______ moles of O2 are required to produce 3.0 moles of iron (III) oxide.
Quickwrite: Explain how to balance a chemical equation and then to use the chemical equation to
determine a mole ratio to solve a mole A → mole B problem. Using problem 5 for example.
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49
Stoichiometry Practice I
1 To prevent corrosion and make paints adhere better, some aluminum products are treated with chromium
(III) phosphate before finishing. Chromium (III) phosphate (CrPO4) is commercially produced by treating
chromium metal with orthophosphoric acid (H3PO4).
Balance the following equation for the reaction.
___Cr(s) + ___H3PO4(aq)
→ ____ H2(g) + ____CrPO4(s)
How many moles of chromium metal are needed to produce 735 g of chromium (III) phosphate?
The reaction of 208 g chromium will release how many moles of hydrogen gas?
2. Sand (silicon dioxide) and charcoal (carbon) are combined to form silicon carbide (SiC), a compound used in
high-strength ceramic materials.
a. Balance the following equation for the reaction.
_____SiO2(s) + _____C(s) → _____SiC(s) +___CO(g)
b. What mass of silicon carbide will be produced from the reaction of 352 g silicon dioxide?
c. If 1.00 g of carbon is reacted, what mass of carbon monoxide is released?
50
Stoichiometry Practice II
When Miss Elizabeth was younger she made more mistakes then she does now (thank goodness). One mistake was
after having to get a new battery for her car she thought she could get some money for recycling it instead of leaving
it with auto shop. Well she carried it around in her trunk for a week while trying to find a place and much to her
surprise it tipped over and spilled sulfuric acid (H2SO4) which ate away at the carpet. Once she saw what had
happened she added some lye (sodium hydroxide) which neutralized the acid producing water and sodium sulfate.
Write and balance the chemical equation.
How many grams of sodium sulfate will be formed if you start with 200 grams of sodium hydroxide and you have an
excess of sulfuric acid?
How many grams of sulfuric acid would be neutralized by 200 grams of sodium hydroxide?
If in fact 25 grams of sulfuric acid spilled would she have to add more sodium hydroxide? Check how much sodium
hydroxide she would need to neutralize 25 grams of sulfuric acid and then compare that amount with 200 grams.
QUICK WRITE: Explain how you solved the question did she add enough sodium hydroxide or not?
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51
Stoichiometry Practice III
Ammonia gas reacts with oxygen gas to form nitrogen monoxide and water
1. Write the chemical reaction formula and balance
2.How many moles of oxygen gas are needed to react with 23 moles of ammonia
3.How many grams of NO are produced when 25 moles of oxygen gas react with an excess of ammonia. Having
an excess means that you don’t have to worry about how much ammonia you are starting with and you have
enough to react with all the oxygen gas available in this case 25 moles.
4. If 24 grams of water are produced, how many moles of nitrogen monoxide are also formed.
5. How many grams of oxygen are needed to react with 6.78 grams of ammonia?
Summarize how you would go about calculating the grams of product given the grams of reactant you start with.
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52
Stoichiometry Practice IV
The compound calcium carbide, CaC 2 is made by reacting calcium carbonate with carbon. Industrially, calcium
carbide is produced industrially in an electric arc furnace at 2000 °C. This method has not changed since its
invention in 1888. Calcium carbide in contact with water, a chemical reaction immediately begins, which yields
two new compounds, one of which is acetylene, a very useful flammable gas. .Balance the equation:
CaCO3
+
C
→
CaC2 +
CO2
1. How many moles of carbon are needed produce 5.0 moles of CO2?
2. How many grams of calcium carbide are produced when 4.0 moles of carbon react with an excess of calcium
carbonate?
3. How many moles of carbon dioxide are produced when 50 gram of calcium carbonate react with an excess of
carbon?
4. How many grams of carbon are needed to react with 200 grams of calcium carbonate?
5.. How many grams of calcium carbonate are needed to form 641 grams of calcium carbide?
Discuss which step is hardest for you to remember.
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53
Stoichiometry Practice V
Octane (C8H18) an important fuel hydrocarbon in gasoline. Higher octane fuel is typically called premium gas and
costs more. Octane is combusted as shown below:
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O
Write all possible molar ratios from this equation (there are 6 ratios)
How many moles of CO2 would be produced by reacting 0.67 moles of octant with excess oxygen? (5.4 mol)
How many moles of H2O would be produced by reacting 0.67 moles of octane with excess oxygen? (6.0 mol H2O)
If we react 228 g of octane C8H18 with oxygen, how many mole of O2 are required?
If we react 228 g of octane C8H18 with excess oxygen, how many mole of CO2 are produced?
If we react 228 g of octane C8H18 with excess oxygen, how many mole of H2O are produced?
Discuss why balanced reactions are needed to solve stoichiometry problems.
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54
g. If we wish to make 7.5 mol CO2, how many grams of C8H18 will be used? (107 C8H18)
h. If we wish to make 7.5 mol CO2, how many grams of O2 do we need? (375 g O2)
i. If we wish to make 7.5 mol CO2, how many grams of H2O will be produced? (152 g H2O)
j. If we have 3.56 g C8H18, how many grams of O2 do we need to react with it?
k. If we have 3.56 g C8H18, how many grams of CO2 do we produce?
l. If we have 3.56 g C8H18, how many grams of H2O do we produce?
m. Using the answers from j, k, and l for burning 3.56 g of octane, check if the law of conservation of mass is
obeyed or not. Write the equation and grams to verify sum of reactants equals sum of products
55
56
Limiting Reagent Worksheet
Definition of Limiting Reactant: The reactant that limits the amounts of the other reactants that can combine and the
amount of product that can form in a chemical reaction.
" I want to make chocolate chip cookies. I look around the HUGE kitchen I work in and find 40 lbs. of butter, two lbs.
of salt, 1 gallon of vanilla extract, 80 lbs. of chocolate chips, 200 lbs. of flour, 150 lbs. of sugar, 150 lbs. of brown
sugar, ten lbs. of baking soda and TWO eggs. It should be clear that it is the number of eggs that will determine the
number of cookies that I can make."
Limiting Reactant - The reactant in a chemical reaction that limits the amount of product that can be formed. The
reaction will stop when all of the limiting reactant is consumed.
Excess Reactant - The reactant in a chemical reaction that remains when a reaction stops when the limiting reactant
is completely consumed. The excess reactant remains because there is nothing with which it can react.
No matter how many tires there are, if there are only 8 car bodies, then only 8 cars can be made. Likewise with
chemistry, if there is only a certain amount of one reactant available for a reaction, the reaction must stop when that
reactant is consumed whether or not the other reactant has been used up.2
Example Limiting Reactant Calculation:
A 2.00 g sample of ammonia is mixed with 4.00 g of oxygen. Which is the limiting reactant and how much excess
reactant remains after the reaction has stopped?
First, we need to create a balanced equation for the reaction:
4 NH3(g) + 5 O2(g)
4 NO(g) + 6 H2O(g)
Next we can use stoichiometry to calculate how much product is produced by each reactant. NOTE: It does not
matter which product is chosen, but the same product must be used for both reactants so that the amounts can be
compared.
The reactant that produces the lesser amount of product in this case is the oxygen, which is thus the "limiting
reactant."
Next, to find the amount of excess reactant, we must calculate how much of the non-limiting reactant (ammonia)
actually did react with the limiting reactant (oxygen).
We're not finished yet though. 1.70 g is the amount of ammonia that reacted, not what is left over. To find the
amount of excess reactant remaining, subtract the amount that reacted from the amount in the original sample.
2
http://www.chem.tamu.edu/class/majors/tutorialnotefiles/limiting.htm
57
We will use this kind of thinking, with mole ratios and molar masses AND Balanced equations to figure out which
reactant is limiting the reaction’s production of products.
For the following reactions, find the following:
Which of the reagents is the limiting reagent?
What is the maximum amount of each product that can be formed?
How much of the other reagent is left over after the reaction is complete?
Answer the questions above given 18 grams of carbon reacts with 16 grams of oxygen to form carbon dioxide
C + O2  CO2
Answer the questions above given 18 grams of carbon reacts with 8 grams of hydrogen to form methane.
C + 2H2  CH4
58
Answer the questions above given 7.5 grams of nitrogen monoxide reacts with 8 grams of oxygen to form nitrogen
dioxide.
___NO + ___O2 → ___NO2
At high temperatures, sulfur combines with iron to form the brown-black iron (II) sulfide:
Fe (s) + S (l) →FeS (s)
In one experiment, 7.62 g of Fe are allowed to react with 8.67 g of S.
a. What is the limiting reagent, and what is the reactant in excess?
b. Calculate the mass of FeS formed.
59
Percent Yield Calculations
1)
Balance this equation and state which of the types of reaction is taking place:
____ Mg + ____ HNO3  ____ Mg(NO3)2 + ____ H2
Type of reaction: _______________________
2)
If I start this reaction with 40 grams of magnesium and an excess of nitric acid, how many grams of hydrogen
gas will I produce?
3)
If 1.7 grams of hydrogen is actually produced, what was my percent yield of hydrogen?
4)
Balance this equation and state what type of reaction is taking place: Type of reaction: __________________
____ NaHCO3  ____ NaOH + ____ CO2
5)
If 25 grams of carbon dioxide gas is produced in this reaction, how many grams of sodium hydroxide should
be produced?
6)
60
If 50 grams of sodium hydroxide are actually produced, what was my percent yield?
Percent Yield Worksheet
1)
Write the equation for the reaction of iron (III) phosphate with sodium sulfate to make iron (III) sulfate and
sodium phosphate.
2)
If I perform this reaction with 25 grams of iron (III) phosphate and an excess of sodium sulfate, how many
grams of iron (III) sulfate can I make?
3)
If 18.5 grams of iron (III) sulfate are actually made when I do this reaction, what is my percent yield?
4)
Is the answer from problem #3 reasonable? Explain.
5)
If I do this reaction with 15 grams of sodium sulfate and get a 65.0% yield, how many grams of sodium
phosphate will I make?
61
Note Taking Guide: Episode 6043
CHEMISTRY: A Study of Matter
Chemical Equations
• a ___________________ way of reporting the _____________ of a _____________ _____________
Reactants
• the _____________ substances in a _____________
• placed on the _____________ side of the _____________
Products
• the substances _____________ during a _____________
_____________
• placed on the _____________ side of the ____________
→ arrow is read as ______________
Coefficients
• used to ____________ ______________
• represent the ______________ of _________________, ______________, or __________ of the
_____________.
Law of Conservation of Mass
Mass of Reactants = Mass of Products
Mass _____________ be _____________ or _____________.
Zn +
HCl
ZnCl2 + H2
H2 + O2
H2O
C3H8 + O2
CO2 + H2O
Guidelines for Balancing Equations
• Start by _____________ an _____________ _____________.
• Draw _____________ around each _____________ in the _____________.
• Begin with __________ molecules or formula unit of the ___________ containing the ___________atoms.
• Balance _____________ ions that appear on __________ sides of the _____________ as a single unit.
• Balance _____________ and _____________ atoms _____________.
KNO3→ KNO2 + O2
Hydrogen and oxygen combine to produce water.
7 Diatomic Elemental Molecules
• Diatomic: _____________ _____________
• ___________, __________, ____________, ___________, ___________, ____________, ___________
Carbon disulfide reacts with oxygen to produce carbon dioxide and sulfur dioxide.
3
© 2004, GPB
62
6.21
Note Taking Guide: Episode 605
Descriptive Abbreviations
( _____ ) ____________
( _____ ) ____________
( _____ ) ____________
( _____ ) ____________
Determining State at Room Temperature
All ____________ are solids except for ____________, which is a ____________.
Most ____________ are ____________ with these exceptions:
liquid – ____________
solids – ____________, ____________, ____________,
____________, ____________, and ____________
All ____________ are solids.
____________ compounds are ____________, unless stated otherwise.
____________ compounds are ____________, unless stated otherwise.
When heated, solid mercury(II)oxide yields mercury and oxygen gas.
Classifying Reactions
1. Synthesis:
____________ or ____________ substances combine to form a more____________ substance.
____________ ____________
Fe (s) + ____________ ____________
H2O (l) + ____________ ____________
2. Decomposition
A ____________ substance is ____________ ____________ into____________ or more ____________
substances.
AB ____________
Activity
2H2O (l) ____________ + ____________
Series of
____________ ____________ + ____________
3. Single Replacement
A free ___________ replaces a ___________ ___________ element in a __________.
A + BY ____________ + ____________
Zn (s) + __________ ___________ + ___________
2Al (s) + __________ ___________ + ___________
Cu (s) + MgCl2 (aq) ____________
Activity Series: an _________ of elements in the order of their _________ to ________
4. Double Replacement
The ____________ of reacting ____________ ____________ each other.
Normally takes place in an ____________ ____________.
Also called ____________ reactions
AX + BY ____________ + ____________
2KI (aq) + __________ __________ + __________
Precipitate: an ____________ ____________
may be ____________ in an equation by ____________ or ____________
NaCl (aq) + ___________ __________ + _________
Metals
Decreasing
Activity
Lithium
Potassium
Barium
Calcium
Sodium
Magnesium
Aluminum
Manganese
Zinc
Chromium
Iron
Cadmium
Nickel
Tin
Lead
(Hydrogen)
Copper
Mercury
Silver
Gold
5. Combustion
Involves the ____________ of a substance with ____________.
Often called ____________.
The ____________ ____________ of a ____________ produces ____________ and ____________.
CxHy + O2 ____________ + ____________
C3H8 (g) + 5O2 (g) ____________ + ____________
CH4 (g) + __________ ___________ + ___________
63
Note Taking Guide: Episode 801
Stoichiometry
CHEMISTRY: A Study of Matter
study of the ____________ relationships in a ____________ ____________
based on ________________ equations
2 Mg + O2 → 2 MgO
The ___________ in a ___________ ___________ give the ___________ ___________ for the
___________ involved in the ___________.
Ex. Problem: When elemental aluminum reacts with elemental iodine, aluminum iodide is produced.
mole ratios: _____ Al: _____ I2
_____ Al: _____ AlI3
_____ I2: _____ AlI3
If you start with 4 moles of Al, how many moles of Al3 will be produced?
Problem Set
Mole to Mole
N2H4 + N2O4→ N2 + H2O
BE SURE TO BALANCE THE EQUATION FIRST!!
Known 2.72 moles N2H4 how many moles N2O4 =
Known 2.72 moles N2H4 how many moles N2 =
Moles and Grams
How many moles of water will be produced when _______ grams of hydrogen gas react with the
oxygen in the air?
(Hint: To “make the switch” between different substances in a reaction, use the ______ ratio from
the ___________ equation.)
64
Problem Set Two
BE SURE TO BALANCE THE EQUATION FIRST!!
In photosynthesis, carbon dioxide and water react to form glucose, C6H12O6 and oxygen gas.
___CO2 + ___H2O → ___C6H12O6 + ___O2
If 15.6 grams of carbon dioxide react, how many moles of glucose will be produced?
How many grams of carbon dioxide must react to produce 0.25 moles of glucose?
When nitrogen and hydrogen react, they form ammonia gas, which has the formula NH3. If 56.0 g of
nitrogen are used up in the reaction, how many grams of ammonia will be produced?
Summary Explain in your own words
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
65
Culinary Chemistry: Stoichiometry Made Simple4
Background
Stoichiometry is based on the law of conservation of mass which states that the mass of the reactants
in a chemical reaction equals the mass of the products. Stoichiometry provides a means for
researchers to use calculations in order to predict the amount of product (mass, moles, volume) that
can be produced by a given quantity of reactants as well as the percent yield for that chemical
reaction. This would be important in the manufacturing of drugs in determining a quantity of
substance needed and, keeping in mind that medication may react or change in accordance with
other metabolic processes of the body, may require an additional amount to compensate for these
effects. Both pharmaceutics and pharmacokinetics address quantifying the amount of drug
necessary for each patient, with a unique weight, and how to best deliver that drug. You will play the
role of pharmacologist by reacting baking soda and vinegar and using stoichiometry to calculate
quantity of product yield.
CH3COOH + NaHCO3  NaCH3COO + H2O + CO2
Vinegar
baking soda
sodium acetate
water
carbon dioxide
Objective: To predict the amount of carbon dioxide gas expected as a product and to calculate percent yield.
Materials:
4 g baking soda
2-250 mL beakers
50 mL vinegar
50-mL graduated cylinder
1 mL disposable pipette
digital balance
Procedure
Task
Response
1. Weigh a clean, dry 250-mL beaker on the digital
balance. Record the mass (g) of this empty beaker.
2. Mass out 4 g of baking soda (NaHCO3) in the 250mL beaker that you weighed in #1. Calculate the
number of moles in 4 g of baking soda (NaHCO3).
Show your work.
3. Measure 50 mL of vinegar (CH3COOH) using the 50mL graduated cylinder. Using the second 250-mL
beaker, record the mass (g) of the vinegar.
4. Using a 1-mL disposable pipette, add 1 mL of
vinegar to the baking soda. What observations
provide evidence that a chemical reaction is
occurring?
4
HASPI revised July 2011 Modified from Living by Chemistry “Mole Tunnel”
66
5. Continue adding vinegar to the baking soda 1 mL
at a time until the chemical reaction no longer
occurs. How will you know that a chemical reaction
is no longer occurring?
6. When your group is confident that there is no
longer a chemical reaction, weigh the beaker with
the new products. Record the total mass (g).
7. Calculate the mass (g) of the products only by
subtracting the weight of the beaker that you
recorded in #1.
8. Record the final weight (g) of the unused vinegar.
9. Based on your measurements, calculate the
amount of carbon dioxide (CO2) that was released
as a product.
10. Calculate the expected amount of carbon dioxide
that would be produced by the chemical reaction.
11. How does your expected CO2 produced
compare to the actual CO2 produced? Can you
explain any possible sources of error?
12. Calculate percent yield of CO2.
actual yield -theoretical yield X 100 = % yield
13. Calculate percent error.
actual yield – theoretical yield X 100 = % error
theoretical yield
14. The law of conservation of matter and energy states
that matter is not created nor destroyed during a
reaction. If this is true, then explain why the mass of the
products is less than the total mass of the reactants.
67
P a r t B . R o o t C a n a l St o i c h i o m et r y
Calcium hydroxide is sometimes used in dentistry to temporarily fill the space left by a root canal. The
equation for the formation of calcium hydroxide can be found below. Balance the chemical equation by
placing the appropriate coefficients on the lines.
NaOH  Ca(OH)2 +
_____ CaCl2 +
Task
NaCl
Response
Molar Mass (g/mol)
1. Calculate the molar mass of the reactants and the
Reactants
CaCl2
products in the chemical reaction above.
NaOH
Ca(OH)2
Product
NaCl
Imagine that a dentist performs this reaction four times using different amounts of the reactants. Fill in the
missing information below.
Reactants
Products
Reaction
Quantity
CaCl2
Ca(OH)2
NaOH
NaCl
1
Moles
1.00 mol
2.00 mol
1.00 mol
2.00 mol
Grams
2
Moles
Grams
3
0.500 mol
55.5 g
Moles
37.0 g
0.200 mol
0.100 mol
Grams
4
Moles
Grams
Task
2. How many moles of Ca(OH)2 are formed for every mole
of NaOH used?
3. For every 0.50 mol of Ca(OH)2 formed, how many moles of
NaCl are formed?
4. How many grams of calcium chloride, CaCl 2, do you
need to make 20.0 g of calcium hydroxide, Ca(OH)2?
68
10.0 g
Response
58.5 g
P a r t C . H uma n B o n e s S t o i ch i o m e t ry
The chemical equation for the reaction that forms calcium phosphate, the main ingredient in human bones, can be
found below. Balance the chemical equation by placing the appropriate coefficients on the lines.
CaCl2 +
Na3PO4   Ca(PO4)2 +
Task
NaCl
Response
Molar Mass (g/mol)
1. Calculate the molar mass of the reactants and the Reactants
CaCl2
products in the chemical reaction above.
Na3PO4
Product
Ca(PO4)2
NaCl
Imagine that a physician performs this reaction four times using different amounts of the reactants in
order to develop human tissue for bone grafting. Fill in the missing information below.
Reaction
Quantity
1
Moles
Reactants
CaCl2
Na3PO4
3.00 mol
2.00 mol
Products
Ca(PO4)2
1.00 mol
NaC
l mol
6.00
Grams
2
Moles
Grams
3
2.00 mol
666 g
Moles
620 g
0.200 mol
0.100 mol
702
g
Grams
4
Moles
Grams
Task
9.92 g
Response
2. For every mole of Na3PO4 used, how many moles of
Ca3(PO4)2 are formed?
3. For every 0.500 mol of Ca(PO4)2 formed, how many
moles of CaCl are used?
4. How many grams of calcium chloride (CaCl 2) do you
need to make 20.0 g of human bone?
69
DOW goes Agro…Agrosciences, that is!
Imagine you are working as a chemist at Dow Chemicals. You are responsible for ordering chemicals for a new
fertilizer that Dow will be producing next year. The following information is necessary for your order:
1 mole contains 6.02 x 1023 molecules
1 mole of gas takes up 22.4 L (or 22.4 dm3) of space
1 mole of fertilizer requires 2 moles of NH3 and 3 moles of CH4
Directions: Use the above information to solve the following problems. Show your work.
1. You are making 150, 000 moles of fertilizer.
a. How many moles of NH3 do you need?
b. How many moles of CH4 do you need?
2.
a. How much will the NH3 weigh in grams?
b. How much will the CH4 weigh in grams?
70
3. Your storage tank holds 1, 000, 000 L. How many moles of gas would it hold?
4. You place your order, but the company that provides CH4 can only obtain 15,000 moles of CH4. How many moles of NH3
will you be able to use with this quantity of CH4?
5. Using your information from question #4…
a. How many molecules of NH3 will you order?
b. How much volume in liters (L) will it take up?
c. How much will it weigh in grams?
6. If it costs $1.75 per mole of fertilizer produced, how much will it cost to make 150, 000 moles?
71
IDENTIFY THE CONTROLS AND VARIABLES
Experiment 1 Smithers is greedy and wants more money so he needs workers
that work harder. Smithers thinks that a special juice will increase the
productivity of workers. He creates two groups of 50 workers each and assigns
each group the same task (in this case, they're supposed to staple a set of
papers). Group A is given the special juice to drink while they work. Group B is
not given the special juice. After an hour, Smithers counts how many stacks of papers each group has
made. Group A made 1,587 stacks, Group B made 2,113 stacks.
You have been hired to evaluate the Smithers experiement.
1. What was the initial observation?_________________________________________________
2. Identify Smithers’ hypothesis___________________________________________________
___________________________________________________________________________
3. Which is the control group? ____________________________________________________
4. Which is the experimental group? ________________________________________________
5. Identify the independent variable. _______________________________________________
6. Identify the dependent variable. _________________________________________________
7. What factors were controlled?__________________________________________________
8. What is the outcome?_________________________________________________________
9. Given the experimental design, what should Smithers' conclusion be? ______________________
____________________________________________________________________________
____________________________________________________________________________
10. How do you think the experiment could be improved? _________________________________
___________________________________________________________________________
___________________________________________________________________________
72
Bellringers
11/4/13 What is the molar mass of Ca(NO2) 2
11/5/13
Which best describes the current atomic theory?
A Atoms consist of electrons circling in definite orbits around a positive nucleus.
B Atoms are composed of electrons in a cloud around a positive nucleus.
C Atoms can easily be split, at which time they become radioactive.
D An atom’s mass is determined by the mass of its neutrons.
After 1911, most scientists accepted the theory that the nucleus of an atom was very dense and very small
and had a positive charge. What led scientists to accept this theory?
A Dalton’s theory of the atom was over 100 years old.
B Scientists before 1911 used the scientific method of inquiry improperly.
C A new model proved that the quantum theory of the atom was inaccurate.
D Rutherford did an experiment firing alpha particles at a thin piece of gold foil.
What is the nuclear composition of uranium-235?
A 92 electrons + 143 protons
B 92 protons + 143 electrons
C 143 protons + 92 neutrons
D 92 protons + 143 neutrons
Which best describes the relationship between subatomic particles in any neutral atom?
A The number of protons equals the number of electrons.
B The number of protons equals the number of neutrons.
C The number of neutrons equals the number of electrons.
D The number of neutrons is greater than the number of protons.
What is the identity of the ion that consists of 7 protons, 6 neutrons and 10 electrons?
What is the identity of the ion that consists of 9 protons, 10 neutrons, and 10 electrons?
11/6/13 What is the mass of 3.01 x 1023 particles of CaSO4?
11/7/13
What is the name of the compound PbO2 ?
A lead oxide
B lead(II) oxide
C lead oxide(II)
D lead(IV) oxide
What is the chemical formula for calcium nitrate?
A CaNO3
B Ca(NO2) 2
C Ca(NO3) 2
D Ca 3 N2
Explain how you determined the formula.
73
11/8/13
Which substance listed in the table is a liquid at 27°C?
AI
B II
C III
D IV
The table shows the lattice energy for some ionic compounds. Based
on these data, which of these compounds would require the most
energy to separate the bonded ions?
11/11/13
What type of bonding is associated with compounds that have the following characteristics:
•high melting points
•conduct electricity in the molten state
•solutions conduct electricity
•normally crystalline solids at room temperature.
A covalent
B ionic
C hydrogen
D metallic
What situation results in a polar covalent bond?
A. two nonmetals bonding, with a small difference in electronegativity
B. two nonmetals bonding, with a large difference in electronegativity
C. two metals bonding, with a small difference in electronegativity
D. a metal and a nonmetal bonding, with a large difference in electronegativity
11/12/13 Which is a unique characteristic of the bonding between metal atoms?
A Atoms require additional electrons to reach a stable octet.
B Atoms must give away electrons to reach a stable octet.
C Atoms share valence electrons only with neighboring atoms to reach a stable octet.
D Delocalized electrons move among many atoms creating a sea of electrons.
High pressure helps to disrupt hydrogen bonds. How would high pressure affect the temperature at which ice will
melt?
A. High pressure will lower the temperature at which ice will melt.
B. High pressure will raise the temperature at which ice will melt.
C. Hydrogen bonds do not affect the freezing point, so it will not change the temperature at which ice will melt.
D. The freezing point will remain the same because the high pressure will negate the effect of the hydrogen bonds
Explain why you selected the answer you did
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
____________________________________________________________________________
74
11/13/13
Which pair of elements would most likely bond to form a covalently bonded compound?
A sodium and fluorine
B barium and chlorine
C phosphorus and oxygen
D magnesium and sulfur
A solid element looks silvery and shiny when its surface has been freshly sanded and polished. It will stretch
without breaking if enough pulling force is applied. This element is most likely classed as a
a. periodic element.
b. nonmetal.
c. halogen.
d. noble gas. e. metal.
The set of elements containing only nonmetals is
a. I, H, Ag.
b. C, Cl, Li.
c. Al, Sr, K.
The set of elements containing only metals is
a. Cu, Br, Fe. b. Zn, Li, Ca. c. Sr, Al, Cl.
d. Br, Fe, He.
e. Cl, S, P.
d. K, O, Ag.
e. P, Ag, N.
In the Periodic Table, elements with similar properties are grouped in
a. diagonal rows.
b. horizontal rows.
c. periods.
d. vertical columns.
e. rectangular blocks.
11/14/13
Which of the three types of radiation will
penetrate the paper and wood?
A alpha, beta, gamma
B alpha and beta only
C gamma only
D beta only
238
Complete and identify the type of nuclear equation 92𝑈
→
234
90𝑇ℎ
+ ______
In the figure, what type of nuclear activity is represented?
A fission
B fusion
C alpha emission
D beta emission
The half-life of phosphorus-32 is 14.30 days. How many
milligrams of a 20.00 mg sample of phosphorus-32 will remain after 85.80 days?
A 3.333 mg
B 0.6250 mg
C 0.3125 mg
D 0.1563 mg
11/15/13
A chemical reaction is represented by the following word equation:
magnesium + sulfuric acid → hydrogen + magnesium sulfate
a. What are the products of this reaction?
b. What are the reactants in this reaction?
When fluorine gas is put into contact with calcium metal at high temperatures, calcium fluoride powder is
created in an exothermic reaction. Write out the formula for the reactants and product, then balance.
75
11/18/13
Which of the following is a chemical property of a substance? The substance
a. floats on the surface of mercury.
b. is clear and colorless.
c. is attracted by a magnet.
d. is soluble in water.
e. coats itself with an oxide when exposed to air.
When zinc metal is dropped into hydrochloric acid, which gas or gases would be produced?
a. oxygen, hydrogen, and carbon dioxide gases
b. hydrogen and oxygen gases
c. oxygen gas only
d. carbon dioxide gas only
e. hydrogen gas only
11/28/13 Which best explains why cations are smaller than the atoms from which they are formed?
A The metallic atom gains electrons, causing a larger effective nuclear pull.
B The metallic atom loses electrons, resulting in loss of an entire energy level.
C The nonmetallic atom gains electrons, causing a larger effective nuclear pull.
D The nonmetallic atom loses electrons, resulting in loss of an entire energy level.
Diagram a bohr atom that has become a cation
11/19/13 Which correctly lists four atoms from smallest to largest radii?
A. I, Br, Cl, F
C. Si, P, S, Cl
B. F, I, Br, Cl
D. Cl, S, P, Si
11/30/13 Which have the lowest electronegativities?
A alkali metals
C rare earth elements
B halogens
D transition metals
11/20/13 How many molecules are contained in 55.0 g of H2SO4 ?
A 0.561 molecule
B 3.93 molecules
C 3.38 x1023 molecules
D 2.37 x 1024 molecules
12/2/13 A compound has an empirical formula of CH2O and a molecular mass of 180 g. What is the
compound’s molecular formula?
A C3H6O 3
C C6H11O7
B C6H12O6
D C12H22O11
12/3/13 Which of the following shows the correct number of atoms of each element in the formula
Mg(NO3)2
A 1 magnesium atom, 2 nitrogen atoms, and 6 oxygen atoms
B 1 magnesium atom, 2 nitrogen atoms, and 5 oxygen atoms
C 1 magnesium atom, 1 nitrogen atom, and 6 oxygen atoms
D 1 magnesium atom, 1 nitrogen atom, and 5 oxygen atoms
76
12/4/13
Which example indicates that a chemical change has occurred?
A When two aqueous solutions are mixed, a precipitate is formed.
B As ammonium nitrate dissolves in water, it causes the temperature of the water to decrease.
C Alcohol evaporates when left in an open container.
D Water is added to blue copper(II) chloride solution. The resulting mixture is lighter blue in color.
List out some other indicators of a chemical change (refer to Unit 2 IN)
12/5/13 Atoms of the noble gases are generally inert because —
A they are too large to react
C they are neutral atoms
B they are not charged
D their outer electron levels are filled
12/6/13What coefficients are required to balance this equation? _Fe2O3 _CO →_Fe _CO2
A 2, 6, 3, 6
B 1, 3, 2, 3
C 1, 1, 2, 2
D 1, 1, 2, 1
12/9/13Consider this reaction: NH3 (g) HCl (g) →NH4Cl (s)
Which type of reaction does this equation represent?
A combustion
B decomposition
C single replacement
D synthesis
12/10/13
There is no doubt that a chemical reaction has occurred if
a. there has been an overall volume change.
b. the form or state has been changed.
c. a new substance has been formed.
d. there has been a change of state.
e. heat has been given off.
Which of the following is a physical property of sugar?
a. It decomposes readily.
b. It is a white crystalline solid
c. It's composition is carbon, hydrogen, and oxygen.
d. It turns black with concentrated sulfuric acid.
e. It can be decomposed with heat.
12/11/13
If the quantity of 1 mol of carbon is 12, what can be said about the quantity of 1 mol of lithium?
A. 1 mol of lithium should also be 12 g.
B. 1 mol of lithium should be 3 g (atomic number).
C. 1 mol of lithium should be 4 g (number of neutrons).
D. 1 mol of lithium should be 7 g (atomic weight).
If one mole of carbon-12 has a mass of 12 g, what should be the mass of 1 mol of the isotope carbon-13 (atomic
number = 6; atomic mass = 13)?
A. 6 g
B. 7 g
C. 12 g
D. 13 g
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12/12/13 What products are formed when the metal potassium is added to water?
A K and H2O
C K O and H2
2
B KOH and H2O
D KOH and H2
Consider this reaction:
3Ca (s) 2H3PO4 (aq) →Ca3(PO4)2 (s) 3H2 (g)
How many moles of calcium are required to produce 60.0 g of calcium phosphate?
A 0.145 mole
B 0.194 mole
C 0.387 mole
D 0.581 mole
12/13/13 Methane (CH 4) is combusted/burned in oxygen according to this balanced chemical equation:
CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g)
What volume of carbon dioxide is formed when 9.36 liters of methane are burned in excess oxygen at STP?
A 9.36 L
B 15.0 L
C 18.7 L
D 22.4 L
12/16/13 Which set of equipment would be most useful to determine the density of a liquid?
A Balance and periodic table
B Periodic table and graduated cylinder
C Balance and graduated cylinder
D Graduated cylinder and thermometer
What is the volume of the liquid in the graduated cylinder?
A 13.00 mL
B 13.50 mL
C 14.00 mL
D 14.50 mL
A student is given a container of potassium nitrate crystals. In order to determine the exact mass of the
potassium nitrate using a triple beam balance, he must know the —
A mass of the filled container and the chemical formula for potassium nitrate
B mass of the filled container and the density of potassium nitrate
C volume of the filled container and the volume of the potassium nitrate
D mass of the empty container and the mass of the filled container
12/18/13
Iodine-131 is a radioactive isotope with a half-life of 8 days. How many grams of a 64 g sample of iodine131 will remain at the end of 24 days?
Copper sulfide is formed when copper and sulfur are heated together. In this reaction, 127 grams of copper
reacts with 41 g of sulfur. After the reaction is complete, 9 g of sulfur remains unreacted. What is the mass
of copper sulfide formed?
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Quarter II Review Questions Practice Test
1. Elements from which two groups in the periodic table would most likely combine with each other to form an ionic
compound?
From: Virginia End-of-Course Assessments, 2001 Chemistry
A 1 and 2
B 1 and 17
C 16 and 17
D 17 and 18
2. What is the approximate mass of one mole of CO2? From: 2008 Virginia End-of-Course Assessments, Chemistry
A
24 g
B
44 g
C
28 g
D
56 g
3. A student calculated the molar mass of Ca(OH)2 as follows:
The answer he calculated is wrong. Which labeled step contains his mistake?
A. Step 1
B. Step 2
C. Step 3
D. Step 4
4. In chemical compounds, covalent bonds form when — From: 2003 Virginia
End-of-Course Assessments, Chemistry
A. the electronegativity difference between two atoms is very large
B. electrons are completely transferred between two metals
C. pairs of electrons are shared between two nonmetal atoms
D. two nonmetal ions are attracted to each other by opposite charges
5. If the diagram below was the correct representation for the Lewis structure of a molecule, then the X would be
representative of the element — From: 2003 Virginia End of Course Assessments,
Chemistry
A Oxygen
C. Fluorine
B. Nitrogen
D. Potassium
6. The sample below contains approximately 9.03 x 1023 atoms of Carbon. The sample most likely contains…
A. 1 mole of Carbon
B. 1.5 moles of Carbon
C. 1 molecule of Carbon
D. 6.022 x 1023 molecules of C
7. The structural formula of methane is shown. From the elements making up the compound,
molecule is most likely…
A. crystalline B. ionic
C. covalent
D. highly polar
this
8. A compound has the empirical formula CH2O and a gram-formula mass of 60 grams per mole. What is the molecular
formula of this compound? From: 2009 Aug NY Regents (Chemistry)
A) CH2O
B) C2H4O2
C) C3H8O
D) C4H8O4
9. The mass of one atom of Potassium is...
A. 1.54 x 1022 g B 6.49 x 10-23 g
C. 3.15 x 10-23 g
D. 1.14 x 1022 g
10. Which atom in the ground state has the most stable valence electron configuration? From: 2009 June NY Regents (Chemistry)
A. K
B. Si
C. Sc
D.Kr
11.
Standard temperature and pressure refers to:
a) 0 atm and 273 K
b) 1 atm and 273 K
c) 101.325 kPa and 0 K
d) more than one of the above
79
12. The Law of Conservation of Mass states that mass is neither created nor destroyed in an ordinary chemical reaction.
When an iron nail rusts, it seems to get heavier in mass. Does the iron nail follow the Law of Conservation of Mass?
A. No, rusting is an exception to the Law of Conservation of Mass.
B. No, since rusting is a chemical change it does not follow the Law of Conservation of Mass.
C. Yes, the iron rearranges its protons so that the masses are the same before and after the reaction and rusting follows
the Law of Conservation of Mass.
D. Yes, iron chemically combines with the oxygen in the air so if you add the oxygen into the mass of the chemicals
before the reaction, the mass after the reaction is the same.
13. When wood burns, a small amount of ashes is made. Why is the mass of the wood before the fire not equal to the
mass of the ashes after the reaction?
A. The mass of the wood has been destroyed.
B. The mass of the wood and the oxygen that allowed it to burn will equal the mass of the ashes and the gas given off
during the burning.
C. The mass of the wood and the ashes equals the mass of the oxygen and the smoke given off during the time that the
wood burned.
D. The wood has holes in it so it is actually lighter in mass than it appears. The mass of just the wood will equal the mass
of just the ashes after the burning.
14.
A.
B.
C.
How does the Law of Conservation of Mass apply to a burning candle?
The amount of wax before the reaction equals the amount of energy afterwards.
The mass of the wick before the reaction equals the mass of the smoke afterwards.
The mass of the wick, wax that burned and the oxygen that helped the flame before the reaction equals the mass of
the smoke and the gases released after the reaction.
D. The mass of the molecules of the candle before the reaction equals the mass of the candle and burned wick after the
reaction.
15.
Which of the following reactions best illustrates the Law of Conservation of Mass?
A. H2O2 → H2O + O2
B. Na + CuS → Na2S + 2 Cu
C. K + AgCl → KCl + Ag
D. NaOH + 2 HCl → NaCl + H2O
16. When sodium chloride reacts with calcium oxide to form sodium oxide plus calcium oxide, which of the following
equations best illustrates the Law of Conservation of Mass?
A. NaCl + CaO → Na2O + Ca Cl2
B 4 NaCl + CaO → 2 Na2O + CaCl2
C 2 NaCl + CaO → Na2O + CaCl2
D 3 NaCl + 2 CaO → Na2O + 3 CaCl2
17. In the following reaction: 2NaN3 decomposes to form 2Na + 3N2. If 500 grams of NaN3 decomposes to form 323.20
grams of N2. How much Na is produced?
18. How many moles of magnesium oxide are produced when 96 grams of oxygen gas react with 133 grams of
magnesium metal
a) 3.00 mol MgO
b) 6.00 mole MgO
c) 5.47 mol MgO
d) 2.74 mol MgO
19. In a chemical reaction, the mass of the products _______.
a) is less than the mass of the reactants
b) is greater than the mass of the reactants
c) is equal to the mass of the reactants
ATOMIC STRUCTURE REVIEW WORKSHEET
80
d) has no relationship to the mass of the reactants
1. What are cathode rays?
2. Why are they called cathode rays?
3. Do the cathode rays have a charge, if so what is the charge on each particle?
4. What are the differences in charge and mass among protons, neutrons, and electrons?
5. A particular atom of potassium contains 19 protons, 19 electrons, and 20 neutrons.
a. What is the atomic number of this atom?
b. What is the mass number?
c. Write the isotopic symbol for this potassium nucleus (as we did in class.)
6. How many electrons, neutrons, and protons are in atoms of chlorine with a mass number of 35 (neutral state)?
7. How many electrons, neutrons, and protons are in the atoms of thorium with a mass number of 232 (neutral state)?
8. Yttrium was discovered in 1794. It is one of the elements used in superconductors. How many electrons, protons,
and neutrons are in an atom of yttrium-88 (neutral state)?
9. Compare the amount of energy involved in chemical changes to the amount of energy resulting from nuclear
changes.
10. What are the differences among the three types of natural radiation?
11. Complete the following Chart
Isotope
Mass Number
Protons
Neutron
Electrons in the
Neutral Atom
Type of Element
carbon-14
phosphorus-32
nickel-63
iridium-192
iron-54
Find the average atomic mass of silver if 51.83% of the silver atoms occurring in nature have a mass of 106.905 amu
and 48.17% of the atoms have a mass of 108.905 amu.
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Bonding Basics Review
Section A: Complete the chart using a periodic table to help you.
Type of Element
Answer these questions:
 An atom that gains one or more electrons will have a ____________________ charge.
 An atom that loses one or more electrons will have a ____________________ charge.
 An atom that gains or loses one or more electrons is called an ____________.
 A positive ion is called a ______________ and a negative ion is called an _______________.
Section B: What is an ionic bond?
 Atoms will transfer one or more ______________________ to another to form the bond.
 Each ion is left with a ______________________ outer shell.
 An ionic bond forms between a ____________ with a positive charge (cation) and a ____________ with a negative
charge (anion).
Section C: What is a covalent bond?
 Atoms ______________________ one or more electrons with each other to form the bond.
 Each atom is left with a ______________________ outer shell.
 A covalent bond forms between two ______________________ elements.
 Draw Lewis Dot Structures showing CO2 and H2O and NH3 and N2
What is the octet rule? __________________________________________________________
What are some exceptions to the octet rule and how many electrons do these exceptions "desire"
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_______________________________________________________________________________________________
Section D: What is a metallic bond?
_______________________________________________________________________________________________
_______________________________________________________________________________________________
Section E: What kind of reaction?
a. NaOH + KNO3 --> NaNO3 + KOH _____________________________
b. CH4 + 2 O2 --> CO2 + 2 H2O _____________________________
c. 2 Fe + 6 NaBr --> 2 FeBr3 + 6 Na _____________________________
d.
CaSO4 + Mg(OH)2 --> Ca(OH)2 + MgSO4 _____________________________
e. Pb + O2 --> PbO2 _____________________________
f. Na2CO3 --> Na2O + CO2_____________________________
Mole Relationships in Chemical Reactions
The mole provides a convenient way of finding the amounts of the substances in a chemical reaction.
The diagram below shows how this concept can be applied to the reaction between carbon monoxide
(CO) and oxygen (O2), shown in the following balanced equation.
O2(g) + 2 CO (g)  2CO2(g)
Use the equation and the diagram to answer the following questions.
1. What information is needed to
make the types of conversions
shown by double-arrow 1 in the
diagram?
2. What conversion factors would be
needed to make the conversions represented by double-arrow 2 in the diagram for CO?
By double-arrow 6 for CO2?
3. What information is needed to make the types of conversions represented by double-arrows 3 and 7 in
the diagram?
4. What conversion factors would be needed to make the conversions represented by double-arrow 3 in the
diagram for CO?
5. Why is it not possible to convert between the mass of a substance and the number of representative
particles, as represented by double-arrow 4 of the diagram?
6. Why is it not possible to use the mass of one substance in a chemical reaction to find the mass of a
second substance in the reaction, as represented by double-arrow 5 in the diagram?
Study Guide – Finals – 1st sem 13-14
A. Use the letters corresponding to the element(s) described below. More than one letter may fit
the description.
83
1. an alkali metal
8. an alkaline earth metal
2. a noble gas
9. an active nonmetal
3. a metalloid
10. an inner transition element
4. a transition element
11. a halogen
5. a nonmetal
12. a metal
6. a lanthanide
13. an actinide
7. has 7 valence electrons
14. has same Lewis structure as silicon
8. has this lewis structure
G
C
B
D
H
I
E
F
B. Periodic trends:
Property
Atomic radius
Group
Period
Ionization energy
Electronegativity
Which group has
a. largest atomic radius
b. highest ionization energy
c. lowest electronegativity
Compare cations and ions with their respective atoms
84
d. smallest size
A
C. Complete the table:
Symbol
Name
Atomic
Mass
Number
Number
Number
Number
Number
of protons
of neutrons
of electrons
28
58
33
40
29
14Si
Cobalt-58
Describe the following:
Atoms
Nucleus
Distinguish:
Ionic bonds
Covalent bonds
Metallic bond
85
What type of elements give
off valence electrons to
achieve a configuration of a
noble gas?
How is a covalent
bond formed?
Write the Lewis structure
for NH3
What type of elements receive
valence electrons to achieve a
configuration of a noble gas?
How is an ionic
bond formed?
Write the Lewis structure
for CO2
Which group of metals is the
most chemically active?
Write the Lewis structure for
F2
Write the Lewis structure
for C2H4
Which group of nonmetals is
the most chemically active?
Write the Lewis structure for
O2
The composition of a compound contains only C, O, and
H atoms. What type of bond
does the compound have?
According to the periodic
table, which two elements in
each set of elements will likely
form an ionic bond?
Write the Lewis structure for
H2O
Given the chemical formula of
a compound, how will you tell
whether the compound is an
ionic compound or molecular
compound?
Of the seven diatomic
molecules, which ones contains
A double bond?
Write the Lewis structure
for N2
A
B
1
2
14
3
17
17
18
18
Elements in the same group
have similar physical and
chemical properties because
they have the same number of
_____________?
What type of elements have
atoms arranged in crystal
structure?
Solid, liquid or gas?
86
A triple bond?
Which groups on the periodic
table would form ions with
the following charges:
a) 1+
b) 1-
c. 2+
d. 2-
Show how you determine the
mass of one mole of CO2
In the periodic table, what
group of elements has the
most stable valence electron
configuration in the ground
state?
Using the electronegativity
Show how you determine the
values on p 263, how would
mass of one mole of
you know if the bond between
Mg (C2H3O2)2
two atoms is ionic?
In a binary ionic compound,
one of the elements is Cl.
Which of the following would
the other element most likely
to be?
Given different pairs of
atoms, how would you decide
which has the most polar
bond?
Show how you determine the
mass of one mole of
Fe(NO3)3
The Lewis structure of an
atom has eight dots. Name
the elements with the same
Lewis structure.
Given several bars of
different metals each
containing one mole.
Identify the metals with the
following approximate
masses.
Cl
I
Mg
Br
What are the seven diatomic
molecules?
a)
b)
c)
d)
Which part of the periodic
table are these located?
Which one has a larger ion
than its neutral atom?
metals __________
a. Ca
b. F
nonmetals _________
c. Zn
d. Cs
metalloids _________
27 g
65 g
59 g
40 g
What type(s) of elements
would make
a. ionic bond
b. covalent bond
87
88