Download Chemical Equations

Chemical Equations
Name: _______________________________________Period: _____Date:_________
Part I: Parts and Meaning of a Chemical Equation:
1. _____________________________________= process by which one or more substances are
changed into one or more different substances (atoms are rearranged)
a) _____________________= original substances(written to the left of the arrow in a
chemical equation)
b) ________________________ = resulting substances(written to the right of the arrow in
a chemical equation)
________
_____
_________
CH4 + 2O2
CO2 + 2H2O
c) Indications of a chemical reaction (chemical change):
•
evolution of ____________ and/or ___________
•
production of a ________ (often seen as bubbles)
•
__________________________
•
formation of a _________________________when two solutions are mixed
(Precipitate = a solid that separates from a solution)
d) __________________ = a substance that speeds up a chemical reaction but is not
permanently consumed in the reaction.
•
Catalysts DO NOT appear as reactants or products!
•
Ex: manganese dioxide is a catalyst in the following reaction:
o 2H2O2
MnO2
O2 + 2H2O
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A. Writing a Chemical Equation:
1) __________________________= a representation of the reactants and products in a
chemical reaction
a) ___________________________________ = a chemical equation in which the
reactants and products in a chemical reaction are represented by words
•
Ex:
sodium + water → sodium hydroxide + hydrogen
__________________
__________________
b) _________________________________ = a chemical equation in which the reactants
and products in a chemical reaction are represented by chemical symbols or
chemical formulas
•
Ex:
Na
+
H2O
reactants
→
NaOH
+
H2
products
c) ____________________________________ (for a chemical equation) = a
“bookkeeping” technique designed to count the number of each type of atom
(ion) represented on each side of a chemical equation
d) ________________________ = whole number that appears to the right and
below a chemical symbol in a chemical formula (if no number is written it is
assumed to be “1”)
•
Indicates the number of atoms or ions
•
Ex: H2O
subscript
subscript (assumed to be “1”)
e) __________________________ = whole number that appears in front of a reactant or
product in a balanced chemical equation (if no number is written it is assumed to
be “1”)
•
Indicates the number of molecules or moles
2
•
Ex:
2 CO2
coefficient
•
Ex:
Al2S3
coefficient (assumed to be “1”)
f) ______________________________________________________= a formula equation
where coefficients are added so equal numbers of each type of atom (ion) are
represented on each side of the equation
•
Ex:
2 Na (s)
+
2 H2O (l)
→
2 NaOH(aq)
reactants
•
•
+
H2 (g)
products
___ molecules of solid sodium reacts with ___ molecules of water to yield ___
molecules of aqueous sodium hydroxide and ___ molecule of hydrogen gas.
OR
_____ moles of solid sodium reacts with ____ moles of water to yield ___
moles of aqueous sodium hydroxide and ____ mole of hydrogen gas.
2. In the chemical equation below, identify the reactants, products, subscripts, and
coefficients
4 Fe + 3 O2 → 2 Fe2O3
•
What are the reactant(s)?= ___________________________
•
What are the product(s)? = _____________________________
•
# of moles of O2 =__________________
•
# of molecules of O2=_______________
•
# of atoms of Fe in 2 Fe2O3 = _______________
•
# of atoms of O in 3 O2 =_____________
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3. Symbols you may see in a chemical equation:
Symbol
Meaning
“yields”; indicates result of a reaction
Indicates a reversible reaction
A reactant or product in the solid state
Alternative to (s); used only for a precipitate (solid) falling out of solution
A reactant or product in the liquid state
A reactant or product in aqueous solution (dissolved in water)
A reactant or product in the gaseous state
Alternative to (g); used only for a gaseous product
Reactants are heated
Pressure at which the reaction is carried out, in this case 2
Temperature at which reaction is carried out, in this case O°C
A catalyst is used to speed up the reaction rate, in this case MnO2 would be
used to speed up the reaction rate.
Part II: Requirements for Chemical Equations:
1. The equation must represent the known facts with all reactants and products identified.
2. The equation must contain the correct formulas of the reactants and products.
3. A chemical reaction obeys the “Law of Conservation of Matter”
• ____________________________________________________ = matter cannot
be either created or destroyed in ordinary chemical or physical means.
• The Law of Conservation of Matter must not be violated!
o
This means you must balance equations. (Equations are balanced by adding
_________________________, NOT subscripts.)
4. Why do we balance equations?
a. The _______________________________________________must not be violated!
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5. Atomic theory can be used to explain why chemical reactions obey the “Law of
Conservation of Matter”.
•
_________ atoms present at the start of a chemical reaction are present at the
end of that chemical reaction (atoms are simply rearranged during a chemical
reaction).
•
Since no atoms are created or destroyed in a chemical reaction no matter is
created or destroyed in a chemical reaction.
•
Since no matter is created or destroyed in the chemical reaction the mass of the
reactants must equal the mass of the products in a chemical reaction.
6. A balanced chemical equation details how a chemical reaction obeys the “Law of
Conservation of Matter”.
Part III: Information a Chemical Equation Does NOT
Supply:
1. Whether the reaction will actually____________. Chemical equations can be written for
reactions that do not necessarily take place.
2. The __________of a reaction.
3. The _____________________atoms or ions take in moving from reactants to products.
Part IV: Balancing Equations
1. Write a word equation
2. Write a formula equation
a) remember naturally occurring ___________________ molecules:
• __________________________________
b) unless otherwise noted, other elements are represented by the element symbol; ex:
magnesium = Mg
c) remember the formulas for acids:
• HCl = Hydrochloric Acid
• HNO3 = Nitric Acid
• H3PO4 = Phosphoric Acid
• CH3COOH = Acetic Acid (NOTE: the positive ion (H+) is at the end)
• H2CO3 = Carbonic Acid
• H2SO4 = Sulfuric Acid
d) remember the rules for writing formulas for ionic compounds (________)
• Metals and Nonmetals!
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e) remember the rules for writing formulas for molecular compounds (______________)
• Only NONMETALS!
f) remember the formula for water, ________
• HOH = hydrogen hydroxide
3. Write a balanced chemical equation by adding_____________________, NOT subscripts
(this will require trial and error, the following guidelines may be helpful)
a) balance the different types of atoms ________________
b) first, balance the atoms of elements that are combined and that appear only
___________on each side of the equation
c) balance ____________________________that appear on both sides of the equation as
single units
d) balance H atoms and O atoms after atoms of all other elements have been
balanced
4. Conduct an atom inventory throughout the process. Be sure to conduct an atom
inventory at the end of the process to be certain you have the correct answer.
5. Be certain that the coefficients represent the SMALLEST possible whole number ratio of
reactants and products.
6. Common problems when balancing equations:
a) You must write correct formulas!
b) Once a correct formula is written, _________________CANNOT be changed!
7. For each of the following, write a formula equation and a balanced chemical equation.
a) Hydrogen reacts with oxygen to produce water.
b) Zinc reacts with hydrochloric acid to produce a solution of zinc chloride and hydrogen
gas.
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c) Aluminum sulfate reacts with calcium hydroxide to form aluminum hydroxide and
calcium sulfate.
Part V: Reaction Rates
1) _____________________________ = the rate (speed) of disappearance of a reactant or the
rate of appearance of a product in a chemical reaction
a) A chemical reaction that takes a long time to happen has a slow reaction rate.
b) A chemical reaction that takes a short time to happen has a fast reaction rate.
A.
Factors Affecting Reaction Rate
1) ______________________________________
a) Reactions occur at different rates depending on the reactants.
b) Some reactions occur almost instantaneously (such as double-replacement
reactions).
c) Other reactions occur slower.
2) __________________________________ = a measure of the number of particles of matter
per unit volume
a) An increase in the concentration of the reactants generally increases reaction
rate.
b) A decrease in the concentration of the reactants generally decreases reaction rate.
3) __________________________________ = a measure of the average kinetic energy of the
particles in a sample of matter
a) An increase in temperature increases reaction rate.
b) A decrease in temperature decreases reaction rate.
4) Presence of a __________________________= a substance that increases the rate of a
chemical reaction without being permanently changed
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a) A catalyst will increase reaction rate.
b) A catalyst is __________ permanently changed in a chemical reaction.
B.
Collision Theory
1) Assumptions of collision theory:
a) Reacting molecules must ____________ with each other.
b) Reacting molecules must collide with sufficient ______________.
c) Reacting molecules must collide in an orientation that can lead to
________________________ of the atoms.
2) Use collision theory to explain why an increase in CONCENTRATION increases
reaction rate:
a) At a _______________ concentration ____________ reactant molecules are present.
b) When more reactant molecules are present more frequent __________________
occur.
c) When more frequent collisions occur there are more chances for molecules to react
(so reactions happen ___________________).
3) Use collision theory to explain why an increase in TEMPERATURE increases
reaction rate:
a) Molecules with a higher kinetic energy move faster, collide more often, and have
more energetic collisions.
b) A higher temperature means that the average kinetic energy of the reacting
molecules is _____________________; at a higher temperature there are more
molecules with a higher kinetic energy.
c) At a higher temperature there are____________________________________________
giving molecules more chances to react (so reactions happen faster).
d) At a higher temperature, more molecules possess enough kinetic energy to react
so a higher percentage of collisions result in molecules reacting (so reactions
happen faster).
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Practice Balancing Equations
For each of the following, write a formula equation and balance the equation. If no
additional coefficients are needed, write “balanced”. Don’t forget about the diatomic
elements!
1. zinc + silver nitrate Æ zinc nitrate + silver
2. barium chloride + sodium sulfate Æ barium sulfate + sodium chloride
3. copper + nitrogen Æ copper (II) nitride
4. magnesium + sulfuric acid Æ magnesium sulfate + hydrogen
5. barium nitrate + ammonium chloride Æ barium chloride + ammonium nitrate
6. potassium + water Æ potassium hydroxide + hydrogen
7. fluorine + aluminum oxide Æ aluminum fluoride + oxygen
8. lithium + phosphoric acid Æ lithium phosphate + hydrogen
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9. aluminum + hydrochloric acid Æ aluminum chloride + hydrogen
10. nickel + nitric acid Æ nickel(II) nitrate + hydrogen
11. sodium chloride + lead(II) nitrate Æ lead(II) chloride + sodium nitrate
12. magnesium + chlorine Æ magnesium chloride
13. iron + oxygen Æ iron(III) oxide
14. water + magnesium nitrate Æ magnesium oxide + nitric acid
15. sodium oxide + water Æ sodium hydroxide
16. iron + copper(II) nitrate Æ iron(II) nitrate + copper
17. calcium + water Æ calcium hydroxide + hydrogen
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18. chlorine + lithium iodide Æ lithium chloride + iodine
19. aluminum oxide Æ aluminum + oxygen
20. carbon + iron(III) oxide Æ iron + carbon dioxide
21. aluminum + zinc chloride Æ aluminum chloride + zinc
22. mercury(II) sulfide + calcium oxide Æ calcium sulfide + mercury(II) oxide
23. bromine + water + sulfur dioxide Æ hydrogen bromide + sulfuric acid
24. diphosphorus pentaoxide + barium oxide Æ barium phosphate
25. silver acetate + sodium phosphate Æ silver phosphate + sodium acetate
26. tin + potassium hydroxide Æ potassium tin(II) oxide (K2SnO2) + hydrogen
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Part VI: Types of Reactions & Predicting Products:
1. ____________________: (S)
• 2 or more substances combine to form one new substance
• General format:
A + B Æ AB
Ex:
NH3 + HCl Æ NH4Cl
2 Na + C12 Æ 2 NaCl
Synthesis Practice: For each of the following, predict the products and write a word
equation. Next, write a formula equation and a balanced chemical equation. Finally, write
the type of reaction represented by each chemical equation.
a) magnesium + oxygen →
b) sodium + fluorine →
c) magnesium + fluorine →
d) lithium + chlorine →
12
e) barium + oxygen →
f) potassium + oxygen →
2. __________________________________: (D) – the opposite of synthesis
• Substances break up or decompose into simpler substances
• General format:
AB Æ A + B
Ex:
H2CO3 Æ H2O + CO2
2 Al2O3 Æ 4 Al + 3 O2
Decomposition Practice: For each of the following, predict the products and write a word
equation. Next, write a formula equation and a balanced chemical equation. Finally, write
the type of reaction represented by each chemical equation.
a) water →
b) mercury(II) oxide →
13
c) magnesium chloride →
d) silver oxide →
3. _________________________________________________: (SD)
• One element replaces another in a compound
• General format:
A + BC Æ AC + B
Ex:
Cl2 + 2 KBr Æ 2 KCl + Br2
2 Na + 2 H2O Æ 2 NaOH + H2
Single Displacement Practice: For each of the following, predict the products and write a
word equation. Next, write a formula equation and a balanced chemical equation. Finally,
write the type of reaction represented by each chemical equation.
a) aluminum + lead(II) nitrate →
b) lithium + water →
14
c) aluminum + sulfuric acid →
d) chlorine + potassium bromide →
e) fluorine + sodium chloride →
f) aluminum + silver nitrate →
g) barium + water →
h) lithium + hydrochloric acid →
15
4. ____________________________________________________: (DD)
• Positive and negative ions are exchanged
• General format:
AB + CD Æ CB + AD
Ex: Ba(OH)2 + H2SO4 Æ BaSO4 + 2 H2O
AgNO3 + NaCl Æ AgCl + NaNO3
Double Displacement Practice: For each of the following, predict the products and write a
word equation. Next, write a formula equation and a balanced chemical equation. Finally,
write the type of reaction represented by each chemical equation.
a) potassium iodide + lead(II) nitrate →
b) sulfuric acid + sodium hydroxide →
c) silver nitrate + sodium phosphate Æ
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d) nitric acid + potassium hydroxide Æ
e) sulfuric acid + potassium hydroxide Æ
f) calcium phosphate + acetic acidÆ
5. Identify the following types of chemical reactions:
__________________
1) 2 H2O2 Æ 2 H2O +O2
__________________
2) 4 Fe + 3 02 Æ 2 Fe2O3
__________________
3) Cl2 + 2 NaBr Æ 2 NaCl + Br2
__________________
4) Zn + H2SO4 Æ ZnSO4 + H2
__________________
5) Pb(NO3)2 + K2CrO4 Æ PbCrO4 + KNO3
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Practice Predicting Products, Balancing Equations, and Types of Reactions
For each of the following, predict the products and write a word equation. Next, write a
formula equation and a balanced chemical equation. Finally, write the type of reaction
represented by each chemical equation on the line next to the number.
____1. zinc + sulfur Æ
____2. potassium + water Æ
____3. calcium + nitric acid Æ
____4. silver oxide Æ
____5. hydrochloric acid + sodium hydroxide Æ
____6. sodium sulfate + calcium nitrate Æ
____7. zinc chloride + ammonium oxide Æ
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____8. zinc + copper(II) acetate Æ
____9. sodium + sulfuric acid Æ
____10. calcium + water Æ
____11. sulfuric acid + potassium hydroxide Æ
____12. chlorine + potassium bromide Æ
____13. zinc + hydrochloric acid Æ
____14. aluminum + iron(III) oxide Æ
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____15.
copper (II) acetate + potassium permanganate Æ
____16.
calcium peroxide Æ
____17.
copper (II) sulfide + barium iodide Æ
____18.
iron (III) nitrate + sodium hydroxide Æ
____19.
nitric acid + aluminum hydroxide Æ
____20.
sodium + oxygen Æ
____21.
lithium + hydrochloric acid Æ
____22.
potassium nitrate + zinc peroxide Æ
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Review Worksheet:
Answer the questions 1-8, using this equation:
2 Na (s) + 2 H2O (l) Æ 2 NaOH (aq) + H2
1. What are the reactant(s)? _____________________
2. What are the product(s)? _______________________
3. How many molecules of H2 are present as a product? ___________
4. How many moles of NaOH are present? ____________
5. How many atoms of H are present in 2 H2O? __________
6. What molecule or compound is a gas? __________________
7. What element or compound was dissolved in water? _________________
8. What element or compound is a solid? _________________
9. Why do we balance equations?
10. How do you correctly notate that heat is needed in the following equation, in order to
produce the product?
2 Cu + O2
2 CuO
11. List the diatomic molecules.
_____________________________________________________________
12. What is a catalyst?
13. Write the formulas for the following acids:
a) Carbonic Acid = ______________________________
b) Nitric Acid = ______________________________
c) Sulfuric Acid = ______________________________
d) Phosphoric Acid = ______________________________
e) Hydrochloric Acid = ______________________________
f) Acetic Acid = ______________________________
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14. List the 4 indicators that a chemical reaction occurred.
15. What is a reaction rate?
16. What are four factors that affect the reaction rate?
17. Using collision theory, EXPLAIN why increasing the concentration, increases the
reaction rate?
18. Using collision theory, EXPLAIN why increasing the temperature, increases the
reaction rate?
_______ 19. chlorine + potassium iodide Æ
_______ 20. magnesium hydroxide + hydrochloric acidÆ
_______ 21. zinc + potassium dichromate Æ
_______ 22. potassium + chlorine Æ
‘
_______ 23. mercury(II) oxide Æ
_______ 24. copper(II) sulfate + zinc Æ
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Predicting Products of Chemical Reactions SUMMARY
TYPE OF REACTION
REACTANTS
PRODUCTS
GENERIC EQUATION
Synthesis (S)
2 or more substances
ONE compound
A + B Æ AB
Decomposition (D)
ONE compound
2 or more elements
and/or compounds
AB Æ A + B
Single Displacement
(SD)
Element + Compound
New compound &
new element
A + BC Æ AC + B
Double Displacement
(DD)
Compound + Compound
2 new compounds
AB + CD Æ AD + CB
Identify the following types of reactions & explain why for the first 4 questions.
1) 2 H2O2
MnO
2
2 H2O + O2 _______________________
a) Why?
2) Cu + 2 AgNO3 → 2 Ag + Cu(NO3)2 __________________________________
a) Why?
3) 4 Al + 3 S → 2 Al2S3
_______________________
a) Why?
4) Zn(NO3)2 + Na2CrO4 → ZnCrO4 + 2 NaNO3 _______________________
a) Why?
5) F2 + 2 LiBr → 2 LiF + Br2 _______________________
6) NH4NO3 → N2O + 2 H2O __________________________________
7) 2 SO2 + O2 → 2 SO3 __________________________________
8) BaO + H2O → Ba(OH)2
_______________________
9) Mg + H2SO3 → MgSO3 + H2
_______________________
10) 3 CuBr2 + Al2O3 → 3 CuO + 2 AlBr3 __________________________
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Unit Learning Map (10 days):
Chemical Reactions/Equations
Mrs. Hostetter
Class:
Chemistry B – PA standard: Describe factors that influence the frequency of collisions during chemical
reactions that might affect the reaction rates.
Instructional Tools:
Unit Essential Question(s):
Guided Notes
Lab Materials:
Models of Chemical Reactions
Chemical Reactions and
What are chemical reactions
and how are they represented?
Concept:
Writing Word Equations,
Formula Equations, and
Balanced Chemical Equations
Lesson Essential Question(s):
1) How is a chemical
reaction represented?
2) Given a description of
a chemical reaction,
how are a word
equation and a formula
equation written?
3) How is a formula
equation balanced by
trial and error?
Vocabulary:
Chemical reaction
(chemical change)
Reactant
Product
Indications of a chemical
reaction
Chemical symbol
Chemical formula
Chemical equation
Word equation
Formula equation
Atom inventory
Subscript
Coefficient
Balanced chemical equation
Concept:
Balanced Chemical
Equations
Lesson Essential Question(s):
1)
2)
3)
How can atomic theory be
used to explain why
chemical reactions obey
the “Law of Conservation
of Matter”?
How are balanced
chemical equations
translated into sentences?
What information is
given/not given by a
balanced chemical
equation?
Vocabulary:
Law of conservation of
Matter
Atomic theory
Atom
Molecule
Formula unit
Catalyst
Symbols in a chemical
equation
Chemical Equations
Reaction Rates
Chemistry Competition
Concept:
Types of Chemical
Reactions and Predicting
Products
Lesson Essential Question(s):
1) How can synthesis,
decomposition, singledisplacement, and
double-displacement
reactions be recognized
and described?
2) Given the reactants,
how can the products
of simple chemical
reactions be predicted?
Vocabulary:
Synthesis reaction
Decomposition reaction
Single-displacement
reaction
Double-displacement
reaction
Concept:
Reaction Rates
Lesson Essential Question(s):
1)
2)
What effect do nature of
reactants, concentration,
temperature, and
presence of a catalyst
have on reaction rate?
How can collision theory
be used to explain why
concentration and
temperature affect
reaction rate as they do?
Vocabulary:
Reaction rate
Concentration
Temperature
Catalyst
Collision theory
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Chemical Equations Vocabulary:
1) Chemical reaction = process by which one or more substances are changed into one or more different
substances (atoms are rearranged)
2) Reactants = original substances(written to the left of the arrow in a chemical equation)
3) Products = resulting substances(written to the right of the arrow in a chemical equation)
4) Indications of a chemical reaction (chemical change): evolution of heat and/or light; production of a
gas (often seen as bubbles); color change; formation of a precipitate when two solutions are mixed
5) Precipitate = a solid that separates from a solution
6) Catalyst = a substance that speeds up a chemical reaction but is not permanently consumed in the
reaction
7) Chemical equation = a representation of the reactants and products in a chemical reaction
8) Word equation = a chemical equation in which the reactants and products in a chemical reaction are
represented by words
9) Formula equation = a chemical equation in which the reactants and products in a chemical reaction
are represented by chemical symbols or chemical formulas
10) Atom inventory = a “bookkeeping” technique designed to count the number of each type of atom
(ion) represented on each side of a chemical equation
11) Subscript = whole number that appears to the right and below a chemical symbol in a chemical
12) Coefficient = whole number that appears in front of a reactant or product in a balanced chemical
equation (if no number is written it is assumed to be “1”)
13) Balanced chemical equation = a formula equation where coefficients are added so equal numbers of
each type of atom (ion) are represented on each side of the equation
14) The Law of Conservation of Matter = matter cannot be either created or destroyed in ordinary
chemical or physical means
15) Synthesis(S) = 2 or more substances combine to form one new substance;
General format: A + B → AB
16) Decomposition (D) = the opposite of synthesis; Substances break up or decompose into simpler
substances; General format: AB → A + B
17) Single Displacement(SD) = One element replaces another in a compound;
General format: A + BC → AC + B
18) Double Displacement(DD) = Positive and negative ions are exchanged;
General format: AB + CD → CB + AD
19) Reaction rate = the rate (speed) of disappearance of a reactant or the rate of appearance of a product
in a chemical reaction
20) Concentration = a measure of the number of particles of matter per unit volume
21) Temperature = a measure of the average kinetic energy of the particles in a sample of matter
22) Assumptions of collision theory = a) Reacting molecules must collide with each other b) Reacting
molecules must collide with sufficient energy c) Reacting molecules must collide in an orientation that
can lead to rearrangement of the atoms
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