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CHAPTER 11 NOTES: CHEMICAL REACTIONS
VOCABULARY:
Products what is formed in a chemical reaction; right of arrow
Reactants what goes into a chemical reaction; left of arrow
yields
+ and
(s) solid
(l) liquid
(g) gas
(aq) aqueous – only works when dissolved in water
Catalyst a substance that speeds up a reaction but is not itself consumed; provides an easier reaction pathway
that requires less activation energy
Activation Energy (Ea) energy necessary to initiate a chemical reaction
Δ heat
Pt
ENERGY OF CHEMICAL REACTIONS:
Exothermic Reaction: ΔH is – Endothermic Reaction: ΔH = +
(heat is a “product”) (heat is a “reactant”)
Energy
Time
Energy
Time
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BALANCED CHEMICAL REACTIONS
Law of Conservation of Matter: matter cannot be created or destroyed in a chemical reaction
WORD FORMULA BALANCED EQUATIONS
1. word equation: Hydrogen gas reacts with oxygen gas to form water
formula equation: ____ H2 + O2 H2O ___________________________________________
diagram: H – H + O = O O + O
H – H H H H H
balanced reaction ____2 H2 + O2 2 H2O ___________________________________________
2. word equation: Magnesium reacts with hydrochloric acid solution (HCl in water) to form
magnesium chloride and hydrogen.
Formula equation: ____ Mg + HCl MgCl2 + H2 __________________________________
diagram: Mg + H – Cl Cl-1
Mg+2
Cl-1
+ H – H
H – Cl
balanced reaction _______ Mg + 2 HCl MgCl2 + H2 ________________________________
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Try balancing these chemical reactions:
a. 2 Na + H2SO4 Na2SO4 + H2
b. 2 K + Cl2 2 KCl
c. S8 + 8 O2 8 SO2
d. 3 F2 + 2 FeBr3 2 FeF3 + 3 Br2
e. 3 H2SO4 + 2 Al Al2(SO4)3 + 3 H2
f. 2 NaNO3 + Ca(MnO4)2 2 NaMnO4 + Ca(NO3)2
g. C4H8 + 6 O2 4 CO2 + 4 H2O
h. 2 C2H6 + 7 O2 4 CO2 + 6 H2O
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Balancing Chemical Equations Balance the equations below: 1) ____ N2 + ____ H2 ____ NH3 2) ____ KClO3 ____ KCl + ____ O2 3) ____ NaCl + ____ F2 ____ NaF + ____ Cl2 4) ____ H2 + ____ O2 ____ H2O 5) ____ Pb(OH)2 + ____ HCl ____ H2O + ____ PbCl2 6) ____ AlBr3 + ____ K2SO4 ____ KBr + ____ Al2(SO4)3
7) ____ CH4 + ____ O2 ____ CO2 + ____ H2O 8) ____ C3H8 + ____ O2 ____ CO2 + ____ H2O 9) ____ C8H18 + ____ O2 ____ CO2 + ____ H2O 10) ____ FeCl3 + ____ NaOH ____ Fe(OH)3 + ____NaCl 11) ____ P + ____O2 ____P2O5 12) ____ Na + ____ H2O ____ NaOH + ____H2 13) ____ Ag2O ____ Ag + ____O2 14) ____ S8 + ____O2 ____ SO3 15) ____ CO2 + ____ H2O ____ C6H12O6 + ____O2 16) ____ K + ____ MgBr ____ KBr + ____ Mg 17) ____ HCl + ____ CaCO3 ____ CaCl2 + ____H2O + ____ CO2 18) ____ HNO3 + ____ NaHCO3 ____ NaNO3 + ____ H2O + ____ CO2 19) ____ H2O + ____ O2 ____ H2O2 20) ____ NaBr + ____ CaF2 ____ NaF + ____ CaBr2
ANSWERS:
1) 1 + 3 2
2) 2 2 + 3
3) 2 + 1 2 + 1
4) 2 + 1 2
5) 1 + 2 2 + 1
6) 2 + 3 6 + 1
7) 1 + 2 1 + 2
8) 1 + 5 3 + 4
9) 2 + 25 16 + 18
10) 1 + 3 1 + 3
11) 4 + 5 2
12) 2 + 2 2 + 1
13) 2 4 + 1
14) 1 + 12 8
15) 6 + 6 1 + 6
16) 2 + 1 2 + 1
17) 2 + 1 1 + 1 + 1
18) 1 + 1 1 + 1 + 1
19) 2 + 1 2
20) 2 + 1 2 + 1
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SYNTHESIS, DECOMPOSITION AND COMBUSTION REACTIONS
Types of Reactions: Synthesis (Combination), Decomposition and Combustion
Synthesis (Combination) – A + B AB (1 product only)
Decomposition – AB A + B (1 reactant only)
Combustion of a hydrocarbon – CxHy + O2 CO2 + H2O
Practice:
Balance each reaction below. Then identify the reaction type.
a. H2 + Br2 2 HBr __synthesis______________
b. C4H8 + 6 O2 4 CO2 + 4 H2O __combustion____________
c. 2 NaOH Na2O + H2O __decomposition__________
d. Ba(ClO3)2 BaCl2 + 3 O2 __decomposition__________
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First write and balance the equation. Then identify the reaction type.
e. phosphorus + oxygen tetraphosphorus decoxide __ synthesis _____________
4 P + 5 O2 P4O10
f. pentane (C5H12) + oxygen carbon dioxide + water __ combustion ____________
C5H12 + 8 O2 5 CO2 + 6 H2O
g. magnesium chlorate magnesium chloride + oxygen ___ decomposition _________
Mg(ClO3)2 MgCl2 + 3 O2
h. when solid calcium carbonate is heated calcium oxide and carbon dioxide are formed
___ decomposition _________
CaCO3 CaO + CO2
i. the formation of calcium nitride from calcium and nitrogen ___ synthesis _____________
3 Ca + N2 Ca3N2
j. sulfur trioxide mixes with water in the atmosphere to form sulfuric acid ___ synthesis ________
SO3 + H2O H2SO4
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NOTES: SINGLE REPLACEMENT REACTIONS & DOUBLE REPLACEMENT REACTIONS
1. Single Displacement Reactions (aqueous ONLY)
metals:
standard: A(s) + BX (aq) AX (aq) + B(s)
example: Cu + 2 AgNO3 Cu(NO3)2 + 2 Ag
metal + acid: standard: A(s) + HX (aq) AX (aq) + H2(g)
example: Mg + 2 HCl MgCl2 + H2
metal + water:
standard: A(s) + H2O(l) AOH(aq) + H2(g)
example: 2 K + 2 H2O 2 KOH + H2
halogens: standard: X2 + AY AX + Y2
example: F2 + 2 KI 2 KF + I2
2. Double Displacement (aqueous only)
standard : AX (aq) + BY (aq) AY(aq) + BX(s)
example : Ba(NO3)2 + NaI BaI2 + NaNO3
3. Identify the reaction type for each reaction below. Then complete and balance the reaction.
_single displacement_ a. Ba + 2 AgNO3 Ba(NO3)2 + 2 Ag
__single displacement________b. F2 + 2 KI 2 KF + I2
__double displacement c. NaOH + CaCl2 2 NaCl + Ca(OH)2
___single displacement d. Zn + H2SO4 ZnSO4 + H2
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WRITING WORD EQUATIONS
__decomposition_______________1. aluminum chlorate aluminum chloride + oxygen
2 Al(ClO3)3 9 O2 + 2 AlCl3
__SR_______________ 2. lithium + iron (III) nitrate lithium nitrate + iron
3 Li + Fe(NO3)3 3 LiNO3 + Fe
__decomposition_______________ 3. magnesium carbonate magnesium oxide + carbon dioxide
MgCO3 MgO + CO2
__synthesis____________ 4. tin + nitrogen tin (IV) nitride
3 Sn + 2 N2 Sn3N4
__SR____________ 5. Zinc reacts with nitric acid to form zinc nitrate and hydrogen Zn + 2 HNO3 Zn(NO3)2 + H2
__decomposition__________6. calcium hydroxide breaks down to form calcium oxide and water Ca(OH)2 CaO + H2O
WRITING WORD EQUATIONS WITH PREDICTING PRODUCTS
__synthesis_______________ 1. aluminum + oxygen 4 Al + 3 O2 2 Al2O3
__SR____________ 2. sodium + silver nitrate
Na + AgNO3 NaNO3 + Ag
__SR_______________ 3. magnesium + hydrochloric acid
Mg + 2 HCl MgCl2 + H2
___DR______________ 4. solutions of iron (III) nitrate + potassium sulfate are mixed
2 Fe(NO3)3 + 3 K2SO4 Fe2(SO4)3 + 6 KNO3
____SR_____________ 5. Chlorine gas is bubbled through a solution of lithium iodide
Cl2 + 2 LiI 2 LiCl + I2
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PREDICTING PRODUCTS
1) ____ Ag2SO4 + __2__ NaNO3 2 AgNO3 + Na2SO4
2) __2__ NaI + ____ CaSO4 CaI2 + Na2SO4
3) __2__ HNO3 + ____ Ca(OH)2 2 H2O + Ca(NO3)2
4) ____ Zn + ___2__ HNO3 Zn(NO3)2 + H2
5) ____ AlCl3 + ____ (NH4)3PO4 AlPO4 + 3 NH4Cl
6) ___3_ Pb + ___2_ Fe(NO3)3 3 Pb(NO3)2 + 2 Fe
7) ___2_ C3H6 + __9__ O2 6 CO2 + 6 H2O
8) ____ Ca + ____ Na2SO4 CaSO4 + 2 Na
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PREDICTING PRODUCTS FOR THREE TYPES OF DECOMPOSITION
REACTIONS:
Try: a. strontium carbonate
______strontium oxide + carbon dioxide____________________
____SrCO3 SrO + CO2_____________________________________________________
b. aluminum carbonate
_____aluminum oxide + carbon dioxide____________________
____Al2(CO3)3 Al2O3 + 3 CO2_________________________________________________
Try: a. calcium hydroxide
_______calcium oxide + water_______________________________
________Ca(OH)2 CaO + H2O__________________________________________________________
b. Iron(III) hydroxide
______iron (III) oxide + water_______________________________
______2 Fe(OH)3 Fe2O3 + 3 H2O____________________________________________________
1. metal carbonate
metal oxide + carbon dioxide
example: sodium carbonate
sodium oxide + carbon dioxide
Na2CO3
Na2O + CO2
2. metal hydroxide
metal oxide + water
example: sodium hydroxide
sodium oxide + water
2 NaOH
Na2O + H2O
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Try: a. barium chlorate
_____barium chloride + oxygen____________________________
_______Ba(ClO3)2 BaCl2 + 3 O2_____________________________________________________
b. lithium chlorate
________lithium chloride + oxygen____________________________
_______2 LiClO3 2 LiCl + 3 O2___________________________________________________________
3. metal chlorate
metal chloride + oxygen
example: sodium chlorate
sodium chloride + oxygen
2 NaClO3
2 NaCl + 3 O2
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KINETICS: RATE OF CHEMICAL REACTIONS
Collision Theory: for a reaction to occur, the reactants must collide with sufficient energy and with the proper
orientation (and in the correct ratio)
Factors Affecting Reaction Rate:
1. Temperature
if temperature is increased, the reaction will be quicker.
faster moving particles collide more often, and more particles will have enough energy (Ea) when they
collide
2. Particle size (surface area)
more exposed particles causes more collisions, so there will be more collisions with the correct
orientation
3. Concentration
Number of particles in a given volume affects rate of concentration – more particles, more collisions
4. Adding a Catalyst or Inhibitor
a catalyst speeds up a reaction by lowering the required activation energy
an inhibitor slows down a reaction by raising the activation energy
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WRITING WORD EQUATIONS
a. lithium + nitrogen lithium nitride
6 Li + N2 2 Li3N
b. aluminum + oxygen aluminum oxide
4 Al + 3 O2 2 Al2O3
c. sodium carbonate sodium oxide + carbon dioxide
Na2CO3 Na2O + CO2
d. zinc + phosphoric acid zinc phosphate + hydrogen gas
3 Zn + 2 H3PO4 Zn3(PO4)2 + 3 H2
e. chlorine gas + lithium iodide lithium chloride + iodine
Cl2 + 2 LiI 2 LiCl + I2
f. sodium hydroxide sodium oxide + water
2 NaOH Na2O + H2O
g. magnesium reacts with hydrochloric acid to form magnesium chloride and hydrogen gas
Mg + 2 HCl MgCl2 + H2
h. solutions of iron (III) chloride and sodium hydroxide react to form iron (III) hydroxide and
sodium chloride
FeCl3 + 3 NaOH Fe(OH)3 + 3 NaCl
i. when sodium is added to water, sodium hydroxide and hydrogen gas are produced\
2 Na + 2 H2O 2NaOH + H2
j. when zinc is placed in a solution of lead (II) nitrate, zinc nitrate and solid lead metal are
formed
Zn + Pb(NO3)2 Zn(NO3)2 + Pb
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SUMMARY - Predicting Products of Chemical Reactions
Class of reaction Reactants Probable products
Synthesis 2 or more substances 1 compound
Decomposition 1 compound 2 or more elements and/or compounds
Combustion Metal and oxygen
Nonmetal and oxygen
Compound and oxygen
Metal oxide
Nonmetal oxide
2 or more oxides
Single Replacement Metal and a compound
Nonmetal and a compound
New compound and the replaced metal
New compound and the replaced nonmetal
Double Replacement 2 compounds 2 different compounds, 1 or which is either a
precipitate, a gas, or water
Identifying Reaction Type Cheat Sheet Reaction Type Clue
Synthesis 1 product
Decomposition 1 reactant
Combustion CxHy + O2 CO2 + H2O
Single Replacement element + compound element + compound
Double Replacement compound + compound compound + compound