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CHEM 1405:
Introductory Chemistry
Houston Community College
Dr. Laura Jakubowski
Chapter 7 – Chemical Reactions
Textbook “Introductory Chemistry: Concepts and Critical Thinking” Seventh Edition by Charles H. Corwin
© 2014 Pearson Education, Inc.
Evidence for Chemical Reactions
• In a physical change, the chemical composition of the substance
remains constant (ice melting or boiling is a physical change)
• In a chemical change, the chemical composition of the substance does
NOT remain constant – a chemical reaction has taken place
• The following indicate a chemical change:
• a gas is produced
• an insoluble solid is produced
in a solution
• a permanent color change is
observed
• an energy change is observed
© 2014 Pearson Education, Inc.
2
Evidence for Chemical Reactions
• A gas is produced – a reaction occurs which produces a gas as a
product, typically seen as bubbles in a solution
• For example, mixing
NaHCO3(s) with
HC2H3O2(aq) produces
CO2(g)
See video:
http://www.youtube.com/watch?v=i_XMkTO65fo
3
Evidence for Chemical Reactions
• An insoluble solid is produced in a solution – two aqueous solutions
are added to give an insoluble solid (called a precipitate)
• For example, mixing
the clear, aqueous
solutions of NaCl(aq)
with AgNO3(aq)
produces a white
precipitate, AgCl(s)
See video:
http://www.youtube.com/watch?v=eGG3EI4mwok
4
Evidence for Chemical Reactions
• A permanent color change is observed – many reactions involve a
permanent color change, acid/base indicators are a good example
• For example,
KMnO4(aq) reacts with
a special solution to
give several color
changes
See video:
http://www.youtube.com/watch?v=kKlXe2mrnHQ
5
Evidence for Chemical Reactions
• An energy change is observed – all reactions involve changes in energy,
exothermic reactions release heat and endothermic reactions absorb
heat
• For example, a gummy
bear reacting with
molten KClO3(l) is
exothermic – both heat
and light are given off
See video:
http://www.youtube.com/watch?v=xJf0o9TNNXI
6
Writing Chemical Equations
• Formulas and symbols are used to describe a chemical reaction as a
chemical equation
A+BC+D
• A and B are reactants and C and D are products
• Physical state is abbreviated by either (s), (l), (g), or (aq)
• A catalyst is a substance
that speeds up a reaction
without being consumed
or permanently altered
(typically written above
the arrow)
© 2014 Pearson Education, Inc.
7
Writing Chemical Equations
• The following elements occur naturally as diatomic molecules, and
should be written as such in a chemical equation
© 2014 Pearson Education, Inc.
8
Writing Chemical Equations
• Write a chemical equation for each of the following chemical reactions:
• mercury liquid and fluorine gas react to give solid mercury(II) fluoride
• zinc metal reacts with sulfuric acid to give aqueous zinc sulfate and hydrogen gas
• aqueous solutions of sodium iodide and silver nitrate yield silver iodide precipitate
and aqueous sodium nitrate
• acetic acid reacts with aqueous potassium hydroxide to give aqueous potassium
acetate plus water
© 2014 Pearson Education, Inc.
9
Writing Chemical Equations
• Write a chemical equation for each of the following chemical reactions:
• mercury liquid and fluorine gas react to give solid mercury(II) fluoride
Hg(l) + F2(g)  HgF2(s)
• zinc metal reacts with sulfuric acid to give aqueous zinc sulfate and hydrogen gas
Zn(s) + H2SO4(aq)  ZnSO4(aq) + H2(g)
• aqueous solutions of sodium iodide and silver nitrate yield silver iodide precipitate
and aqueous sodium nitrate
NaI(aq) + AgNO3(aq)  AgI(s) + NaNO3(aq)
• acetic acid reacts with aqueous potassium hydroxide to give aqueous potassium
acetate plus water
HC2H3O2(aq) + KOH(aq)  KC2H3O2(aq) + H2O(l)
© 2014 Pearson Education, Inc.
10
Balancing Chemical Equations
• It often happens that the number of atoms of each element in the
reactants and products is not the same – it is therefore necessary to
balance the number of atoms using whole number coefficients
• A coefficient multiplies all subscripts in the chemical formula
• 3 H2O has six H atoms and three O atoms
• For example:
H2(g) + Cl2(g)  HCl(g)
H H
H2Cl2
H Cl
Cl H
© 2014 Pearson Education, Inc.
Cl Cl
H Cl
H2(g) + Cl2(g)  2 HCl(g)
H H
Cl Cl
NOT Balanced!
Balanced!
H Cl
H Cl
11
Balancing Chemical Equations
• Aluminum is heated with oxygen gas to give solid aluminum oxide
NOT Balanced:
Al(s) + O2(g)  Al2O3(s)
Al
O O
O
Al
O
Al
O
Balanced:
4 Al(s) + 3 O2(g)  2 Al2O3(s)
Al
O O
Al
O O
Al
© 2014 Pearson Education, Inc.
O O
Al
Al
O
O
O
Al
Al
O
O
O
Al
12
Guidelines for Balancing Chemical Equations
1. Verify the formula of each substance for correct subscripts – NEVER
change subscripts to balance an equation
2. Balance elements by placing a coefficient in front of each substance
a) Begin balancing by starting with the most complex formula
b) Balance polyatomic ions as a single unit, unless the polyatomic ion breaks
down during the reaction (then atoms should be balanced separately)
c) Coefficients MUST be whole numbers
3. After balancing the equation, check (√) each symbol of every element
(or polyatomic ion) to verify that the coefficients are correct and finally,
check the coefficients to make sure they represent the smallest whole
number ratio
ALL equations can be balanced – if you have trouble, check step 1 again
© 2014 Pearson Education, Inc.
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Balance the Chemical Equations
• Aqueous solutions of lead(II) nitrate and potassium iodide produce a yellow
precipitate of lead(II) iodide and an aqueous solution of potassium nitrate
Pb(NO3)2(aq) + KI(aq)  PbI2(s) + KNO3(aq)
• Aqueous solutions of calcium nitrate and sodium carbonate react to give a white
precipitate of calcium carbonate and aqueous sodium nitrate
Ca(NO3)2(aq) + Na2CO3(aq)  CaCO3(s) + NaNO3(aq)
• Aqueous solutions of aluminum sulfate and barium nitrate react to yield a white
precipitate of barium sulfate and aqueous aluminum nitrate
Al2(SO4)3(aq) + Ba(NO3)2(aq)  BaSO4(s) + Al(NO3)3(aq)
© 2014 Pearson Education, Inc.
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Balance the Chemical Equations
• Aqueous solutions of lead(II) nitrate and potassium iodide produce a yellow
precipitate of lead(II) iodide and an aqueous solution of potassium nitrate
Pb(NO
++
2 KI(aq)
KI(aq) 
 PbI
PbI22(s)
(s) ++ KNO
2 KNO
Pb(NO
)2(aq)
3)23(aq)
3(aq)
3(aq)
• Aqueous solutions of calcium nitrate and sodium carbonate react to give a white
precipitate of calcium carbonate and aqueous sodium nitrate
Ca(NO
Na2CO
CaCO
CaCO3(s)
Ca(NO
NaNO3(aq)
2(aq)++Na
2CO
3(aq)
3(s)++2NaNO
3)32)(aq)
3(aq)
3(aq)
• Aqueous solutions of aluminum sulfate and barium nitrate react to yield a white
precipitate of barium sulfate and aqueous aluminum nitrate
Al2(SO
+3+
Ba(NO
BaSO44(s)
(s) ++Al(NO
2 Al(NO
Al2(SO
Ba(NO
)2(aq)3 BaSO
4)3(aq)
3)23(aq)
3)3(aq)
4)3(aq)
3)3(aq)
© 2014 Pearson Education, Inc.
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Balance the Chemical Equations
• Sulfuric acid reacts with aqueous sodium hydroxide to give aqueous sodium sulfate
and water
H2SO4(aq) + NaOH(aq)  Na2SO4(aq) + HOH(l)
• Nitric acid reacts with aqueous barium hydroxide to give aqueous barium nitrate and
water
HNO3(aq) + Ba(OH)2(aq)  Ba(NO3)2(aq) + HOH(l)
• Phosphoric acid reacts with solid manganese(II) hydroxide to give solid
manganese(II) phosphate and water
H3PO4(aq) + Mn(OH)2(s)  Mn3(PO4)2(s) + HOH(l)
© 2014 Pearson Education, Inc.
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Balance the Chemical Equations
• Sulfuric acid reacts with aqueous sodium hydroxide to give aqueous sodium sulfate
and water
HH
NaOH(aq)
Na
Na2SO
2 HOH(l)
2SO
4(aq)
2SO
4(aq)++HOH(l)
2SO
4(aq)++2NaOH(aq)
4(aq)
• Nitric acid reacts with aqueous barium hydroxide to give aqueous barium nitrate and
water
2 HNO
HNO33(aq)
(aq)++Ba(OH)
Ba(OH)22(aq)
(aq)
Ba(NO
Ba(NO3)32)(aq)
2 HOH(l)
2(aq)++HOH(l)
• Phosphoric acid reacts with solid manganese(II) hydroxide to give solid
manganese(II) phosphate and water
2 HH
Mn(OH)22(s)
(s)
Mn
Mn3(PO
6 HOH(l)
3PO
4(aq)
3(PO
2(s)++HOH(l)
3PO
4(aq)++3Mn(OH)
4)42)(s)
© 2014 Pearson Education, Inc.
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Classifying Chemical Reactions
• In this chapter, we study five simple types of chemical reactions:
1. Combination reaction - simple compounds combine to a more complex compound
A + Z  AZ
2. Decomposition reaction - single compound broken down to simpler compounds
AZ  A + Z
3. Single-replacement reaction - more reactive element displaces another
A + BZ  AZ + B
4. Double-replacement reaction - two compounds exchange anions
AX + BZ  AZ + BX
5. Neutralization reaction - an acid and base react to form a salt and water
HX + BOH  BX + HOH
© 2014 Pearson Education, Inc.
18
Classifying Chemical Reactions
Classify each of the following reactions:
• Zn(s) + CuSO4(aq)
• 2 Sr(s) + O2(g)
• Cd(HCO3)2(s)
ZnSO4(aq) + Cu(s)
2 SrO(s)
∆
CdCO3(s) + HOH(g) + CO2(g)
• HC2H3O2(aq) + NaOH(aq)
• AgNO3(aq) + KCl(aq)
NaC2H3O2(aq) + HOH(l)
AgCl(s) + KNO3(aq)
© 2014 Pearson Education, Inc.
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Classifying Chemical Reactions
Classify each of the following reactions:
• Zn(s) + CuSO4(aq)
ZnSO4(aq) + Cu(s)
single-replacement reaction
• 2 Sr(s) + O2(g)
2 SrO(s)
combination reaction
∆
• Cd(HCO3)2(s)
CdCO3(s) + HOH(g) + CO2(g)
decomposition reaction
NaC2H3O2(aq) + HOH(l)
• HC2H3O2(aq) + NaOH(aq)
neutralization reaction
AgCl(s) + KNO3(aq)
• AgNO3(aq) + KCl(aq)
double-replacement reaction
© 2014 Pearson Education, Inc.
20
Classifying Chemical Reactions
Write balanced reactions and classify each of the following:
• Copper metal heated with oxygen gas produces solid copper(II) oxide
• Heating powdered iron(III) carbonate produces solid iron(III) oxide and carbon
dioxide gas
• Aluminum metal reacts with aqueous manganese(II) sulfate to give aqueous
aluminum sulfate and manganese metal
© 2014 Pearson Education, Inc.
21
Classifying Chemical Reactions
Write balanced reactions and classify each of the following:
• Copper metal heated with oxygen gas produces solid copper(II) oxide
2 Cu(s) + O2(g)
∆
2 CuO(s)
combination reaction
• Heating powdered iron(III) carbonate produces solid iron(III) oxide and carbon
dioxide gas
Fe2(CO3)3(s)
∆
Fe2O3(s) + 3 CO2(g)
decomposition reaction
• Aluminum metal reacts with aqueous manganese(II) sulfate to give aqueous
aluminum sulfate and manganese metal
2 Al(s) + 3 MnSO4(aq)
Al2(SO4)3(aq) + 3 Mn(s)
single-replacement reaction
© 2014 Pearson Education, Inc.
22
Classifying Chemical Reactions
Write balanced reactions and classify each of the following:
• Aqueous sodium chromate reacts with aqueous barium chloride to give insoluble
barium chromate and aqueous sodium chloride
• Nitric acid reacts with aqueous potassium hydroxide to give aqueous potassium
nitrate and water
© 2014 Pearson Education, Inc.
23
Classifying Chemical Reactions
Write balanced reactions and classify each of the following:
• Aqueous sodium chromate reacts with aqueous barium chloride to give insoluble
barium chromate and aqueous sodium chloride
Na2CrO4(aq) + BaCl2(aq)
BaCrO4(s) + NaCl(aq) double-replacement reaction
• Nitric acid reacts with aqueous potassium hydroxide to give aqueous potassium
nitrate and water
HNO3(aq) + KOH(aq)
KNO3(aq) + HOH(l)
neutralization reaction
© 2014 Pearson Education, Inc.
24
Combination reactions
• Metal and oxygen gas
metal + oxygen gas  metal oxide
∆
2 Mg(s) + O2(g)
2 MgO(s)
Write a balanced chemical equation for each of the following:
• Zinc metal is heated with oxygen gas in the air to give solid zinc oxide
• Cobalt metal is heated with oxygen gas to yield solid cobalt(III) oxide
© 2014 Pearson Education, Inc.
25
Combination reactions
• Metal and oxygen gas
metal + oxygen gas  metal oxide
∆
2 Mg(s) + O2(g)
2 MgO(s)
Write a balanced chemical equation for each of the following:
• Zinc metal is heated with oxygen gas in the air to give solid zinc oxide
2 Zn(s) + O2(g)
∆
2 ZnO(s)
• Cobalt metal is heated with oxygen gas to yield solid cobalt(III) oxide
4 Co(s) + 3 O2(g)
∆
2 Co2O3(s)
© 2014 Pearson Education, Inc.
26
Metal and Oxygen Gas
2 Mg(s) + O2(g)
∆
2 MgO(s)
See video:
http://www.youtube.com/watch?v=5UJTR-LA1z4
27
Combination Reactions
• Nonmetal and oxygen gas
nonmetal + oxygen gas  nonmetal oxide
∆
S(s) + O2(g)
SO2(g)
*Several products often possible (NO, NO2, N2O, N2O3, N2O4, N2O5)
Write a balanced chemical equation for each of the following:
• Phosphorus and oxygen gas react to give solid diphosphorus pentaoxide
• Chlorine gas is heated with oxygen to give dichlorine monoxide gas
© 2014 Pearson Education, Inc.
28
Combination Reactions
• Nonmetal and oxygen gas
nonmetal + oxygen gas  nonmetal oxide
∆
S(s) + O2(g)
SO2(g)
*Several products often possible (NO, NO2, N2O, N2O3, N2O4, N2O5)
Write a balanced chemical equation for each of the following:
• Phosphorus and oxygen gas react to give solid diphosphorus pentaoxide
4 P(s) + 5 O2(g)
2 P2O5(s)
• Chlorine gas is heated with oxygen to give dichlorine monoxide gas
2 Cl2(g) + O2(g)
∆
2 Cl2O(g)
© 2014 Pearson Education, Inc.
29
Nonmetal and Oxygen Gas
S(s) + O2(g)
∆
SO2(s)
See video:
http://www.youtube.com/watch?v=V1sQO91UvFI
30
Combination Reactions
• Metal and nonmetal
metal + nonmetal  ionic compound
∆
2 Na(s) + Cl2(g)
2 NaCl(s)
Write a balanced chemical equation for each of the following:
• Chromium metal is heated with iodine crystals to give solid chromium(III) iodide
• Manganese metal reacts with bromine vapor to yield solid manganese(IV) bromide
© 2014 Pearson Education, Inc.
31
Combination Reactions
• Metal and nonmetal
metal + nonmetal  ionic compound
∆
2 Na(s) + Cl2(g)
2 NaCl(s)
Write a balanced chemical equation for each of the following:
• Chromium metal is heated with iodine crystals to give solid chromium(III) iodide
2 Cr(s) + 3 I2(s)
∆
2 CrI3(s)
• Manganese metal reacts with bromine vapor to yield solid manganese(IV) bromide
Mn(s) + 2 Br2(g)
∆
MnBr4(s)
© 2014 Pearson Education, Inc.
32
Metal and Nonmetal
2 Na(s) + Cl2(g)
∆
2 NaCl(s)
See video:
http://www.youtube.com/watch?v=Ftw7a5ccubs
33
Decomposition Reactions
• Metal hydrogen carbonates
metal hydrogen carbonate
2 NaHCO3(s)
∆
∆
metal carbonate + water + carbon dioxide
Na2CO3(s) + H2O(g) + CO2(g)
Write a balanced chemical equation for each of the following:
• Lead(II) hydrogen carbonate decomposes on heating
• Copper(I) hydrogen carbonate is decomposed with heat
© 2014 Pearson Education, Inc.
34
Decomposition Reactions
• Metal hydrogen carbonates
metal hydrogen carbonate
2 NaHCO3(s)
∆
∆
metal carbonate + water + carbon dioxide
Na2CO3(s) + H2O(g) + CO2(g)
Write a balanced chemical equation for each of the following:
• Lead(II) hydrogen carbonate decomposes on heating
Pb(HCO3)2(s)
∆
PbCO3(s) + H2O(g) + CO2(g)
• Copper(I) hydrogen carbonate is decomposed with heat
2 CuHCO3(s)
∆
Cu2CO3(s) + H2O(g) + CO2(g)
© 2014 Pearson Education, Inc.
35
Metal Hydrogen Carbonates
2 NaHCO3(s)
∆
Na2CO3(s) + H2O(g) + CO2(g)
See video:
http://www.youtube.com/watch?v=mMVr7XC9_5Y
36
Decomposition Reactions
• Metal carbonates
∆
metal carbonate
CuCO3(s)
metal oxide + carbon dioxide
∆
CuO(s) + CO2(g)
Write a balanced chemical equation for each of the following:
• Copper(I) carbonate decomposes on heating
• Aluminum carbonate is decomposed on heating
© 2014 Pearson Education, Inc.
37
Decomposition Reactions
• Metal carbonates
∆
metal carbonate
CuCO3(s)
metal oxide + carbon dioxide
∆
CuO(s) + CO2(g)
Write a balanced chemical equation for each of the following:
• Copper(I) carbonate decomposes on heating
Cu2CO3(s)
∆
Cu2O(s) + CO2(g)
• Aluminum carbonate is decomposed on heating
Al2(CO3)3(s)
∆
Al2O3(s) + 3 CO2(g)
© 2014 Pearson Education, Inc.
38
Metal Carbonates
CuCO3(s)
∆
CuO(s) + CO2(g)
See video:
http://www.youtube.com/watch?v=TxbEgcjmhqo
39
Decomposition Reactions
• Miscellaneous oxygen-containing compounds
∆
oxygen-containing compound
substance + oxygen gas
∆
2 HgO(s)
2 Hg(l) + O2(g)
Write a balanced chemical equation for each of the following:
• Solid potassium chlorate decomposes upon heating to give solid potassium chloride
and oxygen gas
• Aqueous H2O2 decomposes upon heating to give water and oxygen gas
© 2014 Pearson Education, Inc.
40
Decomposition Reactions
• Miscellaneous oxygen-containing compounds
∆
oxygen-containing compound
substance + oxygen gas
∆
2 HgO(s)
2 Hg(l) + O2(g)
Write a balanced chemical equation for each of the following:
• Solid potassium chlorate decomposes upon heating to give solid potassium chloride
and oxygen gas
2 KClO3(s)
∆
2 KCl(s) + 3 O2(g)
• Aqueous H2O2 decomposes upon heating to give water and oxygen gas
2 H2O2(aq)
∆
2 H2O(l) + O2(g)
© 2014 Pearson Education, Inc.
41
Miscellaneous Oxygen-Containing Compounds
2 HgO(s)
∆
2 Hg(l) + O2(g)
See video:
http://www.youtube.com/watch?v=_Y1alDuXm6A
42
The Activity Series Concept
• The activity of a metal is its ability to compete in a single replacement
reaction – order of this is known as an activity series
Li > K > Ba > Sr > Ca > Na > Mg > Al > Mn > Zn > Fe > Cd > Co > Ni >
Sn > Pb > (H) > Cu > Ag > Hg > Au
• Hydrogen (H) is included in the series to show which metals react with
acids – Cu, Ag, Hg, Au do not (no reaction, NR); others do
• Examples:
Fe(s) + CuSO4(aq)  FeSO4(aq) + Cu(s)
Cu(s) + FeSO4(aq)  NR
Cu(s) + H2SO4(aq)  NR
© 2014 Pearson Education, Inc.
43
The Activity Series Concept
• Some metals are so reactive, they react directly with water at room
temperature – known as active metals (Li, Na, K, Rb, Cs, Ca, Sr, Ba)
• There is also an activity series for halogens (F > Cl > Br > I)
Cl2(g) + 2 NaBr(aq)  2 NaCl(aq) + Br2(l)
Predict whether or not a reaction occurs for the following:
•
•
•
•
•
A gold ring is dropped into sulfuric acid
A zinc granule is dropped into hydrochloric acid
A cadmium foil is put into a lead(II) nitrate solution
A chromium strip is put into water
Aluminum foil is added to an iron(II) sulfate solution
© 2014 Pearson Education, Inc.
44
The Activity Series Concept
• Some metals are so reactive, they react directly with water at room
temperature – known as active metals (Li, Na, K, Rb, Cs, Ca, Sr, Ba)
• There is also an activity series for halogens (F > Cl > Br > I)
Cl2(g) + 2 NaBr(aq)  2 NaCl(aq) + Br2(l)
Predict whether or not a reaction occurs for the following:
•
•
•
•
•
A gold ring is dropped into sulfuric acid
A zinc granule is dropped into hydrochloric acid
A cadmium foil is put into a lead(II) nitrate solution
A chromium strip is put into water
Aluminum foil is added to an iron(II) sulfate solution
No Reaction (NR)
Reaction Occurs
Reaction Occurs
No Reaction (NR)
Reaction Occurs
© 2014 Pearson Education, Inc.
45
Single-Replacement Reactions
• Metal and aqueous salt solution
metal1(s) + salt1(aq)  metal2(s) + salt2(aq)
Cu(s) + 2 AgNO3(aq)
2 Ag(s) + Cu(NO3)2(aq)
Write a balanced chemical equation for each of the following:
• Nickel metal is placed in a tin(II) sulfate solution
• Gold metal is placed in a silver nitrate solution
© 2014 Pearson Education, Inc.
46
Single-Replacement Reactions
• Metal and aqueous salt solution
metal1(s) + salt1(aq)  metal2(s) + salt2(aq)
Cu(s) + 2 AgNO3(aq)
2 Ag(s) + Cu(NO3)2(aq)
Write a balanced chemical equation for each of the following:
• Nickel metal is placed in a tin(II) sulfate solution
Ni(s) + SnSO4(aq)
NiSO4(aq) + Sn(s)
• Gold metal is placed in a silver nitrate solution
Au(s) + AgNO3(aq)
NR
© 2014 Pearson Education, Inc.
47
Metal and Aqueous Salt Solution
Cu(s) + 2 AgNO3(aq)
2 Ag(s) + Cu(NO3)2(aq)
See video:
http://www.youtube.com/watch?v=P5QlfMRvvF8
48
Single-Replacement Reactions
• Metal and aqueous acid solution
metal(s) + acid(aq)  salt(aq) + hydrogen(g)
Zn(s) + H2SO4(aq)
ZnSO4(aq) + H2(g)
Write a balanced chemical equation for each of the following:
• A chunk of cadmium metal is dropped into hydrochloric acid
• Manganese chips are added to sulfuric acid
© 2014 Pearson Education, Inc.
49
Single-Replacement Reactions
• Metal and aqueous acid solution
metal(s) + acid(aq)  salt(aq) + hydrogen(g)
Zn(s) + H2SO4(aq)
ZnSO4(aq) + H2(g)
Write a balanced chemical equation for each of the following:
• A chunk of cadmium metal is dropped into hydrochloric acid
Cd(s) + 2 HCl(aq)
CdCl2(aq) + H2(g)
• Manganese chips are added to sulfuric acid
Mn(s) + H2SO4(aq)
MnSO4(aq) + H2(g)
© 2014 Pearson Education, Inc.
50
Metal and Aqueous Acid Solution
Zn(s) + H2SO4(aq)
ZnSO4(aq) + H2(g)
See video:
http://www.youtube.com/watch?v=9hBCLoWwcWo
51
Single-Replacement Reactions
• Active metal and water
metal(s) + water(l)  metal hydroxide(aq) + hydrogen(g)
Ca(s) + 2 H2O(l)
Ca(OH)2(aq) + H2(g)
Write a balanced chemical equation for each of the following:
• A chunk of iron metal is dropped into water
• A small piece of strontium metal is dropped into water
© 2014 Pearson Education, Inc.
52
Single-Replacement Reactions
• Active metal and water
metal(s) + water(l)  metal hydroxide(aq) + hydrogen(g)
Ca(s) + 2 H2O(l)
Ca(OH)2(aq) + H2(g)
Write a balanced chemical equation for each of the following:
• A chunk of iron metal is dropped into water
Fe(s) + H2O(l)
NR
• A small piece of strontium metal is dropped into water
Sr(s) + 2 H2O(l)
Sr(OH)2(aq) + H2(g)
© 2014 Pearson Education, Inc.
53
Active Metal and Water
Ca(s) + 2 H2O(l)
Ca(OH)2(aq) + H2(g)
See video:
http://www.youtube.com/watch?v=Y9CpQAjqHHo
54
Solubility Rules
• In double-replacement reactions, two aqueous solutions may react to
form a compound that is not soluble (a precipitate)
• There are rules to determine if a compound will be soluble or not:
© 2014 Pearson Education, Inc.
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Applying Solubility Rules
• Are the following compounds soluble or insoluble in water?:
•
•
•
•
•
•
•
•
•
•
sodium sulfate
aluminum nitrate
barium sulfate
lead(II) chromate
ammonium sulfide
lead(II) acetate
mercury(II) bromide
magnesium carbonate
zinc phosphate
calcium hydroxide
© 2014 Pearson Education, Inc.
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Applying Solubility Rules
• Are the following compounds soluble or insoluble in water?:
•
•
•
•
•
•
•
•
•
•
sodium sulfate
aluminum nitrate
barium sulfate
lead(II) chromate
ammonium sulfide
lead(II) acetate
mercury(II) bromide
magnesium carbonate
zinc phosphate
calcium hydroxide
Na2SO4
Al(NO3)3
BaSO4
PbCrO4
(NH4)2S
Pb(C2H3O2)2
HgBr2
MgCO3
Zn3(PO4)2
Ca(OH)2
soluble
soluble
insoluble
insoluble
soluble
soluble
soluble
insoluble
insoluble
soluble
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Double-Replacement Reactions
• Double-replacement reactions
salt1(aq) + salt2(aq)  salt3(s) + salt4(aq)
Pb(NO3)2(aq) + 2 KI(aq)
PbI2(s) + KNO3(aq)
Write a balanced chemical equation for each of the following:
• Aqueous cobalt(II) nitrate is added to a sodium chromate solution
• Aqueous strontium acetate is added to a lithium hydroxide solution
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Double-Replacement Reactions
• Double-replacement reactions
salt1(aq) + salt2(aq)  salt3(s) + salt4(aq)
Pb(NO3)2(aq) + 2 KI(aq)
PbI2(s) + KNO3(aq)
Write a balanced chemical equation for each of the following:
• Aqueous cobalt(II) nitrate is added to a sodium chromate solution
Co(NO3)2(aq) + Na2CrO4(aq)
CoCrO4(s) + 2 NaNO3(aq)
• Aqueous strontium acetate is added to a lithium hydroxide solution
Sr(C2H3O2)2(aq) + LiOH(aq)
NR
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Double-Replacement Reactions
Pb(NO3)2(aq) + 2 KI(aq)
PbI2(s) + KNO3(aq)
See video:
http://www.youtube.com/watch?v=TRq9hnOGvaE
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Neutralization Reactions
• Neutralization reactions
acid(aq) + base(aq)  salt(aq) + water(l)
HCl(aq) + NaOH(aq)
NaCl(aq) + HOH(l)
* An acid-base indicator is often added to show evidence of the reaction
Write a balanced chemical equation for each of the following:
• Nitric acid and ammonium hydroxide produce ammonium nitrate and water
• Chloric acid neutralizes a strontium hydroxide solution
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Neutralization Reactions
• Neutralization reactions
acid(aq) + base(aq)  salt(aq) + water(l)
HCl(aq) + NaOH(aq)
NaCl(aq) + HOH(l)
* An acid-base indicator is often added to show evidence of the reaction
Write a balanced chemical equation for each of the following:
• Nitric acid and ammonium hydroxide produce ammonium nitrate and water
HNO3(aq) + NH4OH(aq)
NH4NO3(aq) + HOH(l)
• Chloric acid neutralizes a strontium hydroxide solution
2 HClO3(aq) + Sr(OH)2(aq)
Sr(ClO3)2(aq) + 2 HOH(l)
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Neutralization Reactions
HCl(aq) + NaOH(aq)
NaCl(aq) + HOH(l)
See video:
http://www.youtube.com/watch?v=AIiQce07u2o
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Household Chemicals
phosphoric acid
carbonic acid
ammonia
acetic acid
(ammonium chlorides)
citric acid
sodium hydroxide
acetylsalicylic acid
magnesium sulfate
hydrate
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Summary
• Evidence for a chemical reaction is any of the following: a gas is
detected, a precipitate is formed in an aqueous solution, a color change
is observed, or a change in energy is observed (exothermic reaction
releases heat and endothermic reaction absorbs heat)
• A reactant undergoes a chemical change to become a product, a
catalyst speeds up a reaction without being permanently altered, a
chemical equation describes a reaction using formulas and symbols,
and it is important to remember that the following elements occur
naturally as diatomic molecules (H2, N2, O2, F2, Cl2, Br2, I2)
• Coefficients are added to a chemical equation to properly balance it
(same number of atoms of each element per side), the subscript in a
chemical formula should not be changed during balancing
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Summary
• Most chemical reactions are classified as: combination, decomposition,
single-replacement, double-replacement, or neutralization
• Three types of combination reactions: metal and oxygen, nonmetal and
oxygen, metal and nonmetal
• Three types of decomposition reactions: metal hydrogen carbonate,
metal carbonate, miscellaneous oxygen-containing compounds
• The activity series lists the relative ability of a metal to undergo a
reaction (a metal higher in the series replaces a lower metal), active
metals (including Li, Na, K, Ba, Sr and Ca) produce H2 gas in water
• Three types of single-replacement reactions: metal and aqueous
solution, metal and dilute acid, active metal and water
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Summary
• To predict whether a substance is soluble or not, refer to the solubility
rules (Table 7.2 in your book)
• In a double-replacement reaction, a precipitation occurs
• In a neutralization reaction, an acid and a base react to yield salt and
water (special type of double-replacement reaction)
Key terms: chemical reaction, precipitate, aqueous solution,
exothermic reaction, endothermic reaction, reactant, product,
catalyst, chemical equation, diatomic molecule, coefficient,
subscript, combination reaction, decomposition reaction, singlereplacement reaction, double-replacement reaction, neutralization
reaction, activity series, active metal, acid, base, salt
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