Reactions in Aqueous Solution
Chapter 4
Big Ideas from 4.1-4.2
Do substances dissolved in water exist as ions,
molecules, or a mixture of the two?
When do precipitates form when two solutions
are mixed?
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Tuesday, March 22 Do Now
1. Notecard check
2. Questions about the terms
3. A 0.1 M solution of acetic acid
(CH3COOH) causes the lightbulb in the
apparatus of Figure 4.2 to glow about as
brightly as a 0.001 M solution of HBr.
How do you account for this fact?
A ___Solution_______ is a homogenous mixture of
2 or more substances
The __Solute________ is(are) the substance(s)
present in the smaller amount(s)
The __Solvent_____ is the substance present in the
larger amount
Solution
Solvent
Solute(s)
Soft drink (l)
H2O
Sugar, CO2
Air (g)
N2
O2, Ar, CH4
Soft Solder (s)
Pb
Sn
4.1
An _electrolyte__________ is a substance that, when
dissolved in water, results in a solution that can conduct
electricity.
A __nonelectrolyte___________ is a substance that,
when dissolved, results in a solution that does not
conduct electricity.
_nonelectrolyte__
_weak electrolyte_
__strong electrolyte_
4.1
Conduct electricity in solution?
_cations__ (+) and _anions___(-)
Strong Electrolyte – __100__% dissociation
NaCl (s)
H 2O
Na+ (aq) + Cl- (aq)
Weak Electrolyte – _chemical equilibrium_____
CH3COOH
CH3COO- (aq) + H+ (aq)
4.1
_solvation_____ is the process in which an ion is
surrounded by water molecules arranged in a specific
manner.
d-
d+
H2O
__Glucose______ does not conduct electricity
No cations (+) and anions (-) in solution
C6H12O6 (s)
H 2O
C6H12O6 (aq)
Strong
Electrolytes
HCl
Weak Electrolytes Nonelectrolytes
CH3COOH
(NH2)2CO
HNO3
HF
CH3OH
HClO4
HNO2
C2H5OH
NaOH
H2O
C12H22O11
Ionic Compounds
Weak Acids
Covalent
Molecules
4.1
Practice Problems
• Pg 156, 4.11 – 4.17
Check for Understanding
• What dissolved species are present in a
solution of a) KCN, b) NaClO4?
• Which solute will cause a lightbulb to glow
more brightly, CH3OH or MgBr2?
Wednesday March 23 Do Now
• What dissolved species are present in a
solution of AgNO3? Of Al2(SO4)3?
• Goal for today: I can write molecular
equations, complete ionic equations, and net
ionic equations.
• I can predict whether or not a precipitate
will form in solution.
Notecard Notes
• Molecular Compounds dissolved in water
– HCl
• Chemical Equilibrium – going between ions
and original substance (HCl not an
example)
Precipitation Reactions
__Precipitate_–insoluble solid that separates from solution
precipitate
Pb(NO3)2 (aq) + 2NaI (aq)
PbI2 (s) + 2NaNO3 (aq)
_Molecular Equation_____
Pb2+ + 2NO3- + 2Na+ + 2I-
PbI2 (s) + 2Na+ + 2NO3-
_Complete Ionic Equation_______
Pb2+ + 2IPbI2
PbI2 (s)
_Net Ionic Equation_______
Na+ and NO3- are _spectator_____ ions
4.2
Writing Net Ionic Equations
1. Write the balanced molecular equation.
2. Write the ionic equation showing the strong electrolytes
3. Determine precipitate from solubility rules
4. Cancel the spectator ions on both sides of the ionic equation
Write the net ionic equation for the reaction of silver
nitrate with sodium chloride.
AgNO3 (aq) + NaCl (aq)
AgCl (s) + NaNO3 (aq)
4.2
Solubility Rules for Common Ionic Compounds
In water at 250C
1.All compounds containing alkali metal cations and the ammonium
ion (NH4+1) are soluble.
2.All compounds containing NO3-, ClO4- (perchlorate), ClO3(chlorate), and C2H3O2- (acetate) anions are soluble.
3.All chlorides, bromides, and iodides are soluble except those
containing Ag+, Pb2+, or Hg2+.
4.All sulfates (SO4-2) are soluble except those containing Hg2+, Pb2+,
Sr2+, Ca2+, or Ba2+.
5.All hydroxides (OH-1) are insoluble except compounds of the alkali
metals, Ca2+, Sr2+,and Ba2+.
6.All compounds containing PO43-(phosphate), S2-(sulfide), CO32(carbonate), and SO32- (sulfite) ions are insoluble except those that
also contain alkali metals or NH4+.
Memorize!
4.2
Predict
• Write out the net ionic equation for the
reaction between AgNO3 and KI. Will a
precipitate form?
• Write out the net ionic equation for the
reaction between Ca(OH)2 and SrCl2. Will
a precipitate form?
Practice Problems
• Pg 157 4.20, 4.21, 4.23, 4.25, 4.26, 4.28
Thursday, March
th
24
Do Now
• Using the following reactants, write out the
net ionic equation:
Sr(NO3)2(aq) + H2SO4(aq) 
Goals: I can define and identify substances as
acids or bases.
Acids
Have a sour taste. Vinegar owes its taste to acetic acid.
Citrus fruits contain citric acid.
React with certain metals to produce hydrogen gas.
React with carbonates and bicarbonates to produce carbon
dioxide gas
Bases
Have a bitter taste.
Feel slippery. Many soaps contain bases.
4.3
Arrhenius_ acid is a substance that produces H+ (H3O+) in water
_ Arrhenius __ base is a substance that produces OH- in water
4.3
A _Bronsted____ acid is a proton donor
A _Bronsted____ base is a proton acceptor
base
acid
acid
base
A _Bronsted_ acid must contain at
least one ionizable proton!
4.3
Monoprotic___ acids
HCl
H+ + Cl-
HNO3
CH3COOH
H+ + NO3H+ + CH3COO-
Strong electrolyte, strong acid
Strong electrolyte, strong acid
Weak electrolyte, weak acid
_Diprotic____ acids
H2SO4
H+ + HSO4-
Strong electrolyte, strong acid
HSO4-
H+ + SO42-
Weak electrolyte, weak acid
__Triprotic___ acids
H3PO4
H2PO4HPO42-
H+ + H2PO4H+ + HPO42H+ + PO43-
Weak electrolyte, weak acid
Weak electrolyte, weak acid
Weak electrolyte, weak acid
4.3
_Neutralization____ Reaction
acid + base
_water__ + __salt__ + _energy_
All _salts/neutralized solutions are strong electrolytes.
HCl (aq) + NaOH (aq)
H+ + Cl- + Na+ + OH-
H+ + OH-
NaCl (aq) + H2O
Na+ + Cl- + H2O
H2O
4.3
Practice Problems
• Pg 157 4.20, 4.21, 4.23, 4.25, 4.26, 4.28
• Problem Set #1 due tomorrow!!!!
• Solubility Rules Quiz on Monday. 10 pts
extra credit on the quiz for a catchy way of
remembering the rules.
Oxidation-Reduction Reactions
(electron transfer reactions)
2Mg (s) + O2 (g)
2Mg
O2 + 4e-
2MgO (s)
2Mg2+ + 4e- ________ half-reaction (lose e-)
2O2-
________ half-reaction (gain e-)
2Mg + O2 + 4e2Mg + O2
2Mg2+ + 2O2- + 4e2MgO
4.4
Zn (s) + CuSO4 (aq)
Zn
ZnSO4 (aq) + Cu (s)
Zn2+ + 2e- Zn is ________ Zn is the ________ agent
Cu2+ + 2e-
Cu Cu2+ is _______ Cu2+ is the _______ agent
4.4
Copper wire reacts with silver nitrate to form silver metal.
What is the oxidizing agent in the reaction?
Cu (s) + 2AgNO3 (aq)
Cu
Ag+ + 1e-
Cu(NO3)2 (aq) + Ag (s)
Cu2+ + 2eAg Ag+ is ________ Ag+ is the _____________
4.4
Oxidation number
The charge the atom would have in a molecule (or an
ionic compound) if electrons were completely transferred.
1. Free elements (uncombined state) have an oxidation
number of zero.
Na, Be, K, Pb, H2, O2, P4 = 0
2. In monatomic ions, the oxidation number is equal to
the charge on the ion.
Li+, Li = +1; Fe3+, Fe = +3; O2-, O = -2
3. The oxidation number of oxygen is usually –2. In H2O2
and O22- it is –1.
4.4
4. The oxidation number of hydrogen is +1 except when
it is bonded to metals in binary compounds. In these
cases, its oxidation number is –1.
5. Group IA metals are +1, IIA metals are +2 and fluorine is
always –1.
6. The sum of the oxidation numbers of all the atoms in a
molecule or ion is equal to the charge on the
molecule or ion.
HCO3Oxidation numbers of all
the atoms in HCO3- ?
O=
H=
3x-2 + 1 + ? = -1
C=
4.4
IF7
Oxidation numbers of all
the atoms in the
following ?
F=
7x-1 + ? = 0
I=
K2Cr2O7
NaIO3
Na =
O=
3x-2 + 1 + ? = 0
I=
O=
K=
7x-2 + 2x+1 + 2x? = 0
Cr =
4.4
Types of Oxidation-Reduction Reactions
Reaction
A+B
C
0
+4 -2
0
S + O2
SO2
Reaction
C
+1 +5 -2
2KClO3
A+B
+1 -1
0
2KCl + 3O2
4.4
Types of Oxidation-Reduction Reactions
Reaction
A + BC
0
+1
+2
Sr + 2H2O
+4
0
TiCl4 + 2Mg
0
AC + B
-1
Cl2 + 2KBr
0
Sr(OH)2 + H2 Hydrogen Displacement
0
+2
Ti + 2MgCl2
-1
Metal Displacement
0
2KCl + Br2
Halogen Displacement
4.4
The Activity Series for Metals
Displacement Reaction
M + BC
AC + B
M is metal
BC is acid or H2O
B is H2
Ca + 2H2O
Ca(OH)2 + H2
Pb + 2H2O
Pb(OH)2 + H2
4.4
Types of Oxidation-Reduction Reactions
Reaction
Element is simultaneously oxidized and reduced.
0
Cl2 + 2OH-
+1
-1
ClO- + Cl- + H2O
Chlorine Chemistry
4.4
Classify the following reactions.
Ca2+ + CO32NH3 + H+
Zn + 2HCl
Ca + F2
CaCO3
NH4+
ZnCl2 + H2
CaF2
__________________
__________________
__________________
__________________
4.4
Solution Stoichiometry
The ________________ of a solution is the amount of
solute present in a given quantity of solvent or solution.
M = ____________ =
moles of solute
liters of solution
4.5
Solution Stoichiometry
What mass of KI is required to make 500 mL of
a 2.80 M KI solution?
M KI
volume KI
moles KI
M KI
grams KI
1L
2.8 mol KI 166 g KI
x
500 mL x
= _____ g KI
x
1000 mL
1 L soln
1 mol KI
4.5
4.5
________________ is the procedure of
preparing a less concentrated solution
from a more concentrated solution.
Dilution
Add Solvent
Moles of solute
before dilution (i)
=
Moles of solute
after dilution (f)
MiVi
=
MfVf
4.5
How would you prepare 60.0 mL of 0.200 M
HNO3 from a stock solution of 4.00 M HNO3?
MiVi = MfVf
Mi = 4.00
Vi =
Mf = 0.200
MfVf
Mi
=
Vf = 0.06 L
Vi = ? L
=
4.5
Gravimetric Analysis
1. Dissolve unknown substance in water
2. React unknown with known substance to form a precipitate
3. Filter and dry precipitate
4. Weigh precipitate
5. Use chemical formula and mass of precipitate to determine
amount of unknown ion
4.6
___________________
In a _____________________ a solution of accurately known
concentration is added gradually added to another solution of
unknown concentration until the chemical reaction between the
two solutions is complete.
________________ – the point at which the reaction is complete
_______________ – substance that changes color at (or near)
the equivalence point
Slowly add base
to unknown acid
UNTIL
The indicator
changes color
(pink)
4.7
What volume of a 1.420 M NaOH
solution is required to titrate 25.00 mL
of a 4.50 M H2SO4 solution?
BALANCE THE CHEMICAL EQUATION!
H2SO4 + NaOH
M
volume acid
acid
H2O + Na2SO4
rx
moles acid
coef.
M
moles base
base
volume base
4.7
What volume of a 1.420 M NaOH solution is
Required to titrate 25.00 mL of a 4.50 M H2SO4
solution?
BALANCE THE CHEMICAL EQUATION!
H2SO4 + 2NaOH
M
volume acid
25 mL x
acid
2H2O + Na2SO4
rx
moles acid
4.50 mol H2SO4
1000 mL soln
x
coef.
M
moles base
2 mol NaOH
1 mol H2SO4
x
base
volume base
1000 ml soln
= _____ mL
1.420 mol NaOH
4.7
(4.72 p.120) What volume of a 0.500 M KOH
solution is required to titrate 10.0 mL of a
0.20 M H2SO4 solution?
H2SO4 + KOH
H2O + K2SO4
M
volume acid
10.0 mL x
acid
rx
moles acid
___ mol H2SO4
____ mL soln
x
coef.
M
moles base
__ mol KOH
__ mol H2SO4
x
base
volume base
____ ml soln
____ mol KOH
= ___ mL
4.7
(4.72 p.120) What volume of a 0.500 M KOH
solution is required to titrate 10.00 mL of a
0.20 M H2SO4 solution?
H2SO4 + 2KOH
2H2O + Na2SO4
M
volume acid
10.0 mL x
acid
rx
moles acid
0.20 mol H2SO4
1000 mL soln
x
coef.
M
moles base
2 mol KOH
1 mol H2SO4
x
base
volume base
1000 ml soln
0.500 mol KOH
= _____ mL
4.7