Transcript Solution Chemistry

Solution Chemistry
Solutions, Problems,
Solutions, Problems.
Does it ever end?
How can you express concentration?
How can you express concentration?
1)
2)
3)
4)
5)
Mass % composition
Molarity
Molality
Mole fraction
Density
Mass % problems:
• Find mass %
• Find amount of solute
• Find total mass of solution
Mass % problems:
• Find mass %
• Mass % =
mass of solute x 100 %
total mass of solution
Don’t forget to add the masses of the solute and
solvent for the total mass
Mass % problems:
• Find amount of solute
• Mass % =
mass of solute x 100 %
total mass of solution
• Multiply by total mass and divide by 100% to
solve for mass of solute
Mass % problems:
• Find total mass of solution
• Mass % =
mass of solute x 100 %
total mass of solution
• Multiply both sides by the mass of solution
first to get it out of the denominator.
Molarity problems:
• Find molarity
• Find amount of solute
• Find volume of solution
Molarity problems:
• Find molarity
• M=
moles solute
Volume of solution (L)
Molarity problems:
• Find amount of solute
• M=
moles solute
Volume of solution (L)
• Molarity x volume= moles!
Molarity problems:
• Find volume of solution
• M=
moles solute
Volume of solution (L)
• Multiply both sides by the volume of solution
first to get it out of the denominator.
OR!
Molarity problems:
• Find volume of solution
• Use the molarity as a conversion factor!
• moles solute x 1 L = Volume of solution!
M
Dilution Problems
M x V = Moles
• Moles of solute in new solution = moles in the
stock solution. Molarity goes down, volume
goes up
Dilution Problems
Example:
What is the concentration of a solution made by
diluting 25 ml of a .50 M HCl solution to a new
volume of 150 ml?
Dilution Problems
Example:
What is the concentration of a solution made by
diluting 25 ml of a .50 M HCl solution to a new
volume of 150 ml?
M x V = moles.
.50 M x .025 L= .0125 moles HCl
M = mol/vol= .0125 mol / .150 L = .083 M
Dilution Problems
1) What is the concentration of a solution made
by diluting 125 ml of a 2.5 M NH3 solution to
a new volume of 350 ml?
2) What is the concentration of a solution made
by diluting 2.5 ml of a 6.0 M NaCl solution to
a new volume of 80. ml?
3) What is the concentration of a solution made
by diluting 30. ml of a 1.0 M Fe(NO3)3
solution with 20. ml of water? (The final
volume should be 20. + 30. = 50. ml)
Dilution Problems
Example:
What volume of a 2.0 M NaOH stock solution is
required to mix 1.50 L of a .150 M NaOH
solution?
Dilution Problems
Example:
What volume of a 2.0 M NaOH stock solution is
required to mix 1.50 L of a .150 M NaOH
solution?
M x V = moles.
.150 M x 1.50 L = .225 moles NaOH
.225 moles NaOH x 1 L/ 2.0 moles= .113 L
Dilution Problems
1) What volume of a 6.0 M NaOH stock solution
is required to mix 1.50 L of a .150 M NaOH
solution?
2) What volume of a 2.0 M MgCl2 stock solution
is required to mix 1.750 L of a .10 M MgCl2
solution?
3) What volume of a 1.0 M HCl stock solution is
required to mix 100. ml of a .10 M HCl
solution?
Volume Stoichiometry
• If you mix 10. ml of .10 M HCl with .10 M
NaOH,
• …it should take 10. ml of the NaOH to react
completely.
Volume Stoichiometry
• If you mix 10. ml of .10 M HCl with .20 M
NaOH,
• …it should take only 5.0 ml of the NaOH to
react completely.
Volume Problems
1) If you react 10.0 ml of .10 M HCl with .050 M
NaOH, what volume of NaOH solution will be
needed?
2) If you react 10.0 ml of .10 M H2SO4 with .050
M NaOH, what volume of NaOH solution will
be needed?
3) If you react 50.0 ml of 1.0 M CaCl2 with 1.9 M
Na2CO3, what volume of Na2CO3 solution will
be needed?
Volume Stoichiometry
• If 10. ml of .10 M HCl reacts completely with
10. ml NaOH,
• …the concentration of the NaOH must be the
same, .10 M
Volume Stoichiometry
• If 10. ml of .10 M HCl reacts completely with
20. ml NaOH,
• …the concentration of the NaOH must be half
of that, .050 M.
Volume problems
• If 25.0 ml of .30 M HCl reacts completely with
25. ml NaOH, what is the concentration of the
NaOH?
• If 10.0 ml of .10 M HCl reacts completely with
20. ml NaOH, what is the concentration of the
NaOH?
• If 15.0 ml of .10 M HCl reacts completely with
50. ml Pb(NO3)2, what is the concentration of
the Pb(NO3)2?
Acids and Bases
Examples?
• Acids
• Bases
Properties of Acids and Bases
• Acids
• Bases
Properties of Acids and Bases
• Acids
Are electrolyte solutions
• Make ions in solution
• Affect indicators
• Have low pH
• Taste sour
• Neutralize bases
Can cause serious burns
Corrode reactive metals
Have more H+ than OH(in solution)
• Bases
Are electrolyte solutions
• Make ions in solution
• Affect indicators
• Have high pH
• Taste bitter
• Neutralize acids
Can cause serious burns
Corrode aluminum only
Have more OH- than H+ (in
solution)
Properties of Both
• Acids
Are electrolyte solutions
• Make ions in solution
• Affect indicators
• Have low pH
• Taste sour
• Neutralize bases
Can cause serious burns
Corrode reactive metals
Have more H+ than OH(in solution)
• Bases
Are electrolyte solutions
• Make ions in solution
• Affect indicators
• Have high pH
• Taste bitter
• Neutralize acids
Can cause serious burns
Corrode aluminum only
Have more OH- than H+ (in
solution)
BrØnsted-Lowry Definition
• Substances that donate a proton (H+ ion) in a
reaction are acids.
• Substances that accept a proton (H+ ion) are
bases.
Arrhenius acids and bases make H+ and OH- ions in
solution. BrØnsted-Lowry bases are also Arrhenius
bases.
pH
• The basic (and acidic) definitions are:
pH= -log [H+]
[H+]= 10-pH
pOH= -log [OH-]
[OH-]=10 -pOH
Kw=[H+][OH-]=1 x 10 -14 (at 25oC)
pH + pOH = 14 (at 25oC)
pH practice
•
If pH is 3.38….
1) What is the pOH?
pH practice
•
If pH is 3.38….
1) What is the pOH? 14-pH= 10.62
pH practice
•
If pH is 3.38….
1) What is the pOH? 14-pH= 10.62
2) What is [H+]?
pH practice
•
If pH is 3.38….
1) What is the pOH? 14-pH= 10.62
2) What is [H+]? 10-3.38= 4.17 x 10-4M
pH practice
•
If pH is 3.38….
1) What is the pOH? 14-pH= 10.62
2) What is [H+]? 10-3.38= 4.17 x 10-4M
3) What is [OH-]?
pH practice
•
If pH is 3.38….
1) What is the pOH? 14-pH= 10.62
2) What is [H+]? 10-3.38= 4.17 x 10-4M
3) What is [OH-]? 10-10.62=2.40x10-11M and
Kw/4.17x10-4M=2.40x10-11 M!
pH practice
•
If [OH-]= 4.8 x 10-6 M…
pH practice
•
If [OH-]= 4.8 x 10-6 M…
1) What is pOH?
pH practice
•
If [OH-]= 4.8 x 10-6 M…
1) What is pOH? -log (4.8 x 10-6 )= 5.32
pH practice
•
If [OH-]= 4.8 x 10-6 M…
1) What is pOH? -log (4.8 x 10-6 )= 5.32
2) What is pH?
pH practice
•
If [OH-]= 4.8 x 10-6 M…
1) What is pOH? -log (4.8 x 10-6 )= 5.32
2) What is pH? 14-5.32= 8.68
pH practice
•
If [OH-]= 4.8 x 10-6 M…
1) What is pOH? -log (4.8 x 10-6 )= 5.32
2) What is pH? 14-5.32= 8.68
3) What is [H+]?
pH practice
•
If [OH-]= 4.8 x 10-6 M…
1) What is pOH? -log (4.8 x 10-6 )= 5.32
2) What is pH? 14-5.32= 8.68
3) What is [H+]? 10-8.68= 2.08 x 10-9 M and Kw/
4.8 x 10-6 = 2.08 x 10-9 M !
Please recall:
• Strong acids and bases dissociate completely
in water. Weak acids/bases do not.
• Strong acids= nitric, hydrochloric, sulfuric,
hydrobromic, hydroiodic, perchloric
• Strong bases-Group 1 & 2 hydroxides—(group
2’s don’t dissolve much)
Please recall:
1. What is the concentration (M) of NaOH if .35
mole NaOH is dissolved in .120 L solution?
2. What is the molarity of HCl if 12 g HCl is
dissolved in .85 L of solution?
3. What is [OH-] if .35 g Ba(OH)2 is dissolved in
.250 L solution?
4. What mass of H2SO4 is in 55 ml of .38 M
H2SO4?
Please recall:
1. What is the concentration (M) of NaOH if .35
mole NaOH is dissolved in .120 L solution?
2. What is the molarity of HCl if 12 g HCl is
dissolved in .85 L of solution?
3. What is [OH-] if .35 g Ba(OH)2 is dissolved in
.250 L solution?
4. What mass of H2SO4 is in 55 ml of .38 M
H2SO4?
Did you
notice?
Analyze these solutions
Contents
pH
[H+] (M)
[OH-] (M)
pOH
1 .023 mol HCl /L
2 1.5g NaOH /L
3 ?
mol
LiOH / L
4 ?
KOH/L
8.50
mol
5 .? gHClO4 /L
6 ?
mol
Ba(OH)2/L
2.50
.020
.0070
Acidic
or Basic
Right!
pH
[H+] (M)
[OH-] (M)
1 .023 mol HCl /L
1.64
.023
4.3x10-13 12.36 Acidic
2 1.5g NaOH /L
12.57 2.7x10-13 .0375
1.43
Basic
3 3.2 x10-6 mol
LiOH / L
8.50
3.2x10-9
3.2x10-6
5.50
basic
4 3.2 x10-3 mol
KOH/L
11.50 3.2x10-12 3.2x10-3
2.50
basic
5 2.0 gHClO4 /L
1.70
6 .0035 mol
Ba(OH)2/L
11.85 1.4x10-12 .0070
Contents
.020
pOH
Acidic
or Basic
5.0x10-13 12.30 acidic
2.15
basic
Conjugates
• After an acid has donated a proton, the rest of
the species is the conjugate base.
HAA- + H+
• After a base has accepted a proton, the
resulting species is the conjugate acid.
B- + H+ HB
What is the conjugate base of…
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HCl
CH3COOH
H2SO4
HSO4H2O
NH4+
NH3
What is the conjugate base of…
ACID (loses H+ to form its) Conjugate base
• HCl
• CH3COOH
• H2SO4
• HSO4• H2O
• NH4+
• NH3
What is the conjugate base of…
ACID (loses H+ to form its) Conjugate base
• HCl
(  H+ and)
Cl• CH3COOH
• H2SO4
• HSO4• H2O
• NH4+
• NH3
What is the conjugate base of…
ACID (loses H+ to form its) Conjugate base
• HCl
(  H+ and)
Cl• CH3COOH(  H+ and)
CH3COO• H2SO4 (  H+ and)
HSO4• HSO4(  H+ and)
SO4-2
• H2O
(  H+ and)
OH• NH4+
(  H+ and)
NH3
• NH3
(  H+ and)
NH2-
What is the conjugate acid of…
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•
•
•
•
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NO3C2O4-2
HPO4-2
HSO4H2O
F-
What is the conjugate acid of…
Base (gains H+ to form its) Conjugate acid
• NO3• C2O4-2
• HPO4-2
• HSO4• H2O
• F-
What is the conjugate acid of…
Base (gains H+ to form its) Conjugate acid
• NO3(+H+  )
HNO3
• C2O4-2
• HPO4-2
• HSO4• H2O
• F-
What is the conjugate acid of…
Base (gains H+ to form its) Conjugate acid
• NO3(+H+  )
HNO3
• C2O4-2 (+H+  )
HC2O4• HPO4-2 (+H+  )
H2PO4• HSO4(+H+  )
H2SO4
• H2O
(+H+  )
H3O+
• F(+H+  )
HF
Nomenclature
• If the anion name
•
ends in….
then the acid name
is…
Fill in the blanks
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HCl is _____________acid
HClO4 is _____________acid
HClO3 is _____________acid
HClO2 is _____________acid
HClO is _____________acid
Hydrogen chloride
Hydrogen chlorate
Fill in the blanks
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•
•
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Hydrogen perchlorate
HCl is _____________acid
HClO4 is _____________acid
HClO3 is _____________acid
HClO2 is _____________acid
HClO is _____________acid
Hydrogen chlorite
Hydrogen hypochlorite
Nomenclature
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•
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If the anion name
ends in….
--ide
(hypo--) --ite
--ite
--ate
(per--) –ate
then the acid name
is…
Hydro___ic acid
Hypo___ous acid
___ous acid
___ic acid
Per ___ic acid
Fill in the blanks
• HNO3 is _____________acid
• HIO4 is _____________acid
• H2CO3 is _____________acid
• H3PO3 is _____________acid
• HBrO is _____________acid
Fill in the blanks
• _____________is hydrocyanic acid
• _____________ is perbromic acid
• _____________ is phosphoric acid
• _____________ is sulfurous acid
• _____________ is hypoiodous acid
Show the conjugate acid/base pairs in the
following reactions.
• HC2O4- + HNO3 
H2C2O4 + NO3-
• HC2H3O2 + PO4-3 
HPO4-2 + C2H3O2 -
Show the conjugate acid/base pairs in the
following reactions.
Acid
• HC2O4- + HNO3 
Base
• HC2H3O2 + PO4-3 
Conjugate
Base
H2C2O4 + NO3Conjugate
Acid
HPO4-2 + C2H3O2 -
Show the conjugate acid/base pairs in the
following reactions.
Acid
• HC2O4- + HNO3 
H2C2O4 + NO3Conjugate
Acid
Base
Base
• HC2H3O2 + PO4-3 
Acid
Conjugate
Base
Conjugate
Acid
HPO4-2 + C2H3O2 Conjugate
Base
[H+] is inversely related to [OH-]
• When [H+] increases, [OH-] decreases in a
water solution, and vice versa.
Review question:
125 ml of a KOH solution is mixed so that the
pH is 12.23
1) What is the pOH, [OH-] and [H+]?
2) What is the [KOH] ?
3) How many moles KOH was used?
4) What mass of KOH was used?
(FMKOH= 56.1 g/mol)
Review question:
125 ml of a KOH solution is mixed so that the pH
is 12.23
1)pOH=1.77;[OH-]=.0170M;[H+]=5.88x10-13M
2) [KOH]=[OH-]= .0170M (it’s a strong base!)
3)moles=MxV=.0170Mx.125L=.00213mol
4) massKOH =molesKOHx FMKOH
= .00213mol x 56.1 g/mol
=.119 g
Strength of acids and bases.
• HCl
• H2CO3
Strength of acids and bases.
• HCl -- strong acid
• H2CO3 -- weak acid
Strength is
determined by
amount of
dissociation
Strength of acids and bases.
• HCl -- strong acid, it dissociates completely
• H2CO3 -- weak acid, dissociates partly
• What about their conjugates?
Strength of acids and bases.
• Cl• HCO3-
Strength of acids and bases.
• Cl- -- not a base
• HCO3- -- weak base
Strength is
determined by
amount of
association
Strength of acids and bases.
• Cl- -- not a base, it does not associate with
water.
• HCO3- -- weak base, it associates partly
• What about their conjugates?
Strength of acids and bases.
The conjugate of a strong acid is not a base
The conjugate of a weak acid is a weak base
The conjugate of a strong base is not an acid
Strength of acids and bases.
The conjugate of a strong acid is not a base
The conjugate of a weak acid is a weak base
the stronger the acid, the weaker the base
and vice versa
The conjugate of a strong base is not an acid
When dissolving acids and bases…
• For an acid, HA
• For a base, B-
When dissolving acids and bases…
• For an acid, HA
HA (aq)H+ (aq) +A- (aq)
• For a base, BB- (aq) +H2O (l) HB (aq) +OH- (aq)
Write the reaction for:
• Ammonia associating with water
• Ammonium dissociating in water
Write the reaction for:
• Ammonia associating with water
NH3(aq) + H2O (l)  NH4+ (aq) + OH- (aq)
• Ammonium dissociating in water
NH4+ (aq)  H+ (aq) + NH3 (aq)
Write the reaction for:
• Cyanide associating with water
• Oxalic acid dissociating in water
On your test, you will be asked to:
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Calculate molarity in dissolving, dilution, & titration
Calculate mass % composition
Calculate mass and moles of solute in solutions
Calculate volume of solution
Calculate pH, pOH, [H+], and [OH-]
Name acids and write formulas for conjugates
Pick out acids, bases, and conjugates in a reaction
Write association and dissociation reactions
Compare strength of acids and bases