Solution Chemistry
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Transcript of Solution Chemistry
Solution Chemistry
Solutions, Problems, Solutions, Problems.
Does it ever end?
How can you express concentration?
How can you express concentration?
1) Mass % composition2) Molarity3) Molality4) Mole fraction5) 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 soluteVolume of solution (L)
Molarity problems:
• Find amount of solute
• M= moles soluteVolume of solution (L)
• Molarity x volume= moles!
Molarity problems:
• Find volume of solution
• M= moles soluteVolume 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 HClM = 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• AcidsAre electrolyte solutions• Make ions in solution• Affect indicators• Have low pH• Taste sour• Neutralize basesCan cause serious burnsCorrode reactive metalsHave more H+ than OH-
(in solution)
• BasesAre electrolyte solutions• Make ions in solution• Affect indicators• Have high pH• Taste bitter• Neutralize acidsCan cause serious burnsCorrode aluminum onlyHave more OH- than H+
(in solution)
Properties of Both• AcidsAre electrolyte solutions• Make ions in solution• Affect indicators• Have low pH• Taste sour• Neutralize basesCan cause serious burnsCorrode reactive metalsHave more H+ than OH-
(in solution)
• BasesAre electrolyte solutions• Make ions in solution• Affect indicators• Have high pH• Taste bitter• Neutralize acidsCan cause serious burnsCorrode aluminum onlyHave 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= 10.622) What is [H+]?
pH practice
• If pH is 3.38….
1) What is the pOH? 14-pH= 10.622) 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= 10.622) What is [H+]? 10-3.38= 4.17 x 10-4M3) What is [OH-]?
pH practice
• If pH is 3.38….
1) What is the pOH? 14-pH= 10.622) What is [H+]? 10-3.38= 4.17 x 10-4M3) 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 )= 5.322) What is pH?
pH practice
• If [OH-]= 4.8 x 10-6 M…
1) What is pOH? -log (4.8 x 10-6 )= 5.322) 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 )= 5.322) What is pH? 14-5.32= 8.683) What is [H+]?
pH practice
• If [OH-]= 4.8 x 10-6 M…
1) What is pOH? -log (4.8 x 10-6 )= 5.322) What is pH? 14-5.32= 8.683) 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 solutionsContents pH [H+] (M) [OH-] (M) pOH Acidic
or Basic
1 .023 mol HCl /L
2 1.5g NaOH /L
3 ? mol LiOH / L
8.50
4 ? mol KOH/L
2.50
5 .? gHClO4 /L .020
6 ? mol Ba(OH)2/L
.0070
Right!Contents pH [H+] (M) [OH-] (M) pOH Acidic
or Basic
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 .020 5.0x10-13 12.30 acidic
6 .0035 mol Ba(OH)2/L
11.85 1.4x10-12 .0070 2.15 basic
Conjugates
• After an acid has donated a proton, the rest of the species is the conjugate base.
HAA- + H+
• After a base has accepted a proton, the resulting species is the conjugate acid.
B- + H+ HB
What is the conjugate base of…
• HCl• CH3COOH• H2SO4
• HSO4-
• H2O• 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…
• NO3-
• C2O4-2
• HPO4-2
• HSO4-
• H2O• 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 then the acid name• ends in…. is…
Fill in the blanks
• HCl is _____________acid• HClO4 is _____________acid
• HClO3 is _____________acid
• HClO2 is _____________acid
• HClO is _____________acid
Fill in the blanks
• HCl is _____________acid• HClO4 is _____________acid
• HClO3 is _____________acid
• HClO2 is _____________acid
• HClO is _____________acid
Hydrogen chlorideH
ydro
gen
chlo
rate
Hydrogen perchlorate
Hydrogen hypochlorite
Hydrogen chlorite
Nomenclature
• If the anion name then the acid name• ends in…. is…• --ide Hydro___ic acid• (hypo--) --ite Hypo___ous acid• --ite ___ous acid• --ate ___ic acid• (per--) –ate 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.
• HC2O4- + HNO3 H2C2O4
+ NO3-
• HC2H3O2 + PO4-3 HPO4
-2 + C2H3O2 -
Acid
Base
ConjugateBase
Conjugate Acid
Show the conjugate acid/base pairs in the following reactions.
• HC2O4- + HNO3 H2C2O4
+ NO3-
• HC2H3O2 + PO4-3 HPO4
-2 + C2H3O2 -
Acid
Acid
Base
Base
ConjugateBase
Conjugate Acid
ConjugateBase
Conjugate Acid
[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+]=5.88x10-13M2) [KOH]=[OH-]= .0170M (it’s a strong base!)3)moles=MxV=.0170Mx.125L=.00213mol4) 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 versaThe 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, HAHA (aq)H+ (aq) +A- (aq)
• For a base, B-B- (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 waterNH3(aq) + H2O (l) NH4
+ (aq) + OH- (aq)
• Ammonium dissociating in waterNH4
+ (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:• 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