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What do we know about water? MP= _0 o C__Bond type= _PC__ BP= _100 o C_Molecule Shape_Bent_ FP= __0 o C__Molecular Polarity_P_ Type of IMF __strong Hydrogen Bonding___
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Learning Objectives• Explain, in terms of composition and properties, why all solutions are
homogeneous mixtures• Label the solute and solvent of a solution• Describe how temperature, pressure, and the nature of the solute and solvent
affect solubility• Predict the solubility of a substance in a polar or nonpolar solvent according to the
general rule for solubility• Determine if a substance is soluble or insoluble in water using the Solubility
Guidelines in Aqueous Solution Reference Table F• Use the Solubility Curves Reference Table G to classify a solution saturated,
unsaturated or supersaturated at a stated temperature• Express the concentration of a solution in molarity, percent concentration by mass
or volume, and parts per million• Perform mathematical calculations to determine the amount of solute and solvent
in a solution of known molarity, percent concentration, or parts per million• Describe the proper procedure for preparing a solution of known molarity• Relate the concentration of dissolved particles to the boiling point and freezing
point of the solution
What do we know about water?
MP= _0oC__ Bond type= _PC__
BP= _100oC_ Molecule Shape_Bent_
FP= __0oC__ Molecular Polarity_P_
Type of IMF __strong Hydrogen Bonding___
Draw a WATER molecule:
Special Characteristics of H2O:
• Capillary Action: Water climbs up a narrow tube• Adhesion: water is attracted to other materials
(meniscus)• Cohesion: water clings to itself
• Surface Tension: strength of H bonding causes water molecules to be attracted inward (bugs can walk on water, rain drops, etc.)
Mixtures• Ratio of components can vary
• Can be separated physically
• Can be homogeneous or heterogeneous
MIXTURE COMPOUND Components?
Elements and/or compounds
2 or more different elements
Combined physically or chemically?
physically
chemically
Homogeneous or Heterogeneous?
homogeneous OR heterogeneous
onlyhomogeneous
Represented by formula?
Maybe, followed by the subscript (aq)
Always, 2 or more different capital
letters, subscript: s, l, g
Are properties the same or different than of components?
Components retain their own properties
Properties are different
a.How decomposed into components?b. Sample means of separation?
a. physically b. filtration, distillation
a. chemically b. electrolysis
Solution: homogeneous mixture of 2 or more compounds
• Aqueous: solution in which water is the solvent
Characteristics of a solution:
1. Transparent2. Particles will not settle out3. Can NOT be filtered4. Homogeneous 5. Can have color
NaCl(aq)
1. SOLUTE: substance that gets dissolved* Substance present in the smaller amountNaCl
2. SOLVENT: substance that does the dissolving * Substance present in the greater amountwater
Soda Water• A mixture of a GAS (CO2(g)) in a LIQUID
• The solvent is WATER and the solute is CO2(g)
Tincture• Solution in which alcohol is the
solvent
• Used to dissolve NP substances
• Ex: Iodine
Why is a solution a mixture?
1. ratio of solute & solvent can vary
2. Physically combined & separated
How to separate a solution into its components?
Evaporation/Dehydration Distillation
Distillation• Separation of 2
or more LIQUIDS by BP
• Liquid with lower BP boils first, rises then condenses into a collection vessel.
• Liquid with higher BP stays in original vessel
Types of solutions:
• Dilute: soln having a low amount of solute• Concentrated: soln having a high amount
of solute• Saturated: soln having the maximum
grams of solute at a given temperature• Unsaturated: soln that can hold (dissolve)
more grams of solute at a given temperature• Supersaturated: soln having more grams
of solute than it can hold at a given temperature UNSTABLE!!!!
Solution EquilibriumIn a saturated soln, the
rate of dissolving=rate of crystallization
Reference Table F:Solubility Guidelines for
Aqueous Solutions
Use ref. table F to determine if the following are soluble (S) or insoluble (I or
ppt)1. KBr 8. KClO3
1. NaHCO3 9. NH4OH
1. Al(OH)3 10. CaCO3
1. Cu(NO3)2 11. CuS
1. Fe3(PO4)2 12. ZnI2
1. PbSO4 13. Mg(C2H3O2)2
1. K2S 14. PbCrO4
Use ref. table F to determine if the following are soluble (S) or insoluble (I or
ppt)1. KBr 8. KClO3
1. NaHCO3 9. NH4OH
1. Al(OH)3 10. CaCO3
1. Cu(NO3)2 11. CuS
1. Fe3(PO4)2 12. ZnI2
1. PbSO4 13. Mg(C2H3O2)2
1. K2S 14. PbCrO4
Reference Table G: Solubility Curves
Table GSolubility Curves at Standard Pressure
Solving Solubility Problems using Ref. Table G:
1.) Identification of a. solute ( formula and mass(g)) b. temperature(s) c. grams of water (solvent) 2.) Use table G to solve based on 100g H2O a. 1 temp: solve directly b. 2 temp: subtract solubilities at each temp. 3.) If solvent is NOT 100g: set up a proportion solubility from graph = x________ 100g H2O g H2O from problem
How many grams of KCI are required to saturate 100g water at 60oC?
Which mass of KI will supersaturate 100g H2O at 16oC?
130g 140g 150g
At which temperature will 80g KNO3/100g H2O be supersturated?
40oC or 50oC?
Which of the following would result in an unsaturated solution of NaCl at 90oC?
30g 40g 50g
Formation of a precipitate:
• When a saturated solution is cooled, solid precipitate forms as the solubility decreases.
• (the solvent can’t “hold” as much solute so it “falls out of solution”
• Hint: 2 temps are given
How many grams of KCI will precipitate out when a saturated solution in 100g water is cooled from 90oC to 70oC?
Practice: 1. Classify the following as unsaturated, saturated, or supersaturated :
a. 115g NaNO3 at 25oC ____________________________
b. 115g NaNO3 at 50oC ____________________________
c. 60g NH3 at 10oC ____________________________
d. 50g KClO3 at 89oC ____________________________
e. 50g KCl at 89oC ____________________________
2. At what temp. do KClO3 & KCl have the same solubility? ________________________
3. How many grams of KNO3 are required to saturate 100g water at 45oC? __________________
4. At what temp will 100g KNO3 saturate 100g water? ___________________________________
5. At 50oC, 100g water is saturated with KNO3 . How many grams of KNO3 will precipitate out when the solution is cooled to 40oC?
6. How much KClO3will precipitate out when a saturated solution in 100g water is cooled from 30oC to 3oC?
7. What is the smallest mass of water required to dissolve completely 23g ammonium chloride at 40oC?
8. How many grams of NaCl are required to saturate 500g water at
100oC?
9. If 75g of a substance will saturate 20g water, what is the solubility
of the substance?
A student was able to dissolve 20g of water with 15.2g of a substance at 46oC. Identify the solute.
Solubility Curves pg 19 HMWK:
1. SO2, NH3, HCl gas2. more3. KClO39. KNO3
4. NaCl 10. 21g5. 95oC 11. 10g6. NH4Cl 12. 12g7. 40g8. 200g
Factors that affect solubilityTemperature
1. Heat on dissolving a solid in a liquid:
increases – more dissolves (heat up sugar & water to make it dissolve2. Heat on dissolving a gas in a liquid: decreases
Factors that affect solubility
Pressure
1. pressure on dissolving a solid in a liquid:
no effect
2. Pressure on dissolving a gas in a liquid: increases ( propane tank, can of soda)
Gases have increased solubility under
___________ Temp, __________ Pressure
Factors that affect solubility
Nature of Reactants
1. Determine POLARITY of solute & solvent
2. Solubility rule: “LIKE DISSOLVES LIKE”
Factors that affect solubility
Nature of Reactants
1. Polar & Ionic will dissolve in _polar_ solvents, NOT __NP___solvents
2. Nonpolar solutes will dissolve in _NP__ solvents, NOT in _P____ solvents
Examples of common solvents
POLAR• Water, H2O
• Alcohol, CH3OH & C2H5OH
NONPOLAR• CCl4
• Liquid benzene & toluene
Alcohol• Are slightly polar so they will dissolve
BOTH polar & nonpolar solutes
• BUT NOT IONIC solutes!!!!
LIKE DISSOLVES LIKESubstance polarity substance polarity will they mix? NaCl H2O _________ ______________
Oil H2O _________ ______________
Br2 H2O _________ ______________
KCl Br2 _________ ______________
NH3 CCl4 _________ ______________
NH4Cl CH3OH _________ ______________
NH3 CH3OH _________ ______________
I2 ___________________ CH3OH _________ ______________
What happens when ionic solute is placed into a polar solvent?
What happens when polar solute is placed into a polar solvent?
Dissociation:• Occurs when ionic solids break apart
into ions when placed in a polar solvent (water)
What happens when polar solute is placed in polar solvent?
What happens when polar solute is placed in polar solvent?
Miscible:• 2 liquids that can mix together
– Polar or ionic with polar or ionic
– Nonpolar with nonpolar
Miscible vs. Immiscible
Solubility Rule HMWK:SOLUTES
polar or nonpolar?
WaterSOLVENTS
CCl4
Alcohol
1. NaClYES NO NO
1. I2NO YES YES
1. Ethanol(C2H5OH) YES YES YES
1. Benzene (C6H6) NO YES YES
1. Br2
NO YES YES
1. KNO3
YES NO NO
1. Toluene NO YES YES
1. Ca(OH)2
YES NO NO
9. Use the solubility rule, “like dissolves like” to compare the solubility of solid iodine in liquid benzene (NP):Iodine will dissolve in benzene because both are nonpolar
10.Use the solubility rule, “like dissolves like” to compare the solubility of solid sodium chloride in liquid water and in liquid benzene (NP):NaCl is ionic (EXTREMELY POLAR) and will dissolve in polar water but not in nonpolar benzene.
11.Use the solubility rule, “like dissolves like” to compare the solubility of liquid ethanol in liquid water and in liquid benzene (NP): Ethanol is slightly polar so it will dissolve in both polar water and nonpolar benzene
12.Why does water dissolve so many ionic compounds? Because the polar water molecule has oppositely charged ends which attract the charged ions of ionic compounds.
In the space provided draw a labeled particle diagram to show the dissociation of NaCl ions by water molecules acting on NaCl crystals:
Quantitative expression of concentration:
1. % composition % by mass = grams solute X100 % by volume = mL solute X100
grams solution mL solution
2. Parts Per million (ppm) = grams solute X 1,000,000 grams solution
3. Molarity
Molarity = moles solute “M” = molar or moles/liter Liter solution
% by mass = grams solute% by volume = mL solute grams solution mL solution
Parts Per million (ppm) = grams solute X 1,000,000 grams solution
Steps to calculate MOLARITY:
1.convert grams, if given, to moles: grams = moles X gram
formula mass
2.convert volume to liters, if necessary
3.use formula from table S: Molarity= moles/liters
4.unit for answer is “M”
Calculate the molarity of CuSO4 that contains 80g solute in 500mL of solution.
Calculate the mass of KClO3 needed to make 780mL of a 0.05M solution.
Grams solute Gram Formula Mass Moles Liters Molarity
1 HC2H3O3 1.0 800mL
2 H3PO4 2.0 2L
3 50.0gCuSO4*5H2O
250mL
4 112gKOH
1.5L
5 100gCaBr2
750mL
6 500mL 3M NaOH
7 1.5L 6M HCl
8 250mL 2M H2SO4
9 750mL 0.1M KBr
10 2.5L 0.1M Ba(NO3)2
11 X gramsNaOH
5L 10M NaOH
12 X gramsH2SO4
750mL 4M H2SO4
13 X gramsKI
1L 0.500M KI
Grams solute Gram Formula Mass Moles Liters Molarity
1 76 g/mol 0.8L 1/.8=1.25M
2 98 g/mol 2/2=1M
3 250g/mol 50/250=0.2 0.250L .2/.250=0.8M
4 56 g/mol 112/56= 2 2/1.5=1.4M
5 200 g/mol 100/200=0.5 0.750L 0.5/0.750=0.67M
6 1.5 moles 0.500L
7 9 moles
8 0.5 moles 0.250L9 0.075 moles 0.750L
10 0.25 moles11 2000g 40 g/mol 50 moles12 294g 98 g/mol 3 moles 0.750L13 83g 166g/mol 0.5 moles
Molarity by Dilution• Acids are usually acquired from chemical
supply houses in a concentrated form. These acids are diluted to the desired concentration by adding water. If all that changes is adding more water to a known molarity of acid, moles acid before dilution (1)= moles of acid after dilution(2). Moles= M x V.
• Dilution formula: M1V1 = M2V2
M1V1 = M2V2
Colligative Properties• Properties that change due to the number of
dissolved particles
Boiling Point ElevationFreezing Point Depression
Boiling Point Elevation• The addition of nonvolatile solute to water
causes the boiling point to raise. (Boils at a temp higher than 100oC)
• This is why you add salt to water when boiling pasta
Freezing Point Depression
• The addition of nonvolatile solute to water causes the freezing point to lower. (freezes at a temp lower than 0oC- stays liquid longer)
• This is why we salt the roads in the winter
Salts that dissociate to produce _more__ moles of ions in
solution cause a _bigger__ effect on BP or FP.
NaCl(s) Na+(aq) + Cl-
(aq)
H2O
CaCl2(s) Ca+2(aq) + 2Cl-(aq)
H2O
Al(NO3)3(s) Al+3(aq) + 3(NO3)-1
(aq)
H2O
Nature of solute on colligative properties:
Ionic solids have a __larger_____ effect on colligative properties than molecular.
NaCl(s) H2O Na+(aq) + Cl-(aq) C6H12O6(s) H2O C6H12O6(aq)
? Which of the following lower the freezing point the most on an icy road?(a) C6H12O6(s) (b) KCl (c) MF2(s) (d) Al(OH)3(s)
? Which of the following raise the boiling point the most when cooking pasta?(a) C6H12O6(s) (b) KCl (c) MF2(s) (d) Al(OH)3(s)
Solubility of a Salt Lab
• Place your group’s data on the data table found on the next slide.
• Calculate the class average and add this column to the data table in your lab.
• Plot, in a third color, the class average on the same set of axes.
Grams KNO3/5gH2O
Grams KNO3/100gH2O
Experimental crystallization temperature
Class Average
1.0 20.0
2.0 40.0
3.0 60.0
4.0 80.0