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- Instructor: Upali Siriwardane (Ph.D., Ohio State University)
- CTH 311, Tele: 257-4941, e-mail: upali@chem.latech.edu
- Office hours: 10:00 to 12:00 Tu & Th ; 8:00-9:00 and 11:00-12:00 M,W,& F
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- Tests will be given in regular class periods from 9:30-10:45
a.m. on the following days:
- September 22, 2004 (Test 1): Chapters 1 & 2
- October 8, 2004(Test 2): Chapters 3,
& 4
- October 20, 2004 (Test 3):
Chapter 5 & 6
- November 3, 2004 (Test 4):
Chapter 7 & 8
- November 15, 2004 (Test 5): Chapter
9 & 10
- November 17, 2004 MAKE-UP: Comprehensive
test (Covers all chapters
- Grading:
- [( Test 1 + Test 2 + Test3 +
Test4 + Test5)] x.70 + [ Homework + quiz average] x 0.30 = Final Average
- 5
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- 1. Types of chemical reactions : combination, decomposition, or
replacement.
- 2. Classes of chemical reactions: precipitation, reactions with oxygen,
acid–base, and oxidation–reduction.
- 3. Solution terms: solution, solute, and solvent.
- 4. Kinds of solutions: gas/liquid, liquid/ liquid, solid/liquid
- 5. Solubility and equilibrium.
- 6. Solution concentration: weight/volume
percent and weight/weight percent.
- 7. Solution concentration: molarity.
- 8. Dilution: Preparing solutions.
- 9. Interconvert molar concentration of ions and illiequivalents/liter.
- 10. Concentration-dependent solution properties: Collegative properties.
- 11. Unique chemical and physical properties of water.
- 12. Role of electrolytes in blood and their relationship to the process
of dialysis.
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- We can classify some chemical reactions according to certain patterns
that are observed. This helps us to predict the products of reactions.
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6
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7
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8
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9
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- 2Al(OH)3(s) g Al2O3(s) + 3H2O(g)
- Fe2S3(s) g 2Fe(s)
+ 3S(s)
- Na2CO3(aq) + BaCl2(aq) g BaCO3(s)
+ NaCl(aq)
- C(s) + O2(g) g CO2(g)
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- Precipitation reactions: mix
reactants together and get an insoluble precipitate (not soluble in
water).
- How do you know what cmpds are insoluble?
- Learn table 7.1
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- 1A salts, NO3-’s, acetates (CH3COO-),
NH4+’s are very soluble.
- Cl-’s, Br-’s and I-’s are soluble
except when combined with Ag+, Pb2+, Hg22+.
- CO32-’s, PO43-’s, S 2-’s
generally insoluble (except for 1A’s and NH4+)
- OH-’s: Ba2+, 1A’s are soluble; others generally
insoluble
- **The SO42-’s of Ba2+, Ag+,
Ca2+, Sr2+, Pb2+are insoluble. Others
are soluble.
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- Ag2SO4
- Li2S
- Pb(NO3)2
- AgCl
- BaSO4
- (NH4)2SO4
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- Zinc sulfate and barium chloride
- Sodium sulfate and potassium chloride)
- Ammonium carbonate and calcium chloride
- Strontium nitrate and potassium phosphate
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- Combustion Reactions: When compounds containing C and H react with O2
(burning or combustion) get CO2 and H2O.
(Greenhouse effect)
- Corrosion: 4Fe(s) + 3O2(g)
g 2Fe2O3(s) rust
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- Acid-base reactions involve transfer of a H+ from the acid
(starts with H) to the base (hydroxide) to form a salt and water
- Oxidation-reduction will be covered in Chapter 9
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- A solution is a homogeneous mixture of two or more substances and is
made up of a solvent and one or more solutes.
- The solutes are the species that
are being dissolved in the solvent. The solvent is usually present in
the greater amt.
- An aqueous solution has ________ as the the solvent.
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- gas in gas --air
- gas in liquid--soda
- gas in solid--gas on solid catalyst
- liquid in liquid
- liquid in solid--mercury amalgam
- solid in liquid
- solid in solid--14-karat gold
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- Ionic compounds (electrolytes) dissociate into ions when dissolved in
water. The solutions conduct electricity.
- Molecular compounds in general do not dissociate into ions in aqueous
solution. The solutions do not conduct electricity and are
________________.
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- 1. A solution is a ___________ mixture. Each species in the solution
- 2. retains its ________ identity.
- 3. __________composition
- 4.clear and transparent (but can have color)
- 5. remains uniform throughout for all time
- 6. can be separated into its components by ___________ means.
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- Solute size is _________________.
- The solute cannot be separated from the solvent by paper filtration.
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- Colloids: have similar properties as solutions but the particle size is
- Colloids behave differently when
exposed to light.
- ________ effect helps distinguish between solutions and colloids.
- Homogenized milk is a _____________.
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- Emulsions, suspensions; larger particle size than solutions. Solute
separates on standing.
- Particle size is > 200nm.
- Filterable.
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- Can dissolve different amounts of solute in solvent.
- Maximum amount of solute that can be dissolved in a given amt of solvent
at a given temp:____________
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- Say a solution is __________ if the maximum amount of solute is
dissolved in a given solvent.
- Solid Dsolution
- Dynamic equilibrium set up between dissolved and undissolved solute
- Maximum amout of solute that can be dissolved in a given amt of solvent
at a given temp: solubility
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- If a solution has less than the max amt dissolved:
- If a solution has more than the max amount dissolved: ______________:
unstable--excess solute will fall to bottom and form a precipitate.
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- Like dissolves like--smaller difference in polarity between solute and
solvent, more soluble.
- Polar solutes in polar solvents
- Non-polar solutes in non-polar solvents
- Ionic solids in polar solvents
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- I. Temperature
- A. ionic compound in water:
- B. Gas in water:
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- II. Pressure
- A. Pressure changes have little effect on the solubility of a solid or
liquid in another liquid.
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- B. The solubility of a gas in a liquid
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- Under 1 atm total pressure, the partial pressure of O2 is 159
mmHg and the solubility of O2 in blood is 44g/100mL.
- In Denver (mile high city) PO2 = 132mmHg and the solubility
of O2 in the blood is 37g/100mL
- Mt Whitney (2.5miles high) PO2 = 98 mmHg and the solubility
of O2 in the blood is 27g/100mL
- Mt Everest (5.8 miles) PO2
= 52 mmHg and the solubility of O2 in the blood is 14g/100mL
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- The solubility of N2 in blood at 37oC and at a
partial pressure of 0.80 atm is 5.6 x 10-4 mol/L.
- A deep sea diver breathes compressed air with the partial pressure of N2
equal to 4.0 atm. How much N2 is dissolved in the blood at
this pressure?
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- Concentration gives us the amount of solute dissolved in a given amt of
solvent or in a given amt of solution.
- There are different ways of expressing concentration.
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- Weight/volume percent
- weight/volume% (W/V%)=
- (mass of solute in g¸ vol of soln in mL) x 100%
- Note that the volume of a
solution does not equal the volume of solute and solvent.
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- Weight/weight percent
- Weight/weight % (W/W%) = (mass of solute ¸ mass of solution) x 100%
- The mass of the solution =
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- Calc the composition of the soln in W/V%: 20.0g acetic acid in 2.50L
sollution
- Calc the W/W % of 31.0 g of KCl
in 152 g of water.
- Calc the W/W% of 50.0 g KCl in 5.00 x 102 mL solution (d =
1.14g/mL)
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- How many grams of solute are needed to prepare:
- A. 2.50 x 102 g of 5.00% (W/W) NH4Cl
- B. 2.50 x 102 mL of 3.50% (W/V) Na2CO3
- Calc the amount of water that must be added to 5.00 g of urea (NH2)2CO
in the preparation of a 16.2 W/W % by mass solution.
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- Molarity (M) = moles of solute ¸ vol of soln in L
- units of molarity: mol of solute/L solution
- M = moles solute(M )/V and #moles = M x V
- Molarity and W/V% are temperature dependent.
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- Calc the molarity of 20.0g acetic acid in 2.50L solution.
- Calc the no of grams of solute needed to make 2.50 x 102 mL
of 0.200M KOH.
- Calc the volume, in ml, needed to provide 2.14g of NaCl from a 0.270M
solution.
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- When a solution is diluted you add more solvent. The no. of moles of
solute does not change. (#moles= M
x V)
- So initial vol x molarity (mol/L) = # mol solute and final vol x new
molarity = same # moles # moli = # molf
- So MiVi = MfVf
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- 50.0mL of a 0.250M sucrose soln was diluted to 5.00 x 102 mL.
What is the molar conc of the resulting solution?
- A 6.00 mL portion of an 8.00M stock solution is to be diluted to 0.400M.
What will be the final volume after dilution?
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- molality (m) = moles of solute/mass in kg of solvent
- A 2.5m (molal) NaCl solution has 2.5moles of NaCl dissolved in 1000g or
1kg of solvent
- Molality is temperature independent.
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- Colligative properties are properties
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- So NaCl(aq) g Na +(aq) + Cl-(aq)
- K2SO4(aq) g 2K+(aq) +
SO42-(aq)
- C12H22O11(aq) g C12H22O11(aq)
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- We are going to examine the effect of adding a solute to a solvent on
- 1. vapor pressure
- 2. freezing point
- 3. boiling point
- 4. osmosis
- Remember that colligative properties depend only on the number of
particles in solution and not on their identity.
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- When a solute is added to a solvent the vapor pressure (equilibrium) of
the solution is lower than that of the pure solvent. (explain)
- Raoult observed the relationship between the amount of the solvent and
the vapor pressure of the solution
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- What effect does vp lowering have on the freezing pt and boiling pt of a
solution?
- Since the vapor pressure of the solution is lower than the vapor
pressure of the pure solvent,
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- When a nonvolatile solute is added to a solvent the freezing point of
the solution is lowered. (explain)
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- Dtf = I mkf kf is the freezing pt
constant
- i = no of particles in solution per formula unit
- For molecular species i =1
- For NaCl i = These
i values
- For K2SO4 i = assume 100%
- For Al2(SO4)3 i = ionization.
- For water kf = 1.86oC/m
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- Dtb = imkb kb is the b. pt.
constant; m is the molality of the solution and i is the no. of
particles in solution.
- For water kb =0.52oC/m
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- What are the normal freezing and boiling pts of
- a. 58.5g NaCl in 100. g of water
- b. 60.0 of urea [(NH2)2CO]
in 100. g of water.
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- Certain materials allow passage of molecules of a certain size through
but not bigger molecules. These are called __________________ membranes.
- When have pure solvent and a
solution separated by a semipermeable membrane (or 2 solutions of
different concentrations), “nature” wants the concentrations in the 2
sides to be the same.
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- So the solvent moves from the less concentrated to the more concentrated
side to try to make the concs of the 2 solns the same. Process is called
- Osmotic pressure (p) is the
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- p= I MRT where M is the molarity
of the soln; R = 0.0821 L atm/Kmol and T is the temp in Kelvin
- Have to remember that osmosis is a colligative property and depends on
the no of particles in solution and not their identity.
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- Blood: 0.30M on particles
- 0.90% saline and 5.0% glucose are also 0.30 M --isotonic with blood
(intracellular fluids)
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- Calc the osmotic pressure of 0.50M NaCl and 0.50M sucrose. Assume a temp
of 25oC.
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- Which has higher m. pt?
- Which has higher b. pt?
- Which has higher vapor pressure?
- Each solution is separated from water by a semipermeable membrane. Which
solution has the higher osmotic pressure?
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Notes
