A.P. Exam Review

Saturday Session #1

“We all have dreams. But in order to make dreams into reality, it takes an awful lot of determination, dedication, self-discipline, and effort.” …Jesse Owens

“Do more than is required of you.” …General George S. Patton

“A man, as a general rule, owes very little to what he is born with - a man is what he makes of himself.” …Alexander Graham Bell

“It is easy to dodge our responsibilities, but we cannot dodge the consequences of dodging our responsibilities.” …Josiah Charles Stamp

“Accept responsibility for your life. Know that it is you who will get you where you want to go, no one else.” …Les Brown

“There is no elevator to success…you have to take the stairs!” …author unknown

“Satisfaction lies in full effort, not in the attainment. Full effort is full victory.” …Ghandi

“There is only the trying. The rest is not our business.” …T.S. Elliot

“The journey is the destination, man…” …Gerald

“What you do in life…echoes in eternity” …Maximus

7 months23 days

2 hours about 5 minutes

Now is the moment for which we have been preparing…

Exam Format

Planck’s EquationSpeed of Light Equation

acid dissociation constant

base dissociation constant

Definition of pH, pOH and p function

Henderson-Hasselbalch Eq.

Mass action expressions

First order integrated rate lawSecond order integrated rate lawHalf-life for 1st order decomposition

Ideal Gas LawDalton’s Law of Partial Pressures

Beer’s Law

All state functions!!!

Gibbs-Helmholtz Eq.

current = charge/time

Lab Techniques and Information for the A.P.

Chemistry Exam

1. Titrationa.) Acid-Base i.) MaVa = MbVb for monoprotic acids ii.) Use D.A. for stoich. (especially if not 1:1 ratios) iii.) Know the pH curves for all scenarios iv.) Know how indicators work to mark the endpoint b.) Redox i.) You need to balanced the redox reaction…often MnO4

- (purple), Cr2O72- (orange) or O2

2- is involved as an oxidizing agent.

Random bonus opportunity

Random Bonus Opportunity #1

Q: In the redox titration lab that we did, what was the ion that got oxidized from the +2 to +3 oxidation state by the permanganate ion?

A: Iron (II) or Fe2+

2. Calorimetrya.) Know the device (cup, water, thermometer, etc.) b.) q = m c T c.) Remember to take system’s perspective if finding H (report in kJ/mol!)

3. Photoelectron Spectroscopy (PES)a.) Shows that electrons exist at discrete energy levels. b.) Based on the Photoelectric Effect i.) KE of ejected electron = h – work required to eject the electron

(energy of light ▲) (▲binding energy or I.E.)

ii.) Binding energy related to nuclear charge, core shielding or repulsions.

Binding energy = energy of light – KE of ejected electron

Random bonus opportunity

Random Bonus Opportunity #2

Q: Who won a Nobel Prize for his explanation of the Photoelectric Effect?

A: Einstein (in 1905…his miraculous year!!!)

← the two 1s electrons

← the one 3s electron← the six 2p electrons

← the two 2s electrons

← the one 3s electron

← the two 3s electrons

Why is the binding energy for the 3s electrons in magnesium a bit higher than the 3s electron in sodium?Due to greater number of protons in the nucleus in magnesium compared to sodium.

The outermost 10 electrons

← the two 3s electrons

On the axes below, draw in the spectral peak for aluminum’s outermost valence electron. Use the position of magnesium’s valence electrons to position the peak appropriately.

0 10

← the two 3s electrons

On the axes below, draw in the spectral peak for aluminum’s outermost valence electron. Use the position of magnesium’s valence electrons to position the peak appropriately.

Core shielding from the 3s electrons in aluminum makes the binding energy of the single 3p electron lesser than that of the 3s electrons in magnesium.

4.) Molar Mass Determinationa.) For gases: i.) Ideal Gas Law: PV = nRT (find “n” along with mass of sample… MM = mass/n) ii.) Graham’s Law: (MM1/MM2)½ = R2/R1 = d2/d1

 b.) For solutes: i.) T = Kmi (concerning freezing pt. depression or boiling pt. elevation)

5. Chromatographya.) Used to physically separate mixtures into their components. b.) Important Terms•Stationary Phase: The paper* (when doing paper chromatography) or [could be] packed glass* beads when doing column chromatography.•Mobile Phase: The solvent.•Rf value: ratio of the distance traveled by the molecule(s) in the mixture being separated and the distance traveled by the solvent *these substances attract strongly to water as hydroxyl groups line their surfaces with hydrogen bonding producing an affinity for the water and the material (paper or glass).

dsaf

6. Spectrophotometrya.) Finding concentrations of species in solution (using visible or U.V. light to make electron transitions take place.) b.) Know Beer’s Law: A = k C (A is the absorbance, k is the constant and C is the concentration) …or longer version: A = abC (“a” is the absorptivity [quantity of light absorbed compared to black body] and “ b” is the path length of the light…also “ab” is the k above in the shorter version) c.) A = -log transmittance (% transmittance should be used as a decimal) d.) I.R. light used to identify bond types

Random bonus opportunity

Random Bonus Opportunity #3

Q: What is the wavelength of light best absorbed by the complex ion FeSCN2+ and what is its resulting color in solution?

A: 447 nm and blood red

7. Gravimetric Analysisa.) A type of quantitative analysis in which the amount of one species in a material is determined by isolating and massing it. b.) Often involves dissolving a material under analysis, precipitating one component, filtering the PPT (insoluble substance with low Ksp), and massing PPT after drying. Knowledge of composition of PPT allows for stoichiometric evaluation of the substances.

Random bonus opportunity

Random Bonus Opportunity #4

Q: For what coin, denomination and date wise, did we determine the silver composition via gravimetric analysis?

A: A pre-1965 dime.

8. Qualitative analysisa.) Know the PPTs and complexes i.) Group I ---chloride PPTs (silver, mercury (I) and lead (II)) ii.) Group II --- sulfide PPTs (bismuth (III), tin (IV), antimony (III), and copper (II)) iii.) Group III --- hydroxide PPTs or complexes (aluminum, nickel (II), iron (III)) iv.) Some complexes to know --- FeSCN2+(blood red), Al(OH)4

- (clear), Cu(NH3)42+ (deep blue),

Ni(NH3)62+ (deep blue), Ag(NH3)2

2+ (clear)b.) Solubility rules predict other PPTsc.) Centrifuging technique to separated.) Flame Test Colors: Na- yellow; Cu- green; K- lavender; Sr & Li- deep red; Ba- pale green; Ca- reddish orange

Random bonus opportunity

Random Bonus Opportunity #5

Q: What substance can be added to a solution to prove the presence of Al3+ by turning the solution blue?

A: catechol violet

9. Electrochemistrya.) Galvanic Cell (spontaneous) set up…Electrolytic Cell (requires power supply) as well.

10. General Lab Techniquesa.) Know glassware and use of devices [pipettes, burettes, cuvettes, flask types, balances, etc.] i.) degree of precision ii.) significant figures (always estimate one place) b.) Common Tests: i.) hydrogen – “pop” test [H2 + O2 → H2O] …accompanied by explosion! ii.) carbon dioxide – limewater test [CO2 + Ca(OH)2 → CaCO3 + H2O] …solution turns cloudy as ppt of calcium carbonate forms.

Random bonus opportunity

Random Bonus Opportunity #6

Q: How are volumetric flasks made, how should they be cleaned and how many graduations would you find on them?

A: painstakingly, scrupulously and one!

8. General Lab Techniques (cont’d)

iii.) water-- cobalt chloride test [CoCl4

2-(this is blue) + H2O ↔ Co(H2O)6

2+(this is pink) + Cl-]

…in the presence of water the pink complex dominates. iv.) oxygen – “glowing splint” test [an “emberred” wooden splint will catch fire in the presence of pure [or somewhat pure] oxygen. c.) Error Analysis: i.) Envision how data and results would change ii.) Percent error [│exp. – true│/ true] x 100%)d.) Handling of Materials and Safety: i.) MSDS usage ii.) Use your experience!

~510 nm

▼Painstakingly made

0.050 M

A = kCA = abC

Absorptivity is defined as the ratio of the absorbed radiation at a specific wavelength and temperature to the absorbed radiation by a black body at the same wavelength and temperature.

cell path length

is the length of sample that the light passes through

concentration