Search found 63 matches
- Tue Mar 20, 2018 11:28 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: catalysts
- Replies: 3
- Views: 825
Re: catalysts
a catalyst is used up (as a reactant) and then produced again (as a product).
- Thu Mar 15, 2018 10:04 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.63
- Replies: 3
- Views: 568
Re: 15.63
FYI If you derive the Arrhenius equation yourself, you may also get ln(k2/k1) = (Ea/R)(1/T1- 1/T2), and it works as well. As long as whatever k you have on the top, you have the corresponding T second.
- Thu Mar 15, 2018 10:02 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Fast or Slow
- Replies: 8
- Views: 963
Re: Fast or Slow
The problem may ask you to determine which is the rate-limiting step, which we know is the slow step. If so, you have to analyze each step to see if it's individual rate law matches the overall rate law. Remember, you may have to use the pre-equilibrium approach in order to do so. Whichver step's ra...
- Mon Mar 12, 2018 12:12 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3009148
Re: Post All Chemistry Jokes Here
Hey girl. Are you made out of salt? Because your SO-DIUM fine. ;)
- Fri Mar 09, 2018 4:15 pm
- Forum: First Order Reactions
- Topic: k' in Pseudo-First-Order Rate Laws
- Replies: 4
- Views: 1525
k' in Pseudo-First-Order Rate Laws
Why is k' used in the pseudo-first-order rate law? Doesn't k' mean the rate constant for the reverse reaction? Thanks!
- Fri Mar 09, 2018 4:10 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Chapter 15 #85
- Replies: 2
- Views: 369
Re: Chapter 15 #85
For example, the rxn for #85a is CH3CHO --> CH3 + CHO You know that in this reaction, the bond between the two carbon atoms is breaking. Therefore, the structure for the activation complex would be [H3C ---- CHO] (and put the little symbol for activation complex) Basically, you put a line to represe...
- Fri Mar 09, 2018 4:04 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: formula on 15.61
- Replies: 3
- Views: 453
Re: formula on 15.61
I have the same question!!
- Mon Feb 26, 2018 2:57 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 14.27
- Replies: 6
- Views: 752
Re: 14.27
It would seem easier to just add up the E values for each half reaction, correct? However, you can only do this when solving for the potential of an entire reaction, not a half reaction. To solve for the potential of a HALF-REACTION, you must find the delta G values of each one, add them together, t...
- Mon Feb 26, 2018 2:53 pm
- Forum: First Order Reactions
- Topic: Calculating slope
- Replies: 4
- Views: 656
Re: Calculating slope
It would make sense that as time increases, ln[A] should decrease as well. However, the rate constant, k, is always a positive number, therefore a negative sign must be put in front to make the slope of the line negative.
- Wed Feb 21, 2018 5:49 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13 c
- Replies: 1
- Views: 226
Re: 14.13 c
Because HCl is a strong acid and likely to dissociate into it's ions.
- Wed Feb 21, 2018 5:48 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard potential and redox
- Replies: 1
- Views: 227
Re: Standard potential and redox
A higher (positive) reduction potential means that it is more likely to be reduced. Therefore if the standard reduction potential is negative, the couple is more liekly to be oxidized and act as a reducing agent ( higher reducing strength).
- Wed Feb 21, 2018 5:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Devising Galvanic Cells
- Replies: 1
- Views: 282
Re: Devising Galvanic Cells
If the mediums you're working with do not include a solid as a conductor. For example, if one ion gets oxidized or reduced to another ion instead of a solid. Therefore it needs an inert conductor like platinum
- Wed Feb 21, 2018 4:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.107 Determining K
- Replies: 1
- Views: 254
Re: 14.107 Determining K
K= [H+]/[OH-]
@pH 1: 1=-log[H+] --> [H+] = 1x10^-1 M
therefore, pOH 13: [OH-]= 1x10^-13 M
@pH 14: [H+]= 1x10^-14 M
therefore, pOH 0: [OH-]= 1x10^0= 1.0 M
There is an error in the solution manual for this problem, so I'd check on Lavelle's website.
@pH 1: 1=-log[H+] --> [H+] = 1x10^-1 M
therefore, pOH 13: [OH-]= 1x10^-13 M
@pH 14: [H+]= 1x10^-14 M
therefore, pOH 0: [OH-]= 1x10^0= 1.0 M
There is an error in the solution manual for this problem, so I'd check on Lavelle's website.
- Tue Feb 20, 2018 4:54 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: K sig figs
- Replies: 4
- Views: 539
K sig figs
How do we know how many sig figs to include when solving for K for our final answer? Is K usually just 1 sig fig?
Thanks
Thanks
- Mon Feb 19, 2018 5:20 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13 part D
- Replies: 2
- Views: 361
Re: 14.13 part D
Same, I thought it would have been Au+(aq) --> Au3+(aq) + 2e- , with Pt(s) as the conducting solid....
- Sat Feb 10, 2018 4:07 pm
- Forum: Biological Examples (*DNA Structural Transitions, etc.)
- Topic: STP [ENDORSED]
- Replies: 8
- Views: 1928
STP [ENDORSED]
Is a reaction at STP (standard Temp and Pressure) @ 0*C or 25*C? I believe I've seen both used so I just want to clarify.
- Tue Feb 06, 2018 1:44 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: 9.75
- Replies: 2
- Views: 350
Re: 9.75
When you draw out the cis molecule (X2 on same side) versus the trans molecule (X2 on opposite sides), and proceed to rotate them, the cis molecule has many more orientations than the other molecule.
- Tue Feb 06, 2018 1:40 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Irreversible Vs. Reversible Expansion
- Replies: 2
- Views: 372
Re: Irreversible Vs. Reversible Expansion
Irreversible is spontaneous in one direction, and is highly unlikely to proceed in reverse. It does less work than reversible expansion because it is typically expanding on a lower pressure. On the other hand, you can think of a reversible expansion as equally proceeding in both directions because t...
- Mon Feb 05, 2018 8:57 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Types of Disorders [ENDORSED]
- Replies: 5
- Views: 707
Types of Disorders [ENDORSED]
When discussing entropy, what's the difference between positional and thermal disorder? (Question 9.85)
- Mon Feb 05, 2018 8:53 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: test question 7 [ENDORSED]
- Replies: 6
- Views: 771
Re: test question 7 [ENDORSED]
I think the "inital deltaH" that you are thinking of is the deltaH(fus) of water, which is needed for the phase change of the ice cube to liquid water. The other steps only require q=mCdeltaT
- Mon Feb 05, 2018 8:50 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy question [ENDORSED]
- Replies: 2
- Views: 391
Re: Entropy question [ENDORSED]
Some people believe that the universe is always expanding, therefore entropy must be increasing.
Other reasons are because an increase in entropy is favorable, and the universe will always go toward the more favorable outcome.
Other reasons are because an increase in entropy is favorable, and the universe will always go toward the more favorable outcome.
- Mon Feb 05, 2018 8:47 am
- Forum: Calculating Work of Expansion
- Topic: Naming Question [ENDORSED]
- Replies: 5
- Views: 762
Re: Naming Question [ENDORSED]
Can think of a reversible reaction as being at equilibrium?
- Sun Feb 04, 2018 10:45 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: change in entropy with change in temperature
- Replies: 2
- Views: 330
Re: change in entropy with change in temperature
You use the one with R when you have V1/V2. You use the one with C when you have T1/T2.
- Wed Jan 31, 2018 8:56 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q(REV)
- Replies: 3
- Views: 343
q(REV)
What exactly is q(REV) and how does it differ from q? Why is the (REV) significant, since when solving for deltaS we tend to replace it with deltaH anyways?
thanks!
thanks!
- Wed Jan 24, 2018 11:19 pm
- Forum: Phase Changes & Related Calculations
- Topic: Calculating the Change in Enthalpy
- Replies: 4
- Views: 633
Re: Calculating the Change in Enthalpy
The change in enthalpy of a phase change will often be given to you, as deltaHfus, deltaHvap. You could also calculate these if you know the amount of heat released or needed (q) and the number of moles, by using the equation q=ndeltaHfus/vap.
- Wed Jan 24, 2018 9:45 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: isothermal system
- Replies: 3
- Views: 430
Re: isothermal system
In an isothermal system, deltaT is zero vecause the temperature is constant. For an ideal gas, deltaU=(3/2)nRdeltaT. Therefore, if deltaT=0, then deltaU=0. I believe this is only for ideal gases...
- Wed Jan 24, 2018 9:43 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Reversible Expansion vs Irreversible Expansion
- Replies: 1
- Views: 183
Re: Reversible Expansion vs Irreversible Expansion
Example... Irreversible: 4 atm --> 2 atm Reversible (@ equilibrium): 3 atm --> 3 atm Which one does more work, the one pushing on 2 atm or the one pushing on 3 atm? @ equilibrium, the system is theoretically doing the max work it can. That's why reversible reactions do not often occur in biological ...
- Wed Jan 24, 2018 6:50 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: deltaH Units
- Replies: 5
- Views: 550
deltaH Units
When putting our final answer, how do we know whether the units for deltaH are kJ or kJ/mol? I've seen both so I was wondering if we would get marked off on the test if we wrote the wrong one. Thanks!
- Sun Jan 21, 2018 9:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: delta n
- Replies: 3
- Views: 3594
Re: delta n
It is also important to note that limiting reactants may still apply to a problem. For example in question 101, you have to determine the limiting reactant and then the amount of moles in excess. You would also the have to add the moles of excess to the moles of product you calculated using the bala...
- Sun Jan 21, 2018 9:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: bond enthalpies
- Replies: 3
- Views: 464
Re: bond enthalpies
In addition, you must do this because it would take much more energy to break the bonds for liquid or solid compounds... the bond enthalpies would extremely high.
- Sun Jan 21, 2018 5:59 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv vs. Cp [ENDORSED]
- Replies: 13
- Views: 11744
Re: Cv vs. Cp [ENDORSED]
Cv is the molar heat capacity of a gas @ CONSTANT VOLUME, whereas Cp is the molar heat capacity of a gas at CONSTANT PRESSURE. In one example (#31), you would use it when doing q=mCdeltaT if you're given an ideal gas but no molar heat capacity. The Cp and Cv for ideal gases can be found on Lavelle's...
- Fri Jan 19, 2018 3:25 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated system
- Replies: 3
- Views: 422
Re: Isolated system
In class we discussed that the Internal Heat, U, of an isolated system has no change since it not affected by q or w, since it is isolated. Therefore, deltaU = 0.
- Thu Jan 18, 2018 6:07 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 3 Methods
- Replies: 2
- Views: 133
Re: 3 Methods
Enthalpy of the total reaction.
- Thu Jan 18, 2018 10:50 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Delta H and q Interchangeability
- Replies: 5
- Views: 598
Re: Delta H and q Interchangeability
This is why sometimes Lavelle will write qp instead of q, indicating it is at constant pressure and is interchangeable with deltaH.
- Wed Jan 17, 2018 11:48 pm
- Forum: Phase Changes & Related Calculations
- Topic: Thermochemistry Sections in Ch 8
- Replies: 2
- Views: 356
Re: Thermochemistry Sections in Ch 8
If you're doing the hw problems, I would say the "enthalpy" section, which starts with problem 8.29.
- Wed Jan 17, 2018 11:43 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cm
- Replies: 3
- Views: 361
Re: Cm
This is as opposed to Cs, which would be specific heat capacity with units J/(g*C)
- Wed Jan 17, 2018 11:40 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.61
- Replies: 3
- Views: 458
Re: 8.61
Just remember that the goal is to get the desired reaction. Sometimes, you have to flip the internal reactions in order to get the correct reactants and products for the desired reaction.
- Wed Jan 17, 2018 11:37 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.45
- Replies: 1
- Views: 159
Re: 8.45
First you have to calculate the number of moles needed to produce that amount of heat absorbed. Since you know that q=n*deltaH, therefore n=(q)/(deltaH). this will give you moles per reaction, but you have to remember that there are 4 moles of CS2 produced per every reaction, so multiply what you go...
- Wed Jan 17, 2018 11:33 pm
- Forum: Calculating Work of Expansion
- Topic: 8.3 Homework
- Replies: 4
- Views: 590
Re: 8.3 Homework
The work is done TO the system, since the outside pressure pushes the piston down causing the compression. Because the system doesn't have to do any work, therefore the work on the interior air is positive. IF the piston moved out to increase the volume inside, then the system would be DOING the wor...
- Thu Dec 07, 2017 6:42 pm
- Forum: Bronsted Acids & Bases
- Topic: Oxoacids
- Replies: 4
- Views: 572
Re: Oxoacids
This explains why oxoacids are strong acids. They are more willing to lose their H+ because after losing the H+, they have more options for resonance, which makes the compound more stable.
- Thu Dec 07, 2017 6:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Finding Q and which way the reaction shifts
- Replies: 1
- Views: 248
Re: Finding Q and which way the reaction shifts
They will either give you the chemical equation or tell you what the reactants and products are. However, you could sometimes assume the direction if one of the compounds is a strong acid because you know it will completely dissociate and is not likely to reform.
- Thu Dec 07, 2017 6:26 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Relationship between Kpa and Ph
- Replies: 3
- Views: 1035
Re: Relationship between Kpa and Ph
pH and pOH take the -log[ H+ or OH-]. They are not the same as their respective Ka or Kb, which shows the relationship between all concentrations in the rxn, not just [H+] or [OH-].
- Mon Dec 04, 2017 5:18 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Ionic Equation
- Replies: 3
- Views: 2048
Re: Ionic Equation
The question is not super clear but if you are referring to writing net ionic equations then you know which species dissociates based on solubility rules and strong acids and bases. There are 3 basic steps to writing net ionic equations: (1) write a balanced equation with the states of matter inclu...
- Mon Dec 04, 2017 5:15 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Proton Transfer Reactions
- Replies: 2
- Views: 449
Re: Proton Transfer Reactions
Sodium is left out because it is a cation completely unrelated to the proton transfer reaction. this is because it gets cancelled out when you do the net ionic equation for the reaction.
- Thu Nov 30, 2017 5:07 pm
- Forum: Sigma & Pi Bonds
- Topic: Localization
- Replies: 3
- Views: 639
Re: Localization
think of resonance!!
- Thu Nov 30, 2017 5:05 pm
- Forum: Naming
- Topic: 17.31 c and d confusion
- Replies: 5
- Views: 910
Re: 17.31 c and d confusion
I forgot to mention that OH2 would be correct IF the transition metal was written on the LEFT side of water... if it was written on the RIGHT, it should be H2O :)
- Thu Nov 30, 2017 5:00 pm
- Forum: Naming
- Topic: 17.31 c and d confusion
- Replies: 5
- Views: 910
Re: 17.31 c and d confusion
Hi Mike, How water is written does not matter, so long as it is correctly written with two hydrogens and one oxygen. H2O and OH2 are equally correct. For part d., because oxalate has the prefix bis-, this has higher priority than "diaqua" as b precedes d. Hope this helps. But I thought th...
- Thu Nov 30, 2017 4:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ch 11 #89
- Replies: 2
- Views: 215
Re: Ch 11 #89
What do you mean by "ratios of the change in equilibrium"?
- Thu Nov 30, 2017 4:46 pm
- Forum: Student Social/Study Group
- Topic: Naming Complexes
- Replies: 6
- Views: 1554
Re: Naming Complexes
and a polydentate is when the ligand can bind at multiple sites the transition metal. However, although N2 has 2 pairs of lone pairs on each nitrogent, it is not a polydentate because it would be impossible for both nitrogens to bind to the T.M. at the same time.
- Thu Nov 30, 2017 4:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Denate
- Replies: 3
- Views: 420
Re: Denate
Sometimes if works if you count the number of Nitrogens because you know that they usually have a lone pair, however you also have to remember that if the nitrogens are right next to each other, they wont both bind at the same time... ultimately I would just draw the Lewis structure because then you...
- Wed Nov 15, 2017 4:32 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Bond Order
- Replies: 5
- Views: 655
Re: Bond Order
Yep so for example if the molecule has 2 single bonds and a double bond in resonance, then the bond order would be (1+1+2)/(3 total regions)= 1.33
- Wed Nov 15, 2017 4:28 pm
- Forum: Hybridization
- Topic: Hybridization significance
- Replies: 2
- Views: 395
Re: Hybridization significance
Hybridization occurs because it allows atoms to form more bonds than their stated number of unpaired e-. For example, Carbon is 2s^2 2p^2, so we know that the ones in the s- orbital are spin paired and the two in the p-orbital are not. By this logic, that should mean that carbon can only form two bo...
- Wed Nov 08, 2017 9:02 pm
- Forum: Ionic & Covalent Bonds
- Topic: 3.77
- Replies: 2
- Views: 1286
Re: 3.77
To determine which one has more ionic character, compare the electronegativities of each. You don't have to know the exact numbers, but know that Cl is more electronegative than I, F is more electronegative than H, etc. The species with the higher difference in EN in each pair is the one with more i...
- Wed Nov 08, 2017 8:59 pm
- Forum: Octet Exceptions
- Topic: 3.55
- Replies: 3
- Views: 371
Re: 3.55
It may also help to draw out the lewis structures for each one. If an atom in one has an unpaired e-, then the species is a radical.
- Sat Nov 04, 2017 4:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic and Covalent Bonds
- Replies: 9
- Views: 1115
Re: Ionic and Covalent Bonds
Ionic bonds join two nonmetal atoms, covalent bonds join two ions. If the electronegativity difference is >2 then it is considered an ionic bond, if electronegativity difference is <1.5 then it is considered a covalent bond. This first part of this answer is a bit mixed up: ionic bonds join ions (t...
- Sat Nov 04, 2017 4:33 pm
- Forum: Lewis Structures
- Topic: Monoatomic Ions and Polyatomic ions
- Replies: 1
- Views: 291
Re: Monoatomic Ions and Polyatomic ions
Monoatomic ions only have one atom, so since it's the only atom, it must be the middle atom.
- Fri Oct 27, 2017 11:02 pm
- Forum: Electronegativity
- Topic: Which atom would carry the formal charge
- Replies: 3
- Views: 865
Re: Which atom would carry the formal charge
If you haven't memorized the periodic trends already, it's also important to know HOW they exists if you are not given the electronegativities. EN increases as you go to the right of the periodic table because as more valence e- are added, they become closer to an octet. You can think of EN as how m...
- Fri Oct 27, 2017 10:33 pm
- Forum: Resonance Structures
- Topic: Resonance in SO4
- Replies: 5
- Views: 793
Re: Resonance in SO4
The most ideal situation is...
1. Formal charge closest to zero
2. central atom w/o charge
3. charges (if any) distributed as evenly as possible among atoms (2- vs 1- and 1-)
Hope this helps!
1. Formal charge closest to zero
2. central atom w/o charge
3. charges (if any) distributed as evenly as possible among atoms (2- vs 1- and 1-)
Hope this helps!
- Sat Oct 21, 2017 9:36 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Solving
- Replies: 2
- Views: 209
Re: Solving
Also, it wouldn't be an equal sign because since it is "uncertain", it can never equal a certain number-- there must be a range of uncertainty where the exact position and velocity of an object lie at a certain time.
- Wed Oct 18, 2017 12:46 pm
- Forum: Properties of Electrons
- Topic: Atomic Spectra and Energy Levels
- Replies: 3
- Views: 476
Re: Atomic Spectra and Energy Levels
This is because as the electron is moving farther away from the nucleus, eventually it will go to infinity , which in that case it's ejected and the Energy=0.
- Wed Oct 18, 2017 12:44 pm
- Forum: Properties of Light
- Topic: Oscillation of Light
- Replies: 3
- Views: 320
Re: Modules
Gabriela Carrillo 1B wrote:Is the module "Chemical Equilibrium Part 1" part of this week's lectures??
Nope, it's just next on the modules because it's the one other topic that he feels is hardest. After the Quantum World we're probably gonna do Chemical Bonds.
- Sun Oct 08, 2017 12:25 pm
- Forum: Significant Figures
- Topic: All students read this sig fig post [ENDORSED]
- Replies: 170
- Views: 33588
Re: All students read this sig fig post [ENDORSED]
On the test on 10/6/17, I had trouble allotting enough time to answer all the questions and I believe it was mostly as a result of me taking my time thinking about what significant figures I should be using throughout my intermittent calculations. Are significant figures a crucial part to the test ...
- Wed Oct 04, 2017 7:10 pm
- Forum: General Science Questions
- Topic: Rusty on High School Chem [ENDORSED]
- Replies: 347
- Views: 416608
Re: Rusty on High School Chem [ENDORSED]
I would definitely get or review an old AP Chem test prep book, in addition to office hours, etc.