## Search found 20 matches

Sat Mar 16, 2019 7:34 pm
Forum: Biological Examples
Topic: biological examples for final
Replies: 9
Views: 390

### Re: biological examples for final

Annalyn Diaz 1J wrote:I would probably also know any industrial and and environmental examples that Dr. Lavelle has gone over in class just in case. I think it's safe to assume there might be a small question on them.

Which ones has he gone over? I can't find anything on that anywhere
Sat Mar 16, 2019 7:29 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Intermediates in Rate Law
Replies: 4
Views: 119

### Re: Intermediates in Rate Law

I believe if you're only trying to write out the rate for an elementary step it needs to be there.

Definitely won't be there for the full reaction though.
Sat Mar 16, 2019 7:27 pm
Forum: Second Order Reactions
Topic: units of K
Replies: 3
Views: 301

### Re: units of K

The best way to go about knowing the units of K is knowing how to find them. Rate should be expressed in m/l*s, so you can write out the units of the reactants and figure it out for a second order reaction, you would have \frac{m*m}{l*l}*k\Rightarrow \frac{m*m}{l*l}*\frac{l}{m*s}\Rightarrow \frac{m}...
Sat Mar 16, 2019 7:21 pm
Forum: Zero Order Reactions
Topic: Half Life and k
Replies: 11
Views: 521

### Re: Half Life and k

Half life is defined as "the time it takes for the concentration of reactant to be half of the original", while k is "the rate at which the reactant is becoming product". The higher k is, the faster the reactant becomes product, the lower the half life will be.
Sat Mar 16, 2019 7:16 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Negative k value
Replies: 2
Views: 304

### Re: Negative k value

Oops, I put in the wrong numbers for that problem. But regardless, can there be a negative k value? Sure. It just depends on the perspective of k. If you have a reaction A\rightarrow B+C and the k you're given is "rate of production of A", it's gonna be negative, because you're losing A.
Sat Mar 16, 2019 7:14 pm
Forum: General Rate Laws
Topic: H.W. Problem 15.17
Replies: 5
Views: 354

### Re: H.W. Problem 15.17

Nandhini_2K wrote:Also why don't we calculate the order for reactant C?

You can, it's just not gonna be very useful
Sat Mar 16, 2019 7:10 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 118
Views: 23878

### Re: Final Jitters

On the day of the final don't study. Take some time (not much, I imagine, since it's in the morning) to just relax. Don't think about chem until it's in front of you.
Sat Mar 16, 2019 7:07 pm
Forum: Balancing Redox Reactions
Topic: Balancing reaction in basic medium
Replies: 1
Views: 245

### Balancing reaction in basic medium

I know how to balance a reaction in a basic medium normally, but there was an exercise that really threw me off (14.5 in 6e) 14.5.d Reaction of elemental phosphorous to form phosphine, PH 3 , a poisonous gas with the odor of decaying fish P_{4}_{(s)}\rightarrow H_{2}PO_{2}^{-}_{(aq)}...
Sat Mar 16, 2019 7:01 pm
Forum: Van't Hoff Equation
Topic: neutral pH not 7?
Replies: 6
Views: 388

### neutral pH not 7?

I thought the neutral pH is when [H+] and [OH-] were the same, which is at pH=pOH=7.

Is that not always the case?
Sat Mar 16, 2019 6:56 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equilibrium constant from G
Replies: 1
Views: 245

### Equilibrium constant from G

Where is the equation $\Delta G=-RTln(K)$ derived from?
Sat Mar 16, 2019 6:53 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Delta S=0 for elemental molecules?
Replies: 2
Views: 229

### Delta S=0 for elemental molecules?

I don't understand why the Delta S is 0 when forming elemental molecules (like O2 or N2, for example).

By grouping them together, shouldn't entropy decrease since there are less possible states for them to be in?
Sat Mar 16, 2019 6:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 275
Views: 114647

### Re: Saying Thank You to Dr. Lavelle

This quarter has been a lot richer than I thought it would be learning wise.
Chemistry has always been my weakestr science subject, so the gentle but no-nonsense approach in this class worked wonders for me.

Thank you so much.
Sat Mar 16, 2019 6:47 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Delta S?
Replies: 2
Views: 289

### Delta S?

Why does irreversible free expansion mean Delta S=0?
Sat Mar 16, 2019 6:44 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity of an object
Replies: 1
Views: 232

### Heat capacity of an object

( I posted this in another section before I noticed it fit better here)

Does heat capacity have to be in J/g*K or can it just be in J/K (applying to a whole object and being an intensive property rather than an extensive one)?
Have we done exercises like that before?
Sat Mar 16, 2019 6:42 pm
Forum: Phase Changes & Related Calculations
Topic: heat capacity of an object
Replies: 3
Views: 276

### heat capacity of an object

Does heat capacity have to be in J/g*K or can it apply to a whole object?
Have we done exercises like that before?
Sat Mar 16, 2019 6:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: using molarity vs moles
Replies: 2
Views: 210

### using molarity vs moles

I can't recall which, but I've seen some exercises in which the volume of the container is not specified, and the solution is to use moles directly.
I don't know if that solution is right and, if it is, in what kind of situation would we use it?
Sat Mar 16, 2019 6:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reducing/oxidizing power?
Replies: 2
Views: 102

### Reducing/oxidizing power?

I'm kinda confused about the difference in reduction potential/reducing power.

Help?
Sat Mar 16, 2019 6:32 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Determining n
Replies: 6
Views: 327

### Determining n

We use the equation \Delta G=-n*F*E to determine the change in Gibbs free energy in a cell reaction, but I'm having some trouble making sure what the value of n is. Taking this exercise, for example (14.9 in 6e): 14.9 Calculate the standard reaction Gibbs free energy for the following cell reactions...
Tue Feb 12, 2019 8:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
Replies: 49
Views: 3505

### Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!

Help with question 2c)? I understand that since we're cooling it kc will also drop because it's dependent on temperature, but what is the detailed explanation?
Fri Jan 11, 2019 8:37 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Help with Q 11.7.c (6e)
Replies: 1
Views: 50

### Help with Q 11.7.c (6e)

11.7 The following flasks show the dissociation of a diatomic molecule, X 2 , over time. (a) Which flask represents the point in time at which the reaction has reached equilibrium? (b) What percentage of the X 2 molecules have decomposed at equilibrium? (c) Assuming that the initial pressure of X 2...