## Search found 51 matches

Sat Mar 18, 2017 7:18 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: pH using Nernst Equation
Replies: 2
Views: 481

### pH using Nernst Equation

W2010 Q4B

1.) How do you know "the cell emf was +0.060V." means Ecell and not E*cell?

2.) How do you know n=1? I thought n=2 from Q4A, which was the redox reaction where 2 electrons were transferred.
Sat Mar 18, 2017 7:07 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy of Rxn
Replies: 1
Views: 407

### Gibbs Free Energy of Rxn

W 2011 Q2

Why is 3H2 ignored in the 1st rxn? Why is H2 ignored in the 2nd rxn?
I thought it was because of a phase difference in the 1st one, but in the 2nd rxn there is no phase difference and it's still ignored.
Sat Mar 18, 2017 5:18 pm
Forum: Second Order Reactions
Topic: Quiz 2 Prep #6
Replies: 1
Views: 357

### Quiz 2 Prep #6

I was wondering why it is correct, when time is supposed to be in seconds? I got to completely different answers when I converted to seconds as opposed to leaving it in minutes.
Sat Mar 18, 2017 3:32 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: 3 different subsitutients for a newman projection
Replies: 1
Views: 597

### Re: 3 different subsitutients for a newman projection

Can you give a molecular formula, or example?
Sat Mar 18, 2017 3:30 pm
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Naming Order (Iso)
Replies: 1
Views: 721

### Re: Naming Order (Iso)

Yes, Iso- is included for alphabetical order, as is Neo-. Di- is not.
Sat Mar 18, 2017 3:29 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: 2013 Final Q8C
Replies: 1
Views: 595

### Re: 2013 Final Q8C

Since they are attached, you can imagine it based on how many carbons and hydrogens there are. If that makes sense.
Sat Mar 18, 2017 2:38 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Priority for Trans vs. Equatorial
Replies: 1
Views: 626

### Priority for Trans vs. Equatorial

Is it a rule that equatorial is prioritized over trans when choosing the most stable conformation for cyclohexanes?
I had made it trans, making the Chloro equatorial down, and the methyl axial up.
Sat Mar 18, 2017 2:06 pm
Topic: Rxn Mechanism for Acid Catalyzed Electrophilic Addition
Replies: 1
Views: 2182

### Rxn Mechanism for Acid Catalyzed Electrophilic Addition

Step 1: Where is Hydrogen that broke off from the H30? I thought the double bond was attacking it, causing it to break off.

Step 2: How are there 2 H20 molecules? How is there a product of H+/H30+?
Fri Mar 17, 2017 9:33 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 291
Views: 136581

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

Dear Dr. Lavelle, Thank you for being the most organized professor I've had thus far. I remember 14A was one of my first classes here, and I was relieved to have all the topics available on your website to practice in advance. During the quarter, the abundance of resources you offered were also very...
Tue Mar 14, 2017 10:30 am
Forum: *Organic Reaction Mechanisms in General
Topic: Q6 Winter 2014 Final Exam
Replies: 1
Views: 617

### Q6 Winter 2014 Final Exam

1.) When a TA went over this at the review session, they said this question has SN1 and SN2 reactions throughout the steps. Is a question like this one possible to appear on the Final? The whole reaction has 4 steps, which confuses me since we have only covered SN2 and Electrophilic Addition Reactio...
Tue Mar 14, 2017 10:11 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation
Replies: 2
Views: 506

### Arrhenius Equation

I was wondering how the Arrhenius Equation would be changed algebraically with the given equation on the formula sheet to the one in the reader?
Thu Mar 09, 2017 12:34 pm
Forum: *Alkenes
Topic: Naming a Alkene with a Functional Group
Replies: 2
Views: 381

### Re: Naming a Alkene with a Functional Group

Functional group gets priority over the double/triple bonds.
Wed Mar 08, 2017 8:09 pm
Forum: *Alkanes
Topic: Naming [ENDORSED]
Replies: 92
Views: 10363

### Re: Naming[ENDORSED]

Leo_Navejas_3B wrote:For substituents do we use common or systematic naming??

I was told common and systematic naming are the same thing.
Wed Mar 08, 2017 8:08 pm
Forum: *Alkanes
Topic: Naming [ENDORSED]
Replies: 92
Views: 10363

### Re: Naming[ENDORSED]

What counts when using the alphabetical reference when naming?

I thought Neo- and Iso- counted, while Tert- didn't? Or is it the opposite? Is there a reason for it?

Mon Mar 06, 2017 8:06 pm
Forum: *Electrophiles
Topic: Halogens
Replies: 4
Views: 987

### Re: Halogens

I wouldn't look at that as a definite rule though.
For example, Exercise 4.1 part d is F by itself, and it is an electrophile.
Sun Mar 05, 2017 2:16 pm
Forum: *Alkanes
Topic: Self-Test 1.4A
Replies: 1
Views: 250

### Self-Test 1.4A

Is it wrong if I wrote the condensed formula with the CH3 methyl next to the CH instead of doubling the end?
Tue Feb 28, 2017 9:16 pm
Forum: *Organic Reaction Mechanisms in General
Topic: # of Steps
Replies: 2
Views: 322

### Re: # of Steps

What is an example where the general rule does not apply?

Mon Feb 27, 2017 7:27 pm
Forum: *Organic Reaction Mechanisms in General
Topic: # of Steps
Replies: 2
Views: 322

### # of Steps

How do you know how many steps are going to be in the reaction mechanism? Or is it just memorizing how many for each type of mechanism?
Tue Feb 21, 2017 1:54 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Concentration vs. Time Graphs
Replies: 2
Views: 422

### Re: Concentration vs. Time Graphs

Yes, but if there are no labels/values given then there is no other way to know? Unless you're given that information, or a rxn.
Tue Feb 21, 2017 10:34 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Concentration vs. Time Graphs
Replies: 2
Views: 422

### Concentration vs. Time Graphs

I was wondering why the reader has that the y-intercept starts at the top for 1st Order and the y-int starts a bit below the top for 0 order, but the textbook has 1st and 0 order y-intercepts starting at the same point. The only difference is of course in the variables/values. How would we know the ...
Tue Feb 21, 2017 10:03 am
Forum: General Rate Laws
Topic: Units of K
Replies: 4
Views: 9012

### Re: Units of K

Starting from M/s you just then divide my M continuously to get the next order units.
Mon Feb 13, 2017 11:29 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram Symbols
Replies: 4
Views: 638

### Re: Cell Diagram Symbols

The bar indicates a separate reaction/solution. A TA said the comma means it's in the same solution.
Hope that helps.
Mon Jan 30, 2017 10:48 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.15
Replies: 2
Views: 329

### 11.15

1. Why does solution's manual use positive RTlnQ instead of negative? How do you know which equations to use?

2. The solution states, "Because deltaG is positive, the reaction will be spontaneous to produce I_2. I thought positive deltaG meant non-spontaneous ?
Mon Jan 30, 2017 4:37 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 9.13
Replies: 1
Views: 299

### 9.13

Why when calculating entropy with a change in temperature are there instances where the equation used is nRln(T2/T1) and then others where we use nCpln(T2/T1)? Does the question have to explicitly say that the rxn is at constant p or v? If it doesn't say then we just assume we can use nRln(T2/T1) to...
Thu Jan 26, 2017 5:03 pm
Forum: Calculating Work of Expansion
Topic: 8.17
Replies: 1
Views: 216

### Re: 8.17

Nvm, someone told me that it was a typo.
Thu Jan 26, 2017 1:33 pm
Forum: Calculating Work of Expansion
Topic: 8.17
Replies: 1
Views: 216

### 8.17

Hi,

For the explanation of the sign of work in this problem has me confused from the solution manual.

Is deltaE the same as deltaU, and that's why q & w switch off signs to balance the internal energy?
Thu Jan 26, 2017 1:05 pm
Forum: Calculating Work of Expansion
Topic: Homework 8.9 [ENDORSED]
Replies: 3
Views: 614

### Re: Homework 8.9[ENDORSED]

Will we be given the conversion factor from torr to atm on the formula sheet?
Thu Jan 26, 2017 12:43 pm
Forum: Calculating Work of Expansion
Topic: Problem 8.3
Replies: 3
Views: 338

### Re: Problem 8.3

Hi,

I am confused, since it initially states the pump depresses the air, but for part a it says to find work if it is compressed. Are we to assume that it was compressed the same distance that it was initially depressed?

Wed Jan 25, 2017 8:47 pm
Forum: Student Social/Study Group
Topic: Quiz 1 Review
Replies: 4
Views: 610

### Re: Quiz 1 Review

I am interested as well! My e-mai is jospamsantana@gmail.com
Wed Jan 25, 2017 8:45 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Reversibly & Isothermally
Replies: 3
Views: 586

### Re: Reversibly & Isothermally

I think it refers to the work, and which equation you would use in your calculations. You would use W=-nRTln(V2/V1).
It also means that deltaU is 0
Tue Jan 17, 2017 3:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Books on Reserves
Replies: 1
Views: 299

### Books on Reserves

Is there a copy of the solutions manual on reserve at any of the libraries, if so which library?

Wed Jan 11, 2017 10:11 am
Forum: Calculating Work of Expansion
Topic: How to achieve maximum work from an electric battery?
Replies: 4
Views: 491

### Re: How to achieve maximum work from an electric battery?

It is right after Example 8.1 under "Thinking Point:". I do not have a hard copy of the text, but it says it's page 407 of 1129, but page 265 on the pdf. Hope this helps.
Sun Dec 04, 2016 10:46 am
Forum: Lewis Structures
Topic: Determining Lewis structures
Replies: 4
Views: 665

### Re: Determining Lewis structures

Does anyone know why the most stable lewis structure for NO2 has charges on N and one of the O's, when there is a structure where all the FC's can be 0?
Sat Dec 03, 2016 3:34 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Weak Acids and Bases
Replies: 2
Views: 342

### Re: Weak Acids and Bases

It is actually if it's exponent is less than or EQUAL TO -4.

Ex: K_a= 3e^(-4), you can use the short cut to find x.
Wed Nov 23, 2016 7:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar/Nonpolar
Replies: 2
Views: 550

### Re: Polar/Nonpolar

I usually look at all the dipole moments in the molecule's VESPR model, which shows visually if there are any dipole moments that cancel. If they don't cancel, then it will be polar.
Mon Nov 14, 2016 7:53 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Numbers [ENDORSED]
Replies: 4
Views: 676

### Re: Coordination Numbers[ENDORSED]

I know that for EDTA it binds 4 times because it has 4 ends where the oxygens are bent, which makes it easier for chelating to occur.
Fri Nov 11, 2016 12:08 pm
Forum: Naming
Topic: naming [ENDORSED]
Replies: 2
Views: 374

### Re: naming[ENDORSED]

You use Bis-, Tris-, Tetrakis-, and Pentakis- for Polydentate ligands
Thu Nov 03, 2016 12:40 pm
Forum: Sigma & Pi Bonds
Topic: Pi Bonds
Replies: 4
Views: 735

### Re: Pi Bonds

Hi,

Here are some notes I took of a TA's explanation of visualizing the Pi bonds. Hope this helps!
Sun Oct 30, 2016 10:00 pm
Forum: Empirical & Molecular Formulas
Topic: Mass % Composition
Replies: 3
Views: 2402

### Re: Mass % Composition

On the sample midterms, it gives the solution in both versions of calculating. Also, my PLF said you can calculate it either way.
Wed Oct 19, 2016 11:16 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 6
Views: 662

### Re: Lewis Structures

Here is an example of Xe breaking the octet rule.
Wed Oct 19, 2016 11:02 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 6
Views: 662

### Re: Lewis Structures

Hi, Does anyone know why for Xenon (Xe) can break the octet guideline?

I wrote out the electron configuration for it thinking it would help me see it visually, but all the d,s, and p orbitals are full. I am not seeing why it can break the octet rule.
Mon Oct 10, 2016 10:40 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Confusion [ENDORSED]
Replies: 3
Views: 819

### Re: Elecreon Configuration Confusion[ENDORSED]

Will we have to know how to write electron configurations for Quiz 1?

I am confused on that topic, and the connections of the diagrams to the atom's structure.
Sun Oct 09, 2016 11:55 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Quiz 1 Preparation: Fall 2014 Question #10 [ENDORSED]
Replies: 6
Views: 906

### Re: Quiz 1 Preparation: Fall 2014 Question #10[ENDORSED]

Oh wow, this whole time i thought Rh was R with a subscript of h. Thank you!

I got how you got energy and combined the two different energy levels to get the change in energy, but I don't get how -7.5539x10^(-20) as the denominator gives you a positive # under the square root.
Sun Oct 09, 2016 9:48 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Quiz 1 Preparation: Fall 2014 Question #10 [ENDORSED]
Replies: 6
Views: 906

### Re: Quiz 1 Preparation: Fall 2014 Question #10[ENDORSED]

Also, how do you know which equation to use? I am confused on the solutions explanation of how they got -2.178x10^(-18) J (Z^2/n^2). At first I was using the equation set up to find frequency, but the realized that wasn't the correct one. Additionally, why is Rh (Rydberg's constant) 3.28984x10^15 on...
Sun Oct 09, 2016 9:12 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Quiz 1 Preparation: Fall 2014 Question #10 [ENDORSED]
Replies: 6
Views: 906

### Re: Quiz 1 Preparation: Fall 2014 Question #10[ENDORSED]

How did you get rid of the negative at the end before square rooting?
Wed Sep 28, 2016 10:15 am
Forum: Balancing Chemical Reactions
Topic: How familiar should we be with Naming compounds? [ENDORSED]
Replies: 8
Views: 1656

### Re: How familiar should we be with Naming compounds?[ENDORSED]

For Quiz 1, then it would not be similar to all the homework questions only certain ones?

Since, in E9 it states: "Epsom salts consist of magnesium sulfate heptahydrate. Write its formula."
Mon Sep 26, 2016 7:07 pm
Forum: Student Social/Study Group
Topic: Off Campus/Apartments Study group
Replies: 5
Views: 848

### Re: Off Campus/Apartments Study group

I'm interested!
Sat Sep 24, 2016 9:48 pm
Forum: Empirical & Molecular Formulas
Topic: Assessment Question #9
Replies: 2
Views: 844

### Re: Assessment Question #9

Just realized this was covered in the video module.
Sorry about that, and thank you for taking your time with the explanation!
Sat Sep 24, 2016 7:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Repost of Assessment Question
Replies: 1
Views: 283

### Repost of Assessment Question

Are we allowed to screenshot a question from the assessment to post on our question, and use for reference/clarity?
Sat Sep 24, 2016 7:46 pm
Forum: Empirical & Molecular Formulas
Topic: Assessment Question #9
Replies: 2
Views: 844

### Assessment Question #9

For question #9 in the assessment states: "8.00g of Vitamin C is analyzed and the results are: C 3.27g, H 0.36g, O 4.37g. Using mass spectrometry its molar mass is determined to be 176.14g*mol^(-1). What is the molecular formula for Vitamin C?" I got lost after you find the ratio for the e...
Sat Sep 24, 2016 6:59 pm
Forum: Empirical & Molecular Formulas
Topic: Assessment Question #8
Replies: 2
Views: 451

### Assessment Question #8

In the Pre-Assessment the question is #8, and states: "Xylitol, a sugar subsitute, has a mass composition of C 39.43%, O 52.58%, H 7.88%, and a molar mass of 152.15 g*mol^(-1). What is its molecular formula? " In the answers all the Hydrogens were not multiples of 5, which was the number I...