Search found 44 matches

by Omer Lavian 2K
Fri Mar 17, 2017 2:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 225
Views: 102157

Re: Saying Thank You to Dr. Lavelle

Dear Professor Lavelle, I just want to say that I am honored to have been a part of your class. You are one of the sweetest and most caring teachers I have had the pleasure of learning from both within and outside of UCLA. I cannot tell you how much I appreciate the amount of resources you provide f...
by Omer Lavian 2K
Tue Mar 07, 2017 2:54 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7726
Views: 1043714

Re: Post All Chemistry Jokes Here

A really deep and important question to ponder as you study for quiz 3 and the final.
by Omer Lavian 2K
Wed Mar 01, 2017 1:08 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7726
Views: 1043714

Re: Post All Chemistry Jokes Here

What in titration is organic chemistry?
by Omer Lavian 2K
Wed Feb 22, 2017 10:46 pm
Forum: *Electrophiles
Topic: Electrophiles and nucleophiles
Replies: 3
Views: 374

Re: Electrophiles and nucleophiles

One thing to keep in mind about this that is kind of counterintuitive to me is that neutral halogens are considered electrophiles. When I think of halogens, I automatically remember that they tend to have a -1 oxidation state, which made it hard for me at first to grasp that NEUTRAL halogens actuall...
by Omer Lavian 2K
Fri Feb 17, 2017 3:01 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Figuring out overall order of reaction based on balanced reaction
Replies: 1
Views: 206

Re: Figuring out overall order of reaction based on balanced reaction

Yes! You're exactly right! The trick is just to know that the order of the reaction and the order for each reactant are separate things.

Sometimes the order of the reactant and the reaction are the same value, but they still represent different things.
by Omer Lavian 2K
Sat Feb 11, 2017 10:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Taking 14BL and 14C at the Same Time
Replies: 1
Views: 277

Taking 14BL and 14C at the Same Time

I heard from someone that there you're "not supposed" to take Chem 14BL at the same time as Chem 14C. Is there some sort of issue with that? Is the workload of those two classes combined considered extremely overwhelming?
by Omer Lavian 2K
Mon Feb 06, 2017 1:22 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic cell vs electrolytic cell [ENDORSED]
Replies: 2
Views: 283

Re: Galvanic cell vs electrolytic cell [ENDORSED]

A galvanic cell uses a redox reaction to create a flow of electrons (current) that can do useful work. For a galvanic cell to work, the redox reaction used must be thermodynamically favorable (delta G must be less than 0, which is the case for a spontaneous reaction), creating a positive voltage. Fo...
by Omer Lavian 2K
Tue Jan 31, 2017 7:26 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7726
Views: 1043714

Re: Post All Chemistry Jokes Here

How does the crystal with no entropy feel?

0 K
by Omer Lavian 2K
Thu Jan 26, 2017 10:43 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Question 9.29
Replies: 1
Views: 219

Re: Question 9.29

This question is more conceptual than it is mathematical. If you think back to the equation with Boltzmann's constant, S = KblnW, you see that the entropy depends on W, the number of possible states (often called microstates) in which a material (an atom, a molecule, a substance, etc.) can exist. Th...
by Omer Lavian 2K
Thu Jan 26, 2017 10:22 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Homework question 8.23
Replies: 1
Views: 260

Re: Homework question 8.23

The problem is asking for the heat capacity of the calorimeter, not the specific heat capacity of the calorimeter. Long story short, if you don't see the words "specific" or "molar" before "heat capacity," then you don't need to worry about mass or moles.
by Omer Lavian 2K
Tue Jan 24, 2017 6:34 pm
Forum: Phase Changes & Related Calculations
Topic: Derivations
Replies: 21
Views: 2160

Re: Derivations

If it's any help at all a guide to integration of polynomials and of x^-1 (also known as 1/x) can be found on the constants sheet.
by Omer Lavian 2K
Tue Jan 17, 2017 10:47 pm
Forum: Administrative Questions and Class Announcements
Topic: CH 8 Which HW Problems to do first?
Replies: 14
Views: 9328

Re: CH 8 Which HW Problems to do first?

Which homework problems go over the heat capacity/calorimetry material we talked about last lecture?
by Omer Lavian 2K
Wed Jan 11, 2017 8:18 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7726
Views: 1043714

Re: Post All Chemistry Jokes Here

What do you call 6.02214 x 10^23 big, white bears?

MOLAR BEARS!
by Omer Lavian 2K
Wed Nov 30, 2016 5:30 pm
Forum: Identifying Acidic & Basic Salts
Topic: 12.65 (e) and (f)
Replies: 4
Views: 977

Re: 12.65 (e) and (f)

I mean water is neutral, so I assume the charge corresponds to the ion and thus the entire complex.
by Omer Lavian 2K
Tue Nov 29, 2016 3:21 am
Forum: Identifying Acidic & Basic Salts
Topic: 12.65 (e) and (f)
Replies: 4
Views: 977

12.65 (e) and (f)

Determine whether an aqueous solution of each of the following salts has a pH equal to, greater than, or less than 7. If pH & 7 or pH ' 7, write a chemical equation to justify your answer. (a) NH4Br; (b) Na2CO3; (c) KF; (d) KBr; (e) AlCl3; (f) Cu(NO3)2. I understand that Al3+ and Cu2+ are small,...
by Omer Lavian 2K
Mon Nov 28, 2016 3:14 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sig Figs for Logarithms and Exponents
Replies: 2
Views: 413

Sig Figs for Logarithms and Exponents

I know this is explained in the course reader, but it's super confusing to me. How do we determine the correct sig figs when doing a logarithm (for example, to find a pH from an H3O+ concentration) and when using exponents (for example, to find an H3O+ concentration from a pH)?
by Omer Lavian 2K
Mon Nov 21, 2016 1:59 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.79
Replies: 2
Views: 255

11.79

A reactor for the production of ammonia by the Haber process is found to be at equilibrium with PN2 " 3.11 bar, PH2 " 1.64 bar, and PNH3 " 23.72 bar. If the partial pressure of N2 is increased by 1.57 bar, what will be the partial pressure of each gas once equilibrium is re-establishe...
by Omer Lavian 2K
Mon Nov 14, 2016 6:53 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Homework 4.77 [ENDORSED]
Replies: 1
Views: 234

Homework 4.77 [ENDORSED]

(a) Draw the bonding and antibonding orbitals that
correspond to the &-bond in H2. (b) Repeat this procedure for
HF. (c) How do these orbitals differ?

Are we expected to determine the shape of molecular orbitals?
by Omer Lavian 2K
Mon Nov 14, 2016 11:30 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.7 c
Replies: 1
Views: 311

11.7 c

(c) Assuming that the initial pressure of X2 was 0.10 bar, calculate the value of K for the decomposition. We are given the original pressure of X2 and are expected to calculate partial pressures based on that for the equilibrium condition of X and X2. Shouldn't we be given the pressure of the syste...
by Omer Lavian 2K
Mon Nov 14, 2016 11:01 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework 17.33
Replies: 2
Views: 362

Re: Homework 17.33

Nina, to answer your question, and maybe this will help with the original question as well, for a molecule to be polydentate, it needs to be able to contribute multiple lone pairs at the same time to a central metal atom. This means that a) there must be at least two atoms with available lone pairs ...
by Omer Lavian 2K
Wed Nov 09, 2016 10:12 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework 17.33
Replies: 7
Views: 711

Re: Homework 17.33

Sorry for posting so much but Liam, I remember Dr. Lavelle drawing the molecule in class with an N-C-C-N structure. I assume that this gives all the N's a formal charge of zero, whereas you have one N with a -1 charge and another with a +1.
by Omer Lavian 2K
Wed Nov 09, 2016 9:54 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework 17.33
Replies: 7
Views: 711

Re: Homework 17.33

Also the SO42- ligand has 4 atoms with lone pairs, but it isn't shaped in a way that would indicate that it is tetra dentate. My guess is that like carbonato, it can be mono or bidentate. Thoughts?
by Omer Lavian 2K
Wed Nov 09, 2016 9:49 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework 17.33
Replies: 7
Views: 711

Re: Homework 17.33

Also the SO42- ligand has 4 atoms with lone pairs, but it isn't shaped in a way that would indicate that it is tetra dentate. My guess is that like carbonato, it can be mono or bidentate. Thoughts?
by Omer Lavian 2K
Sun Nov 06, 2016 5:54 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework 17.33
Replies: 7
Views: 711

Homework 17.33

17.33 Which of the following ligands can be polydentate? If the ligand can be polydentate, give the maximum number of places on the ligand that can bind simultaneously to a single metal center: (a) HN(CH2CH2NH2)2; (b) CO3 2!; (c) H2O; (d) oxalate. What makes a ligand able to be polydentate? Addition...
by Omer Lavian 2K
Sun Nov 06, 2016 5:23 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7726
Views: 1043714

Re: Post All Chemistry Jokes Here

Arrigato Mr. Sulfato!
by Omer Lavian 2K
Mon Oct 31, 2016 1:54 pm
Forum: Hybridization
Topic: Hybridization Beyond sp3
Replies: 2
Views: 366

Hybridization Beyond sp3

I saw someone ask a question about hybridization beyond sp3 here. Will we be expected to know about that for the midterm, the final, or for any other parts of this course?
by Omer Lavian 2K
Tue Oct 25, 2016 9:40 pm
Forum: Lewis Structures
Topic: Homework 3.111
Replies: 2
Views: 306

Re: Homework 3.111

Thank you!
by Omer Lavian 2K
Tue Oct 25, 2016 3:32 pm
Forum: Lewis Structures
Topic: Homework 3.111
Replies: 2
Views: 306

Homework 3.111

3.111 A common biologically active radical is the pentadienyl radical, RCHCHCHCHCHR%, where the carbons form a long chain, with R and R', which can be a number of different organic groups, at each end. Draw three resonance structures for this compound that maintain carbon’s valence of four. I'm conf...
by Omer Lavian 2K
Mon Oct 24, 2016 12:24 pm
Forum: Trends in The Periodic Table
Topic: CH 2, #61 [ENDORSED]
Replies: 2
Views: 362

Re: CH 2, #61 [ENDORSED]

To answer your first question, IN GENERAL, going from left to right across a period on the periodic table, ionization energy increases because while the principle quantum number stays the same (or goes down one in the case of period one elements), the positive charge of the nucleus increases slowly ...
by Omer Lavian 2K
Thu Oct 20, 2016 10:08 pm
Forum: Octet Exceptions
Topic: Homework 3.57 part b [ENDORSED]
Replies: 4
Views: 480

Re: Homework 3.57 part b [ENDORSED]

I think I figured out the issue. The answer shows that sulfur can still have a formal charge of 0 without breaking the octet rule. I suppose that means that breaking the octet rule should be a last resort for if the formal charges can be brought closer to 0. It doesn't seem to be necessary in this e...
by Omer Lavian 2K
Thu Oct 20, 2016 9:55 pm
Forum: Octet Exceptions
Topic: Homework 3.57 part b [ENDORSED]
Replies: 4
Views: 480

Re: Homework 3.57 part b [ENDORSED]

I can't figure out how to post a picture on this forum! I wish I could so we can look at it together. The way I drew it gave sulfur two double bonds and two single bonds, giving it a formal charge of 0.
by Omer Lavian 2K
Wed Oct 19, 2016 11:20 am
Forum: Octet Exceptions
Topic: Homework 3.57 part b [ENDORSED]
Replies: 4
Views: 480

Homework 3.57 part b [ENDORSED]

The problem asks to write the Lewis Structure for HSO3-. The solution manual bonds the hydrogen to one of the oxygen atoms, but can't you bond the hydrogen atom to the sulfur atom? With an expanded octet, the formal charge of sulfur is zero either way, and the only atom with a non-zero formal charge...
by Omer Lavian 2K
Mon Oct 17, 2016 7:12 pm
Forum: Resonance Structures
Topic: Resonance and Electrons [ENDORSED]
Replies: 1
Views: 187

Re: Resonance and Electrons [ENDORSED]

Let's use the example of benzene. As you can see on page 81 of the course reader, there are two different possible Lewis structures for benzene. In this case, this simply means that the double bonds and single bonds in the ring can be rearranged, resulting in two different possible Lewis structures....
by Omer Lavian 2K
Wed Oct 12, 2016 11:50 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework Problem 2.39 Issue
Replies: 4
Views: 581

Homework Problem 2.39 Issue

Determine whether each of the following electron configurations represents the ground state or an excited state of the atom given. I can't pull up a picture of the diagrams for the problem for some reason, but here are the configurations given, at least based on how I interpreted the diagrams. (a) C...
by Omer Lavian 2K
Wed Oct 12, 2016 12:39 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Negative frequency of light?
Replies: 1
Views: 230

Re: Negative frequency of light?

Delta E doesn't represent energy. It represents a change in energy. If an electron transitions from a higher principal quantum number to a lower one, it releases energy, causing a negative delta E and the release of a photon (Think about it this way. If you applied the same equation to a shrinking b...
by Omer Lavian 2K
Mon Oct 10, 2016 9:47 pm
Forum: Photoelectric Effect
Topic: Post Module Questions
Replies: 1
Views: 294

Re: Post Module Questions

1.) Yes. Generally speaking, photoelectric experiments are performed using UV light since it often has sufficient energy to eject electrons from metals. 2.) Yes, I also got 1.99 x 10^-18 J for one photon for question #16. Just good old fashioned E=hv. You seem to have that in the bag! For question #...
by Omer Lavian 2K
Fri Oct 07, 2016 3:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Audio-Visual Topic Question [ENDORSED]
Replies: 1
Views: 309

Audio-Visual Topic Question [ENDORSED]

Number 13 in the Pre-Module Assesment for the Heisenberg Uncertainty Principle states: Two students are 'studying' together when Bob says "I do love you Alice" and Alice responds "But how can I be sure?" Would using Heisenberg's uncertainty principle help them determine or resolv...
by Omer Lavian 2K
Tue Oct 04, 2016 10:36 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Homework Problem 1.11 Issue
Replies: 2
Views: 351

Homework Problem 1.11 Issue

Homework problem 1.11 asks: In the spectrum of atomic hydrogen, several lines are generally classified together as belonging to a series (for example, Balmer series, Lyman series, Paschen series), as shown in Figs. 1.10 and 2.1. What is common to the lines within a series that makes grouping them to...
by Omer Lavian 2K
Mon Oct 03, 2016 8:12 pm
Forum: Properties of Electrons
Topic: Constructive and Destructive Interference [ENDORSED]
Replies: 3
Views: 901

Re: Constructive and Destructive Interference [ENDORSED]

Imagine two sine waves (sort of like the waves Dr. Lavelle has drawn for us in class) of the same wavelength, frequency, and amplitude (distance from the equilibrium position, the point between the peak and the trough, to either a peak or a trough). If the peaks of one wave line up with the peaks of...
by Omer Lavian 2K
Mon Oct 03, 2016 3:21 pm
Forum: Student Social/Study Group
Topic: Hitch Study Group
Replies: 12
Views: 1218

Re: Hitch Study Group

Hey I'm so down for this. I live in building C!
by Omer Lavian 2K
Sun Sep 25, 2016 8:02 pm
Forum: Student Social/Study Group
Topic: Chemistry Jokes
Replies: 31
Views: 4430

Re: Chemistry Jokes

You've never heard of sodium hydroxide? It's so basic!

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