Search found 25 matches

by Josh Ku 3H
Sat Mar 18, 2017 1:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 202
Views: 64804

Re: Saying Thank You to Dr. Lavelle

Dr. Lavelle,

I absolutely hated chemistry before I took your class! You have showed me how important a great instructor is to learning about a topic as I have grown to love chemistry over these past two quarters.

THANK YOU
by Josh Ku 3H
Sat Mar 18, 2017 1:43 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: PdeltaV=deltanRT
Replies: 4
Views: 550

Re: PdeltaV=deltanRT

You would use this as another way to calculate work when the external pressure is constant. When Pex is constant, w = -P(delta)V. If the change in volume is not given and say they give you a reaction, then you would look to see if there is a change in the number of gas molecules (delta)n. If so, you...
by Josh Ku 3H
Sat Mar 18, 2017 1:38 pm
Forum: *Amines
Topic: Chapter 2 #35 and #44
Replies: 2
Views: 495

Re: Chapter 2 #35 and #44

To my understanding, I believe that the one is just there to help you picture the molecule better. Without the one, it just implies that the amine is attached to the first carbon. I think the one comes more into use when you have multiple amine groups so you would have something like Butane-1,4-diam...
by Josh Ku 3H
Sun Mar 12, 2017 11:20 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: staggered vs eclipsed stability
Replies: 3
Views: 399

Re: staggered vs eclipsed stability

I don't recall him saying that eclipsed is the most favorable position so I think you are right with your assumption in that the staggered formation should be more favorable. As you mentioned, a staggered formation would result in less electron-electron repulsion and thus the molecule would have les...
by Josh Ku 3H
Sun Mar 05, 2017 10:59 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 886563

Re: Post All Chemistry Jokes Here

How did the hipster chemist burn his hand?

He picked up his beaker before it was cool.
by Josh Ku 3H
Thu Feb 23, 2017 1:15 pm
Forum: General Rate Laws
Topic: Overall Order of a Reaction
Replies: 2
Views: 283

Re: Overall Order of a Reaction

On page 621 the rate law is experimentally determined. You cannot determine the rate law from the coefficients in the overall reaction, only from elementary steps as seen on page 70 in the course reader.

Hope this helps
by Josh Ku 3H
Sun Feb 12, 2017 11:12 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: C versus R
Replies: 1
Views: 166

Re: C versus R

Based off of the course reader, I think it is because of the equations that they are derived from. For the entropy equation involving volume, it is derived from the work equation (w = -nRTln(V2/V1) ) which has the R constant. As for the equation that involves temperature, it is derived from the expr...
by Josh Ku 3H
Tue Feb 07, 2017 2:33 pm
Forum: Balancing Redox Reactions
Topic: 14.5 Half Reactions
Replies: 4
Views: 433

14.5 Half Reactions

I'm a little confused on writing the oxidation and reduction half reactions. In 14.5 they are looking at the unbalanced equation: O3 + Br- --> O2 + BrO3- It makes sense for how bromine is being oxidized and oxygen is reduced but for the half reaction of oxygen the solution manual uses the equation: ...
by Josh Ku 3H
Sun Feb 05, 2017 8:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram commas vs |
Replies: 1
Views: 226

Re: Cell Diagram commas vs |

I have written down in my notes that if you have a solid metal in reaction, then you should use it as the electrode. If not then use an inert conductor as the electrode (e.g. Pt) to transfer the e-. In this problem Fe and Mn are both in the solution so you would use Pt. The " | " I'm prett...
by Josh Ku 3H
Sun Jan 22, 2017 9:32 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Homework Problem 8.19 and 8.21
Replies: 2
Views: 285

Re: Homework Problem 8.19 and 8.21

For #21, The question gives you the starting temperature of both the copper and the water as well as the mass for both of them. What you want to calculate is the final temperature. Since the copper is in the water, the two should have the same final temperature. With this in mind you use the equatio...
by Josh Ku 3H
Sun Jan 15, 2017 5:43 pm
Forum: Phase Changes & Related Calculations
Topic: CLOSED vs ISOLATED
Replies: 3
Views: 326

Re: CLOSED vs ISOLATED

As mentioned in the course reader an isolated system is one where neither matter or energy can exchange with the surroundings. The system can exchange energy with the surroundings through the transfer of heat. Substances at higher temperatures will have more energy, while things at lower temperature...
by Josh Ku 3H
Wed Nov 30, 2016 5:01 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: 13.11
Replies: 1
Views: 215

13.11

In this question it presents you with a buffered solution with acetic acid in an equal concentration with sodium acetate. The question asks for the pH change when different amounts of NaOH are introduced. By introducing hydroxide ions it causes the concentration of acetic acid to decrease and the co...
by Josh Ku 3H
Tue Nov 15, 2016 11:23 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbital Diagram of NO+ [ENDORSED]
Replies: 1
Views: 1542

Molecular Orbital Diagram of NO+ [ENDORSED]

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=43&t=16787 In the link above chem_mod said it was best to account for the negative charge of CN- by placing an extra electron on the nitrogen since it is more electronegative. I was just wondering if the same applied for molecules with a positi...
by Josh Ku 3H
Mon Nov 14, 2016 4:04 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Carbonate [ENDORSED]
Replies: 1
Views: 405

Carbonate [ENDORSED]

Hi, I was a little confused with the ligand carbonate. The textbook said that carbonate can be both monodentate and bidentate with either 1 or 2 bonds formed with the transition metal. Could you explain why it is only monodentate in some cases? Can ligands such as dien, en, and oxolato also exist as...
by Josh Ku 3H
Sun Nov 13, 2016 9:01 pm
Forum: Naming
Topic: Writing the formula of coordinate compounds
Replies: 1
Views: 297

Writing the formula of coordinate compounds

Hi sorry I was just a little confused on which ligands are supposed to come first when writing out the formula. In the textbook it says the chemical symbols of ligands are written in alphabetical order. To my understanding, I believe it is talking about the actual symbol and not the name. But in the...
by Josh Ku 3H
Sat Nov 12, 2016 8:34 pm
Forum: Naming
Topic: Multiple Ligands
Replies: 1
Views: 232

Re: Multiple Ligands

The ligands are written in alphabetical order (not including prefixes such as mono, di, tri, etc). The textbook has a good explanation of this and so does the course reader on pg 118.

I hope this helps.
by Josh Ku 3H
Sat Nov 12, 2016 8:29 pm
Forum: Naming
Topic: SO42- as OSO32-
Replies: 2
Views: 364

Re: SO42- as OSO32-

Hi, If you're looking at the anionic ligand chart, then I believe SO42- and OSO32- are the same molecule. They both indicate a sulfate molecule which is known as sulfato when it acts as a ligand. The reason why the chart writes OSO32- is to emphasize that it is the oxygen that forms a bond with the ...
by Josh Ku 3H
Sun Oct 30, 2016 3:09 pm
Forum: Balancing Chemical Reactions
Topic: The states of molecules [ENDORSED]
Replies: 1
Views: 303

The states of molecules [ENDORSED]

In the 1st question (part b) on the 2012 midterm it awarded points for labeling the states of the different molecules. I was just wondering if there was any certain rules as to knowing which molecule was a solid, liquid, gas or aqueous since it wasn't stated in the question. For example, how are you...
by Josh Ku 3H
Sat Oct 29, 2016 5:11 pm
Forum: Hybridization
Topic: s-character
Replies: 1
Views: 190

Re: s-character

viewtopic.php?t=1255

I found a question similar to yours. Hopefully this helps
by Josh Ku 3H
Sat Oct 29, 2016 5:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape Review Problem
Replies: 1
Views: 209

Re: Molecular Shape Review Problem

Usually the general rule for Aluminum is that when it does complete its octet it forms coordinate covalent bond with another chlorine molecule. The process is described on page 90 of the textbook but basically the molecule should be tetrahedral around the Aluminum atom.
by Josh Ku 3H
Sat Oct 29, 2016 12:41 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Chapter 4 Question #13 part b
Replies: 1
Views: 260

Chapter 4 Question #13 part b

In part b of the question it asks you to write the Lewis structure, VSEPR formula, molecular shape, and bond angles for POCL3 I understand how the shape will come out to tetrahedral with the three chlorines and an oxygen atom around the phosphorus but the solutions manual said the bond angles should...
by Josh Ku 3H
Sun Oct 23, 2016 2:20 pm
Forum: Hybridization
Topic: Labeling p orbital
Replies: 1
Views: 191

Re: Labeling p orbital

I think the question would have to ask you specifically to write out the different orbitals of the subshell. If its just asking for the electron configuration than you shouldn't have to write it out.
by Josh Ku 3H
Sun Oct 16, 2016 11:46 am
Forum: Resonance Structures
Topic: Breaking the Octet Rule
Replies: 6
Views: 838

Re: Breaking the Octet Rule

I also believe that Boron and Aluminum can have exceptions to the rule as well. They both can have just 6 electrons instead of the eight.
by Josh Ku 3H
Sat Oct 08, 2016 11:14 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Online Module
Replies: 1
Views: 196

Re: Atomic Spectra Online Module

I'm not sure if there is a specific equation to solving this question but the method I used was to first find the energy of each photon and then divide the amount energy produced in one second (11J) by the energy of each photon. You would find the amount energy of each photon through the equation E ...
by Josh Ku 3H
Fri Sep 30, 2016 3:27 pm
Forum: Properties of Light
Topic: Question 1.11
Replies: 2
Views: 296

Question 1.11

Question 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). What is common to the lines within a series that makes grouping them together logical? And the solution was: In...

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