Search found 21 matches

by Joyce Wu 3E
Thu Mar 16, 2017 10:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 200
Views: 44236

Re: Saying Thank You to Dr. Lavelle

Dear Dr. Lavelle, Thank you for the two most amazing education quarters of chemistry. I have never seen a more dedicated professor/ educator to his subject and his students. With countless resources, office hours, and bruincasts, you made sure that every student had the opportunity to succeed in you...
by Joyce Wu 3E
Tue Mar 07, 2017 1:59 am
Forum: *Free Energy of Activation vs Activation Energy
Topic: Standard Gibbs Free Energy of Activation
Replies: 2
Views: 670

Re: Standard Gibbs Free Energy of Activation

The standard Gibbs energy difference between the transition state of a reaction and the ground state of the reactants. Because it usually takes energy for the reaction to happen (energy will be used to break the molecular bonds of the reactants), the gibbs free engery of activation will be positive....
by Joyce Wu 3E
Wed Mar 01, 2017 11:03 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 803045

Re: Post All Chemistry Jokes Here

I'd tell you a good chemistry joke, but all the good ones [Ar]gon
by Joyce Wu 3E
Thu Feb 23, 2017 4:52 pm
Forum: General Rate Laws
Topic: Unique Average Rate Question
Replies: 1
Views: 244

Re: Unique Average Rate Question

Yes that is correct. If B had 2 mols, then the unique rate would be multiplied by 2 for the rate of B
by Joyce Wu 3E
Wed Feb 15, 2017 3:39 pm
Forum: Balancing Redox Reactions
Topic: Winter Midterm 2016: Q5A
Replies: 2
Views: 281

Re: Winter Midterm 2016: Q5A

Whether or not the reaction is reversed is based off of the overall equation that is given in the problem. It was ATP+H2O --> ADP + (HPO4)2- Seeing the 2 reactions given, we see that we needed the fructose molecules to cancel out while having the products and reactants from the given equation stay i...
by Joyce Wu 3E
Wed Feb 08, 2017 12:17 pm
Forum: Phase Changes & Related Calculations
Topic: Phase changes
Replies: 1
Views: 296

Re: Phase changes

Usually when Gas goes to a Liquid, deltaH is a negative. Forming bonds releases energy. In contrast, when Liquid goes to a Gas, deltaH is a positive since it requires energy to break the intermolecular bonds.
by Joyce Wu 3E
Tue Jan 31, 2017 4:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Potential E [ENDORSED]
Replies: 1
Views: 235

Re: Standard Potential E [ENDORSED]

In a galvanic cell, the standard potential E is positive to indicate that the oxidation-reduction reaction is a spontaneous reaction for reduction at the cathode and oxidation at the anode. If it is negative, then it would not be an effective "battery" since it does not spontaneously produ...
by Joyce Wu 3E
Wed Jan 25, 2017 8:34 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: favorability
Replies: 1
Views: 374

Re: favorability

It is not as black and white as that. An endothermic reaction can be spontaneous (favorable) as well. For example, Gibbs free energy is determined by enthalpy, temperature, and entropy (delta(G) = delta(H) - T(Delta(S)). So when delta(H) is positive it means its endothermic. In this case, if delta(S...
by Joyce Wu 3E
Fri Jan 20, 2017 5:26 pm
Forum: Phase Changes & Related Calculations
Topic: 8.29 in Textbook [ENDORSED]
Replies: 2
Views: 317

Re: 8.29 in Textbook [ENDORSED]

Molar heat capacity is the heat required to raise the temperature of 1 mol of a substance by 1 degree C. The reason why NO2 has higher molar heat capacity is because it has more molecular complexity than NO. Due to this, it would take more heat to raise the temp of 1 mol for NO2
by Joyce Wu 3E
Wed Jan 11, 2017 9:02 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 803045

Re: Post All Chemistry Jokes Here

I saw my friends inhaling helium and I was like:
He, He, He
by Joyce Wu 3E
Sat Dec 03, 2016 2:25 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: When to use H-H equation
Replies: 1
Views: 501

Re: When to use H-H equation

We mostly use the H-H equation regarding buffers. This is because this equation involves a weak acid/base and its conjugate through a salt with the same anion (or cation).
by Joyce Wu 3E
Mon Nov 28, 2016 7:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 11.41
Replies: 3
Views: 283

Re: Homework 11.41

We plug in 1.58x10^-3 because that is the molarity (mols/Liter) of CO2. The problem says that at equilibrium, there are 0.0174 grams of CO2. Convert that to mols, it is 3.95x10^-4 mols. We are told that this is within 0.250 liters; thus, the molarity of CO2 would be (3.95x10^-4 mol)/(.250 L) = 1.58x...
by Joyce Wu 3E
Sun Nov 27, 2016 3:06 am
Forum: Administrative Questions and Class Announcements
Topic: About Final
Replies: 3
Views: 392

Re: About Final

He actually posted the link to all the details about the final on his website :) Chem 14A Final Exam 3-6pm, Sunday, December 4. 14A-1, 11am class: Last name A-L in CS50. Last name M-Z in LAKRETZ 110. 14A-3, 1pm class: Last name A-L in CS24. Last name M-Z in CS76. 14A-4, 3pm class: Everyone in MOORE ...
by Joyce Wu 3E
Tue Nov 15, 2016 5:14 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: #4 in Quiz Prep 3 2015 [ENDORSED]
Replies: 1
Views: 298

Re: #4 in Quiz Prep 3 2015 [ENDORSED]

Yes, you are supposed to count en as 2 bonds because it is BIDENTATE which means it can bond at 2 sites (Specifically at the 2 nitrogens).
by Joyce Wu 3E
Thu Nov 10, 2016 9:41 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 803045

Re: Post All Chemistry Jokes Here

How many moles are in a guacamole??
- Avacado's number
by Joyce Wu 3E
Tue Nov 01, 2016 8:32 pm
Forum: Hybridization
Topic: Fall 2014 Quiz 2 Prep #4
Replies: 2
Views: 264

Re: Fall 2014 Quiz 2 Prep #4

So looking at the answer key (with the lewis structures) from the first Carbon from the left to right, it should be sp2, sp, sp2, sp, sp, sp3
by Joyce Wu 3E
Tue Oct 25, 2016 1:45 pm
Forum: Resonance Structures
Topic: Resonance vs. Lewis Structure?
Replies: 9
Views: 867

Re: Resonance vs. Lewis Structure?

If the question requires you to draw the resonance, it will probably always ask you specifically to. Otherwise, the question would state: "draw the most STABLE lewis structure". Which simply means the one with the lowest formal charge.
by Joyce Wu 3E
Wed Oct 19, 2016 3:17 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs. Covalent Bonds [ENDORSED]
Replies: 2
Views: 444

Re: Ionic vs. Covalent Bonds [ENDORSED]

Electronegativity can be defined as "the power of an atom in a molecule to attract electrons to itself". In a non-polar covalent bond, there is an equal sharing of electrons in the bond; thus, the electronegativity difference is very small. In a polar covalent bond, there is an unequal sha...
by Joyce Wu 3E
Wed Oct 12, 2016 4:29 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 803045

Re: Post All Chemistry Jokes Here

Image

But seriously we need to combat global warming and help the polar bears
by Joyce Wu 3E
Tue Oct 04, 2016 4:33 pm
Forum: Student Social/Study Group
Topic: Chemistry Joke
Replies: 18
Views: 1405

Re: Chemistry Joke

Oxygen and Magnesium are going out, like OMg!!
by Joyce Wu 3E
Tue Sep 27, 2016 4:32 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 34806

Re: Rusty on High School Chem [ENDORSED]

I took AP chemistry back when I was a sophomore in high school and am now taking 14A as a freshman in college so I understand how frustrating it is to forget the majority of the chemistry once learned. One tip I would have is to finish all the modules Dr. Lavelle posted on his website and also breez...

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