Search found 22 matches

by Jeannie Huang 3B
Mon Feb 29, 2016 12:50 pm
Forum: *Alkenes
Topic: Homework 1.12C naming
Replies: 2
Views: 357

Re: Homework 1.12C naming

Yup, you want to give the double bond priority in numbering. So give it the lowest number first. In numbering, the priority goes as follows: 1. functional groups like --OH or carboxylic acid 2. double or triple bonds 3. other substituent groups Try to give #1 and #2 the lowest numbers first before p...
by Jeannie Huang 3B
Sat Feb 27, 2016 3:53 pm
Forum: *Alkanes
Topic: Ambident Nucleophiles
Replies: 2
Views: 335

Re: Ambident Nucleophiles

By definition, an ambident nucleophile is a molecule that has available lone pairs of electrons on two or more of its atoms--in other words, 2 places on it where it can react with another molecule. Draw out the Lewis structures to see. (It's similar to the idea of a bidentate ligand from 14A). Refer...
by Jeannie Huang 3B
Mon Feb 08, 2016 3:53 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Negative Cell Potential
Replies: 1
Views: 238

Re: Negative Cell Potential

In electrolysis the Eo value is a negative value. The reaction isn't spontaneous, and you need to use an electric current to overcome the negative voltage and force it to occur.
by Jeannie Huang 3B
Mon Feb 08, 2016 3:47 pm
Forum: Balancing Redox Reactions
Topic: Redox Reactions
Replies: 1
Views: 253

Re: Redox Reactions

It's usually given in the question. It'll specify if it's in acidic or basic solution, and you can balance the H+ and OH- as needed.
by Jeannie Huang 3B
Sun Feb 07, 2016 4:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Water and Cell Diagrams
Replies: 2
Views: 352

Re: Water and Cell Diagrams

When the reaction involves aqueous ions (like Ag+) it's assumed that the water in the solution doesn't affect the reaction. However if another phase of water is involved in the reaction then yes the liquid water (or H+ and OH- ions) should be taken into account.
by Jeannie Huang 3B
Sun Jan 24, 2016 4:58 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Standard residual entropy problem
Replies: 2
Views: 629

Re: Standard residual entropy problem

To answer the question, you need to draw the lewis structure for COF2. You should get a trigonal planar shape with C in the center. You could get 3 different orientations of the molecule since the O can be in one of the three corners. Following the equation, S = k ln W (refer to pg. 32 of course rea...
by Jeannie Huang 3B
Sun Jan 24, 2016 4:46 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.49
Replies: 2
Views: 321

Re: 8.49

I believe the +1 mol is from 2 mol reactants --> 3 mol products. So change of mols was 3-2 =1.
Other people have posted about this question before so I recommend checking those out :]
by Jeannie Huang 3B
Fri Jan 22, 2016 7:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Question 8.49 - Why can you not use a mole ratio?
Replies: 4
Views: 536

Re: Homework Question 8.49 - Why can you not use a mole rati

I believe that the "net production of 1 mole of gas" refers to the fact that 1 mole of OF2 (part of the 2 moles of total reactant) produces 3 moles of product. Thus, the net difference is 3-2 moles = 1 mole of gas difference between reactants and products.
by Jeannie Huang 3B
Mon Jan 11, 2016 1:07 pm
Forum: Trends in The Periodic Table
Topic: Lavelle's favorite periodic table
Replies: 2
Views: 2410

Re: Lavelle's favorite periodic table

Mine is the rice krispy periodic table :)
(this was for my birthday a while back)
https://drive.google.com/file/d/0BzeS9b9yItnNYkVYY0Z5Y2VjWEU/view?usp=sharing
by Jeannie Huang 3B
Sat Dec 05, 2015 8:35 pm
Forum: Lewis Structures
Topic: Determining which element to give a formal charge
Replies: 3
Views: 453

Re: Determining which element to give a formal charge

Although chlorine is in period 3, it's so electronegative that it doesn't like sharing electrons, and usually won't form anything more than one single bond. Thus, it's an exception to the expanded octet rule for periods >= 3.
by Jeannie Huang 3B
Mon Nov 30, 2015 10:11 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 902641

Re: Chemistry Jokes

Q: Why should you never give up studying chemistry even if you feel like you're going to fail the final?

A: Because chem-is-try! <3
by Jeannie Huang 3B
Wed Nov 18, 2015 8:43 pm
Forum: Naming
Topic: Using prefixes bis-, tris-, etc.
Replies: 3
Views: 538

Re: Using prefixes bis-, tris-, etc.

Why does that problem put diaqua before bixoxalato? Isn't it supposed to be according to alphabetical order?
so sodium diaqua bisoxalato ferrate (III)
by Jeannie Huang 3B
Mon Nov 16, 2015 7:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Enrolling in 14BL
Replies: 1
Views: 579

Re: Enrolling in 14BL

The UCLA registrar site says that CHEM14B is an enforced corequisite to CHEM14BL, so I assume they won't let you enroll in the lab until you're in the lecture first...can anyone confirm? I have the same problem. Link: http://www.registrar.ucla.edu/schedule/subdet.aspx?srs=142117200&term=16W&...
by Jeannie Huang 3B
Sun Nov 01, 2015 3:50 pm
Forum: Empirical & Molecular Formulas
Topic: Which methods to use when finding empirical formulas
Replies: 2
Views: 573

Re: Which methods to use when finding empirical formulas

I use the same methods as you do for those types of problems, and it wasn't marked incorrect or anything on the first quiz (after all, we arrive at the same answer). So, I assume it's okay to do so.
by Jeannie Huang 3B
Sun Nov 01, 2015 3:35 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: MO diagrams
Replies: 2
Views: 253

Re: MO diagrams

No. One element would have lower orbitals than the other only if it has a larger electronegativity.
by Jeannie Huang 3B
Sun Nov 01, 2015 3:33 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Valence e- Configuration
Replies: 1
Views: 255

Re: Valence e- Configuration

I'm not quite sure what you're asking, but yes, whenever you want to find the electronic configuration of a diatomic molecule you should draw out the MO diagram. I find, however, that drawing only the middle portion of the diagram (the combined orbitals) is often sufficient to answer questions about...
by Jeannie Huang 3B
Wed Oct 21, 2015 11:40 am
Forum: Electronegativity
Topic: Electronegativity and Bond Strength
Replies: 1
Views: 1009

Re: Electronegativity and Bond Strength

I think the reason for this is that when the electronegativity difference is high, the electrostatic attraction between the positive and negative charges will also be high, causing a shorter bond length. The bond also takes on an increasingly ionic character. I'm not sure, however, if ionic compound...
by Jeannie Huang 3B
Wed Oct 21, 2015 11:21 am
Forum: Electronegativity
Topic: Which element is more electronegative?
Replies: 1
Views: 678

Re: Which element is more electronegative?

Oxygen is more electronegative than chlorine. It has an electronegativity unit of 3.5 while chlorine is 3.0. But I'm fairly certain we only need to know the general trend and not specific details like this. http://butane.chem.uiuc.edu/cyerkes/chem102ae_fa08/homepage/Chem102AEFa07/Lecture_Notes_102/L...
by Jeannie Huang 3B
Fri Oct 09, 2015 11:59 am
Forum: Administrative Questions and Class Announcements
Topic: Differences between 5th Edition and 6th Edition textbook
Replies: 1
Views: 375

Differences between 5th Edition and 6th Edition textbook

I have the 5th edition textbook instead of the 6th. I've realize that some of the homework problems assigned may not correspond to the ones in the 5th edition. For instance, there was a question assigned on black body radiation which we obviously did not cover. I believe that chapter 1 might have be...
by Jeannie Huang 3B
Fri Oct 02, 2015 4:40 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 91
Views: 9063

Re: All students read this sig fig post [ENDORSED]

If we are calculating values using only constants, such as the wavelength of light emitted when an electron jumps from energy level n=4 to n=2, how many sig-figs should we use? Will we be using a sheet for constants and equations during exams (and thus should we follow the amount of sig-figs given t...

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