Search found 20 matches

by Cliff Danza 3F
Wed Mar 08, 2017 1:43 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Electron pair transfer in a stable molecule
Replies: 1
Views: 325

Re: Electron pair transfer in a stable molecule

The example you mention is the electrophilic addition reaction with HBr and Butene. This reaction occurs because the Br atom is more electronegative than the H atom, so it draws electrons toward the Br atom, which leaves H with a delta positive. The double bond in butene is an electron rich region d...
by Cliff Danza 3F
Mon Mar 06, 2017 11:09 pm
Forum: *Alkanes
Topic: Naming with iso- and neo-
Replies: 8
Views: 855

Re: Naming with iso- and neo-

Iso- and Neo- are used in common naming for the shape of the structure, followed by the appropriate carbon alkane/alkene/alkyne group name (like -hexane or -propane), counting all the carbon atoms. Iso- and Neo- are used in IUPAC naming only for the substituents. For example, if there was a decane m...
by Cliff Danza 3F
Mon Feb 27, 2017 12:16 pm
Forum: *Complex Reaction Coordinate Diagrams
Topic: Lewis structure and Shape Question
Replies: 1
Views: 594

Re: Lewis structure and Shape Question

The molecule will have a tetrahedral geometry when considered in 3D, and no matter where you place the two Cl- the dipole moments will not cancel.
by Cliff Danza 3F
Tue Feb 21, 2017 8:06 pm
Forum: General Rate Laws
Topic: Slow Step
Replies: 3
Views: 366

Re: Slow Step

We won't necessarily have to be told which step is the fast or the slow one in a problem. We know that the slow step rate must match the observed rate, which means the first step could be the slow step which would match automatically, or the second step could be the slow step (which causes a bottlen...
by Cliff Danza 3F
Tue Feb 14, 2017 11:20 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Quiz 2
Replies: 3
Views: 422

Re: Quiz 2

The Quiz 2 practice in the coursereader only has Kinetics in it so I think Megan is right.
by Cliff Danza 3F
Tue Feb 07, 2017 12:10 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: What is n? [ENDORSED]
Replies: 8
Views: 814

Re: What is n? [ENDORSED]

For that equation specifically "n" refers to the moles of electrons being transferred in the balanced redox reaction. So yes you will need to know that balanced value if asked for the Gibbs Free energy, which requires balancing the redox equation.
by Cliff Danza 3F
Tue Jan 31, 2017 6:14 pm
Forum: Phase Changes & Related Calculations
Topic: Given quantities
Replies: 2
Views: 329

Re: Given quantities

I had Dr. Lavelle's class for 14A last quarter, so I'm confident in saying any values specific to a compound/atom will be given in a problem if we need them to calculate the answer in 14B as well.
by Cliff Danza 3F
Mon Jan 23, 2017 4:45 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Degeneracy
Replies: 1
Views: 333

Re: Degeneracy

From Wikipedia the definition is: "In quantum mechanics, an energy level is said to be degenerate if it corresponds to two or more different measurable states of a quantum system. Conversely, two or more different states of a quantum mechanical system are said to be degenerate if they give the ...
by Cliff Danza 3F
Mon Jan 23, 2017 4:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Heat
Replies: 1
Views: 224

Re: Heat

The way microwaves work is by creating an electric field that changes the direction of dipole molecules rapidly, transferring to thermal energy. Most often this works on the water in the moisture of the food. There is water vapor in the air, but the amount being heated is too small to lead to injury.
by Cliff Danza 3F
Wed Jan 11, 2017 9:37 pm
Forum: Phase Changes & Related Calculations
Topic: Temperature of sample remaining constant?
Replies: 4
Views: 394

Re: Temperature of sample remaining constant?

During phase changes the heat energy being supplied all goes toward breaking bonds and not toward raising temperature.
by Cliff Danza 3F
Sun Nov 27, 2016 11:35 pm
Forum: Conjugate Acids & Bases
Topic: Resonance and Stability
Replies: 1
Views: 283

Re: Resonance and Stability

Resonance structures are more stable as a rule because the electrons are de-localized, which lowers the potential energy of the system.
by Cliff Danza 3F
Tue Nov 22, 2016 2:29 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: #electrons
Replies: 1
Views: 300

Re: #electrons

In regards to the number of electrons, the reason there can only be 2 electrons in the subshells of the example is because they specify a ml value. For example if all it said was n=3, then that would describe a possible 28 electrons (because of all the s,p,d orbitals and the electrons they hold). If...
by Cliff Danza 3F
Tue Nov 15, 2016 4:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Quiz 3 Prep Fall 2014 [ENDORSED]
Replies: 1
Views: 228

Re: Quiz 3 Prep Fall 2014 [ENDORSED]

Lowering the pressure (by way of increasing volume) will favor the side with more moles of gas. In this reaction there are 3 moles of gas on the right and 2 on the left, so lower pressure will increase SO2 production.
by Cliff Danza 3F
Mon Nov 07, 2016 2:46 pm
Forum: Dipole Moments
Topic: polarity
Replies: 1
Views: 363

Re: polarity

If there are no electron lone pairs, then the dipole moments (toward Cl) would all cancel because of the Trigonal Bi-Pyramidal shape. So the bonds in PCl5 can be considered polar bonds, but the molecule is non-polar.
by Cliff Danza 3F
Mon Oct 31, 2016 2:31 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Anti-bonds in MO Diagram
Replies: 2
Views: 249

Re: Anti-bonds in MO Diagram

Anti-bonds are basically the molecular orbital formula where the two orbital functions are subtracted. This is so the number of atomic orbitals are conserved: start off with 2 atomic orbitals, and then create one 'Bonding' and one 'Anti-Bonding'. This is on page 106-107 in the course reader :)
by Cliff Danza 3F
Mon Oct 24, 2016 7:37 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for Ions
Replies: 4
Views: 399

Re: Electron Configuration for Ions

I believe the correct way is to use the previous noble gas for the element, which would be Kr. If you were to use (Xe)6s^1 then you are describing Cs.
by Cliff Danza 3F
Wed Oct 19, 2016 6:43 pm
Forum: Lewis Structures
Topic: Lewis Structure Problem 3.39 [ENDORSED]
Replies: 1
Views: 266

Re: Lewis Structure Problem 3.39 [ENDORSED]

Generally, brackets are put around an individual ion, and it shows that the Lewis Structure has a charge. I do believe you aren't incorrect if you put brackets around the Cl- , K+ , and Na+ , but for single-atom ions, brackets aren't required.
by Cliff Danza 3F
Mon Oct 10, 2016 9:10 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Confusion [ENDORSED]
Replies: 3
Views: 499

Re: Elecreon Configuration Confusion [ENDORSED]

I think the part of the course reader you are referring to is this: After 4s state/orbital occupied and e- enter 3d state, then 3d state is lower in energy than 4s The reason for this is complicated, but here is a graph I found that illustrates what is going on with the energy levels: http://i.stack...
by Cliff Danza 3F
Wed Oct 05, 2016 8:23 pm
Forum: DeBroglie Equation
Topic: E = mc2 [ENDORSED]
Replies: 1
Views: 422

Re: E = mc2 [ENDORSED]

E=mc^2 is a formula used for matter. Photons do not have a mass, so the equation to calculate their energy is: E=(h*c)/lambda.
by Cliff Danza 3F
Mon Sep 26, 2016 4:35 pm
Forum: Student Social/Study Group
Topic: Chemistry Jokes
Replies: 31
Views: 4372

Re: Chemistry Jokes

Is Silicon the same in Spanish?

Si

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