Search found 19 matches

by 204751840 2E
Sun Mar 19, 2017 9:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 209
Views: 97948

Re: Saying Thank You to Dr. Lavelle

Dr. Lavelle,

Thank you so much for putting the amount of work you do into this class. Chemistry Community has provided me with the ability to quickly get my questions answered about difficult concepts. Your passion for chemistry also keeps me interested in class and makes the subject enjoyable.
by 204751840 2E
Tue Mar 07, 2017 8:19 pm
Forum: *Organic Reaction Mechanisms in General
Topic: 4.26 ochem textbook
Replies: 3
Views: 486

Re: 4.26 ochem textbook

Does the hydrogen have to bond first, or can the steps be written in a different order (i.e. with the Iodine bonding to the carbon structure first.
by 204751840 2E
Wed Mar 01, 2017 9:20 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Activation Energy vs Free energy of activation
Replies: 3
Views: 435

Re: Activation Energy vs Free energy of activation

Odel,

The standard Gibbs free energy of activation is always positive because it always takes some free energy to initiate the reaction.
by 204751840 2E
Wed Feb 15, 2017 12:30 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible vs. Irreversible [ENDORSED]
Replies: 4
Views: 585

Re: Reversible vs. Irreversible [ENDORSED]

Two things that whether or not a system is reversible can affect is entropy and work done on the environment. In the case of a reversible process, Delta S system = -Delta S surrondings. This is not the case with an irreversible process.
by 204751840 2E
Wed Feb 15, 2017 12:20 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding Ka
Replies: 2
Views: 338

Re: Finding Ka

Ka is the k value of the decomposition of a weak acid (i.e., it is the dissociation constant) it is calculated the same way as K for the rxn. A square root is taken in this equation, because the redox reaction has everything doubled, and the Ka is based on the simplest version of the rxn. We had to ...
by 204751840 2E
Wed Feb 15, 2017 12:13 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Winter 2013 Midterm: Question #4
Replies: 3
Views: 433

Re: Winter 2013 Midterm: Question #4

Just to clarify, if the pressure changes, but the volume does not, no work is done, right?
by 204751840 2E
Wed Feb 15, 2017 12:08 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 2013 Midterm 8B
Replies: 4
Views: 497

Re: 2013 Midterm 8B

Angela, both equations work. For whatever reason, they sometimes come out to slightly different numbers, but so long as you show your work and and your calculations are correct you should receive credit. One of the past midterms (either 2016 or 2013, I can't remember) has a situation like this where...
by 204751840 2E
Tue Feb 14, 2017 9:27 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Midterm 2012 #7
Replies: 4
Views: 369

Re: Midterm 2012 #7

You would normally want to make have the equations reduced if you were trying to create a spontaneous rxn (+ E of cell), but it is given with Mn2+ being oxidized so it must be written that way on the final answer.
by 204751840 2E
Sun Feb 12, 2017 1:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: When to add Pt(s) to a cell diagram?
Replies: 2
Views: 339

Re: When to add Pt(s) to a cell diagram?

It should be noted that it needs to be a pure, solid (or liquid, in the case of Hg) metal. Metal ions and metals bonded to larger compounds (Ni(OH)2 for example) are not adequately able to conduct electrons.
by 204751840 2E
Wed Jan 25, 2017 9:46 pm
Forum: Phase Changes & Related Calculations
Topic: Calculating Vaporization of water at 85 C
Replies: 1
Views: 1251

Calculating Vaporization of water at 85 C

The question is stated as: Calculate the standard entropy of vaporization of water at 85 C, given that its standard entropy of vaporization at 100. C is 109.0 J K 1 mol 1 and the molar heat capacities at constant pressure of liquid water and water vapor are 75.3 J K 1 mol 1 and 33.6 J K 1 mol 1, res...
by 204751840 2E
Wed Jan 18, 2017 10:49 pm
Forum: Phase Changes & Related Calculations
Topic: HW 8.67 [ENDORSED]
Replies: 5
Views: 644

Re: HW 8.67 [ENDORSED]

I have a question regarding b) The question is finding the enthalpy of formation for the liquid state of CH3O3, methanol. According to the solutions manual, you have to add the enthalpy of sublimation for carbon, because carbon is a solid in its ground state. Is there any reason why we use the entha...
by 204751840 2E
Thu Jan 12, 2017 11:14 am
Forum: Phase Changes & Related Calculations
Topic: Systems
Replies: 2
Views: 361

Re: Systems

Thanks for the info, very clear and easy to understand.
by 204751840 2E
Fri Dec 02, 2016 10:48 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid strength pattern
Replies: 3
Views: 418

Re: Acid strength pattern

From what I understand, it takes bond length/strength do not always have the same effects on acidity. It takes some more complex organic chemistry to explain, having partly to do with the difference between heterolytic and homolytic bond cleavage and the ability of the conjugate base to stabilize th...
by 204751840 2E
Fri Dec 02, 2016 6:46 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of acids
Replies: 6
Views: 683

Re: Strength of acids

So, higher electron withdrawing ability means a weaker acid? Also, how can one tell what the electron withdrawing ability is of an electron withdrawing group? For example, how would you know that F has a greater electron withdrawing ability than H or CH3? I can see that CH3 would have a lot more ele...
by 204751840 2E
Fri Dec 02, 2016 6:32 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid strength pattern
Replies: 3
Views: 418

Re: Acid strength pattern

The logic from the textbook, which says that acid strength depends on polarity, is correct in putting the acidity of the compounds you mentioned as NH3<H2O<HF, with HF being the strongest acid. As far as bond strength, the WEAKER the H-A bond, the STRONGER the acid. To make it more clear, weaker bon...
by 204751840 2E
Fri Nov 25, 2016 6:53 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Indicators of strong or weak acid/base
Replies: 3
Views: 396

Re: Indicators of strong or weak acid/base

Just to clarify, this means that strong acids and bases have no Ka or Kb?
by 204751840 2E
Sun Nov 13, 2016 5:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Chem Equilibrium
Replies: 3
Views: 303

Re: Chem Equilibrium

By lecture notes does that mean the first 4 pages of the course reader?
by 204751840 2E
Wed Nov 02, 2016 3:43 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011671

Re: Post All Chemistry Jokes Here

Q: How many Heisenbergs does it take to change a light bulb?
A: If you know the number, you don't know where the light bulb is.
by 204751840 2E
Sat Oct 22, 2016 5:24 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bonds for Quiz 2
Replies: 3
Views: 599

Re: Sigma and Pi Bonds for Quiz 2

Nasir, In short, when carbon bonds with other atoms, the first bond is always a sigma bond, and any subsequent bond is a pi bond. A single bond between, say, carbon and hydrogen would be on sigma bond. A triple bond between, for example, 2 carbon molecules would be made up of one sigma bond and 2 pi...

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