Search found 37 matches
- Tue Mar 08, 2016 8:15 pm
- Forum: *Aldehydes
- Topic: Aldehyde Numbering
- Replies: 1
- Views: 1285
Aldehyde Numbering
In the O-chem book it says that because the aldehyde is always on the first carbon, numbering isnt necessary. For example, propanal would not be propan-1-al. However if we put the second one on a test just to be safe would that be counted as wrong?
- Sun Mar 06, 2016 9:29 pm
- Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
- Topic: How can you tell if a molecule is cis (Z) or trans (E)?
- Replies: 3
- Views: 900
Re: How can you tell if a molecule is cis (Z) or trans (E)?
I went to an office hours where the TA said that Cis and Z/ Trans and Z are not the same thing. If thats the case I dont understand the difference because in most examples that weve done theyve seemed pretty interchangeable.
- Sun Feb 28, 2016 9:26 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: R and S Isomers
- Replies: 1
- Views: 431
R and S Isomers
the Organic Chemistry book talks about R and S isomers in chapter 4.3 but it says to see section 3.5 about the R and S system but we didnt cover that chapter. should we still know about them?
- Fri Feb 26, 2016 9:41 am
- Forum: *Nucleophilic Substitution
- Topic: Transition states
- Replies: 1
- Views: 509
Transition states
In SN2 if you are writing the rare laws (not the overall reaction) would you include the transition states for example when carbon has 5 bonds, in the rate law?
- Tue Feb 23, 2016 5:34 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: 4.30
- Replies: 1
- Views: 458
4.30
The question says: the activation energy in an organic reaction is 125 kj.mol. Will this reaction occur at room temperature?
How do I solve this?
How do I solve this?
- Fri Feb 19, 2016 9:09 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Structure for the activated complex (HW 15.85)
- Replies: 3
- Views: 1018
Re: Structure for the activated complex (HW 15.85)
Why for b) would it be termoleuclar? That is what the solutions manual says
- Fri Feb 19, 2016 9:52 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.65
- Replies: 1
- Views: 409
15.65
This question gives that k= 265 L.mol.min and the EA= 39.7x103 and k'= 392 L.mol.min and EA'= 25.4x103. It asks if this reaction is endothermic or exothermic. I would think that it would be exothermic because k<k' but the solutions manual says that it's endothermic because the reverse reaction has a...
- Sat Feb 13, 2016 5:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 2 Winter 2016
- Replies: 18
- Views: 7886
Re: Quiz 2 Winter 2016
Question 61 deals with activation energies so I think we stop there so the last problem we should be able to do on the homework for Quiz 2 would be 55
- Fri Feb 12, 2016 11:47 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Temperature and reaction rate
- Replies: 1
- Views: 455
Temperature and reaction rate
In lecture, professor Lavelle said that from experience cooling slows reactions like when you put food in the fridge. Why then does food not spoil when heating it up or cooking it because temperature would then increase the reaction?
- Mon Feb 08, 2016 12:32 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 2014 Midterm #8
- Replies: 4
- Views: 826
Re: 2014 Midterm #8
Also for this problem i was wondering how you know to take the square root of K to get Ka/ what does Ka represent or mean?
- Sun Feb 07, 2016 11:10 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: delta S surroundings =0
- Replies: 1
- Views: 427
delta S surroundings =0
Conceptually, why is delta S for the surroundings =0 for irreversible reactions?
- Fri Feb 05, 2016 6:23 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 14.37
- Replies: 1
- Views: 480
14.37
For this problem, it asks to find the potential for the cells given. I am confused how to calculate E when the abbreviated cell diagrams have pressures and moles in them. For example, part b reads Zn(s)| Zn2+(aq, .37 mol.L)|| Ni2+ (aq, .059 mol.L)| H2 (g, 1 bar)| Pt(s) I know how to find Eo for the ...
- Fri Feb 05, 2016 6:17 pm
- Forum: First Order Reactions
- Topic: Derivations
- Replies: 1
- Views: 418
Derivations
So for the quiz, we had to know the derivation of entropy and I was wondering if I should know the derivation of first order and second order reactions.
- Sun Jan 31, 2016 3:06 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation vs Reduction
- Replies: 2
- Views: 1350
Oxidation vs Reduction
this may be a dumb question but I am still really confused how to tell in general which is reduced or oxidized. I start to think that I get it and whenever I answer one of the questions I always get the atom/ molecule that oxidized and reduced mixed up. Is there a trick to knowing which one is which?
- Fri Jan 22, 2016 11:00 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Reversible vs Irreverible reactions
- Replies: 1
- Views: 308
Reversible vs Irreverible reactions
I'm still so confused what the difference between reversible and irreversible reactions are and what they mean and how you can tell if a reaction is reversible.
- Thu Jan 21, 2016 12:42 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Problems with formulas
- Replies: 1
- Views: 463
Problems with formulas
As Im going through the problems Im having trouble knowing when to use certain formulas or when to use certain constants for R and I was wondering if someone could help with this problem somehow? Should I just memorize when to use certain formulas and certain constants? -Also in the solutions manual...
- Thu Jan 21, 2016 12:37 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 3/2 and 5/2 R
- Replies: 5
- Views: 2400
Re: 3/2 and 5/2 R
How would we have known this without seeing it in the solutions manual? Is it listed somewhere in the textbook?
- Sun Jan 17, 2016 11:06 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: General Confusion with mictrostates and bulk property
- Replies: 1
- Views: 465
General Confusion with mictrostates and bulk property
In lecture Professor Lavelle gave and example in the course reader with a diagram that shows a vacuum and an ideal gas with a mass that decreases slowly. Im confused on this whole concept and i was wondering if someone could explain it to me. I understand the equations and the concepts but I dont un...
- Tue Jan 05, 2016 7:33 pm
- Forum: Phase Changes & Related Calculations
- Topic: Hm
- Replies: 1
- Views: 479
Hm
Today in disucssion our TA went over phase changes for Enthalpy for example the change in H for vamporization = Hm(vapor)-Hm(liquid) and the reaction is endothermic. I was wondering if someone can explain to me what Hm is?
- Thu Dec 03, 2015 9:51 pm
- Forum: *Titrations & Titration Calculations
- Topic: 12.23
- Replies: 11
- Views: 2623
Re: 12.23
Im still a little confused on what you did to find the final pH..
what would be the chemical equation and also i know that sometimes you have to subtract moles added to find the moles left over? the two may be completely unrelated but im still confused
what would be the chemical equation and also i know that sometimes you have to subtract moles added to find the moles left over? the two may be completely unrelated but im still confused
- Thu Dec 03, 2015 9:21 pm
- Forum: *Titrations & Titration Calculations
- Topic: HW 13.23
- Replies: 3
- Views: 715
Re: HW 13.23
You can calculate the volume because you know that at the stoichiometric point moles of sample is equal to the moles added so since you know molarity of the substance added you can do V=n/M for the substance added
- Thu Dec 03, 2015 9:18 pm
- Forum: *Titrations & Titration Calculations
- Topic: Chapter 13, Q23
- Replies: 1
- Views: 565
Re: Chapter 13, Q23
At the stoichiometric point in the titration, the moles of sample are equal to the moles added. So if you know the molarity of the added substance and now you know the moles than you can divide n/M to find the volume.
- Sun Nov 29, 2015 4:08 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Dissociation Reactions in Water
- Replies: 1
- Views: 430
Dissociation Reactions in Water
Some of the problems ive come across in the homework say to calculate the pH of various molecules (ex. AlCl3 or Cu(NO3)2). How would you write the dissociation reaction for each of these? For example in the solutions manual, AlCl3 is written as Al(H2O)6 3+ + H20 <-> H30+ + Al(H20)5OH2+ I was wonderi...
- Sun Nov 29, 2015 2:55 pm
- Forum: Photoelectric Effect
- Topic: Video: Photoelectric Effect Example
- Replies: 3
- Views: 771
Re: Video: Photoelectric Effect Example
what do you mean post in a different format?
- Sun Nov 29, 2015 2:52 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: determining acid/ base
- Replies: 1
- Views: 511
determining acid/ base
In general, how can you tell just by looking at a molecule if it is an acid or a base? I am confused on the concepts involved in acids and bases so i was also wondering if there is another resource i can go to to just get general help with concepts instead of specific help with questions.
- Sun Nov 29, 2015 2:36 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 12.63 Concepts
- Replies: 1
- Views: 700
12.63 Concepts
just in general im really confused on the concepts of acids and bases in terms of Ka Kb and Kw vs. pka and pkb so for this problem could someone explain how to do it conceptually? "The percentage deprotonation of benzoic acid in a 0.110 M solution is 2.4%. What is the pH of the solution and the...
- Fri Nov 27, 2015 11:26 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Determining pH
- Replies: 3
- Views: 1207
Re: Determining pH
can you explain how to find [H30+] using an ice box?
- Wed Nov 25, 2015 6:05 pm
- Forum: Photoelectric Effect
- Topic: Video: Photoelectric Effect Example
- Replies: 3
- Views: 771
Video: Photoelectric Effect Example
Number 3 on Fall Midterm 2015
- Mon Nov 16, 2015 10:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.67 Why do we use a new initial value?
- Replies: 4
- Views: 532
Re: hw problem 11.67
i think they are referring to the solutions manual for this question. In the ICE box there is an initial and a new initial. Um im not sure why that is I asked my TA and she doesnt even know so I think you can solve the problem without doing it that way
- Fri Nov 13, 2015 4:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solving Quadratic Equations
- Replies: 1
- Views: 279
Solving Quadratic Equations
Is there an easier way to solve the chemical equilibrium problems than by using the quadratic formula because with all the decimals and weird numbers its easy to make mistakes especially when using a scientific calculator. Thanks!
- Mon Nov 02, 2015 4:19 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Bonding vs Antibonding
- Replies: 2
- Views: 2032
Bonding vs Antibonding
Im lost on the whole concept of bonding vs antibonding. I understand in terms of molecular orbital theory because I can memorize how the diagram should look but besides that I dont understand it conceptually. For example on number 77 of the homework it says draw the bonding and antibonding orbitals ...
- Sat Oct 10, 2015 2:10 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization energy for oxygen hw 2.81
- Replies: 3
- Views: 1174
Re: Ionization energy for oxygen hw 2.81
Oxygen has lower ionization energy than Nitrogen because of the repulsion of electrons. The presence of more electron means that electrons shield the outer electrons from the protons. -wouldnt this mean though that ionization energy would decrease across a period then because each element is adding...
- Sat Oct 10, 2015 2:02 pm
- Forum: Trends in The Periodic Table
- Topic: Electron affinity trends
- Replies: 2
- Views: 811
Electron affinity trends
Is there a trend that shows increasing and decreasing electron affinity on the periodic table? If not how would we be able to calculate the electron affinity?
- Sat Oct 10, 2015 1:36 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Chapter 2 question 85
- Replies: 1
- Views: 351
Chapter 2 question 85
"In heavier transition metal elements, especially the lanthanoids and actinoids, there are numerous exceptions to the regular order of orbital occupation predicted by the building up principle.l Suggest why more exceptions would be noted for these elements"
Will someone explain this to me?
Will someone explain this to me?
- Tue Oct 06, 2015 3:51 pm
- Forum: Properties of Light
- Topic: HW 1.57 Balmer series
- Replies: 3
- Views: 953
HW 1.57 Balmer series
The question says "Lines in the Balmer series of the hydrogen spectrum are observed at 656.3, 486.1, 434.0 and 410.2. What is the wavelength of the next series?" So I did the problem and then I looked in the solutions manual and it says that "since the Balmer series n1= 2, the fifth l...
- Sun Oct 04, 2015 3:33 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Homework 1.43
- Replies: 4
- Views: 931
Homework 1.43
For question 43, it asks what is the minimum uncertainty in the speed of an electron confined to within a lead atom of diameter 350pm. Also it asks to model the atom as a one dimensional box w length equal to diameter of the actual atom. I looked up the equation and i found it but we haven't learned...
- Tue Sep 29, 2015 10:36 am
- Forum: Properties of Light
- Topic: Question on photoelectric effect experiement
- Replies: 2
- Views: 503
Question on photoelectric effect experiement
In the photoelectric effect experiment discussed in the last lecture, why didnt increasing the intensity of the first light source increase the number of photons like it did when they changed to a different light source with a higher frequency. I know that increasing the intensity of the light sourc...