Search found 27 matches

Sat Mar 18, 2017 6:25 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: 2012 #5 CIS/TRANS in CYCLOALKENES???!!!
Replies: 3
Views: 916

Re: 2012 #5 CIS/TRANS in CYCLOALKENES???!!!

In my subject I meant Final 2012 Question #5. Here is a photo of the problem:
The answer is Z-cyclooct-4-enone. Thank you!
Sat Mar 18, 2017 4:35 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: 2012 #5 CIS/TRANS in CYCLOALKENES???!!!
Replies: 3
Views: 916

2012 #5 CIS/TRANS in CYCLOALKENES???!!!

1. Could anyone explain why compound B is cis?
2. Do we always include cis/trans on cycloalkenes? Why is cis/trans necessary when we can only draw cycloalkenes in one way?

THANK YOU
Sat Mar 18, 2017 8:35 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: axial/equatorial positions for multiple substituents
Replies: 2
Views: 641

Re: axial/equatorial positions for multiple substituents

Sorry I meant to say, they are on different atoms but next to each other. If you look at problem set #1, https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=88&t=20700&p=59306&hilit=problem+set&sid=1a75ec9167f0318e98a48d5e305b4b6a#p59306, some substituents are attached to different c...
Fri Mar 17, 2017 10:15 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: axial/equatorial positions for multiple substituents
Replies: 2
Views: 641

axial/equatorial positions for multiple substituents

To ensure the highest stability, we put substituents on the equatorial positions. What I'm unsure is, when there are two substituents adjacent to each other, do we put both of them in equatorial positions? What if there are multiple substituents - can I put all of them in equatorial positions if cis...
Sun Mar 12, 2017 3:09 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: p.15 Organic Textbook geometric isomer
Replies: 3
Views: 460

Re: p.15 Organic Textbook geometric isomer

Thank you!
Sun Mar 12, 2017 3:07 pm
Forum: *Haloalkanes
Topic: 2.16
Replies: 4
Views: 1019

Re: 2.16

Thank you!
Sun Mar 12, 2017 3:06 pm
Forum: *Haloalkanes
Topic: Are halides functional groups or substituents? [ENDORSED]
Replies: 2
Views: 1830

Re: Are halides functional groups or substituents?[ENDORSED]

Thank you so much!
Sun Mar 12, 2017 3:04 pm
Forum: *Cycloalkenes
Topic: Organic Chemistry Textbook [ENDORSED]
Replies: 3
Views: 1059

Re: Organic Chemistry Textbook[ENDORSED]

Thank you !
Sun Mar 12, 2017 10:51 am
Forum: *Haloalkanes
Topic: 2.16
Replies: 4
Views: 1019

2.16

Hello! If 2 halides occupy the same carbon, do we have to write the #s separately for each halide, or can we write the both the #s in front?
(i.e. 3,3-chlorofluoropropene or 3-chloro-3-fluoropropene)? Thank you!
Sun Mar 12, 2017 10:45 am
Forum: *Haloalkanes
Topic: Are halides functional groups or substituents? [ENDORSED]
Replies: 2
Views: 1830

Are halides functional groups or substituents?[ENDORSED]

Could someone explain? Thank you so much!
Sun Mar 12, 2017 10:43 am
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: p.15 Organic Textbook geometric isomer
Replies: 3
Views: 460

p.15 Organic Textbook geometric isomer

Why are 1-Butene and 2-methyl-1-propene not geometric isomers? The explanation on the book is "they do not have different atoms or atom groups attached to the sp^2 hybridized carbon atoms of the double bond." Could someone elaborate it, please? Thank you!
Sun Mar 12, 2017 10:39 am
Forum: *Cycloalkenes
Topic: Organic Chemistry Textbook [ENDORSED]
Replies: 3
Views: 1059

Organic Chemistry Textbook[ENDORSED]

The assigned reading on the organic textbook covers more material than what we've gone over in class. Are there any topics we have to know, such as the properties of functional groups or the use of suffix -carbaldehyde? Or should I just focus on the homework problems? Thank you!
Thu Mar 02, 2017 1:47 pm
Forum: *Electrophiles
Topic: CO2
Replies: 5
Views: 1389

Re: CO2

If you look at the lewis structure of CO2, you find that C is the central atom with O on either side. Each oxygen has 2 lone pair electrons, making the charge of oxygen partially negative. Since the oxygen is partially negative, C is partially positive. To determine whether a molecule is electrophil...
Sun Feb 26, 2017 10:25 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Equations for activation energy
Replies: 1
Views: 241

Equations for activation energy

I thought ln(k) = -Ea/RT +ln(A) and k = Ae^(-Ea/RT) are equivalent equations. On the course reader, ln(k) = -Ea/RT +ln(A) shows linear but the other k = Ae^(-Ea/RT) does not. I understand that if we plot them one would obviously be linear and the other is not, but what is the significance of pointin...
Sun Feb 19, 2017 1:39 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units of k for non-integer order reactions
Replies: 1
Views: 542

Units of k for non-integer order reactions

Sometimes we get reaction with a non-integer order, such as 0.5 order with respect to [B]. In this case, how do we determine the units for k?
Fri Feb 17, 2017 1:34 pm
Forum: General Rate Laws
Topic: Homework Help 15.1
Replies: 4
Views: 949

Re: Homework Help 15.1

If you use the unique average rate law, the result should still be the same. -d[A]/dt = -1/3*d[B]/dt d[A]/dt = 1/3*d[B]/dt In this case, A is N2 and B is H2. So the rate of consumption of N2 is 1/3 * rate of consumption of H2 The way the textbook does is more conceptual, which was what I did. You ca...
Sat Feb 11, 2017 3:11 am
Forum: Balancing Redox Reactions
Topic: HW 14.57
Replies: 2
Views: 379

Re: HW 14.57

This value is given on the textbook p. 607. The book asks us to use this value for reduction of water.
Thu Feb 02, 2017 10:05 pm
Forum: Balancing Redox Reactions
Topic: 14.1
Replies: 1
Views: 262

Re: 14.1

C only appears in 2 compounds in the reaction: C2H5OH the reactant and C2H4O the product. First calculate the charge of C in C2H5OH. The charges of H (+1) and O (-2) will be constant, and the overall charge of C2H5OH is 0. C*2 +(1*6)-(2) = 0, C = -2. Then calculate the charge of C in C2H4O. Again, t...
Sun Jan 29, 2017 2:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies for diatomic molecules vs. mean bond enthalpies
Replies: 1
Views: 415

Bond enthalpies for diatomic molecules vs. mean bond enthalpies

Bond enthalpies for halogens like F2 or Br2 are shown in both charts but in different values. For example, the bond enthalpy for F2 is 158 kj/mol in diatomic chart,but 155 in the mean bond enthalpy chart. Why is there a difference and how do we know which one we should use ?
Sun Jan 29, 2017 1:30 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: delta S surrounding vs. delta S system vs. delta S total
Replies: 2
Views: 1743

delta S surrounding vs. delta S system vs. delta S total

When does each of delta S surrounding, system and universe = 0? Isothermal, reversible, .....????????? Can we directly associate isothermal with reversible process? Thank you!
Fri Jan 27, 2017 2:03 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Chapter 8 #67a
Replies: 2
Views: 422

Re: Chapter 8 #67a

Thank you!
Fri Jan 27, 2017 2:02 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Ch 9 # 37d
Replies: 2
Views: 296

Re: Ch 9 # 37d

Thank you very much!
Tue Jan 24, 2017 11:40 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Ch 9 # 37d
Replies: 2
Views: 296

Ch 9 # 37d

How are the 4 solid products more ordered than the 4 solid reactants?
4KClO3(s) --> 3KClO4(s) + KCl(s)
Tue Jan 24, 2017 9:05 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Residual Entropy: NO vs. BF3
Replies: 2
Views: 453

Re: Residual Entropy: NO vs. BF3

W for 1 molecule of NO is 2^1, and 1^1 for BF3. Since NO has a greater W, its residual entropy k*ln(W) would be greater.
Thu Jan 19, 2017 10:40 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Chapter 8 #67a
Replies: 2
Views: 422

Chapter 8 #67a

Hi everyone! Does anyone know why the problem uses the heat of vaporization of water at 25 degrees celsius instead of the standard one? The problem does not state anything about the temperature. Thank you!
Mon Jan 16, 2017 10:28 pm
Forum: Phase Changes & Related Calculations
Topic: Reversible process
Replies: 3
Views: 469

Re: Reversible process

You're welcome!
Tue Jan 10, 2017 10:29 am
Forum: Phase Changes & Related Calculations
Topic: Reversible process
Replies: 3
Views: 469

Re: Reversible process

Hi! I didn't understand the concept until I watched this video: https://www.youtube.com/watch?v=j_6JxoL8qD4 Basically, in reversible process, the gradual change in volume allows the process to be reversed at anytime vs. in the irreversible process, the volume change is one big step (finite), thus ir...