Search found 22 matches
- Fri Mar 17, 2017 6:34 pm
- Forum: *Cycloalkenes
- Topic: Naming cyclodienes
- Replies: 1
- Views: 2051
Naming cyclodienes
On pg 29 of intro to orgo, the ex under "unconjugated dienes" reads as "Cyclo hex -1,4-diene." However, for self-test 1.11A part B (on the bottom of the same page), the answer reads as "1,6-Dimethylcyclo hexa -1,4-diene." Pg 30 continues with ex like "cyclo octa -1...
- Sun Mar 05, 2017 4:42 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Potential Energy and Gibbs free energy reaction Profile
- Replies: 1
- Views: 1118
Potential Energy and Gibbs free energy reaction Profile
On pg 157, the intro to orgo book says that the standard gibbs free energy of activation for both transition steps will be bw the transition states and reactants bc "it is more convenient to determine all diff w respect to the reactants." Could someone please explain why it's more convenie...
- Sun Mar 05, 2017 4:30 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Self Test 4.4A part c
- Replies: 1
- Views: 1075
Self Test 4.4A part c
In this it says that given the graph, step one would have the larger Ea, but how can you tell that? I kinda assumed that since the standard gibbs free energy of activation was larger in the second step, it would have the larger Ea. Thanks :)
- Wed Mar 01, 2017 1:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Clarification on extra credit
- Replies: 3
- Views: 801
- Wed Mar 01, 2017 1:35 am
- Forum: *Nucleophiles
- Topic: Double Bond Nucleophile
- Replies: 1
- Views: 494
Double Bond Nucleophile
On pg 152 of Intro to OChem there is an ex w two steps. The first step displays propene and Hydrogen bromide. In the description for this step it says that propene is the nucleophile, but shouldn't the double bond in propene be labeled the nucleophile. Idk if this is technical or what bc it's more s...
- Wed Feb 15, 2017 2:08 am
- 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: Midterm Winter 2013 problem 5B
- Replies: 10
- Views: 1825
Re: Midterm Winter 2013 problem 5B
CH4 has highest STANDARD molar entropy bc it has highest mass. When the molecule is heavier, its vibrational energy is higher, so it has more entropy. You look at atom positions when you're looking at RESIDUAL entropy. This is when the molecules are given at T=0K. In this case, for ex CH4 and CF4 wo...
- Tue Feb 14, 2017 1:03 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: w=-delta(nRT)
- Replies: 2
- Views: 2832
w=-delta(nRT)
For w=-delta(nRT), is it the change in moles or temperature? I've read the posts here and they've had different answers. Thanks :)
- Mon Feb 06, 2017 3:07 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4008999
- Sun Jan 29, 2017 9:54 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: HW Ch. 8 #41
- Replies: 1
- Views: 444
Re: HW Ch. 8 #41
q=mC(Tfinal-Tinitial)
heat lost by water (-q)=(q) heat heat gained by ice
-mC(Tf-Ti)=mC(Tf-Ti)+n(deltaH fusion of ice)
What you're missing is the mC(Tf-Ti) for ice. Once included you'll get:
-400g(4.184J/Cg)(Tfinal-45C)=50g(4.184J/Cg)(Tfinal-0C)+2.8mol(6010 J/mol)
And so Tfinal=31C
heat lost by water (-q)=(q) heat heat gained by ice
-mC(Tf-Ti)=mC(Tf-Ti)+n(deltaH fusion of ice)
What you're missing is the mC(Tf-Ti) for ice. Once included you'll get:
-400g(4.184J/Cg)(Tfinal-45C)=50g(4.184J/Cg)(Tfinal-0C)+2.8mol(6010 J/mol)
And so Tfinal=31C
- Mon Jan 23, 2017 2:10 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy and Internal Energy relationship
- Replies: 1
- Views: 492
Re: Enthalpy and Internal Energy relationship
The change in internal energy(ΔU) is a a combo of energy transferred from heating(q) and compression(w). When at a constant pressure, q can be equivalent to the change in enthalpy(ΔH), being heat released or absorbed at constant P. So increasing/decreasing ΔH will inc/dec ΔU accordingly. When the rx...
- Sun Jan 15, 2017 10:12 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpy versus standard Enthalpies of formation
- Replies: 2
- Views: 552
Re: Bond Enthalpy versus standard Enthalpies of formation
Based on the textbook problems Lavelle assigned, the problem may tell you which method it wants you to use. If not, I'm p sure that you'll be provided w certain info (aka standard enthalpies of formation or bond enthalpies) which will push you towards using a certain method, and you'll solve the pro...
- Mon Nov 28, 2016 9:10 pm
- Forum: Bronsted Acids & Bases
- Topic: Common Acids/Bases
- Replies: 3
- Views: 745
Re: Common Acids/Bases
I don't think we need to memorize them per se, but rather generally recognize which acids & bases are strong/weak.
- Mon Nov 28, 2016 8:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Negligible x given a small K value
- Replies: 1
- Views: 391
Negligible x given a small K value
What's the largest K value that can be considered a small K (leading to a small x, allowing you to approximate your concentrations)?
- Mon Nov 28, 2016 7:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework 11.41
- Replies: 3
- Views: 746
Re: Homework 11.41
Yeah I realized I forgot a conversion thank you!
- Mon Nov 28, 2016 7:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework 11.41
- Replies: 3
- Views: 746
Homework 11.41
Why do we plug in 1.581x10-3? The x (or molar concentration of CO2) is 1.581M (resulting in Kc=1.58) so I'm not sure how/why we use 1.581x10-3 instead. Thank you!
- Mon Nov 28, 2016 1:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Homework Problem 11.41
- Replies: 3
- Views: 2850
Re: Homework Problem 11.41
Why do we plug in 1.581x10-3? The x (or molar concentration of CO2) is 1.581M (resulting in Kc=1.58) so I'm not sure how/why we use 1.581x10-3 instead.
- Wed Nov 02, 2016 12:38 am
- Forum: Lewis Structures
- Topic: Homework 3.95
- Replies: 1
- Views: 399
Re: Homework 3.95
If you draw out the whole molecule, you'll see that for a non-central Carbon atom that is attached to the central Carbon with a single bond, the Carbon has a FC=4-(2+3)=-1. The -1 FC of CH2 is based off of the Carbon atom. (The two H atoms each have a FC of 0)
- Sun Oct 30, 2016 4:35 pm
- Forum: Lewis Structures
- Topic: Ch 3 question 97
- Replies: 1
- Views: 351
Ch 3 question 97
How is P4 a tetrahedral molecule? It only has 4 atoms and creates a kite shape.
- Fri Oct 28, 2016 9:53 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Midterm
- Replies: 9
- Views: 1341
Re: Midterm
All material covered in Fundamentals and Chapters 1-4 up to the end of hybridization.
Course Reader: All material up to page 105.
Past Midterms in Course Reader: Pages 179-217
For more info go to this link: viewtopic.php?f=157&t=16342
Course Reader: All material up to page 105.
Past Midterms in Course Reader: Pages 179-217
For more info go to this link: viewtopic.php?f=157&t=16342
- Fri Oct 21, 2016 2:25 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Ch 2.1
- Replies: 1
- Views: 473
Ch 2.1
In the textbook it says, "The difference in energy between the ground state and the ionized state is the energy required to remove an electron from the neutral atom in its ground state. The ionization energy itself...is the minimum energy needed to achieve ionization, with the electron removed ...
- Thu Oct 13, 2016 8:26 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Practice Quiz #8
- Replies: 2
- Views: 635
Re: Practice Quiz #8
When the electron transitions fro n=4 to n=3, energy is emitted. So in the equation E=-hR((1/nfinal^2)-(1/ninitial^2)), E becomes -E, and you'll find that after substituting in your numbers your answer will be positive.
- Tue Sep 27, 2016 11:11 am
- Forum: Student Social/Study Group
- Topic: Chemistry Jokes
- Replies: 31
- Views: 9031