Search found 23 matches
- Thu Mar 16, 2017 5:49 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 516873
Re: Saying Thank You to Dr. Lavelle
Dr. Lavelle, Thank you for the past 2 quarters of chemistry. Your lectures always conveyed your enthusiasm for chemistry and for the wellbeing and education of your students and I greatly appreciated it, as well as the extensive amount of time you put into chemistry community, organizing UA sessions...
- Sun Mar 12, 2017 1:40 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: ch15 #51
- Replies: 3
- Views: 671
Re: ch15 #51
I think the rate law is only governed by the slow step, so the overall rate law would be that of the first step.
- Tue Feb 28, 2017 2:20 pm
- Forum: *Alkanes
- Topic: Naming [ENDORSED]
- Replies: 93
- Views: 16320
Re: Naming [ENDORSED]
I think dashes are typically used to separate numbers from words but I'm not completely sure.
- Wed Feb 22, 2017 5:21 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: Activation Energy vs Free energy of activation
- Replies: 3
- Views: 869
Re: Activation Energy vs Free energy of activation
The activation energy is the energy required by a reaction to actually proceed to completion. Free energy of activation refers to Gibbs free energy. When something is referencing E>Ea, it's talking about whether or not the specific reaction or collision etc. has more energy than the activation energ...
- Wed Feb 22, 2017 5:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 2 Prep answers
- Replies: 2
- Views: 771
Re: Quiz 2 Prep answers
They've already been posted in another thread.
- Sat Feb 18, 2017 6:48 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Quiz prep 2 #11
- Replies: 4
- Views: 959
Re: Quiz prep 2 #11
I'm not sure how to find the rate constant here, but I believe the units for activation energy is kJ/mol. Also, I think we aren't being tested on the Arrhenius equation for the quiz.
- Mon Feb 13, 2017 8:10 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Increase in entropy
- Replies: 2
- Views: 561
Re: Increase in entropy
If a gas is allowed to occupy a larger volume, there are more states it can possibly be in (because of the larger volume of space) therefore entropy increases. Similarly, if the temp of a gas increases, then the equation for deltaS = nC ln (T2/T1) is positive, indicating an increase in entropy.
- Sat Feb 04, 2017 2:00 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Units of entropy [ENDORSED]
- Replies: 3
- Views: 820
Re: Units of entropy [ENDORSED]
Yes it is possible. Entropy can be equal to q/T, and the units for q is Joules and Kelvin for T, so the units of your answer can be Joules/Kelvin.
- Fri Jan 27, 2017 4:01 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Clarification on heat transfer but no temp change
- Replies: 2
- Views: 474
Re: Clarification on heat transfer but no temp change
The only time I can really think of this is happening is during a phase change. During this time, you can think of there being no temperature change because the heat is being fully used to break bonds to go from solid to liquid or liquid to gas.
- Fri Jan 27, 2017 3:55 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous
- Replies: 1
- Views: 406
Re: Spontaneous
I believe it is because you're going from a higher energy to a lower energy, which is more favorable than the opposite direction.
- Thu Jan 12, 2017 6:37 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units of Reaction Enthalpies
- Replies: 11
- Views: 2080
Re: Units of Reaction Enthalpies
I think reaction enthalpies are usually written in kJ/mol.
- Fri Dec 02, 2016 5:31 pm
- Forum: *Titrations & Titration Calculations
- Topic: Half way stoichiometric point
- Replies: 1
- Views: 421
Re: Half way stoichiometric point
I assume this means at the buffer point? If you use the Henderson Hasselbach equation, you see that pH = pKA + (log[base]initial/log[acid]initial). At the buffer point, the [base]initial = [acid]initial, and the log of 1 =0. Therefore, at this point, pH=pKA
- Fri Nov 25, 2016 2:12 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3039655
- Fri Nov 18, 2016 1:35 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Bronsted Acids Clarification
- Replies: 1
- Views: 477
Re: Bronsted Acids Clarification
I think it's because they don't disassociate completely in water, so there are still a substantial number of disassociated molecules with the carboxyl group in the solution.
Re: 17.31 d
I think ligands are written alphabetically in the name of the compound but not necessarily in the formula.
- Sun Nov 06, 2016 5:40 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Fall 2014 Quiz 2 prep #9
- Replies: 1
- Views: 529
Re: Fall 2014 Quiz 2 prep #9
Atoms that are paramagnetic have unpaired electrons, and atoms that are diamagnetic have no unpaired electrons. I think it would be possible to have an atom with an even number of electrons be paramagnetic when you have an atom with 4 electrons in the p orbital; 2 electrons would be unpaired, making...
- Thu Oct 27, 2016 12:51 pm
- Forum: Octet Exceptions
- Topic: Free Radicals
- Replies: 2
- Views: 847
Re: Free Radicals
I think you would know when to draw a free radical by counting the number of electrons. Since radicals have 1 unpaired electron, they will always have an odd number of electrons as opposed to the even number of electrons that other compounds would have. As for which atom the unpaired electron would ...
- Thu Oct 20, 2016 9:58 am
- Forum: Lewis Structures
- Topic: Octet Rule Exceptions? [ENDORSED]
- Replies: 3
- Views: 914
Re: Octet Rule Exceptions? [ENDORSED]
Yes, Phosphorus and Sulfur are exceptions because they are in the 3p area of the periodic table. If we look at quantum numbers, Phosphorus and Sulfur both have n=3. Therefore they can both have l for up to 2. l represents the possible orbitals that an element can possess, and if it is possible for l...
- Thu Oct 20, 2016 9:51 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: General Rules on Writing e- Configurations [ENDORSED]
- Replies: 2
- Views: 784
Re: General Rules on Writing e- Configurations [ENDORSED]
So, when we write electron configurations, we fill in electrons for elements based on their order in the periodic table. This is the only "general rule" to follow. When the d orbital becomes available, you would still fill the 4s first, and then proceed filling those in the d orbital. The ...
- Sat Oct 15, 2016 12:05 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: S, P, D, and F Orbitals [ENDORSED]
- Replies: 4
- Views: 1144
Re: S, P, D, and F Orbitals [ENDORSED]
Basically, these orbitals are the wavefunctions of electrons within an atom, so they are mathematical expressions. When we take the square of the wavefunction, we obtain the probability of finding an electron within an area. The reason they are pictured as "spaces" is because people typica...
- Sat Oct 15, 2016 11:53 am
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz Grades
- Replies: 3
- Views: 906
Re: Quiz Grades
Maybe we'll get the quizzes back in our discussion section next week? I'm not completely sure, but I do know that even though the quizzes and tests are assigned a numerical score, the final grade is based on a curve.
- Fri Oct 07, 2016 10:25 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Why h/4π?
- Replies: 2
- Views: 1013
Re: Why h/4π?
I'm pretty sure the value was derived experimentally. My TA said that there was a lot of quantum mechanics behind the final derivation of the value that we don't need to know for this class.
- Sat Oct 01, 2016 12:28 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Clarification for G.7
- Replies: 2
- Views: 683
Re: Clarification for G.7
I believe the question is saying that there is 510 g of the aqueous solution total, and then asking you to figure out the masses of each part of the solution.