Search found 29 matches
- Thu Mar 16, 2017 3:13 pm
- Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
- Topic: Difference between cis and Z, and trans and E
- Replies: 4
- Views: 1672
Re: Difference between cis and Z, and trans and E
From what I understand, the "longest chain" refers to the longest continuous chain of carbon-carbon bonds that you identify as the main chain, which will be determined by the number of carbons in that chain (1C is meth-, 2C is eth-, 3C is prop-, etc.) In terms of deciding whether a particu...
- Sun Mar 12, 2017 5:50 pm
- Forum: *Organic Reaction Mechanisms in General
- Topic: Gibbs Free Energy in Reaction Profiles
- Replies: 2
- Views: 1012
Re: Gibbs Free Energy in Reaction Profiles
In drawing out the transition state (as shown above), are there points associated with writing out the partial charges of the atoms with the partially formed/broken bonds? In other words, will points be deducted if the transition state structure is drawn correctly, but does not include the partial c...
- Wed Mar 08, 2017 9:35 am
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 3 Winter 2017
- Replies: 183
- Views: 29046
Re: Quiz 3 Winter 2017
for #1, why do we need "iso" in front of propyl? wouldn't the 4- signify the branching? If you draw out the structure, you'll see the branching of (CH 3 ) 2 CH, which is how you know to include the prefix iso-. By that same logic, if the branching had (CH 3 ) 3 C, you would use the prefix...
- Wed Mar 08, 2017 8:37 am
- Forum: *Nucleophilic Substitution
- Topic: Reaction profile for SN2 reaction
- Replies: 2
- Views: 1811
Re: Reaction profile for SN2 reaction
Rachel Wile 2D wrote:They would have to specify, but exergonic is much more common than endergonic so if they do not I would draw it the exergonic way.
That's what I was thinking too. Thanks for confirming!
- Wed Mar 08, 2017 12:53 am
- Forum: *Nucleophilic Substitution
- Topic: Reaction profile for SN2 reaction
- Replies: 2
- Views: 1811
Reaction profile for SN2 reaction
In question 4.35 of the homework, it asks us to draw the reaction profile for the reaction: CH3Br + OH ---> CH3OH + Br. I understand how to draw a reaction profile, but how do we know if we should draw the pathway as an exergonic or endergonic reaction? Thanks in advance!
- Sat Mar 04, 2017 11:06 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Winter 2017
- Replies: 87
- Views: 20767
Re: Midterm Winter 2017
Hello Dr Lavelle, Will the additional review session tomorrow be recorded? I was wondering the same thing; I know Dr. Lavelle made an announcement in class about having students volunteer to record the session, but does anyone know if the recordings were posted on Chemistry Community? Thanks in adv...
- Sat Mar 04, 2017 11:03 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Winter 2017
- Replies: 87
- Views: 20767
Re: Midterm Winter 2017
Hello Dr Lavelle, Will the additional review session tomorrow be recorded? I was wondering the same thing; I know Dr. Lavelle made an announcement in class about having students volunteer to record the session, but does anyone know if the recordings were posted on Chemistry Community? Thanks in adv...
- Sun Feb 26, 2017 1:06 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Quiz 2 #9 and #10
- Replies: 3
- Views: 661
Re: Quiz 2 #9 and #10
Can anyone please explain question 9 and 10 for quiz 2? I am having a hard time understanding these questions. There is also a helpful thread in the Announcements section titled "Quiz 2 Winter 2017" if you'd like to either verify that your answers are correct, or if you'd like to scroll t...
- Thu Feb 23, 2017 10:12 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: WHat is the unit of k
- Replies: 4
- Views: 1064
Re: WHat is the unit of k
The solutions manual for question 15.9 also gives a good explanation of how the units for k, rate constant, can differ depending on which reaction order you are dealing with.
- Tue Feb 14, 2017 2:00 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Midterm- Standard Cell Potential values
- Replies: 2
- Views: 515
Re: Midterm- Standard Cell Potential values
Will we be given a table of or a list standard cell potential values? While taking the 2013 winter midterm, when I got to question 8A, I wasn't sure how to get the Enot values I was wondering the same thing too! This is also the case for Question 7 in the 2013 midterm. The answer key shows the stan...
- Mon Feb 13, 2017 1:12 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Winter 2013 Midterm: Question #4
- Replies: 3
- Views: 769
Re: Winter 2013 Midterm: Question #4
For B to C, by looking at the y-axis of the graph, the pressure decreases, so in other words, pressure is not constant. We know from class that under irreversible conditions, pressure is constant, but since that is not the case, we have to use the work equation for variable pressure (reversible work...
- Mon Feb 13, 2017 1:04 am
- Forum: Administrative Questions and Class Announcements
- Topic: Units for final answers on midterm
- Replies: 2
- Views: 520
Re: Units for final answers on midterm
Chem_Mod wrote:You would earn credit, just not full credit. If it didn't explicitly ask for your answer in joules in the question, you could argue for points back. Also, were the units given in the question in joules?
The question doesn't include any units in joules, so would this affect your response? Thank you!
- Sun Feb 12, 2017 8:03 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Units for final answers on midterm
- Replies: 2
- Views: 520
Units for final answers on midterm
Does anyone know if we lose points for giving our final answer in units of kJ rather than J if when converted, they equal the same value? For instance, in the Practice Midterm from Winter 2013, Q4A shows a point breakdown of "-1pt for lack of conversion to J". Since the question didn't exp...
- Sun Feb 12, 2017 12:29 pm
- Forum: General Science Questions
- Topic: Subscripts in a reaction
- Replies: 2
- Views: 690
Re: Subscripts in a reaction
Okay, that's what I was thinking as well. Thank you for confirming!
- Sun Feb 12, 2017 11:48 am
- Forum: General Science Questions
- Topic: Subscripts in a reaction
- Replies: 2
- Views: 690
Subscripts in a reaction
Does anyone know how important is it to keep track of, and write down, the subscripts (s), (l), (aq), (g) in a reaction on our tests/quizzes? In other words, will we be penalized for not including them in our work? Thank you!
- Wed Feb 08, 2017 10:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Resources provided during Midterm 1?
- Replies: 2
- Views: 669
Re: Resources provided during Midterm 1?
The constant sheet will be nearly identical to the one on the quiz. If anything, it may have different bond enthalpies as they pertain to each question. A periodic table will also be provided. Expect the midterm as a whole to look very similar to the last quiz. Hoped this helped! Great, thank you f...
- Wed Feb 08, 2017 10:04 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Posts
- Replies: 23
- Views: 4134
Re: Posts
Does anyone know how to post a new topic/question? I've been trying to figure this out and have been answering questions until now. I couldn't locate the "add post" anywhere on the page. I've even looked at the FAQs and the answer there didn't help. Please let me know; thank you! :) Hi Es...
- Wed Feb 08, 2017 9:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Resources provided during Midterm 1?
- Replies: 2
- Views: 669
Resources provided during Midterm 1?
Much like during the quiz, I know we will have the equation sheet, but does anyone know if it will be the exact same sheet as the one given for the quiz? Additionally, does anyone know if we will be given a periodic table for the midterm? Thank you!
- Sun Feb 05, 2017 5:37 pm
- Forum: Phase Changes & Related Calculations
- Topic: signs of delta H
- Replies: 3
- Views: 1458
Re: signs of delta H
Yes, I believe that would be correct! At the end of your calculation you would keep the negative sign since that is the correct numerical value, and then in your answer, you would interpret the negative H value as the amount of heat being released from the system.
- Sat Jan 28, 2017 6:45 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Bruincast
- Replies: 26
- Views: 10517
Re: Bruincast
The workbooks of the practice quizzes are not turned in like those from last quarter correct? There was also a recent post about this in the Announcements thread titled "Re: Posts", and a student replied to this question saying that they believe we wouldn't be doing that this quarter. If ...
- Sun Jan 22, 2017 8:20 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Posts
- Replies: 23
- Views: 4134
Re: Posts
Well, in answer to your first question, I believe that my TA said that if you post more than one time per week you can get up to 2.5% extra credit this way. I'm terrified that I might be wrong though, so if anyone could confirm or deny this that would be great. Hi Kimberly, yes, I can confirm as th...
- Sun Jan 22, 2017 8:08 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat Released/Absorbed [ENDORSED]
- Replies: 2
- Views: 3239
Re: Heat Released/Absorbed [ENDORSED]
Hi Carla, It was helpful for me to remember that q p = \Delta H = enthalpy. q p gives a measure of heat released or absorbed at a constant pressure. Enthaply, or \Delta H will be negative if the system is losing heat; therefore the system is cold, and the surroundings, hot. This type of reaction wou...
- Sat Jan 14, 2017 6:23 pm
- Forum: Phase Changes & Related Calculations
- Topic: Most Helpful Resource
- Replies: 14
- Views: 2457
Re: Most Helpful Resource
Something that I don't believe has been mentioned yet are the practice exams that Dr. Lavelle provides for us. They are a fantastic resource in terms of being able to test whether or not you can apply the concepts you've studied. In Chem 14A, I found that sometimes reading and studying a concept can...
- Sun Jul 24, 2016 9:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework #4.9 [ENDORSED]
- Replies: 4
- Views: 766
Re: Homework #4.9 [ENDORSED]
Yep! Since the shape of the ICl3 molecule is T-shaped with 3 bonds and 2 lone pairs, we know that the ClICl bond angles are all the same, and should each be less than 90 degrees.
- Tue Jul 19, 2016 8:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Writing Equilibrium Expression K for a Reaction [ENDORSED]
- Replies: 1
- Views: 656
Writing Equilibrium Expression K for a Reaction [ENDORSED]
I just wanted to make sure--In order to write the equilibrium expression, K, for a reaction, we must first make sure the reaction is balanced, correct? For instance, in homework question 11.3b, the reaction is: 4NH 3 + 6NO = 7N 2 + 6H 2 O The answer key uses these stoichiometric coefficients for the...
- Tue Jul 12, 2016 11:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community Points
- Replies: 11
- Views: 1918
Re: Chemistry Community Points
I believe it's one post per week to ensure that you're getting discussion credit for that week, although I'm sure it doesn't hurt to post more than that! I was also wondering, though, if the posts must be made during the week days, or if we still get credit as long as the post is made before the nex...
- Sat Jul 09, 2016 12:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Vs. electron [ENDORSED]
- Replies: 3
- Views: 986
Re: Molecular Vs. electron [ENDORSED]
Knowing that the lone pairs affect the overall shape of the compound--for instance, in H 2 0 the 2 oxygen lone pairs push the hydrogen atoms down to create the bent shape-- for any compound, can we expect that all of the bond angles affected by the repulsion of the lone pairs decrease equally? Thank...
- Wed Jun 29, 2016 11:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz Grades?
- Replies: 2
- Views: 516
Re: Quiz Grades?
In addition to quiz clarifications, I see the syllabus states that our exams are to be written in pen, but does anyone know if this applies to the Preparation quiz that we submit as well? Thank you!
- Fri Jun 24, 2016 1:20 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Fundamentals E [ENDORSED]
- Replies: 1
- Views: 519
Re: Fundamentals E [ENDORSED]
Looking at how I solved this question, I believe that when you divided 2.00g by the molar mass 286.21 g.mol -1 , that was correct. But after that, I still multiplied that fraction by 10mol H 2 0 over 1mol Na 2 CO 3 . 10H 2 O. I put moles of H 2 O as my numerator in the second fraction because moles ...