Search found 100 matches
- Sun Mar 07, 2021 6:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 grade
- Replies: 7
- Views: 409
Re: Midterm 2 grade
I still cannot see my midterm 2 grade on CCLE, is this happening for anyone else??
- Sun Feb 28, 2021 1:04 pm
- Forum: Student Social/Study Group
- Topic: Points needed to pass?
- Replies: 76
- Views: 6645
Re: Points needed to pass?
I believe you must earn 200/400 total points to end with a final passing grade of C-.
- Sun Feb 28, 2021 1:03 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling question 17
- Replies: 2
- Views: 198
Re: Sapling question 17
You use the Nernst equation E=E∘−RTnFln(Q)=E∘−0.0592 Vnlog(Q)
- Sun Feb 28, 2021 1:01 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling week 7/8 #3
- Replies: 2
- Views: 284
Re: Sapling week 7/8 #3
My #3 was a bit different "ClO−2 is oxidized to ClO−4 and Ag+ is reduced to Ag", but for this I used the half reactions: Ag++e−⟶Ag and ClO−2+2H2O⟶ClO−4+4H++4e− and in order to put these two half reactions together in an overall reaction, we then multiply the silver reaction by a factor of ...
- Sun Feb 28, 2021 12:59 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Eo of Concentration Cell
- Replies: 3
- Views: 180
Re: Eo of Concentration Cell
I believe concentration cells consist of anode and cathode compartments that are identical except for the concentrations of the reactant. Because ΔG = 0 at equilibrium, the measured potential of a concentration cell is zero at equilibrium (the concentrations are equal).
- Sun Feb 28, 2021 12:57 pm
- Forum: Balancing Redox Reactions
- Topic: Charge vs Oxidation Number
- Replies: 7
- Views: 443
Re: Charge vs Oxidation Number
Here are some rules that might help! I believe the oxidation number of an atom is the charge the atom would have if it was composed of ions. The oxidation number of an atom is zero in a neutral substance that contains atoms of only one element, and the oxidation number of simple ions is equal to the...
- Wed Feb 24, 2021 9:19 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling Weeks 7 and 8 Question 3
- Replies: 3
- Views: 279
Re: Sapling Weeks 7 and 8 Question 3
I would start by looking at if you can multiply one of the half reactions by a common factor to balance the electron transfer. Then after you combine the equations by adding them, convert from acidic solution (H+) to basic solution (OH−) . Add enough OH− ions to both sides so that all H+ ions can co...
- Wed Feb 24, 2021 9:16 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling 7/8 #3
- Replies: 2
- Views: 167
Re: Sapling 7/8 #3
Look at your oxygens, I believe I noticed 6 oxygens on the left and 5 on the right.
- Wed Feb 24, 2021 9:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Enrollment
- Replies: 5
- Views: 341
Re: Chemistry Enrollment
I emailed the professor and the department and they both said that at this current time they are not planning to expand class sizes and they do not offer PTE. I have to take a quarter off from chemistry which is not ideal, but definitely look at other pre health requirements that you can take in the...
- Wed Feb 24, 2021 9:13 pm
- Forum: Balancing Redox Reactions
- Topic: E naught
- Replies: 15
- Views: 883
Re: E naught
Hi, I am not sure if this is exactly what you are asking, but from sapling I found: The standard potential for a cell, E∘, is a constant and does not depend on the reaction coefficients. Therefore, it will not change when the coefficients are for example doubled.
- Wed Feb 24, 2021 9:11 pm
- Forum: Student Social/Study Group
- Topic: How to Reduce Nervousness before getting results
- Replies: 63
- Views: 4732
Re: How to Reduce Nervousness before getting results
Hi! I usually try to distract myself and focus on getting ahead in the class or dedicating time to other classes. At the end of the day, once you submit an exam, the numerical value is out of your control but the best thing to do is to stay up to date on the upcoming materials in order to definitely...
- Wed Feb 24, 2021 9:09 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridges
- Replies: 41
- Views: 2931
Re: Salt Bridges
a salt bridge, also known as an ion bridge is used to connect the oxidation and reduction half-cells of a galvanic/ voltaic cell, and its purpose is to act as source of spectator ions that can migrate into each of the half cells to preserve neutrality.
- Sat Feb 20, 2021 8:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Half Reaction Standard Reduction Potential
- Replies: 4
- Views: 253
Re: Half Reaction Standard Reduction Potential
From Friday's lecture 2/19, I believe he will either give us the numbers in the problem or it will be linked to a table in the sapling textbook similar to the previous extra homework problems. Worst case scenario we should be able to look the values up!
- Sat Feb 20, 2021 5:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14 B Final
- Replies: 34
- Views: 1463
Re: Chem 14 B Final
The final will definitely be cummulative and the weight of each topic will likely depend on how long we focused on the topic in class, but Dr. Lavelle will send out a few emails closer to the final going into the specifics that will be covered on the final.
- Sat Feb 20, 2021 5:25 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: anode and cathode L/R
- Replies: 14
- Views: 616
Re: anode and cathode L/R
Specifically for the questions that Dr. Lavelle gives us I would just stick with the anode on the left and cathode on the right unless he specifies otherwise in the problem!
- Tue Feb 16, 2021 8:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 14C, 14CL closed after first enrollment pass
- Replies: 7
- Views: 601
14C, 14CL closed after first enrollment pass
Hi,
I was wondering if the department head plans on opening more spots for 14C and 14CL during the spring? I am going to be behind and not able to start upper divisions if I cannot complete 14D in the fall.
I was wondering if the department head plans on opening more spots for 14C and 14CL during the spring? I am going to be behind and not able to start upper divisions if I cannot complete 14D in the fall.
- Mon Feb 15, 2021 4:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Extra homework problems on Midterm 2
- Replies: 14
- Views: 718
Extra homework problems on Midterm 2
Hi,
I was wondering if anyone knows the specific extra textbook homework problems for midterm 2 or where I can a list of which problems are helpful for preparing for midterm 2?
I was wondering if anyone knows the specific extra textbook homework problems for midterm 2 or where I can a list of which problems are helpful for preparing for midterm 2?
- Fri Feb 12, 2021 3:17 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Sapling week 5/6 question 18
- Replies: 8
- Views: 1875
Re: Sapling week 5/6 question 18
Hi! Here is my work for the following problem. Please feel free to ask any follow up questions.
- Fri Feb 12, 2021 3:15 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling 8
- Replies: 5
- Views: 272
Re: Sapling 8
Hi, 1) add 273 degrees to each temperature given to convert the values to kelvin 2)use the equation deltaS= given molar heat capacity * ln(Tf/Ti) 3)use the equation above 3 times to calculate for phase changes --> S1= molar heat capacity of liquid *ln(Tf/Ti) --> S2= standard molar entropy given --> ...
- Fri Feb 12, 2021 3:09 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Sapling Week 5/6 #6
- Replies: 3
- Views: 263
Re: Sapling Week 5/6 #6
Hi! I used the equation deltaS=nCv,mln(Tf/Ti) + nRln(Vf/Vi)
n= given noles of neon gas
Cv,m= given Cv,m
Tf= final temperature
Ti= initial temperature
R= gas constant of 8.314
Vf= final volume
Vi= initial volume
n= given noles of neon gas
Cv,m= given Cv,m
Tf= final temperature
Ti= initial temperature
R= gas constant of 8.314
Vf= final volume
Vi= initial volume
- Thu Feb 11, 2021 12:54 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling week 5&6 #7
- Replies: 2
- Views: 220
Re: Sapling week 5&6 #7
Hi! I struggled with this problem and reading explanations because I am such a visual learner, so I included an image of my work below! Hopefully this helps you out, let me know if you have any questions about my work:)
- Wed Feb 10, 2021 12:42 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: week 5/6 sapling #7
- Replies: 1
- Views: 164
week 5/6 sapling #7
Hi, can someone please help walk me through this problem?
- Sat Feb 06, 2021 5:18 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: isothermal reactions
- Replies: 9
- Views: 406
Re: isothermal reactions
for isothermal reactions, -temperature of system stays constant -transfer of heat in or out of system occurs slow enough that thermal equilibrium is maintained -a helpful example to further understand isothermal reactions is a refrigerator because changes take place but the temperature inside remain...
- Sat Feb 06, 2021 4:52 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: "Reversible" Reaction
- Replies: 5
- Views: 291
Re: "Reversible" Reaction
Reversible reactions are those with infinite number of changes throughout the process and are categorized by the fact that the system and its surroundings can return to original states through reverse path.
- Sat Feb 06, 2021 4:50 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Phase Change
- Replies: 6
- Views: 230
Re: Phase Change
Depending on the system, phase changes may occur at either changes in temperature or changes in pressure!
I attached an image for reference below.
I attached an image for reference below.
- Sat Feb 06, 2021 4:43 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed Systems
- Replies: 14
- Views: 569
Re: Closed Systems
Here is a video that defines the differences between open, closed, and isolated systems: https://www.youtube.com/watch?v=TFP6SvWPOQc As for the specifics for a closed system: -energy can be exchanged with its surroundings but not matter -mass of the system is constant -boundaries are completely closed
- Sat Feb 06, 2021 4:40 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Entropy in systems
- Replies: 6
- Views: 317
Re: Entropy in systems
Here are two helpful videos to help you understand entropy!
https://www.youtube.com/watch?v=YM-uykVfq_E
https://www.khanacademy.org/science/ap-chemistry/thermodynamics-ap/entropy-tutorial-ap/v/introduction-to-entropy
https://www.youtube.com/watch?v=YM-uykVfq_E
https://www.khanacademy.org/science/ap-chemistry/thermodynamics-ap/entropy-tutorial-ap/v/introduction-to-entropy
- Sat Feb 06, 2021 4:38 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Entropy
- Replies: 27
- Views: 1050
Re: Entropy
Dr. Lavelle defined entropy as an extensive property (depends on the # of particles) and denoted by the "S". S= KblnW1W2 (Kb is boltmann constant) A helpful definition of entropy, S, that I found online is: Entropy is a measure of the degree of randomness of particles in a system. In addit...
- Sat Feb 06, 2021 4:33 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Reversible vs Irreversible
- Replies: 3
- Views: 82
Re: Reversible vs Irreversible
Hi! I was a bit confused on this as well, but this is what I found after doing further research: -a reversible process is one in which both the system and its surroundings can return to their original states by following the reverse path; whereas a irreversible process is one in which the system and...
- Mon Feb 01, 2021 9:35 am
- Forum: Phase Changes & Related Calculations
- Topic: endothermic/exothermic
- Replies: 43
- Views: 4337
Re: endothermic/exothermic
Here are two super helpful video links that explain the differences of endothermic and exothermic reactions
https://www.youtube.com/watch?v=eJXL0IrbtqE
https://www.youtube.com/watch?v=0cUK4jcAEaU
https://www.youtube.com/watch?v=eJXL0IrbtqE
https://www.youtube.com/watch?v=0cUK4jcAEaU
- Mon Feb 01, 2021 9:31 am
- Forum: Student Social/Study Group
- Topic: Spring 2021
- Replies: 106
- Views: 11995
Re: Spring 2021
I am taking BL right now with 14B and am thinking about doing 14C and CL next quarter!
- Mon Feb 01, 2021 9:29 am
- Forum: Student Social/Study Group
- Topic: Go treat yourself after MT1!
- Replies: 75
- Views: 4244
Re: Go treat yourself after MT1!
Yes, definitely take care of yourself during midterm weeks and cut yourself some slack after the exams. Remember that there is nothing that you can do after the fact so it is not worth your energy to stress over something that is out of your control! Now that the first midterm is out of the way, is ...
- Mon Jan 25, 2021 10:08 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: sapling #10
- Replies: 4
- Views: 92
sapling #10
Hi can someone help me with the following problem: An ice cube with a mass of 46.4 g at 0.0 ∘C is added to a glass containing 428 g of water at 45.0 ∘C . Determine the final temperature of the system at equilibrium. The specific heat capacity of water, Cs , is 4.184 J/g⋅∘C , and the standard enthalp...
- Sun Jan 24, 2021 9:29 pm
- Forum: Student Social/Study Group
- Topic: Study Group
- Replies: 14
- Views: 403
Re: Study Group
Such a great idea, accountability helps so much in classes like this where the grade is broken down into components on different platforms.
- Sun Jan 24, 2021 9:27 pm
- Forum: Student Social/Study Group
- Topic: Study Strategies
- Replies: 31
- Views: 1083
Re: Study Strategies
I took 14A with Dr. Lavelle and I would say that the best way to study is to complete all of the sapling homework before the due date to stay up to date on the current topics and then complete the extra homework problems listed on the syllabus before each test. I would say that forming study groups ...
- Sun Jan 24, 2021 9:22 pm
- Forum: Student Social/Study Group
- Topic: CHEM 14B Midterm 1 Notes
- Replies: 23
- Views: 1079
Re: CHEM 14B Midterm 1 Notes
Thank you so much! It is so nice to have notes outlined on a computer where you can command F and search the topics that you need to review the most!
- Sun Jan 24, 2021 9:21 pm
- Forum: Student Social/Study Group
- Topic: Favorite Music
- Replies: 113
- Views: 9812
Re: Favorite Music
Jack Johnson is good for doing work while listening to music!
- Sun Jan 24, 2021 9:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: posting screenshots
- Replies: 4
- Views: 520
Re: posting screenshots
Hi, I think that you can copy and paste an image the same way you would text using command c (to copy) and then command v (to paste) or use the attachments button listed below the save draft, preview, and submit buttons after you clicked post reply!
- Sun Jan 24, 2021 9:04 pm
- Forum: Administrative Questions and Class Announcements
- Topic: How to list Chem_Mod posts
- Replies: 25
- Views: 92609
Re: How to list Chem_Mod posts
Does Dr. Lavelle use chem mod for answering chemistry community questions real time in class or the discussions he hosts?
- Sun Jan 17, 2021 4:14 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pKa and pH
- Replies: 3
- Views: 194
Re: pKa and pH
Hi! I hope this helps
pKa= -log(Ka) and pH= -log (H3O+)
and pKa + pKb = 14
pKa= -log(Ka) and pH= -log (H3O+)
and pKa + pKb = 14
- Sun Jan 17, 2021 4:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grading for Chemistry Community Posts
- Replies: 13
- Views: 916
Re: Grading for Chemistry Community Posts
Hi! I believe it depends when your specific TA plans on checking for your posts but I would just try your best to do 5 posts/week so that you can use chem community as a resource for homework, study, concept help throughout the course rather than just cramming in random posts for points towards the ...
- Sun Jan 17, 2021 4:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Exam Format
- Replies: 15
- Views: 989
Re: Exam Format
Hi! The exam format will likely be multiple choice including concepts and calculations depending on the units covered. We will likely have lockdown browser and have to zoom our TAs with an external device such as a phone so that they can monitor our hand movement. You should print out the equation s...
- Sun Jan 17, 2021 3:57 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Registering/Creating Your Chemistry Community Account
- Replies: 40
- Views: 100322
Re: Registering/Creating Your Chemistry Community Account
I haven't been able to register until now, could I make up the points by posting more this week? Hi! You should be able to, last quarter in 14a, the TAs generally only calculated the total mid quarter and at the end, but if you contact your TA and let them know your technological circumstances I am...
- Sun Jan 17, 2021 3:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Accessing the E-textbook [ENDORSED]
- Replies: 125
- Views: 29443
Re: Accessing the E-textbook [ENDORSED]
Pretty sure that Sapling is mandatory, and will actually be collected midnight of the following Sunday, however, is this the only "homework" due?? Yes sapling is the only homework that is taken for a grade, but the extra homework problems that Dr. Lavelle lists on the syllabus and chapter...
- Sun Jan 10, 2021 3:46 pm
- Forum: Ideal Gases
- Topic: Units of Temperature
- Replies: 82
- Views: 3355
Re: Units of Temperature
Juwan_Madaki_3K wrote:When using the ideal gas law, which units should the temperature be in? Kelvins or Celsius?
I believe most of the time in 14B we will be using Kelvin for temperature unless a specific problem indicates otherwise!
- Sun Jan 10, 2021 3:44 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3005995
Re: Post All Chemistry Jokes Here
Did you hear the one about cobalt, radon, and yttrium?
It was ~CoRnY~
It was ~CoRnY~
- Sun Jan 10, 2021 3:41 pm
- Forum: Ideal Gases
- Topic: Reviewing PV=NRT
- Replies: 7
- Views: 330
Re: Reviewing PV=NRT
Where can we find all the answers to the textbook practice problems? I believe it might be on Lavelle's website but I cannot recall under what tab. Given that this concept requires all sorts of equation solving back and forth it might be a good idea to gain a better grasp by literally applying it i...
- Sun Jan 10, 2021 3:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units
- Replies: 27
- Views: 868
Re: Units
I was wondering why when we calculate partial pressure the answer could be either in bars or moles per liter. Is there any unit out of the two that is preferred? Usually the units preferred are given in the question or you can deduce the best units from the units given! Sometimes on tests as well D...
- Tue Dec 08, 2020 8:12 am
- Forum: Student Social/Study Group
- Topic: Finals Study Things
- Replies: 27
- Views: 1283
Re: Finals Study Things
Thank you so much! It is so nice to have everything organized into one neat simple document with hyperlinks, this really helped decrease my stress in regards to organizing all of the topics!
- Tue Dec 08, 2020 8:08 am
- Forum: Student Social/Study Group
- Topic: How to study for class
- Replies: 30
- Views: 1223
Re: How to study for class
I am wondering if anyone has found a good way to study conceptual topics? I always find myself second guessing myself on the exam questions that are more concept based rather than numerical or calculation based.
- Mon Dec 07, 2020 8:47 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: -OH vs OH-
- Replies: 36
- Views: 1234
Re: -OH vs OH-
Hi, I noticed the -OH in today's lecture as well and am used to seeing OH- in both his lectures and the homework, but I am pretty certain that they are the same!
- Mon Dec 07, 2020 8:42 pm
- Forum: Bronsted Acids & Bases
- Topic: acid strength
- Replies: 3
- Views: 231
Re: acid strength
Hi! I found this from sapling textbook which is a helpful list of strong acids and bases, and essentially every other acid or base not listed is considered weak.
- Mon Dec 07, 2020 11:17 am
- Forum: Administrative Questions and Class Announcements
- Topic: Potential Problem with Lecture #28 Upload
- Replies: 1
- Views: 151
Potential Problem with Lecture #28 Upload
Hi,
I am currently trying to watch today's uploaded lecture #28, but there is an error coming up saying "this video file cannot be played. Error:232001". I was wondering if anyone else is running into this issue or if this might be an issue on my end with my computer.
Thank you.
I am currently trying to watch today's uploaded lecture #28, but there is an error coming up saying "this video file cannot be played. Error:232001". I was wondering if anyone else is running into this issue or if this might be an issue on my end with my computer.
Thank you.
- Thu Dec 03, 2020 9:45 am
- Forum: Student Social/Study Group
- Topic: How to study for class
- Replies: 30
- Views: 1223
Re: How to study for class
Hi! I find the extra textbook problems and sapling to be the best as far as simulating test questions, and then I try to find khan academy videos for concepts that I do not understand fully.
- Thu Dec 03, 2020 9:42 am
- Forum: Student Social/Study Group
- Topic: Week 8/9 Thoughts/Worries
- Replies: 66
- Views: 3171
Re: Week 8/9 Thoughts/Worries
I feel like the hardest part for me is grasping the conceptual material for the exams, I feel like there are always questions that surprise me when it comes to the concepts. Do you guys have any good ways or sources to review the conceptual material for the final?
- Thu Dec 03, 2020 9:39 am
- Forum: Student Social/Study Group
- Topic: Calculating grade
- Replies: 24
- Views: 1430
Re: Calculating grade
If we complete the sapling assignments by the due dates are we guaranteed the full 50 points for that portion of our grades?
- Thu Dec 03, 2020 9:36 am
- Forum: Student Social/Study Group
- Topic: How are you?
- Replies: 154
- Views: 12369
Re: How are you?
I was really stressed that I would not end up getting the classes that I need for winter quarter, but I ended up getting them which is such a relief! I am curious, how do you guys plan on reviewing for the final? I want to start reviewing soon so that I avoid the stress of cramming a few days in adv...
- Thu Dec 03, 2020 9:34 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 8
- Views: 436
Re: Coordination Number
Hi, here is a helpful definition that I found on coordination numbers: "Coordination number, also called Ligancy, the number of atoms, ions, or molecules that a central atom or ion holds as its nearest neighbors in a complex or coordination compound or in a crystal" (Britannica). Hope this...
- Thu Dec 03, 2020 9:33 am
- Forum: Naming
- Topic: Writing it out
- Replies: 4
- Views: 241
Re: Writing it out
Hi! In discussion yesterday, I learned that cations (+) come before and anions (-) come after!
- Sun Nov 29, 2020 3:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sapling #2
- Replies: 2
- Views: 150
Re: Sapling #2
Hi! I think that the electron pairs look like this because they drew the lewis structure to resemble the molecular structure, but I do not think this is required. Also, it is linear because there are two regions of electron density, the hybridization is sp and therefore the bond angels are 180 degre...
- Fri Nov 27, 2020 12:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: trigonal planar vs trigonal pyramidal
- Replies: 9
- Views: 684
Re: trigonal planar vs trigonal pyramidal
I believe that trigonal planar has 3 regions of electron density and the bond angels are 120 degrees whereas trigonal pyramidal has 4 regions of electron density and has bond angels of 109.5 degrees.
- Fri Nov 27, 2020 12:22 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 25
- Views: 922
Re: Bond Angles
Here is a helpful summary of the molecular structures that we have done so far and their corresponding bond angles. Please feel free to add to this list! -linear 180 degrees -trigonal planar 120 degrees, -trigonal pyramidal 109.5 degrees -trigonal bipyramidal 90 degrees, 120 degrees -octahedral 90 d...
- Tue Nov 24, 2020 3:39 pm
- Forum: Student Social/Study Group
- Topic: Big Sad: Midterm 2
- Replies: 86
- Views: 5456
Re: Big Sad: Midterm 2
I also felt like the second midterm was a bit more challenging, not necessarily because of harder concepts but because for me it is hard to think through the number of problems we had in 50 minutes especially not being able to mark up a paper and do the process of elimination by crossing things out....
- Mon Nov 16, 2020 4:27 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Valence Electron Question
- Replies: 3
- Views: 259
Re: Valence Electron Question
Hi, when looking on the periodic table, the number of the element group is at the very top. You can follow these numbers in order with groups 1, 2, skip to 13 (and then look at the second # in double digits for example 3 in 13), 14, 15, 16, 17, 18 to figure out the number of valence electrons in eac...
- Mon Nov 16, 2020 4:24 pm
- Forum: Coordinate Covalent Bonds
- Topic: Hydrogen Bonding
- Replies: 7
- Views: 547
Re: Hydrogen Bonding
Hi! I have these notes written down that summarize hydrogen bonding that is repetitive but might help you: -N,O, or F shares a lone pair of e- with positively polarized (electron-deficient) H -partially positive H is bonded to a partially negative N, O, or F -There must be one of these three bonds: ...
- Mon Nov 16, 2020 4:20 pm
- Forum: Student Social/Study Group
- Topic: Winter 2021 Classes
- Replies: 20
- Views: 938
Re: Winter 2021 Classes
Thank you! Also, would it be okay to take the Chem 14BL Lab section from 11am-1:30pm on Friday even though it goes into Chem 14B's friday lecture at 1pm, since the lecture is recorded? Yes! When enrolling, you might get an error notification due to the overlap but you can quickly bypass it by click...
- Mon Nov 16, 2020 4:19 pm
- Forum: Lewis Structures
- Topic: 2B.1 lewis structure part b
- Replies: 5
- Views: 238
Re: 2B.1 lewis structure part b
This is the most stable structure. If Cl were to have two bonds and then two lone pairs, its formal charge would be 7-(4+4/2) which equals +1. so when drawing structures, we should always just go with what gives us the most stable configuration regardless of the atom's electronegativity? yes! Also ...
- Mon Nov 16, 2020 4:16 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 11
- Views: 337
Re: Resonance
Hi! Generally the resonance structure with a formal charge closest to zero is the most stable structure! Try to see if the charges on each atom cancel each other out, and if they do, this is a good indicator that the formal charge is zero and the structure is stable!
- Wed Nov 11, 2020 9:27 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Sapling #20
- Replies: 2
- Views: 598
Sapling #20
"Select which intermolecular forces of attraction are present between CH3CHO molecules" How do you determine what intermolecular forces of attraction are present just by given the molecular formula?
- Wed Nov 11, 2020 8:54 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Helpful screenshot of oxidation rules from textbook
- Replies: 7
- Views: 267
Helpful screenshot of oxidation rules from textbook
I attached a screenshot from the textbook of a helpful list of oxidation rules for calculating oxidation numbers! hope it helps!
- Wed Nov 11, 2020 4:58 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Audio-Visual Modules for MD 2 Material?
- Replies: 5
- Views: 303
Audio-Visual Modules for MD 2 Material?
Hi,
I was wondering if there will be any audio-visual modules for MD2 topics? Right now, the last module is on the Heisenberg Uncertainty Principle.
I was wondering if there will be any audio-visual modules for MD2 topics? Right now, the last module is on the Heisenberg Uncertainty Principle.
- Wed Nov 11, 2020 4:27 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Helpful Summary of What Induced Dipole- Induced Dipole depends on
- Replies: 6
- Views: 339
Helpful Summary of What Induced Dipole- Induced Dipole depends on
Hi, Please feel free to add on to this if I leave anything out, but it was helpful to me to make a bullet point list of all of the things that strength of induced dipole-induced dipole interactions depends on to understand the concept. -polarizability of molecule 1 and 2 (a1a2), distance between 2 m...
- Tue Nov 10, 2020 3:47 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Week 6 Discussion Question- Cobalt
- Replies: 1
- Views: 68
Week 6 Discussion Question- Cobalt
In discussion section today, we were asked what element has the electron [Ar]3d^7 and were given that it is M^2+. Can anyone explain why the answer is cobalt? I thought that if we were given ^2+ we would move two to the left on the periodic table because it is two less electrons but cobalt is two to...
- Tue Nov 10, 2020 3:36 pm
- Forum: Trends in The Periodic Table
- Topic: Which directions do cation and anions of elements move?
- Replies: 3
- Views: 183
Which directions do cation and anions of elements move?
For example, would Br^-2 be two to the right on the periodic table or two to the left of the normal Br?
- Tue Nov 03, 2020 10:41 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration helpful videos
- Replies: 1
- Views: 69
Electron Configuration helpful videos
Hi, I might be the only one but I was struggling to understand electron configurations in the lecture but I found a couple of helpful youtube videos that I will paste below if anyone wants a quick review or summary on how to do electron configurations! I hope this is helpful. https://www.youtube.com...
- Tue Nov 03, 2020 10:21 am
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures
- Replies: 4
- Views: 135
Re: Drawing Lewis Structures
Hi, Dr. Lavelle mentioned in week 4 lecture 3 that you should arrange the lewis structures by choosing the atom with the lowest ionization energy as the central atom and arrange atoms symmetrically around the central atom. It is important to remember that Hydrogen is never a central atom and as far ...
- Tue Nov 03, 2020 10:17 am
- Forum: Trends in The Periodic Table
- Topic: Electron affinity and Ionization energy
- Replies: 7
- Views: 424
Re: Electron affinity and Ionization energy
Hi, ionization energy is the energy required to remove an electron from an atom whereas electron affinity is the energy released when an electron is added to an atom. On a periodic table, both ionization energy and electron affinity decreases down a group and increases across a period.
- Tue Nov 03, 2020 10:13 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Noble Gas Configuration
- Replies: 13
- Views: 480
Re: Noble Gas Configuration
Hi, going off of your question, I am wondering if anyone has a trick or anything on how they remember how to do electron configurations for different compounds?
- Tue Nov 03, 2020 10:12 am
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy
- Replies: 5
- Views: 221
Re: Ionization Energy
Hi, I believe that ionization energy increases that means it is increasingly more difficult to remove an electron. As you move across a period, ionization energy increases, this is because as you move across the period- the atomic radius decreases. As the atomic radius decreases, the atom is essenti...
- Tue Nov 03, 2020 10:08 am
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student - Part II [ENDORSED]
- Replies: 298
- Views: 245036
Re: Advice from a Medical Student - Part II [ENDORSED]
Hi, I am wondering how you went about getting in all the classes that you needed for your undergraduate major at UCLA while also making sure to get in extra classes needed for pre-reqs of med school. Furthermore, how should I go about making sure I am meeting all the course requirements at various m...
- Tue Nov 03, 2020 10:05 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm grades
- Replies: 5
- Views: 272
Re: Midterm grades
Hi, yesterday in Office Hours, Dr. Lavelle said that scores should be out this Thursday!
- Tue Nov 03, 2020 10:04 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Scores
- Replies: 28
- Views: 1127
Re: Midterm Scores
Hi, in office hours yesterday Dr. Lavelle said that scores for midterm 1 should be out this week Thursday 11/5!
- Tue Oct 27, 2020 6:11 pm
- Forum: *Shrodinger Equation
- Topic: For Ms (spin up, spin down)
- Replies: 6
- Views: 547
For Ms (spin up, spin down)
For the value of Ms, is there an arrow always given to indicate whether it is spin up or spin down or is there another way to determine whether the value is + or -1/2?
- Wed Oct 21, 2020 5:23 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Homework up to Q19 and Midterm 1 [ENDORSED]
- Replies: 7
- Views: 228
Re: Homework up to Q19 and Midterm 1 [ENDORSED]
I am wondering if sapling is not in the same order for everyone because some of my questions 1-19 do cover material we have not yet learned such as quantum numbers and some questions past 19 cover material that we have learned such as DeBroglie. Is there anyway that a list of the specific questions ...
- Wed Oct 21, 2020 5:14 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Homework problem #14
- Replies: 2
- Views: 123
Homework problem #14
Calculate the wavelength, in nanometers, of the spectral line produced when an electron in a hydrogen atom undergoes the transition from the energy level n=3 to the level n=2. I am getting 12.66 nm as the answer after doing Rydberg's equation, but sampling is saying this answer is incorrect. Is anyo...
- Wed Oct 21, 2020 2:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: The Midterm Topics
- Replies: 5
- Views: 210
Re: The Midterm Topics
Hi, In discussion today, my TA suggested that we know all the elements that are diatomic, so I thought it would be helpful for me to put them all here if anyone needs them. Hydrogen (H2) Nitrogen (N2) Fluorine (F2) Oxygen (O2) Iodine (I2) Chlorine (Cl2) Bromine (Br2) A sentence I found online said t...
- Wed Oct 21, 2020 2:30 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Lecture 10/21 Question about H-atom problem
- Replies: 3
- Views: 160
Lecture 10/21 Question about H-atom problem
Hi, I was wondering if anyone could tell me how Dr. Lavelle found the mass of 9.1 x 10^-31 kg when he was calculating the change in velocity in the following problem: For H-atom the electron is then confined to its nuclear diameter, 1.7 x 10^-15 m (which would be the electron's uncertainty in positi...
- Wed Oct 21, 2020 9:18 am
- Forum: Empirical & Molecular Formulas
- Topic: Diatomic Elements
- Replies: 3
- Views: 158
Diatomic Elements
Hi, Does anyone know when we should make sure to calculate elements in their diatomic forms? For example, when finding calculating for empirical and molecular formulas, is there ever a time that we would not double the mass of nitrogen, oxygen, or any of the other elements that only exist in diatomi...
- Mon Oct 19, 2020 7:27 pm
- Forum: DeBroglie Equation
- Topic: At What Point does wavelength become undetectable?
- Replies: 8
- Views: 313
Re: At What Point does wavelength become undetectable?
Hi, Dr. Lavelle said that anything shorter than 10^-15 m is not detectable. I also researched further and found that the longest detectable wavelengths is generally from 10^6 to 10^11 m, but also make sure to pay attention to your units!
- Mon Oct 19, 2020 7:11 pm
- Forum: Properties of Light
- Topic: Planck's Constant
- Replies: 7
- Views: 253
Planck's Constant
Hi,
I must have missed this in lecture, but does anyone know the numerical value of Planck's constant?
I must have missed this in lecture, but does anyone know the numerical value of Planck's constant?
- Sat Oct 17, 2020 1:36 pm
- Forum: Student Social/Study Group
- Topic: Discussion 2E groupme
- Replies: 1
- Views: 134
Discussion 2E groupme
Hi is there a groupme for discussion 2E yet?
- Wed Oct 14, 2020 2:42 pm
- Forum: Empirical & Molecular Formulas
- Topic: Discussion problem help
- Replies: 4
- Views: 236
Discussion problem help
194 g/mol of 0.376 g of caffeine burned, 0.682 g CO2, 0.174 g H2O, 0.110 g N2 formed. Determine empirical and molecular formula, write equation for combustion. I started by finding the grams of H and got 0.0196 through dimensional analysis, but I am wondering how to go about finding grams for carbon...
- Wed Oct 14, 2020 1:33 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: E 29 part c
- Replies: 15
- Views: 3207
Re: E 29 part c
Hi, we did this problem in discussion today but I missed the answers. For part a) I ended up getting 0.0423 moles and I was wondering why I got a different answer than posted above? I multiplied 8.61 g * (1 mol/ 202.484 g/mol). I got 202.484 g/mol by adding up the molar mass.
- Wed Oct 14, 2020 1:26 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: E 29 part c
- Replies: 15
- Views: 3207
Re: E 29 part c
Hi, we did this problem in discussion today but I missed the answers. For part a) I ended up getting 0.0423 moles and I was wondering why I got a different answer than posted above? I multiplied 8.61 g * (1 mol/ 202.484 g/mol). I got 202.484 g/mol by adding up the molar mass.
- Sun Oct 11, 2020 1:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Textbook solutions
- Replies: 3
- Views: 139
Textbook solutions
Hi, I am wondering where I can find or gain access to the solutions manual for the textbook? I am working through the extra problems right now and want to double check my answers.
- Sun Oct 11, 2020 12:01 am
- Forum: SI Units, Unit Conversions
- Topic: Unit Rounding
- Replies: 11
- Views: 391
Re: Unit Rounding
Hi, the general rule for rounding is wait until the very end of the problem to round and follow sig figs unless it is given specifically in the question.
- Sat Oct 10, 2020 11:58 pm
- Forum: Empirical & Molecular Formulas
- Topic: Sapling Week 1 #8
- Replies: 23
- Views: 1316
Re: Sapling Week 1 #8
Hi, a great starting point for this problem is to start by forming the molecular formula by counting the number of each element seen in the structure! I had to do research to figure that out, but once you have the molecular formula, you can proceed as you would following the normal steps for determi...
- Sat Oct 10, 2020 11:55 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing equations.
- Replies: 35
- Views: 2504
Re: Balancing equations.
As far as balancing equations, I recommend always starting with the element that is least abundant and then moving to the next least abundant element, and if it ever comes down to needing for example 6.5 as the coefficient to balance one side, use the fractional form of 6.5 --> 13/2 and then multipl...
- Sat Oct 10, 2020 11:53 pm
- Forum: Significant Figures
- Topic: Which number determines sig figs of the answer?
- Replies: 26
- Views: 877
Re: Which number determines sig figs of the answer?
The significant figure depends on what the specific question is asking for, if the question specifically asks about moles then you would refer to the sig fig of the moles given and used throughout the problem.
- Tue Oct 06, 2020 8:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Turning in textbook problems
- Replies: 10
- Views: 272
Re: Turning in textbook problems
Correct! Sapling is the only graded homework assignment that needs to be turned in according to the end of the section covered in class. The current due dates are the end of week 1 and the end of week 3. All other textbook problems are optional but will likely help in review for midterms and final.