Search found 105 matches
- Sun Mar 14, 2021 12:05 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka vs Kb
- Replies: 5
- Views: 411
Re: Ka vs Kb
Usually Ka is associated with acids and Kb with bases. If you need to convert between the two, just use the equation Ka x Kb = Kw = 1x10^-14
- Sat Mar 13, 2021 6:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final jitters
- Replies: 8
- Views: 728
Re: Final jitters
Get lots of sleep and don't psych yourself out - you got this!!! Also don't forget to change your clocks!!!
- Sat Mar 13, 2021 6:03 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetically Stable vs. Thermodynamically Stable
- Replies: 3
- Views: 263
Re: Kinetically Stable vs. Thermodynamically Stable
That all makes sense to me! But for some reason the textbook says that "A thermodynamically stable compound is a compound with a negative standard Gibbs free energy of formation (water is an example)."
- Sat Mar 13, 2021 1:59 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetically Stable vs. Thermodynamically Stable
- Replies: 3
- Views: 263
Kinetically Stable vs. Thermodynamically Stable
Hi can someone tell me how to know if something is thermodynamically stable and kinetically stable? I saw another post on this but every response said something different so now I'm even more confused.
- Sat Mar 13, 2021 1:55 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Arrhenius Eq
- Replies: 12
- Views: 667
Re: Arrhenius Eq
I don't believe we explicitly went over this. I guess you could get it by deriving the lnk= -Ea/RT +lnA, but I would just try to remember the Arrhenius equation by itself so you don't have to try to derive it.
- Fri Mar 12, 2021 3:52 pm
- Forum: General Science Questions
- Topic: Final Nerves and thoughts
- Replies: 11
- Views: 817
Final Nerves and thoughts
I was already a little nervous for the final and then I remembered that it is going to be on daylight savings so we're gonna lose an hour of sleep the night before/morning of the final ;_;. At least it's pi day which means discounted pizza and pie. How are you guys planning to get your stress out th...
- Sun Mar 07, 2021 4:29 pm
- Forum: Student Social/Study Group
- Topic: Fave food
- Replies: 266
- Views: 28709
Re: Fave food
I love sushi, pasta, and waffles!
- Sun Mar 07, 2021 4:27 pm
- Forum: Student Social/Study Group
- Topic: How do you deal with burnout?
- Replies: 144
- Views: 13102
Re: How do you deal with burnout?
I try my best to space out my school work with self care/free time. I know that I get burnout a lot more when I study for long blocks of time, especially when it is all one subject. I find I do a lot better when I divide study time and space it out/alternate between subjects more frequently.
- Sun Mar 07, 2021 4:24 pm
- Forum: Student Social/Study Group
- Topic: Final Study Tips!
- Replies: 38
- Views: 2033
Re: Final Study Tips!
Going to workshops and doing the textbook problems is what really helped me!!
- Sun Mar 07, 2021 4:23 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E naught
- Replies: 13
- Views: 757
Re: E naught
I believe at equilibrium E naught equals zero since K=1 and ln(1) is zero.
- Sun Mar 07, 2021 4:21 pm
- Forum: General Science Questions
- Topic: Final Exam
- Replies: 39
- Views: 1812
Re: Final Exam
I know that there will be a lot of office and ta hours and I think he might do what he did last semester with the last lecture being review but I'm not sure. He will probably send out an email soon!
- Tue Mar 02, 2021 10:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Access to accounts
- Replies: 10
- Views: 667
Re: Access to accounts
I think we still have access to chem community (I think the website is actually open to the general public) but I'm just not sure if we will be able to post on it anymore?
- Tue Mar 02, 2021 10:23 pm
- Forum: Student Social/Study Group
- Topic: Textbook Problem Strategies
- Replies: 17
- Views: 723
Re: Textbook Problem Strategies
I usually try to do them my self first, but for really difficult ones, I will read the solution and see if it helps me to understand the problem better.
- Tue Mar 02, 2021 10:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Step up vs workshops
- Replies: 18
- Views: 942
Re: Step up vs workshops
I like workshops for the extra practice and step-ups when I'm struggling!
- Sun Feb 28, 2021 1:57 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling 7/8 Question 3
- Replies: 2
- Views: 223
Sapling 7/8 Question 3
Can someone please help me with this? I don't understand what I am doing wrong?
- Thu Feb 25, 2021 11:40 am
- Forum: Administrative Questions and Class Announcements
- Topic: TA Office Hours
- Replies: 7
- Views: 376
TA Office Hours
Does anyone know if we can review our Midterms in another TA's office hours? Like if we can't make the time that our own TA has office hours, can we go to a different one's?
- Sun Feb 21, 2021 8:31 pm
- Forum: Student Social/Study Group
- Topic: Post Midterm 2 De-stressing
- Replies: 92
- Views: 6102
Re: Post Midterm 2 De-stressing
I watched WandaVision and caught up on the Bachelor :)
- Sun Feb 21, 2021 8:30 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Boiling point
- Replies: 9
- Views: 597
Re: Boiling point
Isabelle Hales 1J wrote:Hi! Going off of this, is the melting point also found at equilibrium (deltaG = 0)?
I would think so! I'm pretty sure that at the temp for all phase changes (melting point, boiling point, etc) that G=0!!
- Sun Feb 21, 2021 8:28 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Work in a Constant Volume
- Replies: 13
- Views: 852
Re: Work in a Constant Volume
Conceptually: when there is no change in volume, there is no expansion or compression, and therefor no work being done. Mathematically: for the equation w = -P∆V, and so if the change in volume is zero, then the work done will also be zero. for the equation w = -nRT ln V2/V1, the natural log of V2/V...
- Sun Feb 21, 2021 8:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Property
- Replies: 71
- Views: 2904
Re: State Property
A state function is independent of the path or phase changes taken to arrive at the final destination. In other words, it only really cares about the initial and final values.
- Sun Feb 21, 2021 8:23 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Which R Values to use
- Replies: 22
- Views: 8087
Re: Which R Values to use
It honestly depends on which units you need in your final answers. I just keep my equation sheet next to me to help with that!
- Sun Feb 14, 2021 8:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Can We Review our Exams?
- Replies: 69
- Views: 2935
Re: Can We Review our Exams?
I would just email your TA to make sure you can stop by during their office hours and then you should be able to review your midterm :)
- Sun Feb 14, 2021 8:47 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: confusion with notation
- Replies: 11
- Views: 490
Re: confusion with notation
The d stands for "derivative," but I think that professor Lavelle just used that to explain how he was deriving his equations :)
- Sun Feb 14, 2021 8:45 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sapling #19
- Replies: 4
- Views: 224
Re: Sapling #19
The "reverse" of the natural log (ln x) is e^x, so I just raised both sides to look like e^lnk = e^ (the rest of the equation). The e will cancel out with the ln k so you'll end up with k = e^ (the rest of the equation). I hope this helps!
- Sun Feb 14, 2021 8:44 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Sapling Week 5/6 HW #7
- Replies: 7
- Views: 370
Re: Sapling Week 5/6 HW #7
The first thing that I did was try to convert watts to kilojoules (1W = 1J/s). And then the Hvap = energy of the heater/change in mole. I calculated the change in mole by subtracting the final mass from the initial and then converting from grams to mole for each compound. Once you find the Hvap for ...
- Sun Feb 14, 2021 8:41 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Sapling question 7
- Replies: 8
- Views: 387
Re: Sapling question 7
I was a little confused on this as well but I think that because it's asking about the entropy of the liquid samples that the order would be reversed, so the molecules with the highest entropy in gaseous form would have the lowest entropy in liquid form? Again I am not completely sure :/
- Sun Feb 07, 2021 2:24 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Equipartition Theorem
- Replies: 2
- Views: 166
Re: Equipartition Theorem
I'm confused about this also. I wish he had covered this in lecture :/
- Sun Feb 07, 2021 2:18 pm
- Forum: Calculating Work of Expansion
- Topic: Textbook Problem 4A.13
- Replies: 1
- Views: 103
Re: Textbook Problem 4A.13
I was wondering this too but I think it is because the system is at a constant volume, so the volume of the samples is not really something we need to take into account. Additionally, since we aren't asked to find the moles or molarity, and are already given the temperature, we don't need the moles ...
- Sun Feb 07, 2021 2:14 pm
- Forum: Student Social/Study Group
- Topic: Chemistry Community Posts
- Replies: 12
- Views: 615
Re: Chemistry Community Posts
I just click "your posts" and use the number at the top.
- Sun Feb 07, 2021 2:12 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: HW Question
- Replies: 4
- Views: 419
Re: HW Question
To find q requires knowing the molar heat capacity at constant volume. Since CO2 is a linear molecule (if you draw out the lewis structure it shows that CO2 has a linear shape), then the Cv for CO2 is 5/2 R. Use that value for Cv and plug it into your equation for q. For the second part, since the s...
- Sat Feb 06, 2021 1:47 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Week 3/4 Sapling #18
- Replies: 4
- Views: 153
Week 3/4 Sapling #18
I was able to find q, but I am having a really hard time finding U. Can someone please help?
- Sun Jan 31, 2021 8:35 pm
- Forum: Student Social/Study Group
- Topic: Midterm Grades
- Replies: 15
- Views: 641
Re: Midterm Grades
I am not sure but I remember someone saying hopefully by the end of the week?
- Sun Jan 31, 2021 8:32 pm
- Forum: Calculating Work of Expansion
- Topic: assuming room temperature
- Replies: 4
- Views: 448
Re: assuming room temperature
I would think that if we aren't given temperature (and aren't being asked to find it) then we can assume room temp or maybe STP? That's a really good question.
- Sun Jan 31, 2021 8:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling Week 3/4 #10
- Replies: 7
- Views: 382
Re: Sapling Week 3/4 #10
I tried to find the q of ice and the q of water, and then use ΔHfus+qice=−qwater to solve for final temp. I hope that helps!
- Sun Jan 31, 2021 8:17 pm
- Forum: Calculating Work of Expansion
- Topic: Variables in Reversible Expansion
- Replies: 1
- Views: 77
Re: Variables in Reversible Expansion
I have been wondering this too!
- Sun Jan 31, 2021 8:16 pm
- Forum: Student Social/Study Group
- Topic: Sapling Week 3 & 4
- Replies: 2
- Views: 143
Re: Sapling Week 3 & 4
I think it's due next Sunday!!
- Fri Jan 22, 2021 3:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 Content
- Replies: 18
- Views: 642
Midterm 2 Content
Does anyone know up until what content the midterm will cover? Do you think it will cover up until today's lecture?
- Wed Jan 20, 2021 7:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: 4C.3 textbook problem [ENDORSED]
- Replies: 2
- Views: 298
Re: 4C.3 textbook problem [ENDORSED]
Im not sure! It looks like you got the same final temperature as the textbook did!
- Wed Jan 20, 2021 7:54 pm
- Forum: Ideal Gases
- Topic: Inverse Kc [ENDORSED]
- Replies: 41
- Views: 1900
Re: Inverse Kc [ENDORSED]
You use the invert of Kc when using the reverse reaction, and you use Kc^n when multiplying the entire equation by the same coefficient.
- Wed Jan 20, 2021 7:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Simplifying K equations (book 5J.3)
- Replies: 3
- Views: 110
Re: Simplifying K equations (book 5J.3)
I think Professor Lavelle said he wouldn't give us a cubic equation that has a K larger than 1x10^-4 since we did not learn how to do that and it's a lot of extra work.
- Wed Jan 20, 2021 7:49 pm
- Forum: Phase Changes & Related Calculations
- Topic: enthalpy vs temperature
- Replies: 8
- Views: 1460
Re: enthalpy vs temperature
I think it's because as a gas, the steam or vapor has a higher enthalpy than water and thus a higher internal energy
- Mon Jan 18, 2021 9:55 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook 6D.5
- Replies: 3
- Views: 69
Re: Textbook 6D.5
I think that for these problems you need to use the Kb and Ka tables (Table 6d1 I believe). It says it right before the 6D questions but I also didn't see it at first.
- Mon Jan 18, 2021 9:53 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: conjugate base
- Replies: 14
- Views: 430
Re: conjugate base
The conjugate base of a weak acid will be a strong base.
- Thu Jan 14, 2021 9:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling week 1/2 question 5 [ENDORSED]
- Replies: 3
- Views: 234
Re: Sapling week 1/2 question 5 [ENDORSED]
The best way to calculate this is the same way you would calculate Kc: Q = [products]/[reactants], or in this case, Q = [NH3]^2/[N2][H2]^3 and then you can just plug in the concentrations.
- Thu Jan 14, 2021 9:12 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Which Acids and Bases to remember
- Replies: 4
- Views: 197
Re: Which Acids and Bases to remember
Based on previous lectures, it seems we only really need to know the six strong acids (HCl, HBr, HNO3, H2SO4, HI, and HClO4), and the general weak ones that he keeps mentioning (acetic acid, H2SO3, HF, HNO2). For bases, I think we just need to know that group one and two oxides/hydroxides are strong...
- Sun Jan 10, 2021 10:01 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook Problem 5.39
- Replies: 6
- Views: 339
Re: Textbook Problem 5.39
I am also having this issue. I think that the solution manual has a typo.
- Sun Jan 10, 2021 8:33 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Q5
- Replies: 2
- Views: 111
Re: Sapling Q5
For problems like these, you first have to look at all of the molecules that make up the products and reactants, in this case that is NH3, 3I2, N2, and 6HI. Then, you can look at the one step equations given and make note of the ones that contain the molecules you got from step one. Then, from the o...
- Wed Jan 06, 2021 8:22 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Q9
- Replies: 3
- Views: 169
Re: Sapling Q9
I am struggling with this one too.
- Wed Jan 06, 2021 8:19 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Reverse Reactions
- Replies: 12
- Views: 497
Re: Reverse Reactions
I believe so!
- Wed Jan 06, 2021 8:19 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Calculating reaction quotients when given partial pressures
- Replies: 3
- Views: 85
Re: Calculating reaction quotients when given partial pressures
Qp = (P product)/(P reactant)
So for this problem, QP = (PNO2)^2/(PN2O4)
QP= (.5)^2/(.5)
So for this problem, QP = (PNO2)^2/(PN2O4)
QP= (.5)^2/(.5)
- Wed Jan 06, 2021 8:15 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: sapling #2
- Replies: 8
- Views: 351
Re: sapling #2
First, convert from mol to mol/L, so just divide your given mol values by the 5 L. Then, you can set up your I.C.E. or equilibrium table.
- Sat Dec 12, 2020 8:48 pm
- Forum: SI Units, Unit Conversions
- Topic: Avogadro's Number
- Replies: 12
- Views: 2151
Re: Avogadro's Number
When going from moles to atoms/molecules, you would divide by Avogadro’s number, and when going from atoms/molecules to moles, you would multiply by Avogadro’s number.
- Sat Dec 12, 2020 8:45 pm
- Forum: Conjugate Acids & Bases
- Topic: Fundamental J.13 Part C
- Replies: 4
- Views: 274
Re: Fundamental J.13 Part C
That’s a great question. I don’t know if there would be any conjugate pairs because this reaction is between a strong acid and a strong base.
- Sat Dec 12, 2020 8:42 pm
- Forum: Student Social/Study Group
- Topic: Pre-Final Rituals
- Replies: 12
- Views: 731
Re: Pre-Final Rituals
Usually, I either do the same exact thing or the complete opposite: stay up super late studying cause I’m so stressed out and then wake up even more stressed, but this time I’m watching holiday movies and I’m gonna try to go to bed early lol.
- Wed Dec 09, 2020 8:06 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: Favorable forces
- Replies: 1
- Views: 118
Re: Favorable forces
I think a favorable force just refers to the force that acts as the main intermolecular/bonding force. So in NH3, I think hydrogen would be the more favorable force because it's the strongest IMF for NH3. I hope that helps!
- Wed Dec 09, 2020 8:02 pm
- Forum: Hybridization
- Topic: What is s-character?
- Replies: 1
- Views: 217
Re: What is s-character?
I think s-character has to do with the ratio of s to p orbitals in hybridization? So an sp hybrid orbital would have more s character than an sp3 hybrid orbital. I found this chem community post from 2011 that might help more.
viewtopic.php?t=1255
viewtopic.php?t=1255
- Sat Dec 05, 2020 9:11 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Textbook 9C Question #5 part b
- Replies: 2
- Views: 66
Re: Textbook 9C Question #5 part b
This is a really good question. I would assume that it could be monodentate because of its shape and the angles between the two single-bonded oxygens preventing it from successfully bonding to the same metal but I honestly don't know. I found this link from a 2014 chem community post on the same top...
- Sat Dec 05, 2020 9:04 pm
- Forum: Naming
- Topic: HW Question #1
- Replies: 7
- Views: 384
Re: HW Question #1
Yes! I got this one too and it took me longer than I'd care to admit lol. The name of that compound is Tetraamminedichlorocobalt(III) chloride. I got this using the rules Professor Lavelle mentioned in class. Tetra because there are four ammonias and ammine from the chart on the chem 14 A website. D...
- Sat Dec 05, 2020 9:00 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Transition metal number of bonds
- Replies: 3
- Views: 275
Re: Transition metal number of bonds
This is a good question. I don't know if there a specific way to determine the bonding capacity for all transition metals. I know that it's hard to pinpoint and exact number of valence electrons a TM refers, as we've seen with their ability to hold more than a full octet. From what we've done in lec...
- Sat Dec 05, 2020 8:56 pm
- Forum: Hybridization
- Topic: Unhybridized Orbitals in Relation to Hybridized Orbitals
- Replies: 4
- Views: 275
Re: Unhybridized Orbitals in Relation to Hybridized Orbitals
Well it depends. If you remember earlier in the quarter, when we first reviewed unhybridized orbitals, we learned that p orbitals have 3 different orientations-- px, py, and pz. Each p orbital was on a different axis. The reason the unhybridized p orbital was perpendicular rather than in plane was ...
- Sat Dec 05, 2020 8:55 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Quick rundown on coordination numbers?
- Replies: 4
- Views: 156
Re: Quick rundown on coordination numbers?
Hi! Just want to point out the number of bonds and number of ligands are not the same thing. The coordination number is the amount of bonds to the central transition metal atom, but that will not necessarily be the number of ligands. After all, polydentates can form multiple bonds; for example, one...
- Sat Dec 05, 2020 8:53 pm
- Forum: Naming
- Topic: Diatomic Molecules
- Replies: 4
- Views: 241
Re: Diatomic Molecules
That's a really good question. Chloride is a diatomic molecule but in one of the sapling questions I got I had to say dichloride and not just chloride so I am not entirely sure. I hope someone else can clear this up because I had a similar question. You might need to say di- regardless of whether or...
- Sun Nov 29, 2020 2:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pair vs radical
- Replies: 3
- Views: 234
Re: Lone pair vs radical
I'm not entirely sure, but my guess would be that repulsion would be less, as there is less magnitude of negative charge to repel other electrons attached to atoms. I would agree with this. With one less electron, the repulsion will probably be less as the charge cloud is smaller than if there were...
- Sun Nov 29, 2020 2:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Week 8 sapling #18
- Replies: 3
- Views: 161
Week 8 sapling #18
Can someone explain why the structure for H2CCCCH2 would not by cyclical/have the carbons form a square with one hydrogen attached to each carbon instead of the 4 carbons being in a line?
- Tue Nov 24, 2020 6:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sapling #6
- Replies: 5
- Views: 217
Re: Sapling #6
There are two linear structures, just like there are two different "bent" structures. Molecules with 5 charge clouds, 2 bonds, and 3 lone pairs are also considered linear structures. As the others mentioned, this structure is also considered linear because the lone pairs repelling the bond...
- Tue Nov 24, 2020 6:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: carbon hydrogen bonds
- Replies: 6
- Views: 347
Re: carbon hydrogen bonds
I'm a little confused on your question, but I don't believe this would affect bond angles. In our lewis structures, the surrounding atoms often have lone pairs, otherwise, they wouldn't really be a region of electron density. I hope this helps!
- Tue Nov 24, 2020 6:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grading Scale
- Replies: 4
- Views: 175
Re: Grading Scale
I was wondering this too.
- Fri Nov 20, 2020 9:11 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: LDF forces
- Replies: 9
- Views: 408
Re: LDF forces
Yes! All molecules experience London Dispersion Forces!
- Thu Nov 19, 2020 11:44 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2996933
Re: Post All Chemistry Jokes Here
What did silver say to gold at the bar?
"Ay you (Au), get outta here!"
"Ay you (Au), get outta here!"
- Thu Nov 19, 2020 11:42 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2996933
Re: Post All Chemistry Jokes Here
Two chemists walk into a bar. One tells the bartender, "I'll have an H2O." The other says, "I'll have an H2O too!" The second chemist dies.
- Thu Nov 19, 2020 11:40 am
- Forum: Resonance Structures
- Topic: Resonance Structure + Energy
- Replies: 2
- Views: 128
Re: Resonance Structure + Energy
That's a good question. I would assume that resonance structures exist to demonstrate the possibility of different ways the compound can exist, and then the formal charges help us figure out the probability of those structures and their contribution to the resonance hybrid and the actual bond length...
- Thu Nov 19, 2020 11:34 am
- Forum: Lewis Structures
- Topic: H2O Lone Pairs
- Replies: 5
- Views: 379
Re: H2O Lone Pairs
The lone pairs are drawn that way also because the two hydrogen bonds cannot be directly across from each other, because the repulsion from the two lone pairs would be too strong. The only stable way to place the lone pairs is "next" to each other.
- Thu Nov 19, 2020 11:31 am
- Forum: Resonance Structures
- Topic: 2.7 Resonance of N5 cation
- Replies: 2
- Views: 231
Re: 2.7 Resonance of N5 cation
For things like this, I usually also guess and check, or try and calculate the formal charge because that helps me identify where the issues with my structures are.
- Sun Nov 15, 2020 6:07 pm
- Forum: Bond Lengths & Energies
- Topic: Textbook question
- Replies: 3
- Views: 242
Re: Textbook question
The lewis structure of AsF3 reveals that there is one lone pair on the central atom, As, with three single bonds. This shows that AsF3 is a polar molecule (its not symmetrical and there is a clear dipole). AsF5, on the other hand, is nonpolar, as revealed by its symmetrical lewis structure. Polar mo...
- Sun Nov 15, 2020 6:03 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook 1E#11
- Replies: 4
- Views: 226
Re: Textbook 1E#11
Im not completely sure, but I believe the 5s sub shell comes before the 4d sub shell only when the 5s sub shell is incomplete and the 4d sub shell has no electrons. If the 5s sub shell is complete and there is electrons in the 4d subshell, then the 4d subshell will be placed and filled before the 5s...
- Sun Nov 15, 2020 5:59 pm
- Forum: Lewis Structures
- Topic: Textbook Problem 2D.3
- Replies: 2
- Views: 145
Re: Textbook Problem 2D.3
Great question! Ba-Br does have a greater EN difference than Be-Br because Ba is less electronegative. As you pointed out, EN increases going up and across the periodic table. Br is much more electronegative than Ba and Be. Be is more electronegative than Ba. This means that the greatest difference ...
- Wed Nov 11, 2020 5:29 pm
- Forum: Dipole Moments
- Topic: Sapling #17
- Replies: 8
- Views: 4014
Re: Sapling #17
London (dispersion) forces were referred to as Van Der Waals forces and induced dipole-induced dipole forces in lecture. I believe that Professor Lavelle usually refers to them as induced dipole-induced dipole forces because that helps clarify and remind exactly what those forces do. These forces ex...
- Wed Nov 11, 2020 5:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 Content
- Replies: 2
- Views: 109
Midterm 2 Content
I understand that the Midterm will cover material from the last 8 topics in Outline 2 to the end of Outline 3. In outline 2, it is mentioned that we will need to be able to "Describe the interpretation of atomic orbitals in terms of probability". In the textbook section 1D.4, there is an o...
- Sat Nov 07, 2020 4:16 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Element orbital representation
- Replies: 4
- Views: 240
Re: Element orbital representation
Catherine Bubser 2C wrote:Does is matter the order in which these orbitals are written as long as the n number are in order?
It does matter the order in which they are written because different orbitals have different energy levels so electron configuration should be arrange in a specific order.
- Sat Nov 07, 2020 4:13 pm
- Forum: Octet Exceptions
- Topic: Octet Exception for H, He, Li, and Be
- Replies: 5
- Views: 135
Re: Octet Exception for H, He, Li, and Be
Yup! That looks right to me!
- Thu Nov 05, 2020 2:04 pm
- Forum: General Science Questions
- Topic: Grade Breakdown
- Replies: 35
- Views: 2124
Grade Breakdown
Does anyone know Lavelle's grade breakdown/rubric, i.e. how many points equal an A/A-/B/etc.?
- Tue Nov 03, 2020 11:52 pm
- Forum: Student Social/Study Group
- Topic: Favorite TV shows
- Replies: 277
- Views: 34319
Re: Favorite TV shows
I loved Gravity Falls as a kid and still do now. Some great shows I've watched recently are New Girl, Sherlock, and Bojack Horseman. I also plan on watching Brooklyn 99. Omg I love all of those shows (except Bojack Horseman cause I haven't seen that one yet). I also love this show called Psych, but...
- Tue Nov 03, 2020 10:46 pm
- Forum: Resonance Structures
- Topic: Bond Length Measurements
- Replies: 2
- Views: 76
Re: Bond Length Measurements
wait wow I feel stupid now. Thank you lol
- Tue Nov 03, 2020 10:43 am
- Forum: Resonance Structures
- Topic: Bond Length Measurements
- Replies: 2
- Views: 76
Bond Length Measurements
In Monday's lecture, Professor Lavelle mentioned that bond length was measured in amperes. I thought amperes were a measure of energy, so why are they used as the units for a measurement of length?
- Sun Nov 01, 2020 9:39 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Avogadro constant
- Replies: 40
- Views: 2286
Re: Avogadro constant
when converting to moles from number of atoms or vice versa, you would need to use Avogadro's constant.
- Sun Nov 01, 2020 9:34 pm
- Forum: Photoelectric Effect
- Topic: N initial vs. N final
- Replies: 7
- Views: 325
Re: N initial vs. N final
Yup! It also helps to know which energy levels correspond with which series/radiation (Lyman= uv = n=1 and Blamer=visible=n=2).
- Thu Oct 29, 2020 3:03 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2996933
Re: Post All Chemistry Jokes Here
Here are some chem memes I made in my high school chem class lol
- Thu Oct 29, 2020 2:52 pm
- Forum: Student Social/Study Group
- Topic: Lavelle's Jokes
- Replies: 26
- Views: 2135
Re: Lavelle's Jokes
These are memes I made when I took chem in high school lol.
- Wed Oct 28, 2020 1:30 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Simplification for Electron Configuration
- Replies: 3
- Views: 200
Re: Simplification for Electron Configuration
You can only simplify to the previous noble gas (last column in the periodic table). This is because the noble gases have their respective orbitals and sub shells completely filled. You cannot simplify using any other elements. For example, if you were writing the electron configuration for Aluminum...
- Wed Oct 28, 2020 1:27 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Lecture 11
- Replies: 2
- Views: 183
Lecture 11
In Monday’s lecture, Professor Lavelle talked about how for multi-electron atoms after atomic # 20, 4s is higher energy than 3d but I’m still confused as to why. Could someone maybe clarify that please?
- Sat Oct 24, 2020 9:31 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Sapling hw 11
- Replies: 3
- Views: 325
Re: Sapling hw 11
"ℓ" is the quantum number that represents the angular momentum of an electron. It is used to identify which orbital the electron is in (via shape). In this case, n=6 and ℓ=0 because in an s-orbital, ℓ=0. I hope that helps!
- Sat Oct 24, 2020 9:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework 2, 3, 4
- Replies: 3
- Views: 190
Re: Homework 2, 3, 4
We can't really know for sure unless the professor posts the correct 19 questions :(
- Thu Oct 22, 2020 3:37 pm
- Forum: *Shrodinger Equation
- Topic: Electron Density
- Replies: 4
- Views: 130
Re: Electron Density
Ok that makes more sense thank you so much!
- Thu Oct 22, 2020 3:34 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Showing our Work on the Midterm
- Replies: 10
- Views: 408
Showing our Work on the Midterm
Does anyone know if we are allowed to have scratch paper on the midterm?
- Wed Oct 21, 2020 6:13 pm
- Forum: *Shrodinger Equation
- Topic: Electron Density
- Replies: 4
- Views: 130
Electron Density
In lecture today, Professor Lavelle mentioned this equation briefly:
ψ²≡ e⁻ρ distribution
And I am very confused. I don’t really know what this means. Can someone please explain this to me?
ψ²≡ e⁻ρ distribution
And I am very confused. I don’t really know what this means. Can someone please explain this to me?
- Tue Oct 20, 2020 2:13 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg equation
- Replies: 2
- Views: 129
Re: Rydberg equation
I think its 1/lambda
- Fri Oct 16, 2020 5:00 pm
- Forum: DeBroglie Equation
- Topic: Problem 1B.15
- Replies: 3
- Views: 95
Re: Problem 1B.15
I believe it is because kg is the fundamental SI unit for mass. But I'm not sure.
- Thu Oct 15, 2020 9:10 pm
- Forum: *Black Body Radiation
- Topic: What is Black Body?
- Replies: 53
- Views: 2235
Re: What is Black Body?
A black body is something that absorbs all light, but Lavelle said we didn't need to know that.
- Wed Oct 14, 2020 6:15 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Spectral Lines
- Replies: 2
- Views: 154
Spectral Lines
I'm probably overthinking this, but I don't really understand how to determine the number of spectral lines based on given energy levels.
- Tue Oct 13, 2020 1:54 pm
- Forum: Properties of Light
- Topic: Memorizing Wavelengths
- Replies: 10
- Views: 315
Memorizing Wavelengths
Will we need to memorize which wavelengths belong where on the spectrum/ which types of light correspond with which wavelength? If not do you think we'll be given access to this during the test?