Search found 111 matches
- Sun Mar 14, 2021 5:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: THANK YOU DR LAVELLE!
- Replies: 47
- Views: 6267
Re: THANK YOU DR LAVELLE!
commenting to boost :) thank you again to Dr. Lavelle, the TA's, UA's and also my classmates for being so active on CC and always being incredibly helpful <3 i'll miss u all!
- Sat Mar 13, 2021 10:03 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: when can we not use -0.0592/n when finding the E of a cell?
- Replies: 10
- Views: 766
Re: when can we not use -0.0592/n when finding the E of a cell?
since this equation comes from inserting the temp at 298K, we shouldn't use this when the rxn is not occurring at standard conditions
- Fri Mar 12, 2021 8:20 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Does temperature affect A?
- Replies: 9
- Views: 559
Re: Does temperature affect A?
i know that increasing A and T will increase K, but i don't think we'd actually to worry about that for A since in most problems its omitted(like a difference problem)/given to us as a constant
- Fri Mar 12, 2021 8:18 pm
- Forum: Balancing Redox Reactions
- Topic: Balance reaction using OH- or H+
- Replies: 18
- Views: 757
Re: Balance reaction using OH- or H+
the question should indicate whether the rxn occurs in basic or acidic solution!
- Fri Mar 12, 2021 8:15 pm
- Forum: General Rate Laws
- Topic: overall order of the rxn (sapling #7)
- Replies: 9
- Views: 575
Re: overall order of the rxn (sapling #7)
How do we know C is the zero order reactant? We know because in the context of the problem, there are two examples where the concentrations of [A] and [B] stay the same and [C] changes, yet their rates do not change. Since the rates do not change, that means that the concentration of [C] cannot aff...
- Thu Mar 11, 2021 9:35 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: ΔG°, ΔH°, and ΔS°
- Replies: 5
- Views: 1103
Re: ΔG°, ΔH°, and ΔS°
the ° symbol doesn't imply that the rxn is at 298 K, but rather that this is a value calculated from the reaction at equilibrium (i believe). so yes, we can calculate these values at different temperatures. i would assume that H and S will be adjusted to different temperatures but we're normally giv...
- Sun Mar 07, 2021 2:55 pm
- Forum: General Rate Laws
- Topic: overall order of the rxn (sapling #7)
- Replies: 9
- Views: 575
Re: overall order of the rxn (sapling #7)
but would an overall rxn order of (for example) 5 mean anything without the context of the problem? because that could involve multiple first order reactants or one first order and 2 second, with infinite possibility for zero-order reactants?
- Sun Mar 07, 2021 2:53 pm
- Forum: Zero Order Reactions
- Topic: Overall order of the reaction
- Replies: 45
- Views: 1734
Re: Overall order of the reaction
the overall order of a reaction is found by calculating the sum of the orders of the individual reactants
- Sun Mar 07, 2021 2:51 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: sapling #19
- Replies: 3
- Views: 193
Re: sapling #19
i believe we'll be going over this topic in the last 2 lectures! the last ~8 problems on sapling are all from the new content it seems
- Sun Mar 07, 2021 2:50 pm
- Forum: First Order Reactions
- Topic: Sapling #4
- Replies: 3
- Views: 234
Re: Sapling #4
this is a chart kate showed us in her workshop last week that might help you!
- Sun Mar 07, 2021 2:48 pm
- Forum: First Order Reactions
- Topic: Sapling Homework 11
- Replies: 2
- Views: 156
Re: Sapling Homework 11
your set ups are correct so maybe just try it again in the calculator? also maybe theres an issue in how you entered it or because you moved the ln[A] to be before the -kt
- Sun Mar 07, 2021 1:39 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: graphs and order
- Replies: 19
- Views: 853
Re: graphs and order
a linear plot of ln[A] vs time means the rxn is first order,
a linear plot of 1/[A] vs time means the rxn is second order,
a linear plot of [A] vs time means the rxn is zero order.
hope this helps :)
a linear plot of 1/[A] vs time means the rxn is second order,
a linear plot of [A] vs time means the rxn is zero order.
hope this helps :)
- Sun Mar 07, 2021 1:35 pm
- Forum: General Rate Laws
- Topic: overall order of the rxn (sapling #7)
- Replies: 9
- Views: 575
overall order of the rxn (sapling #7)
hi! i'm a bit confused on what the overall order of a reaction means and why we can just add those numbers together? i know how to find values for m,n, and l experimentally but i don't understand why for the overall order of the reaction we just add those values together? thank you in advance!
- Sun Feb 28, 2021 7:18 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling Week 7/8 question 18
- Replies: 3
- Views: 204
Re: Sapling Week 7/8 question 18
i had the exact same question! since removing the parentheses was the solution, i presume that this is because the iron oxide trihydrate acts as a single compound, so adding a coefficient of 2 in front of the whole thing will still multiply the entire compound by 2. we don't need to multiply the wat...
- Sun Feb 28, 2021 7:14 pm
- Forum: Student Social/Study Group
- Topic: Sapling Weeks 7-8 Homework Question
- Replies: 2
- Views: 155
Re: Sapling Weeks 7-8 Homework Question
so your reaction on the right side is correct, but the order is the issue. what the feedback is telling you is that the cathode needs to be on the right, which is referring to the solid Ag. the Cl- ions should both be closest to the salt bridge, so the final answer is what they listed above ^^ hope ...
- Sun Feb 28, 2021 7:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: sapling #11 (changing sign of Ered)
- Replies: 2
- Views: 161
Re: sapling #11 (changing sign of Ered)
ok thank you that makes sense! i just remembered kate went over that in her workshop too lol
- Sun Feb 28, 2021 7:11 pm
- Forum: Balancing Redox Reactions
- Topic: sapling #19
- Replies: 6
- Views: 373
Re: sapling #19
You balanced it right! Don't put the parenthesis... I did that too and Sapling kept marking me wrong :) It should be: 4Fe+3O2+6H2O⟶2Fe2O3∙3H2O Fe2O3•H2O indicates that it contains water. Any chemical compound that has the dot followed by water indicates that it is a hydrate, which means that it's a...
- Sun Feb 28, 2021 5:37 pm
- Forum: Balancing Redox Reactions
- Topic: sapling #19
- Replies: 6
- Views: 373
sapling #19
hi, i'm fairly certain that i've balanced this equation correctly but i'm still getting errors and i'm not sure whats wrong with it. I'm also not totally certain what the product/multiplication of Fe2O3•H2O means so if anyone could also explain that I would really appreciate it. thank you! Screen Sh...
- Sun Feb 28, 2021 4:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: sapling #11 (changing sign of Ered)
- Replies: 2
- Views: 161
sapling #11 (changing sign of Ered)
hi! i'm a bit confused on #11 in sapling because i thought that we should be changing the signs for the standard reduction potentials if the reaction is being oxidized. by this logic, all of my E˙ cell potentials ended up being negative when i did cathode - anode. can anyone explain what i'm doing w...
- Sat Feb 20, 2021 1:45 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Textbook 4A.11
- Replies: 6
- Views: 790
Re: Textbook 4A.11
i'm not 100% certain on the definition of the heat capacity of the calorimeter, but google says it the quantity of heat absorbed by the calorimeter for each temperature increase of 1 ˙C, which makes sense with the definition of C we've established with other compounds like liquid water or ice. you w...
- Sat Feb 20, 2021 1:38 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Thermodynamically Favorable
- Replies: 27
- Views: 1776
Re: Thermodynamically Favorable
a rxn is thermodynamically favorable if the ∆G˙ is negative, and unfavorable if ∆G˙ is positive!
this same rule applies to molecules as well, meaning that a compound will be thermodynamically stable if the ∆G˙of formation is negative, and unstable if ∆G˙ of formation is positive
this same rule applies to molecules as well, meaning that a compound will be thermodynamically stable if the ∆G˙of formation is negative, and unstable if ∆G˙ of formation is positive
- Sat Feb 20, 2021 1:34 pm
- Forum: Calculating Work of Expansion
- Topic: Work sign
- Replies: 46
- Views: 1899
Re: Work sign
work done on a system is positive, work done by the system is negative!
- Wed Feb 17, 2021 3:44 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: textbook 4I.7 part c
- Replies: 2
- Views: 151
Re: textbook 4I.7 part c
hi! i'm a bit confused on part c of this problem, which is asking for "changes in entropy of the surroundings and of the system for the freezing of 1 mol C2H5OH liquid" this part of the answer is confusing me because they wrote ∆Hfus as a negative value despite the equation for ∆Ssurr = -...
- Wed Feb 17, 2021 3:16 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: textbook 4J.1
- Replies: 1
- Views: 112
textbook 4J.1
this question is "why are so many exothermic reactions spontaneous?" the answer says: Screen Shot 2021-02-17 at 3.14.36 PM.png is another suitable answer for this that the ∆H for an exothermic reaction will typically be large? i didn't understand why the entropy is greater if heat is relea...
- Wed Feb 17, 2021 3:06 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: textbook 4I.7 part c
- Replies: 2
- Views: 151
textbook 4I.7 part c
hi! i'm a bit confused on part c of this problem, which is asking for "changes in entropy of the surroundings and of the system for the freezing of 1 mol C2H5OH liquid" this part of the answer is confusing me because they wrote ∆Hfus as a negative value despite the equation for ∆Ssurr = -∆...
- Sun Feb 14, 2021 11:59 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Does ∆U depend on q, w, and T?
- Replies: 5
- Views: 289
Re: Does ∆U depend on q, w, and T?
i'm not sure where you got that first equation for ∆U but i would assume that equation is some derivation/comes from the equations for q and w. i believe that ∆U does depend on q w and T just given that it represents internal energy. you can't change the internal energy without some type of heat or...
- Sun Feb 14, 2021 11:51 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Sapling #5, Week 5/6
- Replies: 2
- Views: 177
Re: Sapling #5, Week 5/6
as said above, flipping T1 and T2 will just change the sign of the final calculation, but the answer for this one was a positive value (at least thats what mine said was correct lol)
- Sun Feb 14, 2021 11:48 pm
- Forum: Calculating Work of Expansion
- Topic: When work is positive and negative
- Replies: 3
- Views: 215
Re: When work is positive and negative
yes you're correct! if work is done on the system, its sign is positive. if work is done by the system, its sign is negative
- Sun Feb 14, 2021 11:46 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Does ∆U depend on q, w, and T?
- Replies: 5
- Views: 289
Re: Does ∆U depend on q, w, and T?
i'm not sure where you got that first equation for ∆U but i would assume that equation is some derivation/comes from the equations for q and w. i believe that ∆U does depend on q w and T just given that it represents internal energy. you can't change the internal energy without some type of heat or ...
- Sun Feb 14, 2021 11:40 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed System
- Replies: 52
- Views: 2583
Re: Closed System
a closed system is just that, closed, but heat can still be transferred in and out of the system. it's like a closed tupperware! we can still heat the food using the microwave, but the matter inside is still the same
- Sun Feb 14, 2021 9:02 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: sapling #6
- Replies: 1
- Views: 148
sapling #6
for #6, i thought we would have to include a constant (5/2) to be multiplied by R because neon is a monoatomic ideal gas. i understand how to do the problem (separating the change in volume then adding to the change in temperature) and i tried using this constant during the first step where i calcul...
- Sun Feb 14, 2021 8:57 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Sapling 3
- Replies: 13
- Views: 543
Re: Sapling 3
Yeprem wrote:I don't know why I was doubting myself thinking there had to be something in the middle columns too. Thank you!
could you explain why nothing goes in the middle columns? is it impossible for both dH to be negative and dS to be positive (or vice versa)? thank you!
- Wed Feb 10, 2021 2:23 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: is this a possible equation? [ENDORSED]
- Replies: 1
- Views: 99
is this a possible equation? [ENDORSED]
so i'm watching lecture 13 from 2/5 and i'm a bit confused on the deltaS= q/T equation. since we said that q=-w, are we also allowed to consider deltaS= -w/T another equation? if that's wrong could someone please explain? thank you in advance!
- Sun Feb 07, 2021 11:12 pm
- Forum: Calculating Work of Expansion
- Topic: Sapling #14
- Replies: 11
- Views: 433
Re: Sapling #14
For path A, we need to know the number of moles (n). We find this by using PV=nRT Where P is given (2.54 atm), V is given (3.98L), T is given (298K) and R is the constant 0.0821 Latm/Kmol After solving for n, you would plug it into w=-nRT x ln(Vf/Vi) We use this specific equation because it is a re...
- Sun Feb 07, 2021 10:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling #11 (Week 4-5)
- Replies: 5
- Views: 311
Re: Sapling #11 (Week 4-5)
hi! if you set the q of water = -q iron, it should give you the right answer because they both have the same Tfinal since no heat is lost to the surroundings.
- Sun Feb 07, 2021 10:40 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: R constants
- Replies: 40
- Views: 2107
Re: R constants
depending on the unites, we will use a different value of R. all are listed on the constants sheet. if you have a problem that has L.atm, you would use .08206. if the problem is with joules, you use 8.314
- Sun Feb 07, 2021 10:31 pm
- Forum: Calculating Work of Expansion
- Topic: Sapling #14
- Replies: 11
- Views: 433
Re: Sapling #14
thank you! whatever i do though i still can't get the correct calculation for this problem and i think it might have to do with the moles. are we using delta n or just n, and which value of the pressure do we use to calculate n? thanks
- Sun Feb 07, 2021 9:56 pm
- Forum: Calculating Work of Expansion
- Topic: Sapling #14
- Replies: 11
- Views: 433
Re: Sapling #14
can anyone explain why we can't use the original w= -P dV equation instead? i'm comfortable using the other but i don't understand why my answer using w= -P dV is wrong.
- Sat Jan 30, 2021 5:04 pm
- Forum: Calculating Work of Expansion
- Topic: Integral
- Replies: 9
- Views: 554
Re: Integral
volume has very very small changes so it's written as dv!
- Sat Jan 30, 2021 4:19 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: steam causing burns
- Replies: 40
- Views: 1212
Re: steam causing burns
yes! steam causes burns instead of just 100 C water because of the extra amount of energy used to convert liquid water into water vapor. all that extra energy hits the skin and converts steam back to a liquid, causing the burn
- Fri Jan 29, 2021 12:41 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: textbook 4D.23
- Replies: 3
- Views: 213
textbook 4D.23
can anyone explain why we have to rewrite the equation as N2+ (5/2)O2 >>> N2O5 ? the question explain why we need to do that or how it changes the outcome of the problem. in general, if anyone could explain the steps to this problem i would really appreciate it!!
- Thu Jan 28, 2021 1:18 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Topic 5I, question 33 (5I.33)
- Replies: 1
- Views: 40
Topic 5I, question 33 (5I.33)
can anyone explain why they calculated the moles for the NH4(NH2CO)2 ? if this counts as a pure solid, then it should be irrelevant right? it's not used anywhere else in the actual calculation so is there a reason for adding this or no? thank you!!
- Sun Jan 24, 2021 7:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: approximating
- Replies: 10
- Views: 387
Re: approximating
we can assume x is not significant if the percent protonation is less than 5% and if the Ka is less than 10^-4. i normally check both rules though to make sure the approximation is safe to make
- Sun Jan 24, 2021 7:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 #5
- Replies: 4
- Views: 171
Re: Sapling Week 2 #5
i think the reason why its telling you to add them in the solution is because its assuming you didn't leave [B] in the denominator as x- (1.29*10^-5). since 1.29*10^-5 is equal to [BH+], that's the extra bit its telling you to add. basically since the Kb was less than 10^-3, you probably left out th...
- Sun Jan 24, 2021 7:17 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: pH of weak acid
- Replies: 9
- Views: 381
Re: pH of weak acid
we can assume x is not significant if the percent protonation is less than 5% and if the Ka is less than 10^-3. however, i normally check first to see if the 5% rule works even if the questions doesn't ask for percent protonation because sometimes the Ka<10^-3 but the percent is still above 5%. it m...
- Sun Jan 24, 2021 7:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How to tell if a salt is acidic, basic or neutral
- Replies: 7
- Views: 1166
Re: How to tell if a salt is acidic, basic or neutral
this depends on whether the cation or anion is often found in strong bases or strong acids. If the cation of a strong base pairs with an anion of a weak acid, it would be a basic salt. If both are strong or both are weak, the salt is neutral. If the cation of a weak base pairs with an anion of a str...
- Sun Jan 24, 2021 7:07 pm
- Forum: Student Social/Study Group
- Topic: UA Sessions
- Replies: 2
- Views: 97
Re: UA Sessions
commenting here so i don't forget to check back hehe i really need to go this week!
- Sun Jan 24, 2021 7:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Homework #7
- Replies: 10
- Views: 310
Re: Sapling Homework #7
does anyone know why in this question we don't have to account for ignoring the Na in the .058M solution? I initially tried to calculate what the molarity would be without the Na and I used that value in my calculations instead. can we just ignore that since we ignore Na as a product and as a reacta...
- Sun Jan 17, 2021 9:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Week 1 Sapling 3
- Replies: 11
- Views: 460
Re: Week 1 Sapling 3
yes! i personally think graphing is a faster method of finding the x values but you can also use the quadratic formula to solve :)
- Sun Jan 17, 2021 9:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Box quadratic equation
- Replies: 10
- Views: 539
Re: ICE Box quadratic equation
normally there will be a negative answer that would be extraneous if it ends up being a quadratic equation. but if thats not the case, i'm not sure how to differentiate. anyone else know what to do?
- Sun Jan 17, 2021 9:19 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Total Pressure
- Replies: 26
- Views: 1830
Re: Total Pressure
total pressure is the sum of all the equilibrium partial pressures
- Sun Jan 17, 2021 9:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 1 #6
- Replies: 10
- Views: 377
Re: Sapling Week 1 #6
i agree with the comment above because unfortunately you dint ask any specific question. that said, you would solve this equation as if the molarities given were the equilibrium molarities and use those values to find Q. Q would equal [NH3]^2/([N2]*[H2]^3)
- Sun Jan 17, 2021 3:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: shifts left or right
- Replies: 23
- Views: 1025
Re: shifts left or right
shifting to the left favors reactant production, and shifting to the right favors product production!
- Sun Jan 17, 2021 1:22 pm
- Forum: Ideal Gases
- Topic: Sampling hw #4
- Replies: 16
- Views: 1723
Re: Sampling hw #4
i just redid this problem after the comments here said to use the inverse Kp, but that kept giving me the wrong answer even though ever other part of my problem was set up similarly to everyone's in the comments. i only got the correct answer once i used 391 instead of 1/391, can anyone explain why ...
- Sun Jan 10, 2021 11:41 pm
- Forum: Ideal Gases
- Topic: Gas constant R
- Replies: 26
- Views: 1117
Re: Gas constant R
Why is the gas constant a constant? To me that part is a bit confusing because I would have thought the gas constant differs for each gas. my understanding is that the gas constant has more to do with the state of the matter rather than its content if that makes sense? like it doesn't matter if its...
- Sun Jan 10, 2021 11:38 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 74
- Views: 4207
Re: PV=nRT
P is pressure, V is volume in liters, n is moles, R is a constant (that changes depending on the unit of pressure), and T is temperature (in Kelvin)
- Sun Jan 10, 2021 11:37 pm
- Forum: Ideal Gases
- Topic: n/V = concentration
- Replies: 19
- Views: 2153
Re: n/V = concentration
n/V is rearranging the variables to represent concentration because n=mols of x and V is liters!
- Sun Jan 10, 2021 11:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Q
- Replies: 53
- Views: 1919
Re: K vs. Q
Q is P/R at any time during the reaction and we can use it to determine which reaction is favored.
- Mon Jan 04, 2021 9:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 1A module #18
- Replies: 5
- Views: 168
1A module #18
For a balanced chemical equation with all stoichiometric coefficients equal to one, what is the simplest expression for the equilibrium constant? A. The ratio of the equilibrium concentrations of reactants to the equilibrium concentrations of products. B. The ratio of the equilibrium concentrations ...
- Wed Dec 16, 2020 12:33 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Finding PH and POH
- Replies: 6
- Views: 418
Re: Finding PH and POH
Does anyone know why the [OH-] is different from the pOH. Why is it a very small negative number? Thanks in advance! the [OH-] is different from pOH in the same way [H+] is different from pH! [OH-] is the concentration of OH- ions in the water and the pOH is used instead of just the concentration b...
- Wed Dec 16, 2020 12:28 am
- Forum: Octet Exceptions
- Topic: Exceptions outside the ones we memorized
- Replies: 6
- Views: 388
Re: Exceptions outside the ones we memorized
i'm fairly certain that any d-block element in groups 15,16,17, and 18 can have an expanded octet, but to different extents
- Tue Dec 15, 2020 9:56 am
- Forum: Student Social/Study Group
- Topic: Final Exam
- Replies: 49
- Views: 2440
Re: Final Exam
i don't think i got the full 1.5 hours because it took a while to check everyone's papers but towards the end i had to guess on easy fundamental problems bc i didn't have enough time to do the full calculation :( definitely not enough time
- Sun Dec 13, 2020 2:31 am
- Forum: Naming
- Topic: Cobalt vs Cobaltate
- Replies: 16
- Views: 1059
Re: Cobalt vs Cobaltate
the overall compound is an ion, so you add an "ate" at the end
- Sun Dec 06, 2020 9:25 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Does pH indicate strength of an acid?
- Replies: 26
- Views: 2364
Re: Does pH indicate strength of an acid?
yes! a lower pH indicates a strong acid :)
- Sun Dec 06, 2020 9:24 pm
- Forum: Naming
- Topic: Sapling #9 question 1
- Replies: 11
- Views: 616
Re: Sapling #9 question 1
Hi, this was very helpful and wanted to add in my compound for others to see a different example. Compound: [Co)NH 3 ) 5 Cl]Cl 2 Practically the same steps as Idella, Since NH3 is my ligand and there are five, I said Penta ammine. Next is the one chlorine, so I did not put a prefix just "chlor...
- Sun Dec 06, 2020 9:16 pm
- Forum: Student Social/Study Group
- Topic: Professor Lavelle's hat
- Replies: 17
- Views: 991
Re: Professor Lavelle's hat
gonna add a comment in here so i don't forget to come back and check it hahaha
Re: Sapling 1
hi! use the original name first, the prefix is irrelevant for the alphabetical naming order.
- Sun Dec 06, 2020 9:12 pm
- Forum: Naming
- Topic: "(en)" Sapling
- Replies: 19
- Views: 856
Re: "(en)" Sapling
hi! en is shorthand for NH2CH2CH2NH2, which is ethylenediamine, a bidentate ligand.
- Thu Dec 03, 2020 8:25 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: ligand vs polyatomic
- Replies: 3
- Views: 382
Re: ligand vs polyatomic
thank you both!! these were really helpful
- Thu Dec 03, 2020 6:28 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: ligand vs polyatomic
- Replies: 3
- Views: 382
ligand vs polyatomic
i've watched the lecture and a few youtube videos about ligands by now and maybe something just hasn't clicked yet but is there a difference between ligands and polyatomic ions? i understand that the more complex ions are created through reactions but i previously learned about CN- as just a polyato...
- Sun Nov 29, 2020 5:42 pm
- Forum: Sigma & Pi Bonds
- Topic: coplanar bonding
- Replies: 1
- Views: 160
Re: coplanar bonding
someone else explained it here very well!! https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=30&t=68848&p=278161&hilit=coplanar&sid=8a3b656ed31d8fef121069bf63826893&sid=8a3b656ed31d8fef121069bf63826893#p278161 basically it has to do with pi-bonds and that they should be placed ...
- Sun Nov 29, 2020 5:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: #13 Sapling Week 8
- Replies: 18
- Views: 582
Re: #13 Sapling Week 8
tetrahedral is correct! if it's not cooperating when you write that in maybe its a spelling error? otherwise i'm not sure how to help :(
- Sun Nov 29, 2020 5:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sapling #17
- Replies: 10
- Views: 475
Re: Sapling #17
there's no favorable orientation here because none of these are resonance structures! the molecule will have the same charges no matter the shape so any orientation will work
- Sun Nov 29, 2020 4:13 pm
- Forum: Hybridization
- Topic: e density
- Replies: 30
- Views: 1026
Re: e density
yes, every bond or lone pair is considered a region of electron density!
- Sun Nov 29, 2020 4:12 pm
- Forum: Hybridization
- Topic: Sapling Week 7/8 HW #11
- Replies: 13
- Views: 550
Re: Sapling Week 7/8 HW #11
^ i think you're right! 4 regions of electron density translates to sp3, 5 is d1sp3, 6 is d^2 sp^3, etc.
- Sun Nov 22, 2020 9:10 pm
- Forum: Trends in The Periodic Table
- Topic: Ionic Character
- Replies: 11
- Views: 491
Re: Ionic Character
more ionic vs more covalent character in a bond will relate to the polarizability/polarizing power of an atom, the size of an atom, and it's electronegativity. periodic trends are very important for this!
- Sun Nov 22, 2020 9:08 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Expanded Octets
- Replies: 9
- Views: 399
Re: Expanded Octets
does anyone here know what the limit is on an expanded octet? i understand why/how they exist but how do we know that an atom can only hold (for example) a max of 10 electrons and not say 16 electrons?
- Sun Nov 22, 2020 6:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 21
- Views: 661
Re: Bond Angles
as others have said, bond angles are experimentally determined so we don't need to calculate them. however, as long as you can remember the shape of a molecule and how the atoms are arranged, you can probably determine an angle by dividing the number of atoms around the central atom by 360
- Sun Nov 22, 2020 6:51 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: London Forces [ENDORSED]
- Replies: 19
- Views: 774
Re: London Forces [ENDORSED]
yes, LDF are found in all molecules, but they are the weakest bonds!
- Sun Nov 15, 2020 11:40 pm
- Forum: Lewis Acids & Bases
- Topic: Classification of Lewis Acids and Bases
- Replies: 5
- Views: 263
Re: Classification of Lewis Acids and Bases
a lewis acid would be an electron acceptor and a lewis base would be an electron donor.
lewis acids can also be: a molecule w electron-deficient central atoms, polar double bonds, and cations.
lewis bases can be any atom/molecule with extra electrons or molecules with a lone pair
lewis acids can also be: a molecule w electron-deficient central atoms, polar double bonds, and cations.
lewis bases can be any atom/molecule with extra electrons or molecules with a lone pair
- Sun Nov 15, 2020 11:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: Saplong 15
- Replies: 6
- Views: 348
Re: Saplong 15
everyone has stated why its HF above, but I think it's also important to remember that the bond lengths between H and other molecules in group 17 increase as you go down!
- Sun Nov 15, 2020 11:31 pm
- Forum: SI Units, Unit Conversions
- Topic: picometer conversion
- Replies: 13
- Views: 1760
Re: picometer conversion
1 picometer = 1 * 10^-12 meters, but i think it might be more important to remember angstroms!! ( 1 * 10^-10 meters) both of these are on our formula sheet though
- Sun Nov 15, 2020 11:29 pm
- Forum: Resonance Structures
- Topic: bond length
- Replies: 37
- Views: 1425
Re: bond length
we won't need to know anything exact, but know that the order from longest to shortest goes single>double>triple
- Sun Nov 15, 2020 8:51 pm
- Forum: Bond Lengths & Energies
- Topic: Bond length
- Replies: 1
- Views: 89
Re: Bond length
i saw a post where someone explained it, ill add the link!!
https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=31&t=67475&sid=46008056ab505b72841f0ac3d7c559c6
https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=31&t=67475&sid=46008056ab505b72841f0ac3d7c559c6
- Sun Nov 15, 2020 7:27 pm
- Forum: Resonance Structures
- Topic: Sapling Weeks 5 and 6 # 3
- Replies: 2
- Views: 161
Re: Sapling Weeks 5 and 6 # 3
knowing that the overall charge of the ion should be 3-, i drew single bonds between the P and each O so that every oxygen would have a negative formal charge. phosphorus will have one lone pair to satisfy its formal charge and 5 valence e-. hope this helps!!
- Sun Nov 15, 2020 7:18 pm
- Forum: Lewis Structures
- Topic: Sapling weeks 5/6 Question 4
- Replies: 6
- Views: 339
Re: Sapling weeks 5/6 Question 4
Okay, I've gotten to the last part of this question where there is a table with bond lengths. I'm not sure what ample & overwhelming bond character mean. Hi Jacquelyn! so, in this question, ample just means sufficient or enough to be deemed to have this bond character while overwhelming would b...
- Sun Nov 15, 2020 7:08 pm
- Forum: Resonance Structures
- Topic: Resonance Structures Clarification
- Replies: 8
- Views: 333
Re: Resonance Structures Clarification
i'm also wondering how do we know which contributes the most/least to the structure of an ion?
- Sun Nov 08, 2020 5:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: MIDTERM 2 Textbook Sections
- Replies: 6
- Views: 236
Re: MIDTERM 2 Textbook Sections
look at the outlines on his website!! he'll probably tell us which exact outlines to know but i'm assuming we should know the rest of outline 2 and outline 3
- Sun Nov 08, 2020 5:30 pm
- Forum: Properties of Light
- Topic: Study Advice
- Replies: 50
- Views: 2078
Re: Study Advice
i recommend the drop in sessions and workshops because they answer and explain all the questions so well!! i also use the worksheets from other discussion sections and i think those problems are the most helpful for practice and you can go to any TA for help with them.
- Sun Nov 08, 2020 5:25 pm
- Forum: Student Social/Study Group
- Topic: grade worries
- Replies: 119
- Views: 14581
Re: grade worries
i'm worried about grades and if i'll have enough time to prepare for our next exam but we have plenty of review options so i feel confident we can study to all do well!!
- Sun Nov 01, 2020 11:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm grades
- Replies: 19
- Views: 799
Re: Midterm grades
to the person above, i'm pretty sure most of them are all or none, but i know at least one of the multiple choice questions offers partial credit if you had the right answer but the wrong explanation or something like that!
- Sun Nov 01, 2020 7:25 pm
- Forum: Photoelectric Effect
- Topic: Sapling hw #12
- Replies: 5
- Views: 334
Re: Sapling hw #12
i normally use the other equation, freq= Rydberg constant*((1/n^2)-1/n^2)) where the order is n1-n2, for problems like this. i find it easiest to calculate and does the two electron levels in one step! hope this helps
- Sun Nov 01, 2020 7:22 pm
- Forum: Properties of Light
- Topic: Is c always the speed of light?
- Replies: 92
- Views: 4928
Re: Is c always the speed of light?
yes, c is a constant always equal to 3 x 10^8 m/s
- Sun Nov 01, 2020 7:20 pm
- Forum: DeBroglie Equation
- Topic: wrong equation?
- Replies: 6
- Views: 674
Re: wrong equation?
i think you might've combined 2 equations or something like that because the speed of light shouldn't be involved as far as i know! it could also be you trying to convert lambda to frequency but put the c in the wrong place? i'm not sure why you have that written but just know that its wavelength= h...
- Sun Nov 01, 2020 12:13 am
- Forum: Student Social/Study Group
- Topic: Halloween!!!
- Replies: 73
- Views: 3090
Re: Halloween!!!
happy halloween!! i worked at the polls today and will be everyday until election day so halloween was catching up on hw for me :( still had some reese's tho!!
- Sat Oct 31, 2020 10:24 pm
- Forum: Photoelectric Effect
- Topic: Lyman Series
- Replies: 30
- Views: 1130
Re: Lyman Series
yes it should end in n=1! Lyman corresponds to UV light so it has a higher energy level
- Mon Oct 26, 2020 12:09 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra Post-Assessment Survey Question
- Replies: 4
- Views: 222
Re: Atomic Spectra Post-Assessment Survey Question
i'm confused what this question means when it says wavelengths plural and how you knew to divide 1 by that. could you explain how you got there? and if you did solve the rest of the problem i would also rly appreciate if you could explain it! thanks
- Mon Oct 26, 2020 12:07 am
- Forum: General Science Questions
- Topic: Sapling Homework
- Replies: 14
- Views: 788
Re: Sapling Homework
we don't need to do the week 4 problems before the midterm! only 1-19 will be tested on and the rest are for week 4 which we can do afterwards :)
- Sun Oct 25, 2020 6:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: CCLE DOWN
- Replies: 6
- Views: 415
Re: CCLE DOWN
it's back up now! but i've also saved sapling as a bookmark on my computer and it worked for me!
- Sun Oct 25, 2020 5:58 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation Confusion
- Replies: 3
- Views: 247
Re: Shrodinger Equation Confusion
similar to calculus or when computing a rate of change, you always do final-inital. that way it should be positive since it ends on a lower n level than it starts!