is there a reason WHY platinum is like the default thing we use?
are there any situations where we would add a different element (?) as an electrode? if so, what are those elements and how we would tell which one to use?
Search found 101 matches
- Fri Mar 12, 2021 10:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: When to use Platinum
- Replies: 14
- Views: 805
- Fri Mar 12, 2021 10:11 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Value of E Naught in a Concentration Cell
- Replies: 3
- Views: 372
Re: Value of E Naught in a Concentration Cell
wait, can someone remind me the difference between a concentration cell and a galvanic cell please?
- Fri Mar 12, 2021 10:06 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts and intermediates
- Replies: 10
- Views: 632
Re: Catalysts and intermediates
in terms of equations/laws, which ones can/cannot have catalysts and/or intermediates in them again?
i saw someone mention that intermediates can't be in rate laws but is there anything else?
i saw someone mention that intermediates can't be in rate laws but is there anything else?
- Fri Mar 12, 2021 8:32 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb Calorimeter
- Replies: 14
- Views: 4726
Re: Bomb Calorimeter
I've heard about an open, closed, and isolated system but what exactly is a perfect system?
What characterizes such a system and are there any examples besides a bomb calorimeter?
What characterizes such a system and are there any examples besides a bomb calorimeter?
- Fri Mar 12, 2021 7:53 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Activation Energy and Catalysts
- Replies: 7
- Views: 3511
Re: Activation Energy and Catalysts
i understand why adding a catalyst will decrease the activation energy for the forward reaction, but im a bit confused as to why it's the same for the reverse. can someone explain this please?
- Sat Mar 06, 2021 2:21 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Molecularity
- Replies: 10
- Views: 466
Re: Molecularity
can someone please remind me what exactly molecularity is used for again? i understand how to find it (i think) but im still a bit confused on what to do after that.
- Sat Mar 06, 2021 2:08 pm
- Forum: First Order Reactions
- Topic: Graphing
- Replies: 20
- Views: 998
Re: Graphing
can someone sort of summarize what characteristics of the line give away what order it is? or maybe link a different question thread that answers this please?
- Sat Mar 06, 2021 2:02 pm
- Forum: First Order Reactions
- Topic: Bimolecular and first order
- Replies: 3
- Views: 252
Re: Bimolecular and first order
can someone please clarify what a biomolecular equation is please? like what are some things you can look at to know if an equation is biomolecular and why it's significant to note this?
- Sat Mar 06, 2021 1:42 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Kinetic control
- Replies: 14
- Views: 923
Re: Kinetic control
i've seen this mentioned a few times in this thread but what are we referring to when we mentioned potential outcome? and can someone explain a bit more in depth as to how that is controlled by rate of formation?
- Fri Mar 05, 2021 7:17 pm
- Forum: Balancing Redox Reactions
- Topic: states of matter
- Replies: 58
- Views: 2379
Re: states of matter
Outside of Sapling and more generally, can someone please explain how to determine states of matter when balancing redox reactions?
I finished the Sapling homework and all but I did not completely understand it.
I finished the Sapling homework and all but I did not completely understand it.
- Fri Feb 26, 2021 7:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Writing Cell Diagrams
- Replies: 5
- Views: 358
Re: Writing Cell Diagrams
just to add on, others have mentioned that solids need to be on the outermost part on both ends. something i learned recently from my AAP PLF is that, if there is not a solid on either/both sides, then you would need to add platinum - "Pt(s)" - wherever needed. i forgot the exact reason fo...
- Fri Feb 26, 2021 7:22 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: coulomb?
- Replies: 18
- Views: 1144
Re: coulomb?
like other's have said, a coulomb is essentially another unit for charges.
if you take physics (at least this is the case for physics 5C) you'll be seeing it used a lot more
if you take physics (at least this is the case for physics 5C) you'll be seeing it used a lot more
- Fri Feb 26, 2021 7:17 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Undergoing oxidation/reduction
- Replies: 9
- Views: 532
Re: Undergoing oxidation/reduction
while i get that we can sorta just memorize that positive = reduction and negative = oxidation, why exactly is that?
like what sort of concepts explain why that is?
like what sort of concepts explain why that is?
- Fri Feb 26, 2021 7:14 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Oxidizing/reducing power
- Replies: 4
- Views: 641
Re: Oxidizing/reducing power
just for some clarification, when we say "strength" in relation to reducing/oxidizing power what exactly do we mean?
- Fri Feb 26, 2021 7:10 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: dilutions and Ecell
- Replies: 16
- Views: 3343
Re: dilutions and Ecell
i always get a bit confused with this but can someone briefly explain what exactly dilution is please?
i guess more specifically, what it means to dilute something/what is happening when something is being diluted
i guess more specifically, what it means to dilute something/what is happening when something is being diluted
- Sat Feb 20, 2021 12:51 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gas Constant R
- Replies: 43
- Views: 3968
Re: Gas Constant R
i think the easiest way to know which value of R to use is to look at the units of the other values you are given in the question. based on that, you can determine which R value to use as your objective is to cancel things out so you are left with the correct units for your answer.
- Sat Feb 20, 2021 12:39 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Kekule Structures
- Replies: 3
- Views: 336
Re: Kekule Structures
this sounds very unfamiliar to me, was it mentioned in lecture previously? if so, can someone tell me which one please?
- Sat Feb 20, 2021 12:36 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Stable vs Unstable Gibbs Free Energy
- Replies: 16
- Views: 2533
Re: Stable vs Unstable Gibbs Free Energy
wait im a bit confused by this. what exactly are we referring to when we're talking about stable vs unstable? like of the compound?
- Sat Feb 20, 2021 12:30 am
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Residual Entropy
- Replies: 8
- Views: 518
Re: Residual Entropy
can someone remind me what residual entropy is please?
- Sat Feb 20, 2021 12:28 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Calculating degeneracy
- Replies: 18
- Views: 3494
Re: Calculating degeneracy
is 'W' in any specific units?
- Fri Feb 12, 2021 11:21 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Temperature for Gibbs Free Energy Calculations
- Replies: 6
- Views: 441
Re: Temperature for Gibbs Free Energy Calculations
yes! My AAP PLF mentioned recently that not converting the temperature to Kelvin is a common mistake amongst students. it's best to get into the habit of always converting temperature to Kelvin, even if sometimes you can get away with leaving it in celsius (ex: when equations use delta/the change in...
- Fri Feb 12, 2021 11:16 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous as Written
- Replies: 10
- Views: 554
Re: Spontaneous as Written
wait, can someone please explain what exactly is meant when we say "as written"? has that phrasing ever been mentioned in lecture, if so when/which one?
- Fri Feb 12, 2021 11:14 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: delta g naught vs delta g
- Replies: 4
- Views: 248
Re: delta g naught vs delta g
can someone explain a bit more about how things will look differently in the equation/value if we are talking/using delta g naught vs delta g please? im a bit confused still
- Fri Feb 12, 2021 10:54 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Bomb Calorimeter
- Replies: 17
- Views: 853
Re: Bomb Calorimeter
wait what exactly are bomb calorimeters? has this mentioned in lecture before? if so, when/where and how solid should we be on this topic?
- Fri Feb 12, 2021 10:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q equation
- Replies: 21
- Views: 3638
Re: q equation
like others have already said, which equation you use depends on what you are being given in the question. if something is given in terms of mass (grams usually), then you would use q=mCAT whereas being given moles would mean you use q=nCAT
- Sat Feb 06, 2021 12:27 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Application of Second Law
- Replies: 3
- Views: 176
Re: Application of Second Law
going off of this, on exams will we only be given situations where we are only dealing with isothermal reversible expansions so that we can use those equations or is there a chance we'll be exposed to other instances where we'd have to use other ones? if so, what would those equations be?
- Sat Feb 06, 2021 12:23 am
- Forum: Calculating Work of Expansion
- Topic: Reversible Expansion
- Replies: 7
- Views: 303
Re: Reversible Expansion
Going along with this, can someone please explain a bit more conceptually what the difference is between a reversible and irreversible expansion?
- Sat Feb 06, 2021 12:12 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Extensive vs intensive property for heat capacities
- Replies: 7
- Views: 338
Re: Extensive vs intensive property for heat capacities
Adding on to this question, i keep getting extensive/intensive properties confused with state/non-state properties (?).
Can someone please, i guess, connect these two and explain how they relate to one another and/or how to distinguish between them?
Can someone please, i guess, connect these two and explain how they relate to one another and/or how to distinguish between them?
- Sat Feb 06, 2021 12:07 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Stable Form in Enthalpies of Formation
- Replies: 11
- Views: 511
Re: Stable Form in Enthalpies of Formation
i was reading through this thread and i saw the word "diatomic" come up a bit - can someone briefly explain what this means again please?
- Sat Feb 06, 2021 12:05 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy reactions
- Replies: 9
- Views: 457
Re: Enthalpy reactions
I am still confused with the bond enthalpy method...
how exactly do we determine/know which bonds are being formed and which are being broken? would we have to draw a lewis structure or are there ways for us to just know?
how exactly do we determine/know which bonds are being formed and which are being broken? would we have to draw a lewis structure or are there ways for us to just know?
- Sat Jan 30, 2021 1:08 am
- Forum: General Science Questions
- Topic: MT 1 Grades
- Replies: 8
- Views: 429
Re: MT 1 Grades
this is a bit late but grades, at least based on my experience in 14A in the fall, will be released within a week to a week-and-a-half from when the last group of students have taken the exam. this is because the Dr. Lavelle and the TAs will review the questions/exams and reassign points (ie partial...
- Sat Jan 30, 2021 12:58 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: percent ionization
- Replies: 7
- Views: 3692
Re: percent ionization
sort of going off the original question, can someone briefly explain what deprotonation is again please?
- Sat Jan 30, 2021 12:53 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: isolated system Drawing
- Replies: 4
- Views: 475
Re: isolated system Drawing
hello!! so i understand that the internal energy and pressure is constant in an isolated system, but im a bit confused about the second part of the original question. was "constant external pressures" a mis-type or is it possible to apply that to an isolated system? if so, how?
- Sat Jan 30, 2021 12:46 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 5661
Re: Kelvin or Celsius?
as everyone has already said, temperature is always in Kelvin. this is not limited to just the PV = nRT equation as we will see throughout the remaining weeks
- Mon Jan 25, 2021 2:52 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 1/25 Lecture Example Question
- Replies: 5
- Views: 294
1/25 Lecture Example Question
hello!! i had a question about the last example Dr. Lavelle went over in today's lecture (around the 50:30 min mark).
Why is the temperature used in the equation +6.9 degrees Celsius? And if it was through some sort of calculation, what was that process?
Why is the temperature used in the equation +6.9 degrees Celsius? And if it was through some sort of calculation, what was that process?
- Sat Jan 23, 2021 5:17 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: R values
- Replies: 9
- Views: 263
Re: R values
Just to make sure I understand, the value of R is the same - the only difference is the units. And then the way to determine which units we use depends on what we are trying to find? Like, we would look at which units would cancel out and help us find the answer?
- Sat Jan 23, 2021 5:03 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Exothermic and Endothermic Reactions
- Replies: 9
- Views: 1329
Re: Exothermic and Endothermic Reactions
to add on to this question, can someone sort of explain more what a catalyst is and give examples?
- Sat Jan 23, 2021 3:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Studying for Midterm #1
- Replies: 63
- Views: 2703
Re: Studying for Midterm #1
As everyone has already said, going over the textbook problems help but also make sure that you understand the concepts behind equations/principle's as not all the questions on midterms involve actual calculating.
- Sat Jan 23, 2021 3:26 pm
- Forum: Ideal Gases
- Topic: Equilibrium Constant (Q and K)
- Replies: 13
- Views: 662
Re: Equilibrium Constant (Q and K)
As others have already stated Q and K are not the same.
While they do use the same equation, they are used for different situations. K is specifically at equilibrium whereas Q is for at any point during the reaction.
While they do use the same equation, they are used for different situations. K is specifically at equilibrium whereas Q is for at any point during the reaction.
- Sat Jan 23, 2021 3:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 1 Allowed Materials and Procedure
- Replies: 6
- Views: 330
Re: Midterm 1 Allowed Materials and Procedure
As everyone has previously stated we are allowed to use a calculator during the exam as well as two sheets of paper - Equation Sheet and the Periodic Table. Regarding scratch paper, my TA last quarter in 14A did NOT allow us to use any beyond the two sheets of paper. Additionally, it is important th...
- Fri Jan 15, 2021 11:55 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Memorizing relationship of Q and K
- Replies: 9
- Views: 481
Re: Memorizing relationship of Q and K
hello! others have already answered your question but i would like to also put in my own two-cents. during my AAP PLF session this topic came up and the way i sort of learned to think about it is: what is Q doing to try to reach equilibrium (K)? in the case Q<K, Q will (over time) increase. this mea...
- Fri Jan 15, 2021 11:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Conjugate Seesaw ??
- Replies: 5
- Views: 192
Re: Conjugate Seesaw ??
this is my opinion, but for this class i think we should have a pretty solid understanding of what is meant by a conjugate seesaw for possible conceptual questions on the exams. additionally, it may help to have a good grasp on this topic as it could be applied to non-conceptual questions as well (e...
- Fri Jan 15, 2021 11:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When x is negligible in Equilibrium constant
- Replies: 34
- Views: 1525
Re: When x is negligible in Equilibrium constant
since there's sort of two values being given, just to check my understanding, K should be less than 10^-3 but to be safe (as values can be close to one another) we should just use 10^-4 as our sort of baseline to determine when x is negligible?
- Fri Jan 15, 2021 11:14 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: today's lecture
- Replies: 8
- Views: 228
Re: today's lecture
so i understand that if the equilibrium constant is less than 10^-4, approximation is okay.
i am a bit confused/curious though as to why 10^-4 is the baseline or value that allows for approximation. is that just something memorize or is there reasoning behind it?
i am a bit confused/curious though as to why 10^-4 is the baseline or value that allows for approximation. is that just something memorize or is there reasoning behind it?
- Fri Jan 15, 2021 11:09 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Exam Format
- Replies: 15
- Views: 1160
Re: Exam Format
Adding on to this, does anyone know/has anyone heard how the Zoom calls will work this quarter since we aren't taking the exams during our discussion?
- Sun Jan 10, 2021 4:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating Equilibrium Concentrations
- Replies: 10
- Views: 422
Re: Calculating Equilibrium Concentrations
You should be careful with the liquids. While solvents aren't taken into account for the K value, liquids that are reacted together can be involved in the K concentration. can you (or anyone else who reads this) please explain this a bit more? i thought for the sake of this class we only take into ...
- Sun Jan 10, 2021 3:59 pm
- Forum: Ideal Gases
- Topic: Sapling Homework
- Replies: 22
- Views: 955
Re: Sapling Homework
This is also a sapling related question but I'm having trouble figuring out where to go for the Chem14B homework... I took 14A last quarter so all I see is my work from Chem14A. Does anyone know how to access the Chem14B homework? this may have already been answered but i access my 14B homework by ...
- Sun Jan 10, 2021 3:54 pm
- Forum: Ideal Gases
- Topic: Bars to atm [ENDORSED]
- Replies: 41
- Views: 1884
Re: Bars to atm [ENDORSED]
for this course do we prefer one unit over the other? or does it really just depend on what the question is asking for?
- Sun Jan 10, 2021 3:52 pm
- Forum: Ideal Gases
- Topic: value of R
- Replies: 24
- Views: 1057
Re: value of R
what exactly does R represent?
im a bit confused since it can be equal to different values depending on the units
im a bit confused since it can be equal to different values depending on the units
- Sun Jan 10, 2021 3:22 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4798
Re: Kc vs Kp
like others have previously said, the way you can tell if you use Kc or Kp is by looking at the units you are given in the equation. Kc is when you use mols whereas Kp is when you see atms/bars
- Sat Dec 12, 2020 12:43 am
- Forum: Conjugate Acids & Bases
- Topic: What is the difference between a lewis acid and bases and Bronsted acids and bases?
- Replies: 7
- Views: 540
Re: What is the difference between a lewis acid and bases and Bronsted acids and bases?
like others already said, yup! one is in term of electrons while the other is in terms of hydrogen ions
- Sat Dec 12, 2020 12:37 am
- Forum: Amphoteric Compounds
- Topic: Recognizing Amphoteric Compounds
- Replies: 9
- Views: 756
Re: Recognizing Amphoteric Compounds
im sorry im blanking, can someone quickly explain what an amphoteric compound is please?
- Sat Dec 12, 2020 12:05 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond angles
- Replies: 12
- Views: 856
Re: Bond angles
as others have already mentioned, yes, you should have at least a general idea of the bond angles of each structure. this includes knowing the values (90, 109.5, 120, 180) and whether the angle is the value itself or if it would be less than that value (<90, <109.5, <120, <180).
- Sat Dec 12, 2020 12:01 am
- Forum: Administrative Questions and Class Announcements
- Topic: Grading scale
- Replies: 29
- Views: 3262
Re: Grading scale
like others have already mentioned a grading scale hasn't really been set for this class beyond a C- = 50%. i would like to assume that Dr. Lavelle is waiting until after the final to curve the rest of the grades based on what our class distribution is. something to remember with this is that grades...
- Fri Dec 11, 2020 11:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Updating Lockdown Browser
- Replies: 10
- Views: 1246
Re: Updating Lockdown Browser
Hello!
so i did some digging through old posts and found this thread that was created prior to midterm 2:
viewtopic.php?f=157&t=67682&hilit=update+respondus
hopefully that link works and that it helps you!
so i did some digging through old posts and found this thread that was created prior to midterm 2:
viewtopic.php?f=157&t=67682&hilit=update+respondus
hopefully that link works and that it helps you!
- Sun Dec 06, 2020 1:10 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligand names
- Replies: 6
- Views: 334
Re: Ligand names
adding on to this question, how do we know the charge of a ligand (ie if it is neutral or not)? is that something we just need to memorize or is there a process to figure it out?
- Sun Dec 06, 2020 1:03 pm
- Forum: Naming
- Topic: Order of Ligands/naming
- Replies: 28
- Views: 1212
Re: Order of Ligands/naming
What about when you're presented with the names+prefixes already and you have to find the opposite?
Like, does the order you write the ligands/formulas in the square brackets matter?
Like, does the order you write the ligands/formulas in the square brackets matter?
- Sun Dec 06, 2020 1:00 pm
- Forum: Naming
- Topic: Polydentate
- Replies: 8
- Views: 421
Re: Polydentate
Would it be better for us to just memorize which are the most common polydentate ligands or should we get into the habit of drawing the lewis structure?
- Sun Dec 06, 2020 12:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Partial Credit on the Final
- Replies: 6
- Views: 360
Re: Partial Credit on the Final
Someone please correct me if I am wrong, but I do not believe we will be given any opportunities for partial credit on the final as the exam is multiple choice. Unless the final exam changes to free response, there likely will not be any chance for partial credit.
- Sun Dec 06, 2020 12:04 pm
- Forum: Administrative Questions and Class Announcements
- Topic: grading
- Replies: 11
- Views: 693
Re: grading
this was asked earlier but curving grades should NEVER hurt or bring down a student's grade, it should only help it if ever. this applies not only to this course - if Dr. Lavelle does curve our grades - but any class that says they will do so at the end of a quarter.
- Sun Nov 29, 2020 8:48 pm
- Forum: Hybridization
- Topic: delocalized pi bonds
- Replies: 15
- Views: 592
Re: delocalized pi bonds
just to clarify, the best way to determine if there is a delocalized pi bond is to first draw a lewis structure and then see if there is resonance? if there is resonance then there is a delocalized pi bond, but if not, there is none? can someone briefly explain how resonance connected to a delocaliz...
- Sun Nov 29, 2020 8:32 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: chelates
- Replies: 4
- Views: 386
Re: chelates
so the only thing needed for a chelate is that there needs to be multiple lone pairs? and once something is a chelate we automatically know it'll form a coordinate compound?
- Sun Nov 29, 2020 8:18 pm
- Forum: Lewis Structures
- Topic: Tips on drawing Lewis structures
- Replies: 21
- Views: 2246
Re: Tips on drawing Lewis structures
To add on to this, are there any Lewis structures that you all think we should all be pretty solid with? Like not necessarily know them by heart but be able to do them with ease if that makes sense?
- Sun Nov 29, 2020 8:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: grading
- Replies: 11
- Views: 693
Re: grading
I have spoken a bit with some upperclassmen who have previously taken Chem14A with Dr. Lavelle and/or have been an AAP PLF for him and they have stated that he typically curves grades at the end of the quarter, hence why he may not have provided an exact grading scale on the syllabus. Not 100% if th...
- Sun Nov 29, 2020 8:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Questions About Final
- Replies: 7
- Views: 495
Re: Questions About Final
Like some have already stated, our Chem 14A final is set for Sunday, December 13. I believe on MyUCLA it mentions the time, which is 11:30AM - 1PM PST. I would like to assume this is correct as the syllabus states that we will have a final that lasts for 1 hour and 30 minutes. Additionally, the syll...
- Sun Nov 22, 2020 1:06 pm
- Forum: Resonance Structures
- Topic: Resonance Hyrbid
- Replies: 11
- Views: 646
Re: Resonance Hyrbid
this is a bit of a dumb question but what exactly do we mean when we say something is delocalized? i've seen it in a couple of posts and im a bit confused as to what that exactly means
- Sun Nov 22, 2020 12:59 pm
- Forum: Hybridization
- Topic: Double bonds structures
- Replies: 5
- Views: 305
Re: Double bonds structures
As a sort of follow up question, if an atom has a triple bond is it locked into position or is it able to move around?
- Sun Nov 22, 2020 12:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Number of Molecular Shapes
- Replies: 6
- Views: 234
Re: Number of Molecular Shapes
Hello! As everyone else has already mentioned, memorizing a VSEPR chart would probably be the best thing to do. If it is of any help, my PLF said that the most common ones we will see are structures with 0, 1, and 2 lone pairs so it would be best to be solid on those. Structures with 3+ lone pairs c...
- Sun Nov 22, 2020 12:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Tips for memorizing different molecular shapes
- Replies: 9
- Views: 2253
Re: Tips for memorizing different molecular shapes
I am not the best with memorization so I was a little bit worried about getting down all the different molecular shapes and their corresponding VSEPR formula. Does anyone have any tips on the best ways to help yourself remember? Thank you! Hello! I mentioned this on a different post but my PLF rece...
- Sun Nov 22, 2020 12:30 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Remembering Molecular Shapes
- Replies: 4
- Views: 267
Re: Remembering Molecular Shapes
Hello! My PLF for this course recently suggested we use the charts online to create flashcards to help memorize the different molecular shapes. Their suggestion was to have the steric number, number of lone pairs, and the VSEPR formula on the front while the name of the shape, bond angle, and hybrid...
- Sun Nov 15, 2020 3:12 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: Order of Intermolecular Forces
- Replies: 5
- Views: 390
Re: Order of Intermolecular Forces
adding on to this, where would van der waals be in the order?
- Sun Nov 15, 2020 3:06 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: Hydrogen Bonding
- Replies: 5
- Views: 321
Re: Hydrogen Bonding
Adding on/to reiterate what has already been said, there are two things needed to create a hydrogen bond: 1) a Hydrogen acceptor (this can be F, O, N, or S) 2) a Hydrogen donor (hydrogen; only if it has a partial positive) sort of disclaimer: this is information that I received during an AAP PLF ses...
- Sun Nov 15, 2020 2:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bent v. angular
- Replies: 27
- Views: 1513
Re: bent v. angular
Does anyone know if Dr. Lavelle will be using bent and angular interchangeably or if only one will be used on the midterm/final exam? I understand that they're the same thing, but I would like to know which one we should get more used to using if possible.
- Sun Nov 15, 2020 2:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angles
- Replies: 16
- Views: 1210
Re: bond angles
though the explanations make some sense, im still a bit confused in the process of finding the actual value of a bonding angle. can someone possibly explain an example? maybe one of the ones from lecture?
- Sun Nov 15, 2020 2:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone-Lone Pair vs Lone Bonding Pair vs Bonding-Bonding Pair?
- Replies: 5
- Views: 532
Re: Lone-Lone Pair vs Lone Bonding Pair vs Bonding-Bonding Pair?
In today's lecture Dr. Lavelle said that the repulsion strength of electron regions is lone-lone pair>lone bonding pair>bonding-bonding pair. What is the difference between a lone-lone pair and a lone-bonding pair or a lone bonding pair and a bonding bonding pair? Thank you! Adding on to this quest...
- Sat Nov 07, 2020 7:00 pm
- Forum: Ionic & Covalent Bonds
- Topic: Coulomb's PE
- Replies: 3
- Views: 158
Re: Coulomb's PE
Adding on to what's already been said, if we are expected to use the formula to actually calculate or solve something it would likely be provided on the equation sheet we're allowed to have during tests. I'm not sure if Coulomb's potential energy equation is there, but I would recommend checking!
- Sat Nov 07, 2020 6:58 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity Difference Between 1.5 and 2
- Replies: 4
- Views: 244
Re: Electronegativity Difference Between 1.5 and 2
To add on to this question, what are some more theoretical approaches to determining whether a bond is ionic or covalent? Audra gave the example of observing its solubility in water, but if we were in a situation where we are unable to do that how else could we determine the type of bond? I know we ...
- Sat Nov 07, 2020 6:49 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Lengths
- Replies: 10
- Views: 853
Re: Bond Lengths
To add on to this question, will bond lengths always be given to us in a problem or will we sometimes have to calculate it? If so, what would the process to do that look like?
- Wed Nov 04, 2020 7:48 pm
- Forum: Resonance Structures
- Topic: How are bond lengths measured experimentally?
- Replies: 2
- Views: 200
Re: How are bond lengths measured experimentally?
Adding on to this, I am not sure if anyone else has taken Physics 5B but is the concept of electron diffraction in chemistry similar to what we learn about in 5B with light diffraction?
- Wed Nov 04, 2020 7:35 pm
- Forum: Lewis Structures
- Topic: Electrons in Lewis Structures
- Replies: 8
- Views: 401
Re: Electrons in Lewis Structures
Looking at the row in the periodic table always helps me. When you count the rows [1,2,13,14,15,16,17,18] when you omit the d block. You can see that the number of electrons correspond to the row because there are 8 rows. Hope that makes sense! Quick question, can you explain why you omit the d-blo...
- Wed Nov 04, 2020 7:24 pm
- Forum: Lewis Structures
- Topic: Coordinate Covalent Bonds & Lewis Acid-base Reactions
- Replies: 6
- Views: 394
Re: Coordinate Covalent Bonds & Lewis Acid-base Reactions
Adding on to this, does anyone know to what extent we will need to know this for the second midterm?
We haven't talked about acids/bases but I do know that it is mentioned in the syllabus, not sure if we'll cover it by week 7 though.
We haven't talked about acids/bases but I do know that it is mentioned in the syllabus, not sure if we'll cover it by week 7 though.
- Wed Nov 04, 2020 7:01 pm
- Forum: Lewis Structures
- Topic: Lewis Structure
- Replies: 7
- Views: 208
Re: Lewis Structure
To add on to this question, we would determine which element has the lower ionization energy by the trends in the periodic table right? And that's something you just sort of have to memorize?
- Wed Nov 04, 2020 6:47 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: F orbitals?
- Replies: 21
- Views: 766
Re: F orbitals?
As many of our peers have said, no, we will not need to know f-orbitals as in depth as the s, p, and d-orbitals.
I am in AAP and my PLF said that it's good to know that they are a thing and exist, but that's pretty much as far as this class will go with f-orbitals.
I am in AAP and my PLF said that it's good to know that they are a thing and exist, but that's pretty much as far as this class will go with f-orbitals.
- Wed Nov 04, 2020 6:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Participation Points [ENDORSED]
- Replies: 62
- Views: 3644
Re: Participation Points [ENDORSED]
I thought it was 50 posts at the end of the quarter! Do we have ways to make up? This is what I thought so too because, according to an upperclassman that took Chem 14A with Lavelle in the past, as long as you have the required number of posts by the end of the quarter we should get full credit. I ...
- Sun Oct 25, 2020 2:44 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Printouts for Midterm
- Replies: 8
- Views: 393
Re: Printouts for Midterm
Has Dr. Lavelle said whether we will be able to write on these printouts once the exam begins? Or should we have separate papers for scratch work?
Additionally, do we know if these will be the same printouts for our second midterm and final?
Additionally, do we know if these will be the same printouts for our second midterm and final?
- Sun Oct 25, 2020 2:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: How many questions on Midterm?
- Replies: 6
- Views: 374
Re: How many questions on Midterm?
Also just to confirm, Respondus will log us out of the test once 50 minutes has passed right? Even if have not necessarily finished?
Does that mean our "additional 5 minutes" are for BEFORE we begin the exam?
Does that mean our "additional 5 minutes" are for BEFORE we begin the exam?
- Sun Oct 25, 2020 2:23 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 6
- Views: 341
Re: Orbitals
I believe that he was demonstrating that the upper bound of l is n-1. It can take on any possible values from 0 to n-1, with n-1 being the upper bound value. I don't think that if n=2 l could equal 1, but it could equal 0 or 1. This is a chart that I used to better understand it. When n=3, l can ha...
- Sun Oct 25, 2020 2:00 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electrostatic potential
- Replies: 2
- Views: 118
Re: Electrostatic potential
Adding on to this, to clarify, the electrostatic potential equation is different than Coulomb's Law right? Because in Coulomb's Law there is the constant k in the equation as well?
- Sun Oct 25, 2020 1:45 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Paired vs. Parallel Spins
- Replies: 5
- Views: 489
Re: Paired vs. Parallel Spins
Minahil_Tufail_1L wrote:Hi, I'm confused on how to figure out when electrons are either paired or have parallel spins. Is there a general rule to determine this?
To add on to this question, can someone please clarify what it means for a spin to be "paired" or "parallel"?
- Sun Oct 25, 2020 1:35 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity and Electronegativity
- Replies: 9
- Views: 457
Re: Electron Affinity and Electronegativity
this might be a dumb question but i'm blanking: how do we determine electronegativity? is there something we'd look at on the periodic table or something like that?
- Fri Oct 16, 2020 10:03 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectroscopy N?
- Replies: 3
- Views: 196
Re: Atomic Spectroscopy N?
in the Rydberg equation is the n^2 in the denominator always the initial energy level? As Will said in their post, the "n^2" in the denominator does NOT refer to the initial energy level. "n", unless otherwise specified, is just an energy level. In the case of the example proble...
- Fri Oct 16, 2020 9:52 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra
- Replies: 5
- Views: 226
Re: Atomic Spectra
For the equation V = -R((1/n^2)-(1/n^2)) How do we know which n value (the final or initial n value) to put first in the equation? Some of our classmates already responded with this but the difference of something is always going to be found by calculating final - initial . Because of this, the fir...
- Fri Oct 16, 2020 9:33 pm
- Forum: Properties of Light
- Topic: rydberg equation
- Replies: 7
- Views: 404
Re: rydberg equation
is the Rydberg equation just E= -(hR)/(n^2) ? I believe that the equation you mentioned is the empirical equation for an H-Atom. Rydberg's equation is similar but still different. Here is the equation based on a quick Google search. Pretty sure this is correct though because I vaguely remember usin...
- Fri Oct 16, 2020 9:25 pm
- Forum: Properties of Electrons
- Topic: Using empirical equation for h-atom
- Replies: 4
- Views: 137
Re: Using empirical equation for h-atom
Ex. Calculate the frequency of light emitted by a hydrogen atom when an electron makes a transition from the fourth to the second principal quantum model. I understand how professor lavelle changed the equation from e=hv to v=e/h to find the frequency. But i do not understand where the fractions su...
- Fri Oct 16, 2020 7:48 pm
- Forum: Einstein Equation
- Topic: Einstein Equation
- Replies: 10
- Views: 1881
Re: Einstein Equation
Adding on to this question, is there a specific way we should be writing the "v" or frequency in the equation E = hv? Every lecture I get a bit confused because the symbol for frequency looks exactly like "v" for velocity and i'm not too sure how to make a distinction.
- Fri Oct 16, 2020 6:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Where can I buy a webcam for a reasonable price?
- Replies: 60
- Views: 3726
Re: Where can I buy a webcam for a reasonable price?
So is the consensus that if we are able to use a second device (ie a phone or another laptop) to show our workspace for the duration of a test/exam we do NOT need to buy a webcam?
- Thu Oct 08, 2020 5:47 pm
- Forum: Significant Figures
- Topic: intermediate calculations with sig figs
- Replies: 8
- Views: 280
Re: intermediate calculations with sig figs
I know the rules of sig figs, but when we have problems that requires multiple steps/calculations, should we follow the rules of sig figs for each step, or should we have numbers with more sig figs than what is technically allowed and just make sure the final answer has the correct number of sig fi...
- Thu Oct 08, 2020 12:20 pm
- Forum: Properties of Light
- Topic: Converting wavelength to Angstrom
- Replies: 5
- Views: 891
Re: Converting wavelength to Angstrom
sorry if this is a sort of dumb question but what is an angstrom? is it something we will need for this course?
- Thu Oct 08, 2020 12:14 pm
- Forum: Properties of Light
- Topic: Vaccum?
- Replies: 7
- Views: 209
Re: Vaccum?
For the Audio-Visual Topic: Photoelectric Effect the professor states in the module video that the Photoelectric Experiment is done under a vaccum. What does this mean? Hello! This may be repetitive but something in "vacuum" essentially means a space devoid of any matter/particles. I thin...
- Thu Oct 08, 2020 11:56 am
- Forum: Balancing Chemical Reactions
- Topic: State in chemical reactions
- Replies: 13
- Views: 459
Re: State in chemical reactions
Will we be penalized for not including the state of each element in the chemical reactions? It's easier for me to visualize the formula without the extra information but I don't know if that's something that's important to have in the answer. To add on to this question, does anyone have any tips fo...