Search found 112 matches
- Tue Mar 09, 2021 9:05 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Textbook 6N.1 Part B
- Replies: 1
- Views: 239
Re: Textbook 6N.1 Part B
This is a typo! Here's a screenshot from the Solutions Manual:
- Tue Mar 09, 2021 8:29 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.7 Increasing strength as reducing agents
- Replies: 1
- Views: 136
Re: 6M.7 Increasing strength as reducing agents
I was wondering this as well! I'm still not too sure, but I'll just put down my thoughts. If anyone could clarify or add on, that'd be great. 1) If the metal has different reduction potentials, we are considering the best reduction potential (or most positive/negative) when we classify the elements....
- Tue Mar 09, 2021 8:20 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Textbook Question 7C.11
- Replies: 1
- Views: 220
Re: Textbook Question 7C.11
Hello! I believe the explanation is just emphasizing the point that the rate constant and the rate of a reaction are very different things. In an equilibrium reaction, the forward and reverse reactions occur at equal rates, so the concentrations of reactants and products should remain fairly constan...
- Tue Mar 02, 2021 11:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: LS7a
- Replies: 16
- Views: 2178
Re: LS7a
I took LS 7A with Dr. Maloy last quarter! The workload was alright, but only if you remember to focus on lectures over Launchpad. Launchpad contains the weekly readings and mini quizzes that you have to do before class lectures. However, a lot of this (roughly 50-60%) was totally irrelevant to the c...
- Tue Mar 02, 2021 10:57 pm
- Forum: Balancing Redox Reactions
- Topic: Textbook 6L.3 Solution
- Replies: 2
- Views: 183
Re: Textbook 6L.3 Solution
I definitely agree; you don't really need the E values for balancing equations. In terms of the relationship between E naught and galvanic cell reactions, know that the reactions must be spontaneous, so the overall E must be positive.
- Tue Mar 02, 2021 10:55 pm
- Forum: General Science Questions
- Topic: Midterm 2 Reactions
- Replies: 79
- Views: 7572
Re: Midterm 2 Reactions
I feel like the midterms were pretty fair so far. If there's anything I've learned from Midterm 2, it's to review the concepts alongside the practice problems. I usually only have time to do Sapling and textbook problems, and now I'll spend some time reviewing major concepts from the outline. If the...
- Tue Mar 02, 2021 12:30 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Sapling Nernst Explanation
- Replies: 3
- Views: 242
Sapling Nernst Explanation
Hi! I posted this about a week or two back, but I didn't get replies. I'm hoping to repost so maybe someone can explain this to me: Hello! For Week 8 Sapling, I had this question: What would the potential of a standard hydrogen electrode (S.H.E.) be under the given conditions? [H+]=0.64 M P(H2)=4.9 ...
- Tue Mar 02, 2021 11:33 am
- Forum: General Science Questions
- Topic: Study Habits
- Replies: 19
- Views: 1609
Re: Study Habits
Hello! For me, the most helpful practice for course content is doing the Sapling and textbook problems. These most accurately reflect what Dr. Lavelle will test for on his midterms and finals. Before I can dive into practice, though, I like to read the book and handwrite notes (sparingly). I will sa...
- Tue Feb 23, 2021 9:14 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Sapling Question about the Explanation
- Replies: 2
- Views: 210
Re: Sapling Question about the Explanation
Jamie Wang 3C wrote:I also had the same question because wouldn't the ratios be off?
That is literally what I thought haha. Maybe someone knows ?
- Tue Feb 23, 2021 7:40 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling 13 week 7/8
- Replies: 2
- Views: 176
Re: Sapling 13 week 7/8
Hello! I believe that the reduction reaction is spontaneous if the reduction potential is positive. I went for reduction potential and using E(cathode) - E(anode) > 0. I'm unsure about oxidation potential, but assuming that you can calculate it by flipping the reduction potential sign, that means th...
- Tue Feb 23, 2021 7:33 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Sapling Question about the Explanation
- Replies: 2
- Views: 210
Sapling Question about the Explanation
Hello! For Week 8 Sapling, I had this question: What would the potential of a standard hydrogen electrode (S.H.E.) be under the given conditions? [H+]=0.64 M P(H2)=4.9 atm T=298 K After a lot of attempts, I was able to finally get the answer. I knew my Q was a little off, BUT when I tried to read th...
- Tue Feb 23, 2021 7:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Sapling 13
- Replies: 2
- Views: 200
Re: Sapling 13
Hello! I don't see the answer choices, but I can explain the reasoning for this problem. The reduction reaction will occur if the overall reduction potential, calculated by E(cathode) - E(anode), is positive. Since oxidation occurs at the anode, the phrase "oxidize Cr to Cr3+ , but not Fe to Fe...
- Tue Feb 23, 2021 7:09 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Week 7/8 Sapling #9
- Replies: 3
- Views: 216
Re: Week 7/8 Sapling #9
Hello!
The problem specifies copper (I), and I believe you used the standard reduction potential for copper (II).
To save you the search, here it is:
Cu+(aq) + e– → Cu(s)
+0.52
Hope this helps!
The problem specifies copper (I), and I believe you used the standard reduction potential for copper (II).
To save you the search, here it is:
Cu+(aq) + e– → Cu(s)
+0.52
Hope this helps!
- Tue Feb 23, 2021 4:17 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Sapling #7
- Replies: 2
- Views: 223
Re: Sapling #7
Hi there! I was stuck on this too haha. Your first part is completely correct, but for the second part, the order you place the elements/compounds in the line diagram matters. The shared ion (Cl-) should occupy the middle two spots of the diagram (both of them). The very left should have the anode (...
- Tue Feb 16, 2021 4:20 pm
- Forum: Ideal Gases
- Topic: Chem BL
- Replies: 107
- Views: 10555
Re: Chem BL
Like a few other people on this thread, I'm planning on taking Chem 14BL next quarter (Spring) and continuing the chem series next year. I was planning on taking one chem course at a time, but depending on how much better it is to take Chem 14C and Chem 14CL together, I might just do that.
- Tue Feb 16, 2021 4:17 pm
- Forum: Phase Changes & Related Calculations
- Topic: Focus 4.1
- Replies: 1
- Views: 278
Re: Focus 4.1
I don't really have a definite answer other than there's no other way to do the problem. I think this is just one of those situations where you have to make the correct assumptions or act on the provided information.
- Tue Feb 16, 2021 4:15 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 4C.11
- Replies: 4
- Views: 204
Re: 4C.11
Yup! Just make sure to plug in the right numbers and check your units (kJ vs. J) but that's all :)
- Tue Feb 16, 2021 4:10 pm
- Forum: Student Social/Study Group
- Topic: Midterm 2 Nerves
- Replies: 40
- Views: 2250
Re: Midterm 2 Nerves
I felt that. I've been trying to get into a good 3-4 day long schedule to review concepts and practice questions before the midterm, but keeping up with the ongoing material is like an added challenge.
- Tue Feb 16, 2021 1:19 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation Number Guide
- Replies: 2
- Views: 457
Re: Oxidation Number Guide
Hello! I would use lewis structures to find formal charges and chemical formulas to find oxidation numbers—formal charge divides bonding pairs equally, and oxidation numbers assign both the electrons in a bonding pair to the more electronegative atom in the pair. However, both should add up to the o...
- Thu Feb 11, 2021 1:23 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 4F.7
- Replies: 1
- Views: 131
Re: 4F.7
Hello! On the Unit 4 Outline, it says: Calculate changes in entropy due to changes in volume (ΔS = nRln(V2/V1)) = constant pressure Calculate changes in entropy due to changes in temperature (ΔS = nCln(T2/T1)) = constant volume Also, there are two different molar heat capacities depending on constan...
- Thu Feb 11, 2021 1:04 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Kelvin conversion
- Replies: 40
- Views: 3563
Re: Kelvin conversion
Hello! This is just in response to what decimal place we should use. I would use the entire 273.15 because the past Sapling homework, I kept using 273 and getting the problem wrong. I will say in that case the numbers were huge (something like 10^40), so the .15 really made a difference. However, no...
- Thu Feb 11, 2021 12:55 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Larger molar entropy leads to a higher ordered arrangement?
- Replies: 3
- Views: 205
Re: Larger molar entropy leads to a higher ordered arrangement?
Hello! The way I thought about it was the higher the change in entropy, the more disordered the molecule becomes when transitioning from liquid state to gas state. Therefore, if molecule A had a higher change in entropy than molecule B, the liquid form of A was originally more ordered than the liqui...
- Thu Feb 11, 2021 12:32 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Sapling number 5
- Replies: 1
- Views: 128
Re: Sapling number 5
Hello! Looking at the formulas, I think we would have to use ΔS = nC*ln(T2/T1). We are given T1, T2, and C. We are also given the information necessary to solve for n using the ideal gas law PV=nRT. PV = nRT (8.00 kPa)(12.00 L) = n (8.314 kPa*L/K*mol)(25+273.15)K Note that the R used was 8.314 kPa*L...
- Thu Feb 11, 2021 12:19 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: sapling 18
- Replies: 5
- Views: 362
Re: sapling 18
Hi!
For thermodynamics and equilibrium constants, there is a formula relating them: ΔG = -RTlnK.
You can calculate ΔG using the link for the table on Sapling..
Hope that helps!
For thermodynamics and equilibrium constants, there is a formula relating them: ΔG = -RTlnK.
You can calculate ΔG using the link for the table on Sapling..
Hope that helps!
- Sun Feb 07, 2021 5:45 pm
- Forum: Administrative Questions and Class Announcements
- Topic: tips if you're struggling!
- Replies: 77
- Views: 5950
Re: tips if you're struggling!
Thank you for sharing tips! I do the same things (especially doing the problems in the days leading up to the exams)! I tend to prioritize sapling, then textbook, then lecture. I also wanted to point out that you should always check your answers several times if you have time left in the exams! I do...
- Sun Feb 07, 2021 5:38 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: sapling #18
- Replies: 1
- Views: 157
Re: sapling #18
Hi there! Since deltaU = q + w, we also need to calculate the work done by the system. I found w using w = - Pex*deltaV = -(1 atm)(deltaV). To calculate delta V (Vf - Vi), I use V = nRT/P. delta V = Vf - Vi = nRTf/P - nRTi/P (n, R, and P do not change) = nR/P (Tf - Ti) = 0.981 mol * 8.3145 J/(mol*K)...
- Sun Feb 07, 2021 5:34 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling 3/4 #18
- Replies: 2
- Views: 165
Re: Sapling 3/4 #18
Hello! I believe we use deltaU = q + w. First, I used the formula q = nC deltaT, given that C is the constant‑pressure molar specific heat, to find q. q = 0.305 mol * 29.1 J/(mol*K) * 19.9K = 176.6 J. Then, I find w using w = - Pex*deltaV = -(1 atm)(deltaV). To calculate delta V (Vf - Vi), I use V =...
- Sun Feb 07, 2021 5:20 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond breaking and forming
- Replies: 11
- Views: 407
Re: Bond breaking and forming
Hello! I normally compare the lewis structures of the products and the reactants, noting which bonds change. Sometimes, I miss bonds though when I try to see which bonds form and break. Otherwise, I count all the bonds for both sides and calculate the enthalpy of the reactants and products using bon...
- Sun Feb 07, 2021 4:30 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Textbook Problem 4D.11
- Replies: 1
- Views: 161
Re: Textbook Problem 4D.11
4D.11 The oxidation of nitrogen in the hot exhaust of jet engines and automobiles occurs by the reaction N2(g)+O2(g)→2NO(g)ΔH°=+180.6kJ (c) When the oxidation of N2 to NO was completed in a bomb calorimeter, the heat absorbed was measured as 492 J. What mass of nitrogen gas was oxidized? First, we n...
- Wed Jan 27, 2021 3:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 1 Ka/Kb Values
- Replies: 10
- Views: 501
Re: Midterm 1 Ka/Kb Values
Hello! Since the problems we've done so far (textbook + sapling + lecture examples) have provided the Ka/Kb values, I'm 99% sure we don't have to memorize them. The only things we'll probably have to remember is Kw (10^-14) and know the strong acids/bases because we assume that they dissociate compl...
- Wed Jan 27, 2021 3:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units for Kp
- Replies: 4
- Views: 225
Re: Units for Kp
I don't think so? As long as you make sure to use the correct units when calculating (including accounting for other constants and variables) + reporting the unit with your answer. I would get used to unit conversion just in case you're asked for a specific unit, though.
- Wed Jan 27, 2021 3:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook Problem 6D.5
- Replies: 5
- Views: 309
Re: Textbook Problem 6D.5
Hi there!
I'm think you're asking where they got the Kb value? My best guess is that the book tells you at the top of the exercises to refer to table 6C.1 and 6C.2 for the Ka and Kb values b/c we definitely do not have enough information to calculate it ourselves.
Hope this helps! :)
I'm think you're asking where they got the Kb value? My best guess is that the book tells you at the top of the exercises to refer to table 6C.1 and 6C.2 for the Ka and Kb values b/c we definitely do not have enough information to calculate it ourselves.
Hope this helps! :)
- Wed Jan 27, 2021 2:59 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling Learning Week 3 and 4 Homework Question 10
- Replies: 4
- Views: 273
Re: Sapling Learning Week 3 and 4 Homework Question 10
Hi there! First off, we know that the only contributor of heat is the liquid water in the cup (since we're ignoring the surroundings), and the heat will flow from the liquid water to the ice cube. When the ice cube fully melts, it will still be liquid water at 0 C, so we need to account for the rise...
- Wed Jan 27, 2021 2:24 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling Question #10
- Replies: 2
- Views: 294
Re: Sapling Question #10
Hi there! First off, we know that the only contributor of heat is the liquid water in the cup (since we're ignoring the surroundings), and the heat will flow from the liquid water to the ice cube. When the ice cube fully melts, it will still be liquid water at 0 C, so we need to account for the rise...
- Thu Jan 21, 2021 10:53 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: R values
- Replies: 9
- Views: 290
Re: R values
When the problem says the system is at constant pressure, do we assume that the pressure is the standard 1 atm? Hi there! All we know is that the system is at constant pressure, so the pressure does not change. I don't think we can assume that pressure is the standard, but some problems do say to a...
- Thu Jan 21, 2021 10:50 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: R values
- Replies: 9
- Views: 290
Re: R values
Hi there! I'll just put down my thoughts here and maybe someone can add on? I believe those two values are mathematically the same, and there are conversions to prove this. However, I don't fully understand this myself because there's a unit of time in one of those R constants (in the 8.314 J/mol*K...
- Thu Jan 21, 2021 10:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How to find pH
- Replies: 3
- Views: 233
Re: How to find pH
Hi there! We do use an ICE table, but after we find the stand-in values for each concentration, we have to set up the Ka or Kb equation. I believe the book says you have to use Tables 6C.1 and 6C.2 to solve these problems, as these tables give you the Ka and Kb values. You'll need the values for all...
- Thu Jan 21, 2021 10:40 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: R values
- Replies: 9
- Views: 290
Re: R values
Hi there! I'll just put down my thoughts here and maybe someone can add on? I believe those two values are mathematically the same, and there are conversions to prove this. However, I don't fully understand this myself because there's a unit of time in one of those R constants (in the 8.314 J/mol*K,...
- Thu Jan 21, 2021 6:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Studying for Midterm #1
- Replies: 63
- Views: 3210
Re: Studying for Midterm #1
Hi there! Skimming what others have said, I definitely agree that practice is the best way to go. Before you start the review, make sure to really and I mean REALLY read each bullet point on the outlines. It kind of feels like the worst when you miss a problem because you forgot to review that one c...
- Thu Jan 21, 2021 2:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Identifying Acidic vs. Basic Salts
- Replies: 2
- Views: 466
Re: Identifying Acidic vs. Basic Salts
Hi there! As a rule of thumb, I like to split the salt into the anion and cation and write the acid/base forms. Then, I compare the strengths of the acid/base. For example, K3PO4 splits into K and PO4, which would make the acid H3PO4 and base KOH. Since H3PO4 is a weak acid and KOH is a strong base,...
- Fri Jan 15, 2021 3:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 1 #2
- Replies: 3
- Views: 203
Re: Sapling Week 1 #2
Hello!
For Kc, you used the mols O2 instead of the concentration of O2. I believe that's the only problem!
Hope this helped!
For Kc, you used the mols O2 instead of the concentration of O2. I believe that's the only problem!
Hope this helped!
- Fri Jan 15, 2021 3:13 pm
- Forum: General Science Questions
- Topic: Significant Figures and Rounding
- Replies: 9
- Views: 516
Re: Significant Figures and Rounding
Hey there! I was part of Dr. Lavelle's Chem 14A class last quarter, and all of our exams were multiple choice. The answer choices/values were also different from each other, so there was pretty much no way that you could miss a question due to significant figures alone. I'm not sure if he will keep ...
- Fri Jan 15, 2021 1:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 #6 - Classifying Salts
- Replies: 4
- Views: 302
Re: Sapling Week 2 #6 - Classifying Salts
Hey there! I'm not sure if this is always valid but my rule of thumb is to check the compound's anion and cation, writing the acid/base form of the anion and cation and comparing the strengths. If the base of the cation is stronger than the acid of the anion, the salt is acidic. If the base of the c...
- Fri Jan 15, 2021 11:08 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Review
- Replies: 2
- Views: 130
Re: Review
Hey there! I'm not sure if this is always valid but my rule of thumb is to check the compound's anion and cation, writing the acid/base form of the anion and cation and comparing the strengths. If the base of the cation is stronger than the acid of the anion, the salt is acidic. If the base of the c...
- Thu Jan 14, 2021 1:42 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 HW #6
- Replies: 2
- Views: 175
Re: Sapling Week 2 HW #6
Hi there! I actually had a lot of issues with this problem as well, but I realized that I made a lot of small mistakes. Other than that, I used your exact logic. For reference, I'm going to list out the strong acids and bases: STRONG ACIDS: HCl, HNO3, H2SO4, HBr, HI, HClO4, HClO3 LiClO4 , KCl , NaF ...
- Thu Jan 07, 2021 3:08 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5.33
- Replies: 3
- Views: 111
Re: 5.33
Hi there! You could use the process of elimination to reach the answer (that's actually probably what I would do). However, you can also consider that the reaction is a decomposition reaction where X2 separates into two separate X's. Therefore, the main change is that a bond was broken, which would ...
- Thu Jan 07, 2021 3:04 pm
- Forum: Ideal Gases
- Topic: Reaction Quotient(Q) vs. Equilibrium Constant(K)
- Replies: 9
- Views: 1220
Re: Reaction Quotient(Q) vs. Equilibrium Constant(K)
Hi there! Reaction quotient (Q) and equilibrium constant (K) have the same overall formula: [products]/[reactants]. However, the equilibrium constant specifically tells us what the ratio should be when the reaction hits equilibrium, and it only changes if temperature changes. The Q tells us the rati...
- Thu Jan 07, 2021 3:01 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Positive and negative delta H
- Replies: 5
- Views: 427
Re: Positive and negative delta H
Hello! Yes, I tend to think of enthalpy as a relative measure of the energies in the products and reactants. Also, the way I understand enthalpy is that it focuses on the molecules/atoms/compounds in the reaction instead of the system. For exothermic reactions, the reaction would release heat. Altho...
- Thu Jan 07, 2021 2:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Including H2O
- Replies: 7
- Views: 372
Re: Including H2O
Hello! Since water in an aqueous reaction is technically a pure liquid (the solvent), we can ignore it in the K calculations. Alternatively, we could write it in the K calculations, but the concentration of water would be 1 because it is the solvent. Therefore, the K value would not change. Hope tha...
- Thu Jan 07, 2021 2:51 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Direction of a non-equilibrium reaction
- Replies: 11
- Views: 559
Re: Direction of a non-equilibrium reaction
Hi there! Q and K both have the same formula ([products]/[reactants]), but K specifically describes when the reaction is in equilibrium and Q can be used to describe the reaction whenever. K is also a set value (as long as temperature does not change), but Q can change. Reactions want to approach eq...
- Fri Dec 11, 2020 8:49 pm
- Forum: Student Social/Study Group
- Topic: Plans for Relaxing After Finals
- Replies: 98
- Views: 21298
Re: Plans for Relaxing After Finals
I planned to crochet a cardigan or sweater, so I look forward to doing that! I might also draw a few stickers and upload them to my RedBubble because it's been a while. I will also probably binge New Girl or the Crown idk which one yet. Long story short, I'll be catching up with my hobbies and relax...
- Fri Dec 11, 2020 8:36 pm
- Forum: Student Social/Study Group
- Topic: Struggling on topics
- Replies: 6
- Views: 458
Re: Struggling on topics
Hi there! When you said "last minute studying," I felt that. If you already know which topic you are struggling with, the first thing I would do is ACTIVELY review notes on the topic if you have them. Otherwise, I would go reread the section in the textbook. The last resort is the lectures...
- Fri Dec 11, 2020 8:26 pm
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: Buffer Definition
- Replies: 4
- Views: 1505
Re: Buffer Definition
Hi there! A buffer is a solution that can resist pH changes. They're super important for biological systems because these systems need to maintain homeostasis and avoid dramatic changes. Therefore, a lot of biological systems will have buffers. One example of these systems is the bicarbonate buffer ...
- Fri Dec 11, 2020 3:48 pm
- Forum: Lewis Acids & Bases
- Topic: Week 10 Sapling #6
- Replies: 7
- Views: 645
Re: Week 10 Sapling #6
Hi there!
NH3 is a weak base since it can donate electrons or accept protons from the nitrogen lone pairs. However, NaCl is not an acid or a base; it's a salt. I think you'd have to put it in the other category.
Hope that helps! :))
NH3 is a weak base since it can donate electrons or accept protons from the nitrogen lone pairs. However, NaCl is not an acid or a base; it's a salt. I think you'd have to put it in the other category.
Hope that helps! :))
- Fri Dec 11, 2020 3:46 pm
- Forum: Student Social/Study Group
- Topic: studying for exams
- Replies: 21
- Views: 2618
Re: studying for exams
Hi! I try to do practice problems from the textbook or online to practice the formulas. Occasionally, I skim the textbook, but the practice is overall a lot more important to me. I really only consult the textbook if I fail to understand something. If I want to practice concepts, I go to Chemistry C...
- Wed Dec 02, 2020 5:38 pm
- Forum: Naming
- Topic: Bis-, Tris-, Tetrakis- Ex
- Replies: 1
- Views: 136
Re: Bis-, Tris-, Tetrakis- Ex
Hi there! In terms of what they mean, the roots match up with the other roots we're familiar with. di- = bis- tri- = tris- tetra- = tetrakis- However, we only use the bis- tris- tetrakis- when the ligand already has a root inside (like ethyleneDIamine) or the compound is polydentate, meaning it is a...
- Wed Dec 02, 2020 5:33 pm
- Forum: Naming
- Topic: Roman Numeral
- Replies: 3
- Views: 179
Re: Roman Numeral
Hi there! You could calculate the oxidation number either way. The important thing to note is that the overall compound should be neutral (so the total oxidation number for the elements in the bracket AND outside the bracket should be zero aka all the elements in the entire compound), but the coordi...
Re: Sapling 1
Hi! For naming the compound, you arrange the ligand in alphabetical order based on the name, not the prefix. For example, tetraammine would come before dichloro because the A in ammine comes before the C in chloro. If they give you the name and you have to write out the formula, make sure to write i...
- Wed Dec 02, 2020 5:23 pm
- Forum: Student Social/Study Group
- Topic: Thoughts on Switching Majors?
- Replies: 35
- Views: 2632
Re: Thoughts on Switching Majors?
Hi! I guess my first thought would be what fields am I interested in + am I interested in the point of majoring/double majoring or minoring (though I think you could also just minor first and then switch to majoring if the requirements for major/minor aren't that off). Personally, I love biology and...
- Wed Dec 02, 2020 5:08 pm
- Forum: Bronsted Acids & Bases
- Topic: Strong vs. weak acids and bases
- Replies: 3
- Views: 185
Re: Strong vs. weak acids and bases
I would normally just memorize the list, but it might help to relate the weak/strong acid/base to chemistry concepts. For example, to find if acids is comparatively weaker or stronger, you can find the elements on the periodic table and compare them using trends. I think in his lecture today Dr. Lav...
- Tue Nov 24, 2020 3:29 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3918568
Re: Post All Chemistry Jokes Here
I wouldn't say this is a joke, but I remember thinking it was kinda funny so I just wanted to share a chem experience! When I was first learning nomenclature in my chemistry class, the teacher joked that our local lake was full of dihydrogen monoxide. My whole class started saying things like "...
- Tue Nov 24, 2020 3:24 pm
- Forum: Significant Figures
- Topic: Multiplying versus adding
- Replies: 10
- Views: 703
Re: Multiplying versus adding
Yes! For significant figures, they follow these rules: adding/subtracting: round to the nearest place after the decimal point (least decimal places) (ex. 0.1 + 0.10 + 0.100 = 0.3, you should round to the tenths because of the three added numbers, 0.1 has the closest spot to the decimal point after t...
- Tue Nov 24, 2020 3:07 pm
- Forum: Sigma & Pi Bonds
- Topic: Rotation of sigma and pi bonds
- Replies: 5
- Views: 318
Re: Rotation of sigma and pi bonds
Hi there! Like the people above me have stated, I think it's something we have to just know and memorize. However, if you're asking about how we knew the bonds could or could not rotate, I can try to explain conceptually. If you consider that the sigma bond is kind of like two balls (molecules) atta...
- Tue Nov 24, 2020 2:59 pm
- Forum: Hybridization
- Topic: Increasing s-character
- Replies: 1
- Views: 172
Re: Increasing s-character
Hi there! I'm not completely sure how to explain it, so I just wrote out my thought process. First, the hybrid orbitals result from combining the s and p (maybe d) orbitals in a way that the hybrid orbitals are considered equal to one another. Example: combining one s and two p makes three sp2 orbit...
- Tue Nov 24, 2020 2:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sapling #6
- Replies: 5
- Views: 255
Re: Sapling #6
If we consider electron domain geometry (where we include the lone pair electron clouds), the geometry would be trigonal bipyramidal. With this in mind, we remove the electron clouds because the question asks for the molecular geometry. The three electron clouds would be situated in the equator part...
- Mon Nov 16, 2020 10:21 pm
- Forum: Lewis Structures
- Topic: Lewis Acids and Bases
- Replies: 5
- Views: 202
Re: Lewis Acids and Bases
First off definitions: Lewis acid: accepts electron pairs Lewis base: donates electron pairs The easiest way to tell if an atom is a lewis acid or base is to look at the charge (if it has one). If it is an anion (negative, like S2-), it can probably donate electrons (lewis base). If it is a cation (...
- Mon Nov 16, 2020 10:12 pm
- Forum: Dipole Moments
- Topic: 3F5
- Replies: 3
- Views: 120
Re: 3F5
For a molecule to have H bonding, the H atom must be bonded to an N, O, or F atom. Also, this polar bond would only attract other atoms with lone pairs (or other hydrogens), but these atoms have to be bonded to N, O, F as well. When you draw out the lewis structures for butanol and diethyl ether, yo...
- Mon Nov 16, 2020 10:04 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Textbook Problem 1D.23
- Replies: 3
- Views: 320
Re: Textbook Problem 1D.23
Hi! It's true that the 4d subshell has 5 orbitals (-2, -1, 0, +1, +2). However, this information only fits with n = 4 and l = 2. The question adds on that the magnetic quantum number must be -2. This refers to only one of the 5 orbitals (the one marked -2), so the answer is one orbital (only one orb...
- Mon Nov 16, 2020 3:35 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Difference between formal charge and oxidation number?
- Replies: 6
- Views: 2417
Re: Difference between formal charge and oxidation number?
Hi! Formal charge refers to the charge that an atom would have if the electrons in their shared bonds were split evenly. Therefore, electronegativity and polarity have no bearing on the formal charge. In comparison, oxidation number takes this electronegativity and polarity in mind when dividing th...
- Mon Nov 16, 2020 3:34 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Difference between formal charge and oxidation number?
- Replies: 6
- Views: 2417
Re: Difference between formal charge and oxidation number?
Hi! Formal charge refers to the charge that an atom would have if the electrons in their shared bonds were split evenly. Therefore, electronegativity and polarity have no bearing on the formal charge. In comparison, oxidation number takes this electronegativity and polarity in mind when dividing the...
- Mon Nov 16, 2020 3:27 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook problem 2A17
- Replies: 4
- Views: 193
Re: Textbook problem 2A17
Hi there! The best way I can explain this is to look at the Periodic Table. The row Manganese is on includes 4s, 3d, and 4p, so we only look at those subshells (not the 3s, 3d, 3p ones, even if they share the same principal number). However, the subshells for 4s and 4p are empty for Mn4+. Therefore...
- Mon Nov 16, 2020 3:23 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook problem 2A17
- Replies: 4
- Views: 193
Re: Textbook problem 2A17
Hi there! The best way I can explain this is to look at the Periodic Table. The row Manganese is on includes 4s, 3d, and 4p, so we only look at those subshells (not the 3s, 3d, 3p ones, even if they share the same principal number). However, the subshells for 4s and 4p are empty for Mn4+. Therefore,...
- Mon Nov 16, 2020 3:17 pm
- Forum: Ionic & Covalent Bonds
- Topic: Textbook Problem 2A.5
- Replies: 3
- Views: 248
Re: Textbook Problem 2A.5
Hi! We have to use the [Ar] noble gas core because Zinc is losing electrons, pushing it backwards in terms of electron configuration. In this case, Zinc lost 4 electrons to become Zn4+. This normally "pushes" Zinc back to Iron's location on the Periodic Table in terms of number of electron...
- Mon Nov 16, 2020 12:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion of a Bonding-Bonding Pair
- Replies: 6
- Views: 333
Re: Repulsion of a Bonding-Bonding Pair
Hello! The lone pairs refer to the unbonded electrons attached to the central atom. The bonded pairs refer to the electrons within the chemical bonds between the central atom and the other atoms. Since electrons are negative, they repel each other (like-like charge). The textbook states that the lon...
- Mon Nov 16, 2020 10:39 am
- Forum: Bond Lengths & Energies
- Topic: F2 Bond Strength
- Replies: 6
- Views: 4533
Re: F2 Bond Strength
I believe that the amount of electrons plays a role. Fluorine has a lot of valence electrons, and the repulsions between them weaken the bond. At least those are my initial thoughts (?)
- Sun Nov 15, 2020 11:55 pm
- Forum: Trends in The Periodic Table
- Topic: 2nd Ionization Energy
- Replies: 1
- Views: 113
Re: 2nd Ionization Energy
Hello! The second ionization energy will always be higher than the first b/c it's harder to remove an electron from a positively charged ion vs. a neutral ion. When you take your second electron, you consider that you have already removed one electron from the neutral atom, turning it into a cation....
- Sun Nov 15, 2020 11:49 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Steps to writing ground state electron configuration
- Replies: 2
- Views: 3981
Re: Steps to writing ground state electron configuration
Hello! Before we start writing electron configurations, we need to remember this sequence of orbitals: 1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s2, 4p6, 4d10, and so on and so forth. Then, you use the Periodic Table to locate the atom you want to write an electron configuration for. I think the easiest way f...
- Sun Nov 15, 2020 11:26 pm
- Forum: Lewis Structures
- Topic: Hydrogen Bonding
- Replies: 12
- Views: 661
Re: Hydrogen Bonding
Hi! So hydrogen bonds have to include a N, O, F molecule b/c these atoms are extremely electronegative, meaning that in a bond with hydrogen, they will hog the electrons. This is why the bond becomes polar, and partial charges form on the atoms. These partial charges are the ones that cause H bonds ...
- Sun Nov 15, 2020 11:01 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Square Planar vs. Tetrahedral
- Replies: 7
- Views: 1011
Re: Square Planar vs. Tetrahedral
I think I figured it out (?) I think the central atom in the square planar shape has two lone pairs in addition to the four atoms, which could push the atoms to the four square-like corners. If anyone could confirm that'd be great
- Sun Nov 15, 2020 10:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Square Planar vs. Tetrahedral
- Replies: 7
- Views: 1011
Square Planar vs. Tetrahedral
Hello! I was doing the 2.E. exercises in the book when I realized that I don't really know the difference between tetrahedral and square planar concerning lewis structures. When I drew the lewis structures of CH2F2, for example, I had no idea why it was tetrahedral vs. square planar. Can anyone tell...
- Wed Nov 11, 2020 11:31 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: Ion-dipole interactions with symmetrical molecules
- Replies: 1
- Views: 168
Re: Ion-dipole interactions with symmetrical molecules
Hello! I believe an ion-dipole interaction would still occur BUT it would be between the sodium ion and the individual chlorine atoms. Even though the molecule is symmetrical, this just means that the bond dipoles cancel each other out --> the net dipole is zero --> the molecule is nonpolar. All we ...
- Wed Nov 11, 2020 11:24 pm
- Forum: Lewis Structures
- Topic: Textbook q 2B #15
- Replies: 2
- Views: 207
Re: Textbook q 2B #15
Hello! I think the rule that you used for determining the central atom in a lewis structure depends on the ionization energy (the central atom has the lowest IE). Technically, nitrogen does have a higher IE than chlorine, so why is it the central atom? Because of weird lewis structures and exception...
- Wed Nov 11, 2020 10:58 pm
- Forum: Resonance Structures
- Topic: Sapling Q4
- Replies: 1
- Views: 128
Re: Sapling Q4
Hello! Not gonna lie, this question was pretty tricky so I used google to help me. I checked your lewis structure first, and it technically fits all the rules for lewis structures, so nice job :) The problem is carbamate is CH2NO2-. This formula automatically hints that the nitrogen should be bonded...
- Wed Nov 11, 2020 10:52 pm
- Forum: Lewis Structures
- Topic: Lewis Acids and Bases
- Replies: 2
- Views: 218
Re: Lewis Acids and Bases
Hello! A lewis acid will ACCEPT electrons, and a lewis base will DONATE these electrons. For your question, it's important to note that once a lewis base donates the electrons, they technically could accept these electrons back (like a lewis acid). Therefore, the molecule that was previously a lewis...
- Wed Nov 11, 2020 10:39 pm
- Forum: Dipole Moments
- Topic: partial dipole
- Replies: 2
- Views: 90
Re: partial dipole
Hello! First off, I'm not sure if I misinterpreted your question, but here are my thoughts! I don't believe partial dipole moments exist, so I wasn't sure if you meant a mix of partial charge and dipole moments OR temporary dipole moments. If you were asking about the partial charges + dipole moment...
- Wed Nov 11, 2020 10:28 pm
- Forum: Dipole Moments
- Topic: Electron distortion
- Replies: 1
- Views: 93
Re: Electron distortion
Hello! In terms of the level of electron distortion, an element with high polarizability (alpha) means that its electron cloud will have a large tendency to distort. So if polarizability increases, the level of electron distortion increases. Now, we relate polarizability to the formula: potential en...
- Wed Nov 04, 2020 6:46 pm
- Forum: Lewis Structures
- Topic: Coordinate Covalent Bonds & Lewis Acid-base Reactions
- Replies: 6
- Views: 404
Re: Coordinate Covalent Bonds & Lewis Acid-base Reactions
All of the above is correct! I just wanted to clarify that a coordinate covalent bond is just a bond that forms when one atom (of the two in the bond) contributes both of the electrons necessary to form that bond.
Hope y'all have a nice day!
Hope y'all have a nice day!
- Wed Nov 04, 2020 6:44 pm
- Forum: Trends in The Periodic Table
- Topic: Van der Waals radius
- Replies: 3
- Views: 216
Re: Van der Waals radius
Hi everyone! I think Dr. Lavelle mentioned ionic radii and covalent radii during his lecture on periodic trends, but I'm not too sure about van der waal radii. All three should be a measurement of half the distance between two bonded atoms, but depending on the nature of the bond, we label the dista...
- Wed Nov 04, 2020 6:35 pm
- Forum: Student Social/Study Group
- Topic: Favorite TV shows
- Replies: 277
- Views: 51699
Re: Favorite TV shows
Hello!
First off, I've watched a LOT of the recommendations above + I would say all of them are really good! Second, I just wanted to add a recommendation of my own, especially if you like crime/forensics. It's called Bones, and I think it's on Hulu (?)
Feel free to let me know what you think!
First off, I've watched a LOT of the recommendations above + I would say all of them are really good! Second, I just wanted to add a recommendation of my own, especially if you like crime/forensics. It's called Bones, and I think it's on Hulu (?)
Feel free to let me know what you think!
- Wed Nov 04, 2020 6:30 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Removing Electrons from orbitals
- Replies: 4
- Views: 358
Re: Removing Electrons from orbitals
Hi there! I'm not absolutely sure if this is the answer you're looking for, but here are my thoughts! The electrons that would be removed from an atom to form a cation are the valence electrons. The valence electrons are in the orbital furthest from the nucleus. To find the answer to your question, ...
- Wed Nov 04, 2020 6:27 pm
- Forum: Lewis Structures
- Topic: Central atom
- Replies: 4
- Views: 187
Re: Central atom
Hey there! I believe the central atom has the lowest ionization energy, which means it's more willing to give up its electrons vs. the other atoms in the ion/molecule. Therefore, the central atom is more willing to form bonds, as bonds are created due to interactions between two atoms' electrons. Th...
- Wed Oct 28, 2020 1:32 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic vs Molecular Spectroscopy (Outline 2)
- Replies: 3
- Views: 121
Re: Atomic vs Molecular Spectroscopy (Outline 2)
Hi guys! I just wanted to hop into this discussion and ask for some clarification. I understand the differences between atomic spectroscopy and molecular spectroscopy, but how does it relate to the electronic transitions?
Thanks!
Thanks!
- Wed Oct 28, 2020 1:26 am
- Forum: *Shrodinger Equation
- Topic: For Ms (spin up, spin down)
- Replies: 6
- Views: 648
Re: For Ms (spin up, spin down)
Hi there! I thought you were asking if the +1/2 and -1/2 corresponded to a specific arrow (up/down). Generally, I believe the up arrow, which corresponds to spin up, represents a spin number of +1/2. Therefore, the down arrow, which corresponds to spin down, represents a spin number of -1/2. Hope th...
- Wed Oct 28, 2020 1:12 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: How many electrons in an atom
- Replies: 1
- Views: 542
Re: How many electrons in an atom
Hello! First off, the principal quantum number (n) indicates the shell, the angular quantum number (l) represents the subshell within the shell, and the magnetic quantum number (ml) represents the orbital within the subshell within the shell. With that in mind, let's look at the problems. A. n = 2 T...
- Wed Oct 28, 2020 12:57 am
- Forum: Properties of Light
- Topic: rydberg's constant
- Replies: 11
- Views: 1031
Re: rydberg's constant
Hello! I also just wanted to add on a little bit to everyone's answers. The R = 3.28984 x10^15 Hz is used for the Rydberg equation with frequency, or v = R(1/n1^2 - 1/n2^2). In comparison, the R = 1.097x10^7 m is used for the Rydberg equation with wavelength, or 1/wavelength = R(1/n1^2 - 1/n2^2). As...
- Tue Oct 27, 2020 11:44 pm
- Forum: Properties of Light
- Topic: rydberg's equation
- Replies: 2
- Views: 114
Re: rydberg's equation
Hello! Concerning the formula with 1/wavelength vs. the formula with frequency, I believe they're the same. In fact, they can be connected through the c = v * wavelength formula. However, I do believe that the Rydberg constant (R) changes depending on the formula. For the 1/wavelength one, R = 1.097...
- Thu Oct 22, 2020 10:49 am
- Forum: Properties of Light
- Topic: N=1, N=2 For Lyman and Balmer Series
- Replies: 5
- Views: 664
Re: N=1, N=2 For Lyman and Balmer Series
Hi there! In the Balmer series, n1 = 2, and in the Lyman series, n1 = 1. For the most part, I find this helpful in solving problems, especially when they want us to find n1 and n2. If the problem states that the light wavelength, frequency, or radiation type, you can immediately find n1 using the Ba...
- Thu Oct 22, 2020 10:35 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: textbook 1A.3
- Replies: 4
- Views: 235
Re: textbook 1A.3
I am not sure if my answer is correct but I am leaning toward "A". Because frequency("v") is related to the speed("c") in the equation c=h*v a decrease in the frequency would result in a decrease in the speed of the radiation. But I am not 100% so if someone could doub...
- Thu Oct 22, 2020 10:33 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: textbook 1A.3
- Replies: 4
- Views: 235
Re: textbook 1A.3
A. is false because the speed of light (electromagnetic radiation) is constant, c=3x10^8 m/s. B. is false because frequency and wavelength are inversely proportional as c=wavelength x frequency. So if frequency decreases, then wavelength would have to increase. C. is true because since the electric...
- Thu Oct 22, 2020 9:29 am
- Forum: Einstein Equation
- Topic: Sapling
- Replies: 2
- Views: 177
Re: Sapling
Hi there! For part two, you are trying to see how many photons you can remove with the energy given. To find the number of emitted photons, you need to divide the amount of energy given (7.40×10^−7 J) by the work function (2.726 - 10^-19 J/photon), the amount of energy needed to remove one photon. U...