Search found 102 matches
- Sun Feb 28, 2021 3:41 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling #4
- Replies: 6
- Views: 322
Re: Sapling #4
Your final reaction isn't properly balanced. There should be 3HNO3, 3NO2, and 3H2O
- Sun Feb 28, 2021 3:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Liquids and Solids in Equilibrium Calculations
- Replies: 12
- Views: 569
Re: Liquids and Solids in Equilibrium Calculations
Yes, liquids and solids are always ignored in equilibrium calculations
- Sun Feb 28, 2021 3:33 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: qrev
- Replies: 27
- Views: 1440
Re: qrev
qrev refers to the amount of heat that is produced in a reversible process!
- Sun Feb 28, 2021 3:32 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Diamond vs. Graphite
- Replies: 23
- Views: 981
Re: Diamond vs. Graphite
Yes it is possible, but it would take an insane amount of time
- Sun Feb 28, 2021 3:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community Points
- Replies: 24
- Views: 964
Re: Chemistry Community Points
I believe that the points are capped at 50!
- Sun Feb 28, 2021 3:30 pm
- Forum: Student Social/Study Group
- Topic: Winter GEs?
- Replies: 33
- Views: 2330
Re: Winter GEs?
I'm currently taking a cluster so not sure about which GEs are good, but I do know for sure that the Scand and Classics classes are popular
- Sun Feb 28, 2021 3:25 pm
- Forum: Student Social/Study Group
- Topic: Exercising Our Minds and Bodies
- Replies: 120
- Views: 14554
Re: Exercising Our Minds and Bodies
I try to run a few miles during the weekend! I love blasting music and forgetting about the work I have by exercising
- Sun Feb 28, 2021 3:25 pm
- Forum: Student Social/Study Group
- Topic: Post Midterm 2 De-stressing
- Replies: 92
- Views: 5748
Re: Post Midterm 2 De-stressing
I always take naps after all my midterms. Post-midterm/final naps are the best
- Sun Feb 28, 2021 3:16 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation states for final?
- Replies: 13
- Views: 634
Re: oxidation states for final?
I think we should be knowing the general oxidation rules, which are helpful when solving problems
- Sun Feb 28, 2021 3:16 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in ∆G = -nFE
- Replies: 80
- Views: 3626
Re: n in ∆G = -nFE
n in the equation ∆G = -nFE is the number of electrons that are being transferred, which you can find by balancing the half-reactions
- Sun Feb 28, 2021 3:15 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling Week 7/8 question 18
- Replies: 3
- Views: 195
Re: Sapling Week 7/8 question 18
You have to remove the parentheses for the hydrate! Although I'm not so sure why myself either...
- Sun Feb 28, 2021 3:14 pm
- Forum: General Science Questions
- Topic: Midterm 2 Reactions
- Replies: 79
- Views: 4772
Re: Midterm 2 Reactions
I also found it very surprising that most of the midterm was conceptual questions. I will be definitely studying more of those concepts for the final.
- Mon Feb 08, 2021 4:07 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: work and pos/neg
- Replies: 9
- Views: 460
Re: work and pos/neg
Work is positive when work is being done on a system, whereas work is negative when a system is doing work.
- Mon Feb 08, 2021 4:06 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 12
- Views: 448
Re: Hess's Law
I think for Hess's Law there is some trial and error you have to do when solving a problem. I think I always try to cancel things out in a way so that the products will end up in the products side and reactants will end up in the reactants side.
- Mon Feb 08, 2021 4:03 pm
- Forum: Student Social/Study Group
- Topic: Spring 2021
- Replies: 106
- Views: 11384
Re: Spring 2021
I plan to take 14C during spring quarter and 14BL during summer. While it's useful to have it in person, I heard 14BL is easier online so I'm gonna take it before fall 2021.
- Mon Feb 08, 2021 4:02 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: DeltaE vs DeltaU
- Replies: 13
- Views: 520
Re: DeltaE vs DeltaU
DeltaE and DeltaU can be used interchangeably!
- Mon Feb 08, 2021 4:01 pm
- 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: 4G.5
- Replies: 3
- Views: 220
Re: 4G.5
Cis isomers have similar groups placed on the same side of a double bond. Trans isomers have similar groups placed on opposite sides of a double bond.
- Mon Feb 08, 2021 3:58 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy
- Replies: 6
- Views: 301
Re: Entropy
There are different equations involving entropy and you use them based on what the question asks for. Entropy is a measure of how much the energy of atoms and molecules become more spread out.
- Mon Feb 08, 2021 3:53 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed vs Isolated System
- Replies: 30
- Views: 1122
Re: Closed vs Isolated System
The difference between an isolated and closed system is that a closed system can still exchange energy with its surroundings. An isolated system cannot exchange matter or energy with its surroundings. An example of an isolated system is a thermos or cooler, while an example of a closed system could ...
- Mon Feb 08, 2021 3:51 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: ideal gases and Cpm and Cvm
- Replies: 4
- Views: 277
Re: ideal gases and Cpm and Cvm
You can tell if the ideal gas is monoatomic, linear molecule or a nonlinear molecule by drawing out its lewis structure. That way, you can determine its 3D structure.
- Mon Feb 08, 2021 3:49 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Does phase matter in Hess's Law?
- Replies: 21
- Views: 1793
Re: Does phase matter in Hess's Law?
Yes, they do matter! Two compounds would have to be the same phase to "cancel out" when using Hess's law.
- Mon Feb 08, 2021 3:48 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: dT versus ΔT
- Replies: 8
- Views: 702
Re: dT versus ΔT
Just as others have states, delta T is for a large overall change in temperature, while dT is for infinitely small changes in temperature.
- Wed Feb 03, 2021 4:46 pm
- Forum: Student Social/Study Group
- Topic: Best study methods
- Replies: 9
- Views: 426
Re: Best study methods
I think the textbook questions and UA worksheets are both extremely helpful. The midterm questions have been very similar to both problem sets. I didn't really attend review sessions but I still did all the worksheets I could find. Sapling is also definitely helpful because it provides a step by ste...
- Wed Feb 03, 2021 4:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling 10
- Replies: 2
- Views: 205
Re: Sapling 10
The first thing I did was I changed the mass of the ice cub into kilojoules. You can do this by using the molar mass of water to find the amount of moles of ice, and then multiply it by the heat of fusion of water. This amount of energy is the heat required to melt ice. After you get this amount of ...
- Wed Feb 03, 2021 4:38 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community Points
- Replies: 11
- Views: 428
Re: Chemistry Community Points
I think that as long as you have 50 posts by the end of this quarter you will be fine. Any other score you have right now will be updated in the future!
- Wed Feb 03, 2021 4:37 pm
- Forum: Student Social/Study Group
- Topic: Best kdrama?
- Replies: 30
- Views: 1737
Re: Best kdrama?
Start-Up is a popular kdrama that had its final episode not too long ago. My favorite kdramas of all time are She Was Pretty, Strong Woman Do Bong Soon, While You Were Sleeping, and Kill Me Heal Me! I especially loved Kill Me Heal Me.
- Wed Feb 03, 2021 4:34 pm
- Forum: General Science Questions
- Topic: Midterm 1 Reactions
- Replies: 70
- Views: 3998
Re: Midterm 1 Reactions
Yeah, I think the test went as I expected. The structure was pretty much the same for Chem14A so there was nothing too surprising. I'm really glad that the problems were similar to the textbook ones because doing all of those really helped me. Reviewing sapling also helped me understand the content.
- Wed Feb 03, 2021 4:32 pm
- Forum: Student Social/Study Group
- Topic: Midterm Scores
- Replies: 25
- Views: 712
Re: Midterm Scores
They should be coming out sometime tonight. Good luck everybody, we all did our best :)
- Wed Feb 03, 2021 4:32 pm
- Forum: Student Social/Study Group
- Topic: Shoutout to Dr. Lavelle
- Replies: 8
- Views: 453
Re: Shoutout to Dr. Lavelle
Yes, thank you Dr. Lavelle for being so accommodating to the digital setting and giving extensions when needed!
- Wed Feb 03, 2021 4:31 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 10
- Views: 336
Re: Midterm
They should be coming out sometime this evening :)
- Wed Feb 03, 2021 4:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14BL Summer?
- Replies: 4
- Views: 152
Re: Chem 14BL Summer?
I'm planning on taking it for session A, which already has a designated professor. Session C does not seem to have one yet!
- Sat Jan 30, 2021 8:48 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Work Definition
- Replies: 33
- Views: 955
Re: Work Definition
Work is the energy transferred by the system to its surroundings, and its equation is W=-PΔV
- Sat Jan 30, 2021 8:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: is HClO3 weak or strong? [ENDORSED]
- Replies: 49
- Views: 3851
Re: is HClO3 weak or strong? [ENDORSED]
HClO3 is considered a strong acid. So is HClO4 :)
- Sat Jan 30, 2021 8:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: change in celsius = change in kelvin
- Replies: 22
- Views: 7459
Re: change in celsius = change in kelvin
Kelvin and Celsius are two different units of temperature. The equation to calculate either one is kelvin = celsius + 273.15
- Sat Jan 30, 2021 8:42 pm
- Forum: Phase Changes & Related Calculations
- Topic: when to assume x is insignificant
- Replies: 86
- Views: 6271
Re: when to assume x is insignificant
If in the expression (x)/(initial concentration) x 100 is less than 5%, you can ignore the x value!
- Sun Jan 24, 2021 11:12 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Percent ionization
- Replies: 10
- Views: 1029
Re: Percent ionization
Percent ionization is the percentage of the compound that has been ionized or dissociated.
- Sun Jan 24, 2021 11:01 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 18
- Views: 513
Re: Phase Changes
Heat is required if a substance goes from liquid to gas. In the phase change diagram, the process of liquid to gas, or fusion, has the same temperature over time because the bonds need to be broken.
- Sun Jan 24, 2021 10:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Neutral, unknown, or charged?
- Replies: 6
- Views: 195
Re: Neutral, unknown, or charged?
For an acid, when pH>pKa, the charged species is dominant. On the other hand, if pH<pKa, the neutral species is dominant. Hope this helps!
- Sun Jan 24, 2021 10:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pka, Ph, charged and neutral species
- Replies: 7
- Views: 353
Re: Pka, Ph, charged and neutral species
Yes, I believe that that is correct!
- Sun Jan 24, 2021 10:49 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat released/ gained
- Replies: 22
- Views: 890
Re: Heat released/ gained
When bonds are being broken, energy is required. On the other hand, energy is released when bonds are formed.
- Sun Jan 24, 2021 9:45 pm
- Forum: Student Social/Study Group
- Topic: Favorite Music
- Replies: 113
- Views: 9399
Re: Favorite Music
When I study, I listen to lofi and there a ton of playlists on YouTube. These days I've been listening to a lot of j-pop like Yoasobi because it's super catchy. I also listen to a lot of k-indie and kr&b :)
- Sun Jan 17, 2021 6:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling HW Q3
- Replies: 3
- Views: 114
Re: Sapling HW Q3
The first thing you would have to do is setting up an ICE chart with HA <-> H+ + A-. With the given initial concentration of the acid, you would create an expression and have to solve for x in a quadratic equation. Once you get x, which is the concentration of H+ ions, you can solve for pH by taking...
- Sun Jan 17, 2021 5:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: percent ionization, percentage protonated
- Replies: 4
- Views: 226
Re: percent ionization, percentage protonated
Percent ionization is the percentage of the compound that has been ionized or dissociated. Percent protonation refers specifically to the percentage of hydronium ions that was dissociated.
- Sun Jan 17, 2021 5:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pure Liquids (Solutes)
- Replies: 7
- Views: 286
Re: Pure Liquids (Solutes)
I don't think there are any other pure liquids we should be memorizing, but if there are, they would be notated as a (l) in the chemical equation.
- Sun Jan 17, 2021 5:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Picking answer from quadratic solutions
- Replies: 12
- Views: 726
Re: Picking answer from quadratic solutions
You would pick the solution that is less than the initial concentration when using quadratic equations.
- Sun Jan 17, 2021 5:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling HW Q7
- Replies: 3
- Views: 187
Re: Sapling HW Q7
In this problem, you can solve for Kb because Ka is given since Kb = Kw/Ka. After you get the value of Kb, you would set up an ICE chart to make an equation for Kb. In this case, it would be Kb = [HOCl][OH-]/[OCl-]. Since HOCl and OH- would be regarded as "x" by using the ICE chart, you ca...
- Sun Jan 17, 2021 5:45 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Sapling Week 1 #6
- Replies: 7
- Views: 501
Re: Sapling Week 1 #6
For this problem, you set up the equation for Q, which is ([NH3]^2) / ([H2]^3 * [N2]) as mentioned above. You would then plug in the given concentrations for each reactant/product and get a value for Q. After compared the value of Q to K, you would see that K>Q, which means that more products are fo...
- Sun Jan 10, 2021 11:43 pm
- Forum: Student Social/Study Group
- Topic: Comfort Movies
- Replies: 168
- Views: 21734
Re: Comfort Movies
My favorite comfort movies include the Studio Ghibli films or old Disney movies for nostalgia :)
- Mon Jan 04, 2021 1:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Can I do hw if I don't have sapling yet?
- Replies: 16
- Views: 405
Re: Can I do hw if I don't have sapling yet?
For sapling, you can get the free trial, but even then it's due on Week 2 so you don't need to worry too much about it. There's also an online PDF available for the textbook so you can access it without Sapling.
- Mon Jan 04, 2021 1:49 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pure Substance [ENDORSED]
- Replies: 7
- Views: 263
Re: Pure Substance [ENDORSED]
A pure substance is anything thats a pure liquid or a solid. For a liquid, this means that they are not aqueous and are usually notated with a (l) in a reaction. Ultimately, a pure substance does not affect the concentration in a reaction.
- Mon Jan 04, 2021 1:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Sapling HW
- Replies: 3
- Views: 121
Re: Sapling HW
The first sapling HW is due on Week 2 :)
- Mon Jan 04, 2021 1:45 pm
- Forum: Student Social/Study Group
- Topic: Advice for someone who didn't take 14A with professor Lavelle
- Replies: 61
- Views: 2602
Re: Advice for someone who didn't take 14A with professor Lavelle
I would definitely do all the textbook problems and going to as many UA sessions as you can. If you can't make them, try to find the worksheets they make. All of those worksheets and the textbook have problems that are very similar to the ones on the midterms and final. Also, stay on top of your poi...
- Sun Dec 06, 2020 8:39 pm
- Forum: Lewis Acids & Bases
- Topic: Weak/ Strong Acids and Bases
- Replies: 6
- Views: 403
Re: Weak/ Strong Acids and Bases
There's a list of strong acids and bases you can find online and I think we have to memorize them. Anything not on that list would be considered weak. There's also a list from sapling if it helps: https://sites.google.com/site/chempendi ... cids-bases
- Sun Dec 06, 2020 8:35 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Negative pH of acid
- Replies: 16
- Views: 634
Re: Negative pH of acid
Acids cannot have a negative pH; the pH scale ranges from 0-14.
- Sun Dec 06, 2020 8:33 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sapling #10. How can you tell which solution has a higher pH?
- Replies: 7
- Views: 1732
Re: Sapling #10. How can you tell which solution has a higher pH?
Generally, a strong base has OH- ions and a strong acid has H+ ions. A strong base also has a higher pH while a strong acid has a lower pH. Thus, in this problem we are essentially ordering the molecules from most basic to most acidic. Ca(OH2) is a stronger base than RbOH because it contains one mor...
- Sun Dec 06, 2020 8:27 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: H2CO3 vs H2GeO3 acid strength
- Replies: 4
- Views: 234
Re: H2CO3 vs H2GeO3 acid strength
H2CO3 is a stronger acid because C is more electronegative than Ge. We can see the electronegative trend with a periodic table; up a column is more electronegative. As others mentioned, because C is more electronegative, it would be easier for the H+ ions to dissociate in water and is thus a stronge...
- Sun Dec 06, 2020 8:25 pm
- Forum: Naming
- Topic: Order of Ligands/naming
- Replies: 28
- Views: 1073
Re: Order of Ligands/naming
Ligands are simply ordered in alphabetical order!
- Sun Nov 29, 2020 6:14 pm
- Forum: Lewis Structures
- Topic: Sapling Week 7/8 #12
- Replies: 8
- Views: 322
Re: Sapling Week 7/8 #12
This problem is essentially combining concepts we learned from the last midterm. In this problem, we can find the compound's molecular formula by using the mass percentage composition. By finding the molecular formula, you can draw its lewis structure.
- Sun Nov 29, 2020 6:12 pm
- Forum: Student Social/Study Group
- Topic: Favorite TV shows
- Replies: 277
- Views: 33379
Re: Favorite TV shows
I've been watching a lot of anime over quarantine and I'm currently watching Hunter x Hunter! I also loved Stranger Things, The End of the F***ing World, Erased, ATLA, and On My Block.
- Sun Nov 29, 2020 6:08 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent
- Replies: 9
- Views: 430
Re: Bent
Yes, bent and angular mean the same regarding the lone pairs that result in its shape.
- Sun Nov 29, 2020 6:04 pm
- Forum: Student Social/Study Group
- Topic: Final Format
- Replies: 35
- Views: 1513
Re: Final Format
Not sure if it will be more heavily based on the topics towards the end of the quarter, but we should be familiar with all content from the entire quarter because it is cumulative. The format should all be MC though.
- Sun Nov 29, 2020 6:02 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: sigma vs pi bonds
- Replies: 33
- Views: 1926
Re: sigma vs pi bonds
We can determine the number of sigma and pi bonds depends on what type of bond it is (single, double, or triple). As we know, triple bonds are stronger than double, which are stronger than single.
- Sun Nov 29, 2020 5:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Weekly Discussion grades
- Replies: 9
- Views: 301
Re: Weekly Discussion grades
Hi, you don't necessarily have to do 5 posts each week but it's a good idea to so you can keep track of the amount of posts you have. To answer your question, you should just make sure you have 40 by the end of this week!
- Thu Nov 19, 2020 12:26 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: quantum number f
- Replies: 6
- Views: 686
Re: quantum number f
The subshell f starts on the 4th level (4f) but is only seen in 6th period elements. The fact that they have different quantum numbers may be a little confusing!
- Thu Nov 19, 2020 12:22 pm
- Forum: Lewis Structures
- Topic: H2O Lone Pairs
- Replies: 5
- Views: 356
Re: H2O Lone Pairs
A water molecule is not linear but bent. This bent structure explains why the two lone pair electrons would be next to each other rather than on opposite ends. The lone pair electrons in the water molecule are most stable when next to each other.
- Thu Nov 19, 2020 12:19 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: variations in electron configuration names
- Replies: 3
- Views: 138
Re: variations in electron configuration names
Yes, valence shell configuration includes both ground state and excited state configuration.
- Tue Nov 17, 2020 10:34 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Length vs Size of Molecule
- Replies: 14
- Views: 689
Re: Bond Length vs Size of Molecule
Both CH4 and CCl4 are single bonds. But the reason why CCl4 has a higher boiling point is because it has more electron shells. This makes the polarizability increase, thus increasing the strength of LDFs, which then increases the boiling point.
- Tue Nov 17, 2020 10:27 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Cu and Cr Exceptions
- Replies: 3
- Views: 197
Re: Cu and Cr Exceptions
Yes I believe that is correct but I doubt we would have to know that for our midterm!
- Tue Nov 17, 2020 10:26 pm
- Forum: Student Social/Study Group
- Topic: Midterm 2
- Replies: 19
- Views: 901
Re: Midterm 2
For the last midterm I definitely benefitted a lot from doing a ton of problems. I tried to do all the UA worksheets and textbook problems and looked over sapling again. I honestly found the textbook problems to be the most helpful for the test.
- Fri Nov 13, 2020 3:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14B Waitlist
- Replies: 6
- Views: 574
Re: Chem 14B Waitlist
I saw a post that explained that we can't expect it to be exactly the same with the asynchronous format, but it's most likely so.
- Fri Nov 13, 2020 3:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lecture Content for 11/13
- Replies: 3
- Views: 162
Re: Lecture Content for 11/13
No, I believe today's lecture content is not on the midterm since it was on the VSEPR model which isn't part of our syllabus for the upcoming test.
- Fri Nov 13, 2020 3:23 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Sapling #13 (hydrogen bonds)
- Replies: 1
- Views: 150
Re: Sapling #13 (hydrogen bonds)
For this problem, you have to determine which elements in the urea molecule that the water would form hydrogen bonds with. Hydrogen bonds are formed with the elements F, O, and N. You can use this information to find how many hydrogen bonds a urea molecule can have, thus giving us the amount of wate...
- Fri Nov 13, 2020 3:17 pm
- Forum: Resonance Structures
- Topic: formal charges
- Replies: 2
- Views: 100
Re: formal charges
Are you referring to electronegativity trends in general? Because if so, the electronegativity trend happens to be that across a period is more electronegative, and up a group is more electronegative.
- Fri Nov 13, 2020 3:15 pm
- Forum: Lewis Structures
- Topic: Sapling #2
- Replies: 5
- Views: 244
Re: Sapling #2
There are three oxygen atoms surrounding the central carbon atom, and two of the oxygen atoms have a single bond while the other has a double bond. The oxygen atoms with a single bond have a negative charge, and this is because of formal charge.
- Fri Nov 06, 2020 3:09 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity Difference Between 1.5 and 2
- Replies: 4
- Views: 216
Re: Electronegativity Difference Between 1.5 and 2
Just like the answer above mentioned, we would have to observe the molecule's solubility to determine if it has ionic or covalent properties. Other than that, I'm pretty sure any problem we are given related to this would be more specific and not involve an ambiguous value between 1.5 and 2.
- Fri Nov 06, 2020 3:07 pm
- Forum: Resonance Structures
- Topic: Bond lengths
- Replies: 20
- Views: 639
Re: Bond lengths
Hi, I don't think we actually have to draw the double bonds shorter than single bonds for accuracy. I think we should just be able to know that single bonds are longer than double bonds, which are longer than triple bonds.
- Fri Nov 06, 2020 3:05 pm
- Forum: Student Social/Study Group
- Topic: Test Anxiety
- Replies: 62
- Views: 2858
Re: Test Anxiety
I always listen to some good music before test anxiety so I feel more confident going into the test! When I'm actually taking the test, I make sure to read each question super carefully because they can get tricky. After I look at the answer choices, I always use process of elimination to determine ...
- Fri Nov 06, 2020 3:03 pm
- Forum: Lewis Structures
- Topic: Electron Configuration; Aufbau Principle
- Replies: 5
- Views: 204
Re: Electron Configuration; Aufbau Principle
I love that principle too, it's really helpful with figuring out electron configurations. Thank you for sharing!
- Fri Nov 06, 2020 3:01 pm
- Forum: Resonance Structures
- Topic: question 9 on sapling
- Replies: 3
- Views: 106
Re: question 9 on sapling
Hi, because they gave that the bond length for the perchlorate ion is 144pm for all four bonds which is close to the double bond between Cl and O, we can determine that the bonds in the ion are probably all double bonds. Because the resonance structures C and D have mostly double bonds, I inferred t...
- Mon Oct 26, 2020 10:03 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Subshells
- Replies: 2
- Views: 166
Re: Subshells
This is because of the Aufbau principle, which means that electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels. In general, 4s is filled before 3d because it is lower in energy. However, there are two exception to this rule which is with a half full 3d ...
- Mon Oct 26, 2020 9:58 pm
- Forum: General Science Questions
- Topic: assuming limiting reactant
- Replies: 4
- Views: 372
Re: assuming limiting reactant
Yes, I believe that in this question you just assume that PCl3 is the limiting reactant and you can only use that value to solve for the mass of HCl.
- Mon Oct 26, 2020 9:54 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Sapling Homework #22
- Replies: 3
- Views: 211
Re: Sapling Homework #22
Hi! For this question, you would first use DeBroglie's equation ( v = h/m*lambda) to find the velocity of the electron with the given wavelength and the mass of an electron (9.11 x 10^-31kg). After finding the velocity, you can plug the value into the kinetic energy equation 1/2mv^2.
- Mon Oct 26, 2020 9:50 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: sapling question 27
- Replies: 3
- Views: 148
Re: sapling question 27
Since this problem is dealing with uncertainties, you would just ignore the value 8x10^6 m/s and use Δv= 0.01x10^6m/s instead.
- Mon Oct 26, 2020 9:47 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: s/p/d Blocks
- Replies: 2
- Views: 83
Re: s/p/d Blocks
For the s,p,d,f orbitals, electrons will generally fill up the lower energy orbitals first. This is why 4s is filled up first before the 3d because the 4s orbital is lower in energy. This is known as the Aufbau principle, which means that electrons fill atomic orbitals of the lowest available energy...
- Wed Oct 21, 2020 10:05 pm
- Forum: Einstein Equation
- Topic: Scratch paper during the exam
- Replies: 19
- Views: 520
Re: Scratch paper during the exam
Yeah I'm pretty sure the test policies for the midterm would depend on your TA !
- Wed Oct 21, 2020 10:01 pm
- Forum: DeBroglie Equation
- Topic: Sapling question 25
- Replies: 5
- Views: 357
Re: Sapling question 25
Hi, to find the energy of the electron, the problem gives a hint that the electron's energy is a function of mass and velocity. So to find the energy, you need to first find the velocity of the electron using DeBroglie's equation (v=h/m*lambda). After you find the velocity, you plug that into the ki...
- Wed Oct 21, 2020 9:55 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Homework problem #14
- Replies: 2
- Views: 122
Re: Homework problem #14
Hi, one mistake that often happens is switching up 3 and 2. I don't know if this is the case, but make sure that 2 is N1 and 3 is N2 in the Rydberg equation! After you plug those numbers in and get the frequency, you can use the equation lambda = c/v to get the wavelength.
- Wed Oct 21, 2020 9:30 pm
- Forum: Properties of Light
- Topic: N2 vs N1
- Replies: 6
- Views: 332
Re: N2 vs N1
In the Rydberg formula, N1 means the final energy level and N2 means the initial early level. Since in this case 5 is N2 and 2 is N1, this means that the electron travelled from energy level 5 to energy level 2. The electron is not getting excited, but rather emitting energy.
- Wed Oct 21, 2020 9:26 pm
- Forum: Photoelectric Effect
- Topic: Do we need to know about the Paschen or Brackett series for midterm 1?
- Replies: 7
- Views: 249
Re: Do we need to know about the Paschen or Brackett series for midterm 1?
As others mentioned, I think it's a good idea to know what energy level transitions each series fall under but I don't think we need to know about them in too much detail!
- Sat Oct 17, 2020 12:17 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Textbook 1B.25
- Replies: 2
- Views: 176
Textbook 1B.25
"What is the minimum uncertainty in the speed of an electron confined to within a lead atom of diameter 350. pm? How would you model the atom as a one-dimensional box with a length equal to the diameter of the actual atom?" I'm using the equation [(Mass of the electron)(delta v)](delta x)=...
- Tue Oct 13, 2020 9:42 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Post-Module number 20
- Replies: 2
- Views: 215
Re: Heisenberg Post-Module number 20
Thank you so much for your explanation! I also realized that I solved it wrong. I realized that I should just use the ΔE(k)=1/2m(Δv)^2 formula for the first part of the question, and I would multiply that answer by avogadro's number for the second part since it's asking for "per mole of hydroge...
- Tue Oct 13, 2020 9:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: wavelengths for light
- Replies: 9
- Views: 229
Re: wavelengths for light
I'm pretty sure we won't be expected to know the specific wavelengths for each color, but as mentioned above, knowing the ranges would be a good idea.
- Tue Oct 13, 2020 3:30 pm
- Forum: DeBroglie Equation
- Topic: Pre Assessment Questions
- Replies: 3
- Views: 132
Re: Pre Assessment Questions
When the peak interacts with another trough, they essentially "cancel each other out" and would result in a smaller wave. On the other hand, if a peak interacts with another peak, the amplitudes are added together and become bigger.
- Tue Oct 13, 2020 3:28 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: post module #14
- Replies: 5
- Views: 241
Re: post module #14
The answer for this would be D! Heisenberg's principle doesn't really apply to large objects so uncertainties aren't measurable.
- Tue Oct 13, 2020 3:26 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Post-Module number 20
- Replies: 2
- Views: 215
Heisenberg Post-Module number 20
Hi everybody! I'm struggling a bit with number 20 for the Heisenberg uncertainty principle post-module questions. 20. Use the above uncertainty in velocity to calculate the electron's uncertainty in kinetic energy. Then calculate the uncertainty in kinetic energy per mole of electrons (that is, per ...
- Tue Oct 06, 2020 10:20 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: mmol/mL vs. mol/L
- Replies: 6
- Views: 5090
Re: mmol/mL vs. mol/L
Yes I believe so, because the extra m in mmol and mL would cancel each other out since they're both measured in "milli".
- Tue Oct 06, 2020 2:04 am
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactant and Limiting Reagent
- Replies: 7
- Views: 208
Re: Limiting Reactant and Limiting Reagent
I think that while the definitions of reagent and reactant are different, the terms limiting reactant and limiting reagent are the same and can be used interchangeably as mentioned earlier. It can also be called a limiting agent.
- Mon Oct 05, 2020 12:12 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Question about Mass%
- Replies: 14
- Views: 367
Re: Question about Mass%
We use 100g because it makes it easier to imagine the sample mass. Since we already found the mass compositions of each element, we can just use those percentages and treat them as if they were grams. By converting them to grams we can then convert to moles to find the empirical formula.
- Mon Oct 05, 2020 11:55 am
- Forum: Balancing Chemical Reactions
- Topic: Balancing chemical equations involving combustion
- Replies: 15
- Views: 467
Re: Balancing chemical equations involving combustion
Yes, you can always assume that O2 is one of the reactants. A combustion reaction involves a hydrocarbon (molecule with just carbons and hydrogens) and O2 as the reactants and with H2O and CO2 as the products.
- Mon Oct 05, 2020 11:49 am
- Forum: Balancing Chemical Reactions
- Topic: Stoichiometric Coefficients
- Replies: 20
- Views: 403
Re: Stoichiometric Coefficients
Yup, there are always problems that don't provide a balanced equation. It's always a good idea to double check!