Search found 99 matches

by Alara Aygen 3K
Mon Feb 22, 2021 10:15 am
Forum: Balancing Redox Reactions
Topic: Oxidizing vs Reducing
Replies: 41
Views: 86

Re: Oxidizing vs Reducing

I was having trouble with this too, thanks!
by Alara Aygen 3K
Mon Feb 22, 2021 10:13 am
Forum: Student Social/Study Group
Topic: We made it through Midterm 2!
Replies: 58
Views: 159

Re: We made it through Midterm 2!

Congratulations to everyone! We're almost there!
by Alara Aygen 3K
Mon Feb 22, 2021 10:12 am
Forum: Student Social/Study Group
Topic: Balance / Self Care Tips
Replies: 41
Views: 96

Re: Balance / Self Care Tips

Taking walks and watching my favorite shows really help me to ease my mind!
by Alara Aygen 3K
Mon Feb 22, 2021 10:11 am
Forum: Student Social/Study Group
Topic: How to Reduce Nervousness before getting results
Replies: 33
Views: 82

Re: How to Reduce Nervousness before getting results

I feel the same way! Reading these helped me, so thank you!
by Alara Aygen 3K
Mon Feb 22, 2021 10:08 am
Forum: Student Social/Study Group
Topic: Chem 14B Final
Replies: 37
Views: 83

Re: Chem 14B Final

Last quarter Dr. Lavelle created many extra final review sessions. They really helped me. If he does it again this quarter, I highly suggest attending them.
by Alara Aygen 3K
Tue Feb 16, 2021 1:41 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Number Guide
Replies: 2
Views: 30

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 ...
by Alara Aygen 3K
Tue Feb 16, 2021 12:56 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: When to Use An Equation
Replies: 2
Views: 15

Re: When to Use An Equation

I believe that is the equation for internal energy of an ideal gas.
by Alara Aygen 3K
Tue Feb 16, 2021 12:54 pm
Forum: Student Social/Study Group
Topic: Midterm 2 Nerves
Replies: 40
Views: 152

Re: Midterm 2 Nerves

Hello, I am also very nervous but here are some things I'm doing to help myself feel more prepared for the test! 1.) Of course, workin on sapling and tb problems, but also making note of what TYPES of questions there are (how they ask the question). Often times the question itself seems very daunti...
by Alara Aygen 3K
Tue Feb 16, 2021 12:53 pm
Forum: Student Social/Study Group
Topic: Fave food
Replies: 99
Views: 204

Re: Fave food

I love apple pie and ice cream!
by Alara Aygen 3K
Tue Feb 16, 2021 12:52 pm
Forum: General Science Questions
Topic: No Lavelle Chem 14C?
Replies: 40
Views: 187

Re: No Lavelle Chem 14C?

I think Dr. Lavelle teaches general chemistry and since 14C is organic chemistry we'll have a new instructor.
by Alara Aygen 3K
Mon Feb 08, 2021 4:44 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: dT versus ΔT
Replies: 8
Views: 27

Re: dT versus ΔT

dT uses integrals to find really small changes in temperature. Delta t is much bigger since it is the overall change in temperature.
by Alara Aygen 3K
Mon Feb 08, 2021 4:42 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: using equations
Replies: 10
Views: 32

Re: using equations

I usually write down the "known" and "unknown" values and figure out which equation is better to use with the given information.
by Alara Aygen 3K
Mon Feb 08, 2021 4:40 pm
Forum: Student Social/Study Group
Topic: Spring 2021
Replies: 104
Views: 433

Re: Spring 2021

I am currently taking 14BL and I would have preferred taking it inperson. If you have the chance and time to take it inperson, it might be more beneficial since you will be able to study in an actual lab.
by Alara Aygen 3K
Mon Feb 08, 2021 4:36 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Most accurate method
Replies: 6
Views: 33

Re: Most accurate method

I think Hess's Law and standard enthalpies have relatively the same level of accuracy, and they are both more accurate than the bond enthalpies.
by Alara Aygen 3K
Mon Feb 08, 2021 4:34 pm
Forum: Student Social/Study Group
Topic: Culinary Chemistry
Replies: 62
Views: 341

Re: Culinary Chemistry

Wow! These are all very interesting posts. I will definitely check out some of these videos.
by Alara Aygen 3K
Mon Feb 01, 2021 3:36 pm
Forum: Administrative Questions and Class Announcements
Topic: Chemistry Community Posts
Replies: 17
Views: 57

Re: Chemistry Community Posts

Was there a way to make up missed points last quarter?
by Alara Aygen 3K
Mon Feb 01, 2021 3:34 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm #1 Results
Replies: 18
Views: 112

Re: Midterm #1 Results

I believe it will be similar to last quarter, so maybe they will be out by this Friday.
by Alara Aygen 3K
Mon Feb 01, 2021 3:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Grading scale
Replies: 29
Views: 214

Re: Grading scale

I think the grading scale gets finalized after the final. For now we know that a C- equals to 50%
by Alara Aygen 3K
Mon Feb 01, 2021 3:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: endothermic/exothermic Q and K
Replies: 16
Views: 94

Re: endothermic/exothermic Q and K

In endothermic reactions heat goes into the system and results in a positive delta H. In exothermic reactions heat goes out of the system and results in a negative delta H.
by Alara Aygen 3K
Mon Feb 01, 2021 3:24 pm
Forum: General Science Questions
Topic: Midterm 1 Reactions
Replies: 70
Views: 350

Re: Midterm 1 Reactions

I also felt like it was harder than I have expected.
by Alara Aygen 3K
Mon Jan 25, 2021 3:51 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 1/25 Lecture Example Question
Replies: 5
Views: 46

Re: 1/25 Lecture Example Question

That was the change in temperature. (Final temperature = 31.9 degrees Celsius) - (Initial temperature = 25 degrees Celsius) = 6.9
Then you plug that value in the equation: (mass)x(specific heat capacity)x(delta T = change in temp) to find the value of heat given off by the reaction.
by Alara Aygen 3K
Mon Jan 25, 2021 3:46 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q Calculations
Replies: 6
Views: 19

Re: Q Calculations

Yes, you need to convert to moles as it is the correct unit for that calculation (unless it specifically asks for mmol).
by Alara Aygen 3K
Mon Jan 25, 2021 3:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to understand if -x is insignificant
Replies: 13
Views: 47

How to understand if -x is insignificant

Hi, can someone explain me when we leave out -x (in the denominator) while calculating the equilibrium constant/concentrations?
by Alara Aygen 3K
Mon Jan 25, 2021 3:42 pm
Forum: General Science Questions
Topic: Study Tips for midterm
Replies: 24
Views: 64

Re: Study Tips for midterm

Reviewing sapling questions and doing the problems in the outline really help.
by Alara Aygen 3K
Mon Jan 25, 2021 3:39 pm
Forum: Phase Changes & Related Calculations
Topic: calculator/ calcutation error
Replies: 5
Views: 41

Re: calculator/ calcutation error

I sometimes have the same problem. Putting the numbers that have powers in parentheses solves the problem.
by Alara Aygen 3K
Fri Jan 22, 2021 10:21 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa vs pH
Replies: 3
Views: 20

Re: pKa vs pH

I don't think pka equals to pH. pKa is the negative log of the acidity constant, Ka, but I believe they can be used to find out the pH of the solution since pH depends on [H3O+] concentration as well.
by Alara Aygen 3K
Thu Jan 21, 2021 12:56 pm
Forum: Student Social/Study Group
Topic: Practicing for Midterm 1
Replies: 12
Views: 64

Re: Practicing for Midterm 1

Doing the problems mentioned in the outlines and attending the UA workshops really help!
by Alara Aygen 3K
Wed Jan 20, 2021 7:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa and Ka
Replies: 27
Views: 78

Re: pKa and Ka

pKa is the -log of Ka. This means higher the Ka, smaller the pKa and vice versa
by Alara Aygen 3K
Wed Jan 20, 2021 7:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to fill in 2nd row of ICE table?
Replies: 25
Views: 71

Re: How to fill in 2nd row of ICE table?

You can determine it by the information you are given in the problem. For example if it says there was an addition to one of the reactants you can put a +x in the second row of that reactant. That would mean the product is decreasing as the reaction is favoring the reactant.
by Alara Aygen 3K
Wed Jan 20, 2021 7:19 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating pH/pOH for Weak Acids/Bases
Replies: 7
Views: 53

Re: Calculating pH/pOH for Weak Acids/Bases

It is because weak acids and bases do not completely disassociate in water. If it was a strong acid or base you could directly used the concentration because you would know that the concentration of the acid or base would equal to the concertation of [H30+] or [OH-] as they completely disassociate i...
by Alara Aygen 3K
Mon Jan 11, 2021 3:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #3 Question
Replies: 5
Views: 26

Re: Sapling #3 Question

When you write out your Kc expression, you get Kc= (2x)^2/ (xx- x)^2. Algebraically, you can take the square root of both sides, to cancel out the squares on the rigth side of the equation in order to make it easier for yourself to calculate. That's why you'd have 2x/(xx-x), instead of (2x)^2/ (xx-...
by Alara Aygen 3K
Mon Jan 11, 2021 3:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #3 Question
Replies: 5
Views: 26

Re: Sapling #3 Question

I am having trouble understanding that problem as well. How did you know we need to use 2X instead of (2X)^2?
by Alara Aygen 3K
Mon Jan 11, 2021 3:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Outline 1 Learning Objective [ENDORSED]
Replies: 5
Views: 71

Re: Outline 1 Learning Objective [ENDORSED]

Yes! A high K value indicates that the reaction favors the products, which means it is more soluble.
by Alara Aygen 3K
Mon Jan 11, 2021 2:42 pm
Forum: General Science Questions
Topic: Lecture Question [ENDORSED]
Replies: 5
Views: 40

Re: Lecture Question [ENDORSED]

We look at the stoichiometric coefficients. If we assume O2 has changed by -X, we can safely assume that N2 and N2O have changed by -2X and +2X respectively because both of their stoichiometric coefficients equal to two.
by Alara Aygen 3K
Mon Jan 11, 2021 2:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw
Replies: 9
Views: 52

Re: Kw

Alara Aygen 3K wrote:I believe it is found through experimentation


But can someone explain why [H3O+] and [OH-] concentrations need to be equal?
by Alara Aygen 3K
Mon Jan 11, 2021 2:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw in Lecture
Replies: 5
Views: 51

Re: Kw in Lecture

Kw is the equilibrium constant for: [H3O+][OH-] (the autoprotolysis of water)
by Alara Aygen 3K
Mon Jan 11, 2021 2:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw
Replies: 9
Views: 52

Re: Kw

I believe it is found through experimentation
by Alara Aygen 3K
Sun Jan 10, 2021 9:17 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K relationship
Replies: 12
Views: 66

Re: Q and K relationship

Q represents a constant at a specific time during the experiment. That's why if Q is bigger than or smaller than K, the reaction will shift because it won't be at equilibrium. If Q=K, then, it is at equilibrium. Hope this helps.
by Alara Aygen 3K
Mon Jan 04, 2021 5:34 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B Discussion Links
Replies: 5
Views: 55

Re: 14B Discussion Links

Hi, Dr. Lavelle sent out an email earlier today with TA Office Hours and Discussion sections for lecture 1 and 2. He said there was a problem with the zoom links for lecture 3, and those links will be posted once the problem is fixed. I'm not sure when they'll be posted on CCLE.
Hope this helps.
by Alara Aygen 3K
Mon Jan 04, 2021 5:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature Difference
Replies: 4
Views: 55

Re: Temperature Difference

I think changing temperature changes the rate at which the equation takes place. So, in this case the rate would be slower at lower temperatures.
by Alara Aygen 3K
Mon Jan 04, 2021 3:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining the favored substances
Replies: 3
Views: 18

Determining the favored substances

Hello, I just wanted to clarify something. When we want to determine the favored substance (products or reactants) do we look at the denominator and numerator of the Kc equation [if the denominator is bigger reactants are favored and if the numerator is bigger products are favored]? Also what does &...
by Alara Aygen 3K
Mon Jan 04, 2021 3:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Kc
Replies: 15
Views: 92

Re: K vs. Kc

They are used interchangeably.
by Alara Aygen 3K
Mon Jan 04, 2021 2:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Chemistry Posts in 14B
Replies: 153
Views: 2280

Re: Chemistry Posts in 14B

We need to create additional 50 posts for 14B (5 posts each week). So, in total we will have 100 posts.
by Alara Aygen 3K
Mon Dec 07, 2020 10:43 am
Forum: Conjugate Acids & Bases
Topic: What is a conjugate acid or base?
Replies: 5
Views: 59

Re: What is a conjugate acid or base?

If you are given a base and asked to find the conjugate acid, you need to add one H atom since Bronsted bases are proton acceptors.
If you are given an acid and asked to find the conjugate base, you need to remove one H atom, since the Bronsted acids are proton donors.
by Alara Aygen 3K
Mon Dec 07, 2020 10:40 am
Forum: Student Social/Study Group
Topic: Chem Website
Replies: 4
Views: 35

Re: Chem Website

If I am not mistaken, it was LL14A20.
by Alara Aygen 3K
Mon Dec 07, 2020 10:37 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: ligand
Replies: 3
Views: 10

Re: ligand

Ligands attach to the central metal ion and form coordination compounds.
by Alara Aygen 3K
Mon Dec 07, 2020 10:34 am
Forum: Student Social/Study Group
Topic: Step-up Sessions in Week 10
Replies: 5
Views: 41

Step-up Sessions in Week 10

Hi! Does anyone know what are the topics of the step-up sessions during this week? In the "final review sessions" pdf, every review session has a topic except for the step-up sessions. Are they general review?
by Alara Aygen 3K
Mon Dec 07, 2020 10:32 am
Forum: Bronsted Acids & Bases
Topic: pKA and KA
Replies: 4
Views: 43

Re: pKA and KA

Hi! They are inversely related. KA is the concentration of the acid, so higher the KA stronger the acid. pKA correspond to the pH scale, so higher the pKA weaker the acid.
by Alara Aygen 3K
Mon Nov 30, 2020 2:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: electronic geometry vs molecular geometry
Replies: 9
Views: 57

Re: electronic geometry vs molecular geometry

Hi! Electron geometry is the arrangement of electron groups. Molecular geometry is the arrangement of atoms.
by Alara Aygen 3K
Mon Nov 30, 2020 2:03 pm
Forum: Sigma & Pi Bonds
Topic: sigma bonds
Replies: 4
Views: 50

Re: sigma bonds

Electron density around the nuclei is higher in sigma bonds than in pi bonds. This causes sigma bonds to be stronger.
by Alara Aygen 3K
Mon Nov 30, 2020 1:56 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 7
Views: 78

Re: Resonance Structures

Hi! Resonance structures represent the same compound. The only aspect that differs is the arrangement of electrons (the number of electrons are the same).
by Alara Aygen 3K
Mon Nov 30, 2020 1:52 pm
Forum: Student Social/Study Group
Topic: Final Exam Study Tips
Replies: 48
Views: 283

Final Exam Study Tips

Hi! I was wondering how everyone will be studying for the final. Since it will be cumulative I don't know where to start studying. Does anyone have any tips?

Thank you in advance!
by Alara Aygen 3K
Mon Nov 30, 2020 1:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Finals Week
Replies: 12
Views: 183

Re: Finals Week

Finals are after week 10. So you don't have to worry about lectures. Downloading your calendar from MyUCLA might help you to track them better.
by Alara Aygen 3K
Tue Nov 24, 2020 11:05 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2 Results
Replies: 10
Views: 132

Re: Midterm 2 Results

Thank you!
by Alara Aygen 3K
Mon Nov 23, 2020 3:42 pm
Forum: Sigma & Pi Bonds
Topic: Delocalized Pi Bond
Replies: 5
Views: 46

Re: Delocalized Pi Bond

Hi! A delocalized pi bond means that electrons are free to move over the nuclei.
by Alara Aygen 3K
Mon Nov 23, 2020 3:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2 Results
Replies: 10
Views: 132

Midterm 2 Results

Does anyone know when we can expect our results, before or after the holiday?
by Alara Aygen 3K
Mon Nov 23, 2020 3:38 pm
Forum: Student Social/Study Group
Topic: Post Midterm Blues
Replies: 71
Views: 652

Re: Post Midterm Blues

I feel the same way. I was hoping for a really good exam; I thought I understood the topics well, but it was worse than the first one.
by Alara Aygen 3K
Mon Nov 23, 2020 3:36 pm
Forum: Student Social/Study Group
Topic: Exercising Our Minds and Bodies
Replies: 112
Views: 591

Re: Exercising Our Minds and Bodies

I try to go on regular walks where I can rest my mind and focus on nature.
by Alara Aygen 3K
Mon Nov 23, 2020 3:33 pm
Forum: Student Social/Study Group
Topic: How have your study habits changed?
Replies: 45
Views: 342

Re: How have your study habits changed?

I used to be like that too, taking wordy and lengthy notes. After the first midterm, I focused more on solving questions than taking long notes.
by Alara Aygen 3K
Tue Nov 17, 2020 12:29 pm
Forum: Lewis Structures
Topic: Most stable/ resonance structure
Replies: 3
Views: 28

Re: Most stable/ resonance structure

I believe that the most stable structure will be among one of the resonance structures you draw. The structure which the formal charges of the individual atoms are closest to zero will be favored. Also, you can look at the most electronegative atom, if it has the negative formal charge that structur...
by Alara Aygen 3K
Tue Nov 17, 2020 12:24 pm
Forum: Bond Lengths & Energies
Topic: Higher Melting Point
Replies: 5
Views: 65

Re: Higher Melting Point

The ion-ion forces between NaCl is stronger than the dipole-dipole interactions between HCl molecules. As the bond gets stronger, the boiling/melting point increases since more energy will be needed to break the bonds.
by Alara Aygen 3K
Tue Nov 17, 2020 12:20 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B and 14BL
Replies: 13
Views: 157

Re: 14B and 14BL

I will personally take them together, but there are also people who want to take BL after they take 14B.
by Alara Aygen 3K
Tue Nov 17, 2020 12:19 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Possible orbital amount
Replies: 1
Views: 28

Possible orbital amount

Hello! Can someone tell me how many orbitals can n=7 have?
by Alara Aygen 3K
Mon Nov 16, 2020 3:41 pm
Forum: Coordinate Covalent Bonds
Topic: Hydrogen Bonding
Replies: 5
Views: 47

Hydrogen Bonding

Hi! Can someone explain me why two NO molecules cannot form hydrogen bonds?
by Alara Aygen 3K
Mon Nov 09, 2020 2:10 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity vs. Electron Affinity vs. Ionization Energy
Replies: 6
Views: 41

Re: Electronegativity vs. Electron Affinity vs. Ionization Energy

Electronegativity is the ability to attract electrons. Electron affinity is the amount of energy released when a new electron is added to the neutral atom. Ionization energy is the minimum energy needed to remove the least tightly held electron. Hope this helps!
by Alara Aygen 3K
Mon Nov 09, 2020 2:07 pm
Forum: Coordinate Covalent Bonds
Topic: Is a Hydrogen Bond a Coordinate Covalent Bond? [ENDORSED]
Replies: 8
Views: 212

Re: Is a Hydrogen Bond a Coordinate Covalent Bond? [ENDORSED]

H bonds usually happen between H atoms and more electronegative atoms like F, O, and N. They are more like attractions than actual bonds. So, I don't think it is a coordinate covalent bond.
by Alara Aygen 3K
Mon Nov 09, 2020 2:04 pm
Forum: Student Social/Study Group
Topic: Chemistry Among Us
Replies: 43
Views: 461

Re: Chemistry Among Us

I would call out green just to be sure.
by Alara Aygen 3K
Mon Nov 09, 2020 2:03 pm
Forum: Electronegativity
Topic: Electronegativity vs. Electron Affinity
Replies: 8
Views: 38

Re: Electronegativity vs. Electron Affinity

Electronegativity is the ability to attract electrons. Electron affinity is the amount of energy released when a new electron is added to the neutral atom.
by Alara Aygen 3K
Mon Nov 09, 2020 2:00 pm
Forum: Ionic & Covalent Bonds
Topic: delta + or -
Replies: 12
Views: 97

Re: delta + or -

If the atom pulls the electrons it is delta negative and if the electrons are moving away from an atom it is delta positive
by Alara Aygen 3K
Mon Nov 02, 2020 1:24 pm
Forum: Lewis Structures
Topic: Different Lewis Structures
Replies: 6
Views: 53

Re: Different Lewis Structures

I believe they are different
by Alara Aygen 3K
Mon Nov 02, 2020 12:58 pm
Forum: Lewis Structures
Topic: Two different SO4^-2 structures
Replies: 2
Views: 27

Two different SO4^-2 structures

Hi! In today's lecture Dr. Lavelle mentioned two different SO4^-2 structures. One of them had a double bond. Can someone explain me why it is a better representation and how do we choose which structure to use?
by Alara Aygen 3K
Mon Nov 02, 2020 12:46 pm
Forum: Resonance Structures
Topic: Lecture 11/2
Replies: 5
Views: 41

Re: Lecture 11/2

You also need to think about the overall charge of the molecule. In NO3^- , it is minus 1. For example, in SO4^-2 it is -2. If the overall charge is negative you add that number of electrons to the other electrons to find the total electrons. If the overall charge is + (e.g. NH4^1) you substract tha...
by Alara Aygen 3K
Mon Nov 02, 2020 12:41 pm
Forum: Lewis Structures
Topic: Additional Stability
Replies: 2
Views: 25

Additional Stability

Hi! Can someone explain me the reason why delocalized electrons have additional stability?

Thanks in advance!
by Alara Aygen 3K
Mon Nov 02, 2020 10:35 am
Forum: Administrative Questions and Class Announcements
Topic: Chem 14B Enrollment
Replies: 27
Views: 348

Re: Chem 14B Enrollment

I tried to take Chem 14A last spring, but it was already full by the time of my second pass. So, I would suggest you take it during your first pass because this class fills up fast too. However, if you think you have other classes that may fill up faster then go with them!
by Alara Aygen 3K
Mon Oct 26, 2020 12:03 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: z electrons
Replies: 8
Views: 64

Re: z electrons

Hi! It should be the atomic number.
by Alara Aygen 3K
Mon Oct 26, 2020 11:43 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8731
Views: 1489114

Re: Post All Chemistry Jokes Here

I would write more chemistry jokes, but all the good ones argon.
by Alara Aygen 3K
Mon Oct 26, 2020 11:23 am
Forum: Limiting Reactant Calculations
Topic: What counts as theoretical yield?
Replies: 8
Views: 102

Re: What counts as theoretical yield?

The theoretical yield is the maximum amount of product you can get based on your calculations. However, this amount is usually not achieved in the actual experiment because of technicalities. Thus, the theoretical yield is usually higher than the actual yield.
by Alara Aygen 3K
Mon Oct 26, 2020 10:15 am
Forum: Photoelectric Effect
Topic: Lyman Series
Replies: 30
Views: 220

Re: Lyman Series

Hi! If it is Lyman series, n=1 should be in the equation. However, don't assume it only has to be the final state. If the e- is absorbing energy than n=1 is probably the initial state. Similarly, if e- is emitting energy than n=1 is probably the final state. Hope this helps!
by Alara Aygen 3K
Mon Oct 26, 2020 10:14 am
Forum: Photoelectric Effect
Topic: Lyman Series
Replies: 30
Views: 220

Re: Lyman Series

Hi! If it is Lyman series, n=1 should be in the equation. However, don't assume it only has to be the final state. If the e- is absorbing energy than n=1 is probably the initial state. Similarly, if e- is emitting energy than n=1 is probably the final state. Hope this helps!
by Alara Aygen 3K
Mon Oct 26, 2020 10:09 am
Forum: DeBroglie Equation
Topic: Sapling Question #19
Replies: 2
Views: 21

Re: Sapling Question #19

Yes, you should convert the units to m and kg if you are using De Broglie's equation for other units to cancel out.
by Alara Aygen 3K
Mon Oct 26, 2020 10:07 am
Forum: Administrative Questions and Class Announcements
Topic: Sapling Homework Score
Replies: 3
Views: 38

Sapling Homework Score

Hello,

I did the sapling homework (except for 3 questions, which I'll do by the end of this week) and currently my score is 90% on sapling. However, the grade section on CCLE did not update itself. Do you know when it updates the score or what should I do if it doesn't update?
Thanks in advance!
by Alara Aygen 3K
Mon Oct 19, 2020 11:06 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Negative sign in En expression
Replies: 8
Views: 74

Re: Negative sign in En expression

Hi,

It is negative because the electron is going from a higher energy level to a lower energy level, thus losing energy. Also keep in mind that the electron has started with 0 energy.
by Alara Aygen 3K
Mon Oct 19, 2020 10:47 am
Forum: DeBroglie Equation
Topic: E=pc and E=pv
Replies: 10
Views: 81

Re: E=pc and E=pv

I believe they are the same thing
by Alara Aygen 3K
Mon Oct 19, 2020 10:46 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectroscopy Post-Assessment Question
Replies: 6
Views: 55

Re: Atomic Spectroscopy Post-Assessment Question

I might be wrong about this but I believe it can detect molecules because every molecule absorb different wavelengths.
by Alara Aygen 3K
Mon Oct 19, 2020 10:41 am
Forum: Photoelectric Effect
Topic: Units of the Work Function
Replies: 7
Views: 51

Re: Units of the Work Function

I believe it is energy per electron. You might need to convert it to moles if the question specifically asks you to do so.
by Alara Aygen 3K
Mon Oct 19, 2020 10:36 am
Forum: DeBroglie Equation
Topic: Units [ENDORSED]
Replies: 3
Views: 48

Re: Units [ENDORSED]

It should be kg! It will cancel out with Planck's constant.
by Alara Aygen 3K
Fri Oct 16, 2020 4:09 pm
Forum: Photoelectric Effect
Topic: Homework Question
Replies: 2
Views: 28

Homework Question

Hi, This is a question from the homework. It is asking for the maximum number of electron that can be ejected by a burst of photons with a total energy of 9.69x10^-7 J. I calculated the work function as 5.54x10^-19 J/photon. I thought that "work function x # of e-" should equal to the tota...
by Alara Aygen 3K
Fri Oct 16, 2020 4:01 pm
Forum: Photoelectric Effect
Topic: photoelectric effect
Replies: 17
Views: 143

Re: photoelectric effect

Yes, the first time they conducted the experiment they called it the threshold energy because the amount of energy needed to eject an electron had to be higher than that. I believe the work function is a more accurate term, but they mean the same thing.
by Alara Aygen 3K
Fri Oct 16, 2020 9:15 am
Forum: General Science Questions
Topic: Credit for community forum [ENDORSED]
Replies: 7
Views: 92

Re: Credit for community forum [ENDORSED]

Hi, Additionally to what everyone has said, this is from his last email: "Posting admin questions in a Quantum section, or Fundamentals questions in a Quantum section, is clearly not valid and makes a mess of the forum that is carefully organized by topic to assist students. To receive Chemistr...
by Alara Aygen 3K
Mon Oct 12, 2020 1:15 pm
Forum: Photoelectric Effect
Topic: Focus-Topics Photoelectric Effect Assessment Question #34
Replies: 2
Views: 19

Focus-Topics Photoelectric Effect Assessment Question #34

Hello, can someone explain me how to solve this question please? "Molybdenum metal must absorb radiation with a minimum frequency of 1.09x10^15 /s before it can emit an electron from its surface. If molybdenum is irradiated with 194 nm light, what is the maximum possible kinetic energy of the e...
by Alara Aygen 3K
Mon Oct 12, 2020 1:07 pm
Forum: Photoelectric Effect
Topic: Solving photoelectric effect questions
Replies: 4
Views: 31

Solving photoelectric effect questions

Hello, this was a question from the audio-visual focus assessment modules and I can't find the correct answer. "Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 10^5 m/s. The work function for sodium is 150.6 k.J /mol. What is the kinetic energy of the ejecte...
by Alara Aygen 3K
Mon Oct 12, 2020 12:59 pm
Forum: Properties of Light
Topic: Properties of light
Replies: 3
Views: 47

Properties of light

Hello, this was a question from the audio-visual focus assessment modules: "To interpret the result of photoelectric experiments the model of light needs to change from a _________ model to a _________ model." I said "wave, photon" but apparently it is wrong. Can someone tell me ...
by Alara Aygen 3K
Mon Oct 12, 2020 12:54 pm
Forum: Photoelectric Effect
Topic: Detector in Photoelectric Experiment
Replies: 4
Views: 29

Re: Detector in Photoelectric Experiment

Hi,
I might be wrong about this, but as far as I know, the detector detects both the number of ejected electrons and their kinetic energy. So, an electron may not have an excess energy but the detector will still detect it as an individual electron.
by Alara Aygen 3K
Mon Oct 12, 2020 12:49 pm
Forum: Properties of Light
Topic: Origin of c=λv
Replies: 3
Views: 59

Re: Origin of c=λv

Hello,
In the wave model λ and v are inversely proportional. For example, if one of them doubles, the other will decrease by half. Thus, creating a constant. In this case, it is c=3.00x10^8.
by Alara Aygen 3K
Mon Oct 05, 2020 12:56 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity and Dilution of a Solution
Replies: 6
Views: 65

Molarity and Dilution of a Solution

Hi, This question was from the Audio-Visual Focus-Topic Assessments. For some reason, I can't get the correct answer. Can someone explain it to me please? "A solution is prepared by dissolving 55.1g of KCl in approximately 75mL of water and then adding water to a final volume of 125mL. What is ...
by Alara Aygen 3K
Mon Oct 05, 2020 12:45 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 14
Views: 191

Re: Combustion

Hi, combustion is a type of oxidation reaction. In other words, combustion of an organic molecule means that, that organic molecule is reacting with oxygen [it is also called 'burning' or 'oxidation' ]. So, O2 must be in the reactants side and these reactions usually result in CO2 and H20. Hope that...
by Alara Aygen 3K
Mon Oct 05, 2020 12:15 pm
Forum: Balancing Chemical Reactions
Topic: Stoichiometric Coefficients
Replies: 20
Views: 149

Re: Stoichiometric Coefficients

Hi,
Sometimes some of the coefficients may be missing. So even though you see one stoichiometric coefficient, the rest of the equation may be unbalanced. It is always good to check before solving the question.
by Alara Aygen 3K
Mon Oct 05, 2020 12:07 pm
Forum: Balancing Chemical Reactions
Topic: L.35
Replies: 9
Views: 113

Re: L.35

This is the explanation in the "Solution Manual Errors" pdf (It can be found on Dr. Lavelle's website):

L.35 in the textbook question:
In the third reaction step the compound "FeBr2" needs to be "Fe3Br8".
I hope that helps.
by Alara Aygen 3K
Mon Oct 05, 2020 11:58 am
Forum: Balancing Chemical Reactions
Topic: Balancing chemical equations involving combustion
Replies: 15
Views: 117

Re: Balancing chemical equations involving combustion

I believe that is correct. He also gave a key concept which said "Combustion or burning or oxidation" from this statement, I understand that combustion is a type of oxidation reaction. Since it is an oxidation reaction we can add O2 on the reactant side.

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