Search found 87 matches

by Xinyu Li 1C
Sun Feb 21, 2021 11:38 pm
Forum: General Science Questions
Topic: MT 2 grades
Replies: 32
Views: 103

Re: MT 2 grades

It usually comes out within a week following the midterm.
by Xinyu Li 1C
Sun Feb 21, 2021 11:29 pm
Forum: Student Social/Study Group
Topic: Fave food
Replies: 99
Views: 204

Re: Fave food

I love bite sized nutter butter cookies!
(definitely not a healthy choice tho)
by Xinyu Li 1C
Sun Feb 21, 2021 11:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter Calibration
Replies: 4
Views: 17

Re: Calorimeter Calibration

To calibrate the calorimeter, all you need to do is divide heat gained by the calorimeter (or heat lost by the reaction) by the change in temperature.

Ccal=qcal/delta T
by Xinyu Li 1C
Sun Feb 21, 2021 11:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Classes for Biochem Majors
Replies: 6
Views: 31

Re: Classes for Biochem Majors

From my understanding, the 14 series is designed for life science majors. You probably need to take the 30 series to fulfill your major prereqs. Best of luck.
by Xinyu Li 1C
Sun Feb 14, 2021 9:51 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: values
Replies: 3
Views: 22

Re: values

I don't think we'll be expected to memorize any of these. Everything we need to solve the problem should be provided on the test or the constants and equation sheet.
by Xinyu Li 1C
Sun Feb 14, 2021 9:49 pm
Forum: Calculating Work of Expansion
Topic: Work Done on System?
Replies: 12
Views: 46

Re: Work Done on System?

I think work done on the system is when energy is being applied, like compression. Whereas, work done by the system would be expansion since the system is using energy to push against external pressure.
by Xinyu Li 1C
Sun Feb 14, 2021 9:46 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Residual Entropy
Replies: 5
Views: 21

Re: Residual Entropy

From my understanding, residual entropy ignores thermal motion and can be calculated by using the Boltzmann equation (S = Kb * ln W).
by Xinyu Li 1C
Sun Feb 14, 2021 9:43 pm
Forum: Ideal Gases
Topic: Chem BL
Replies: 89
Views: 396

Re: Chem BL

I think people usually take it with 14C. I might take it next quarter if it doesn't fill up by second pass.
by Xinyu Li 1C
Sun Feb 07, 2021 7:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Can We Review our Exams?
Replies: 69
Views: 241

Re: Can We Review our Exams?

I think you can review questions you missed in your TA's office hours. Just shoot them an email.
by Xinyu Li 1C
Sun Feb 07, 2021 7:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2
Replies: 31
Views: 138

Re: Midterm 2

I don't think Professor Lavelle posted an outline for midterm 2 yet.
by Xinyu Li 1C
Sun Feb 07, 2021 6:54 pm
Forum: Student Social/Study Group
Topic: Chemistry Community Posts
Replies: 9
Views: 54

Re: Chemistry Community Posts

Use the number you see when you click on "Your posts".
by Xinyu Li 1C
Sun Feb 07, 2021 6:40 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: deltaU
Replies: 29
Views: 100

Re: deltaU

Delta U is the change in internal energy. You can calculate delta U by using the following formula:

Delta U = n * Cv * delta T
by Xinyu Li 1C
Sun Feb 07, 2021 6:09 pm
Forum: Student Social/Study Group
Topic: Silly Mistakes?
Replies: 60
Views: 282

Re: Silly Mistakes?

Thank you so much for sharing this!
by Xinyu Li 1C
Sun Jan 31, 2021 11:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Taking the Anti-Log
Replies: 36
Views: 111

Re: Taking the Anti-Log

Like everyone said, you'd do 10^(-pKa) to go from pKa to Ka.
by Xinyu Li 1C
Sun Jan 31, 2021 11:13 pm
Forum: General Science Questions
Topic: Midterm 1 Reactions
Replies: 70
Views: 350

Re: Midterm 1 Reactions

I didn't feel as confident about this midterm. I felt it was more difficult than 14A midterms.
by Xinyu Li 1C
Sun Jan 31, 2021 11:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Factors that affect the equilibrium constant
Replies: 25
Views: 59

Re: Factors that affect the equilibrium constant

Professor Lavelle said the only factor that affect K is temperature.
by Xinyu Li 1C
Sun Jan 31, 2021 11:11 pm
Forum: Student Social/Study Group
Topic: Average amount of study hours per week
Replies: 28
Views: 134

Re: Average amount of study hours per week

Usually I just watch the lectures and do a UA worksheet. So around 6 hours per week.
by Xinyu Li 1C
Sun Jan 31, 2021 11:09 pm
Forum: Student Social/Study Group
Topic: Spring 2021
Replies: 104
Views: 433

Re: Spring 2021

I'm planning to take 14BL next quarter!
by Xinyu Li 1C
Sun Jan 24, 2021 10:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to find equations
Replies: 4
Views: 18

Re: How to find equations

Add water (H20) to the reactant and hydronium ion (H3O+) if it's an acid or hydroxide ion (OH-) if it's a base. The balance everything out.

Ex: HClO + H2O = H3O+ + ClO-
by Xinyu Li 1C
Sun Jan 24, 2021 10:38 pm
Forum: Student Social/Study Group
Topic: Midterm Study Tips
Replies: 41
Views: 150

Re: Midterm Study Tips

Rosa told me that there's a helpful review midterm sheet from last year.

Link: viewtopic.php?f=160&t=58508&p=224708&hilit=pizza+rolls&sid=297c8e7a86a4e1bca675da3c35540d64#p224708
*if the link doesn't work, search pizza rolls
by Xinyu Li 1C
Sun Jan 24, 2021 10:07 pm
Forum: Student Social/Study Group
Topic: UA Sessions
Replies: 5
Views: 49

Re: UA Sessions

by Xinyu Li 1C
Sun Jan 24, 2021 10:06 pm
Forum: Student Social/Study Group
Topic: UA session ?
Replies: 1
Views: 17

Re: UA session ?

UA sessions are peer learning sessions hosted by undergraduate assistants (UA). These are small group discussions and Q&A.
by Xinyu Li 1C
Sun Jan 17, 2021 11:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Simplifying Quadratic Equations
Replies: 5
Views: 20

Re: Simplifying Quadratic Equations

Professor Lavelle mentioned in lecture that some textbook uses 10^-3 but he prefers us go by 10^-4 just to be on the safe side. You can always check by dividing X by initial, if X is less than 5% of initial then it's okay to approximate.
by Xinyu Li 1C
Sun Jan 17, 2021 11:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw Uses
Replies: 6
Views: 27

Re: Kw Uses

You can use it for all problems involving pH I believe.
by Xinyu Li 1C
Sun Jan 17, 2021 11:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Box Units
Replies: 6
Views: 41

Re: ICE Box Units

You can! Just make sure you convert it into molar concentration before you calculate K.
by Xinyu Li 1C
Sun Jan 17, 2021 11:05 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Weak vs. Strong Acids and Bases
Replies: 9
Views: 62

Re: Weak vs. Strong Acids and Bases

There is a list of strong acids and bases in the textbook. But generally, strong acids will contain halogens (Cl, Br, I) and strong bases will contain elements from group 1 & 2 (Li, Na, K, Rb, Cs, Ca, Sr, Ba).

https://sites.google.com/site/chempendi ... #h.p_ID_32
by Xinyu Li 1C
Sun Jan 17, 2021 10:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: C in ICE Box
Replies: 19
Views: 82

Re: C in ICE Box

The change in reactants is always negative and the change in products is always positive because reactants are being used up to form products.
by Xinyu Li 1C
Sun Jan 17, 2021 10:53 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: When would K be unchanged?
Replies: 31
Views: 93

Re: When would K be unchanged?

K would also change when the coefficients of the species in a reaction are multiplied by a number. In that case, K would be raised to the power of that number.
by Xinyu Li 1C
Sun Jan 10, 2021 9:43 pm
Forum: Student Social/Study Group
Topic: Chemistry Community Points
Replies: 12
Views: 85

Re: Chemistry Community Points

Yes, you will. Oftentimes there are less people posting questions so this is bound to happen.
by Xinyu Li 1C
Sun Jan 10, 2021 9:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 10^3-10^-3
Replies: 2
Views: 20

Re: 10^3-10^-3

Like the Josh said, technically it would be favoring one side or the other unless K=0, just not "strongly favored."
by Xinyu Li 1C
Sun Jan 10, 2021 9:31 pm
Forum: Student Social/Study Group
Topic: Chemistry Community
Replies: 29
Views: 114

Re: Chemistry Community

Sunday 11:59 PM PST is the official deadline for your weekly posts but most TAs will allow you to make up for missed points in the following weeks.
by Xinyu Li 1C
Sun Jan 10, 2021 9:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Substances for Calculating K
Replies: 4
Views: 11

Re: Substances for Calculating K

I think Professor Lavelle said that solids don't have a concentration (since it's not in liquid) and changes in solvent concentration is insignificant so it is excluded from calculations.
by Xinyu Li 1C
Sun Jan 10, 2021 9:09 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 348

Re: Units of Temperature

You should use Kelvin.
by Xinyu Li 1C
Sun Dec 06, 2020 9:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 5
Views: 35

Re: Coordination Number

You are really close. The coordination number for this compound is actually 6 because there are 6 coordinate covalent bond here, 1 from SO4 and 5 from (NH3)5. 1+5=6

Note: each NH3 contributes 1 coordinate covalent bond
by Xinyu Li 1C
Sun Dec 06, 2020 9:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Zoom Link
Replies: 6
Views: 82

Re: Final Zoom Link

I'd assume it's the same TA link as our last midterm but I'm not 100% sure.
by Xinyu Li 1C
Sun Dec 06, 2020 9:16 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: HW Question coordination number
Replies: 4
Views: 28

Re: HW Question coordination number

Coordination number = number of coordinate covalent bond

There are 6 coordinate covalent bond here, 1 from each ligand (1 SO4 + 5 NH3). Hope this helps.
by Xinyu Li 1C
Sun Dec 06, 2020 9:08 pm
Forum: Student Social/Study Group
Topic: Week 8/9 Thoughts/Worries
Replies: 66
Views: 503

Re: Week 8/9 Thoughts/Worries

I'm a very worried about making silly mistakes and not doing well on the final. Especially since there is no partial credit and grade is heavily dependent on exam scores :<
by Xinyu Li 1C
Sun Dec 06, 2020 8:58 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Textbook Problem 9C7
Replies: 1
Views: 15

Re: Textbook Problem 9C7

Chelating complexes are complexes containing a ligand that forms a ring of atoms that includes the central metal atom. In order to form a chelate, you need a ligand with the ideal geometry, which is (atom w/ lone pair) + (spacer) + (spacer) + (atom w/ lone pair) and the bonds need to be able to rota...
by Xinyu Li 1C
Sun Dec 06, 2020 8:53 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework Problem 9C.7
Replies: 5
Views: 61

Re: Homework Problem 9C.7

In order to form chelating complexes, you need bonds that can rotate (single bonds) and the the ideal geometry, which is (atom w/ lone pair) + (spacer) + (spacer) + (atom w/ lone pair)

In this case, the answer would be b) because a) and c) have too many spacers between atoms w/ lone pairs.
by Xinyu Li 1C
Sun Dec 06, 2020 8:48 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8731
Views: 1489313

Re: Post All Chemistry Jokes Here

Two chemists meet for the first time at a symposium. One is American, one is British. The British chemists asks the American chemist, "So what do you do for research?" The American responds, "Oh, I work with arsoles." The Brit responds, "Yes, sometimes my colleagues get on m...
by Xinyu Li 1C
Sun Dec 06, 2020 8:44 pm
Forum: Naming
Topic: Homework Problem 9C.1
Replies: 4
Views: 34

Re: Homework Problem 9C.1

I think Professor Lavelle said both are acceptable.
by Xinyu Li 1C
Sun Dec 06, 2020 8:40 pm
Forum: Sigma & Pi Bonds
Topic: Pi bonds
Replies: 7
Views: 53

Re: Pi bonds

Pi bond is the lateral or side-by-side overlap of 2 orbitals (4 orbital overlap). It do not allow bound atoms to rotate and have 1 nodal plane. It usually between p- and d- orbitals.
by Xinyu Li 1C
Sun Dec 06, 2020 7:53 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling 5
Replies: 6
Views: 56

Re: Sapling 5

(en) refers to NH2CH2CH2NH2, or ethylenediamine. It's a bidentate ligand (coordination number=2). And chlorine is a monodentate ligand (coordination number=1). So together, the coordination number for [Co(en)2(CO)2]Br is 2*2+2*1=6.
by Xinyu Li 1C
Sun Dec 06, 2020 7:43 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling Question #5
Replies: 3
Views: 52

Sapling Question #5

For each metal complex, give the coordination number for the metal species.
[Pt(en)Cl2]

Are we expected to know the name and denticity for ligands like ethylenediamine(en) and 1,2-bis(diphenylphosphino)ethane(dppe) on the midterms?
by Xinyu Li 1C
Sun Nov 22, 2020 11:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Thanksgiving
Replies: 26
Views: 206

Re: Thanksgiving

I think it's highly likely that we will have a lecture on Friday, but discussions should be cancelled. Happy Thanksgiving :3
by Xinyu Li 1C
Sun Nov 22, 2020 11:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 25
Views: 163

Re: Bond Angles

I think we will need to know the bond angles for electron pair geometries (without lone pair), like 180, 120, 109, 90; and that having lone pairs influences the bond angles between bonded atom. But I doubt we will be required to memorize specific bond angles for different molecules.
by Xinyu Li 1C
Sun Nov 22, 2020 11:00 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 7
Views: 32

Re: Ionic and Covalent Bonds

Ionic
- Typically between metal and nonmetal
- Involve transfer of electrons

Covalent
- Typically between nonmentals
- Involve sharing of electrons
by Xinyu Li 1C
Sun Nov 22, 2020 10:57 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: Dipole-Induced-Dipole and Dipole-Dipole
Replies: 10
Views: 149

Re: Dipole-Induced-Dipole and Dipole-Dipole

Dipole-dipole is between two polar molecules whereas dipole-induced dipole is between a polar molecule and a nonpolar molecule.

Examples
dipole-dipole: HF-HF (HF is polar)
dipole-induced dipole: HCl-N2 (HCl is polar and N2 is nonpolar)
by Xinyu Li 1C
Sun Nov 22, 2020 10:52 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Optimal Formal Charge Configuration
Replies: 3
Views: 49

Re: Optimal Formal Charge Configuration

Typically, you want to place the negative formal charge on the more electronegative atom and the positive formal charge on the less electronegative atom. Hope this helps.
by Xinyu Li 1C
Sun Nov 22, 2020 10:49 pm
Forum: Sigma & Pi Bonds
Topic: Pi Bonds with s Orbital
Replies: 4
Views: 35

Re: Pi Bonds with s Orbital

That would not be possible because the s orbital is spherical. You need at least two p orbitals to form a pi bond.
by Xinyu Li 1C
Sun Nov 22, 2020 10:45 pm
Forum: Hybridization
Topic: Strength of Sigma Bonds vs Pi Bonds
Replies: 5
Views: 44

Re: Strength of Sigma Bonds vs Pi Bonds

Sigma bonds are stronger because it's a head-on overlap between the orbitals, which allows electron density to be concentrated to a much larger degree between the two nuclei.
by Xinyu Li 1C
Sun Nov 22, 2020 10:41 pm
Forum: Student Social/Study Group
Topic: Finals!
Replies: 43
Views: 358

Re: Finals!

Yes, it will be cumulative.
by Xinyu Li 1C
Sun Nov 22, 2020 10:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: NO2- Bent Molecular Geometry
Replies: 7
Views: 61

Re: NO2- Bent Molecular Geometry

NO2- have 2 electron pairs and 1 lone pairs, making it AX2E, which is bent/angular.
Image
by Xinyu Li 1C
Sun Nov 22, 2020 10:32 pm
Forum: Sigma & Pi Bonds
Topic: Pi Bond Name
Replies: 5
Views: 44

Re: Pi Bond Name

Pi is the greek version of the letter p. In this case, it's referring to the p orbital. Pi bonds are commonly formed between p orbitals, as shown in Dr. Lavelle's lecture. However, d orbitals can also engage in pi bonding.
by Xinyu Li 1C
Sun Nov 15, 2020 11:56 pm
Forum: Dipole Moments
Topic: Which interactions are intermolecular?
Replies: 7
Views: 60

Re: Which interactions are intermolecular?

Yes, these are intermolecular forces since they are interactions between molecules rather than within molecules.
by Xinyu Li 1C
Sun Nov 15, 2020 11:55 pm
Forum: Student Social/Study Group
Topic: Midterm 2 content
Replies: 20
Views: 157

Re: Midterm 2 content

I think this midterm will be more focused on bonding and Lewis structures. So just be ready to calculate formal charge.
by Xinyu Li 1C
Sun Nov 15, 2020 11:52 pm
Forum: Student Social/Study Group
Topic: Class grade
Replies: 18
Views: 155

Re: Class grade

I'm on a pre-med track and am currently a pre-psychobio major. Is anyone in a similar boat to me who knows what the consequences of changing to P/NP will be? What are the pros or cons? I believe changing to P/NP gives you credit without having it affect your GPA in a negative way (if you at least p...
by Xinyu Li 1C
Sun Nov 15, 2020 11:47 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B and 14BL
Replies: 6
Views: 46

Re: 14B and 14BL

I think people usually take 14BL with 14C.
by Xinyu Li 1C
Sun Nov 08, 2020 10:50 pm
Forum: Photoelectric Effect
Topic: Participation points
Replies: 16
Views: 176

Re: Participation points

My TA said it's fine as long as you have 50 posts by the end of the quarter.
by Xinyu Li 1C
Sun Nov 08, 2020 10:46 pm
Forum: Student Social/Study Group
Topic: Mid-quarter Check in
Replies: 67
Views: 294

Re: Mid-quarter Check in

I'm feeling very burnt out and my mental health is taking a hit. The quarter system makes me want to die i_i
by Xinyu Li 1C
Sun Nov 08, 2020 10:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Taking Bio and Chem simultaneously
Replies: 26
Views: 114

Re: Taking Bio and Chem simultaneously

I'm taking LS7B and CHEM14A this quarter along with LS30A and another GE. The workload is not too bad but it's certainly not light. It's definitely doable if you are willing to put in the effort.
by Xinyu Li 1C
Sun Nov 08, 2020 10:39 pm
Forum: Ionic & Covalent Bonds
Topic: Difference Between Ionic & Covalent Bonds
Replies: 11
Views: 65

Re: Difference Between Ionic & Covalent Bonds

Aside from what everyone mentioned, ionic bonds tend to be stronger than covalent bonds due to the coulombic attraction between ions of opposite charges. However, covalent bonds are stronger than ionic bonds in water.
by Xinyu Li 1C
Sun Nov 08, 2020 10:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 1 answer key
Replies: 13
Views: 108

Re: Midterm 1 answer key

Dr. Lavelle said that he'll go over some of the questions but we won't be able to see which question we missed.
by Xinyu Li 1C
Sat Oct 24, 2020 9:25 pm
Forum: Administrative Questions and Class Announcements
Topic: Constants in the tests
Replies: 5
Views: 47

Re: Constants in the tests

You can use the "Constants and Equations" sheet from Dr. Lavelle's website during the midterm.
by Xinyu Li 1C
Sat Oct 24, 2020 9:12 pm
Forum: Properties of Electrons
Topic: Question 12 on sapling week 2
Replies: 4
Views: 57

Re: Question 12 on sapling week 2

I think it's just different units. It can also be:



by Xinyu Li 1C
Sat Oct 24, 2020 8:56 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Post-Module Assessment #29
Replies: 4
Views: 59

Re: Photoelectric Effect Post-Module Assessment #29

luludaly2B wrote:Thank you! I did this and then multiplied by 1000, in order to convert the number into J from kJ. Is this correct?


Yes :)
by Xinyu Li 1C
Sat Oct 24, 2020 8:51 pm
Forum: DeBroglie Equation
Topic: Textbook Question 1B.15
Replies: 6
Views: 74

Re: Textbook Question 1B.15

In part b, you are given the threshold frequency, which is the minimum frequency of radiation required to remove an electron from a metal surface. To solve this problem, just calculate the work function from threshold frequency using: \phi =hf_{o} \phi = work function h = Planck constant f_{o} = thr...
by Xinyu Li 1C
Sat Oct 24, 2020 8:38 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Roman Numerials Next to Metals
Replies: 3
Views: 75

Re: Roman Numerials Next to Metals

The roman numerals indicate the charge and oxidation state of transition metal ions. Typically, you want the overall charge to be zero.

Ex: if sulfide have a charge of -2, you'd want the iron ion to have a charge of +2, written as iron (II) or
by Xinyu Li 1C
Sat Oct 24, 2020 8:29 pm
Forum: Student Social/Study Group
Topic: Topic 1.C
Replies: 2
Views: 35

Re: Topic 1.C

Dr. Lavelle told us that the midterm covers everything up the materials discussed on Wednesday's lecture :)
by Xinyu Li 1C
Sat Oct 24, 2020 8:24 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Amplitude
Replies: 16
Views: 85

Re: Amplitude

Increasing amplitude = increasing intensity. I don't think it's related to wavelength and/or frequency. But I could be wrong.
by Xinyu Li 1C
Sat Oct 24, 2020 8:17 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr Frequency Condition: v
Replies: 3
Views: 46

Re: Bohr Frequency Condition: v

I think they are both referring to frequency.
by Xinyu Li 1C
Sat Oct 24, 2020 8:08 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Textbook Question 1B.25
Replies: 4
Views: 81

Re: Textbook Question 1B.25

I think it stands for reduced Planck constant, which is equal to .

Edit: spelling
by Xinyu Li 1C
Sat Oct 24, 2020 8:05 pm
Forum: Photoelectric Effect
Topic: Calculations
Replies: 18
Views: 122

Re: Calculations

I usually keep all of my digits and round at the very end, not sure if it's correct. But, I don't think it will be a big deal for midterm since it's multiple choice.
by Xinyu Li 1C
Sat Oct 24, 2020 8:00 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Post-Module Assessment #29
Replies: 4
Views: 59

Re: Photoelectric Effect Post-Module Assessment #29

The work function is basically the minimum E needed to remove an electron from a metal surface. In this case, it is already given to you in the unit kJ/mol. To find the energy required to remove an electron from ONE sodium atom, just divide 150.6 kJ/mol by Avogadro's number.
by Xinyu Li 1C
Sat Oct 24, 2020 7:55 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Problem
Replies: 6
Views: 67

Re: Photoelectric Effect Problem

2878.68 nm? I'm not too sure.
by Xinyu Li 1C
Sat Oct 24, 2020 7:47 pm
Forum: DeBroglie Equation
Topic: Sapling Weeks 2-4 #22
Replies: 4
Views: 36

Re: Sapling Weeks 2-4 #22

Your approach to the question sounds right to me, maybe double check your calculations?
by Xinyu Li 1C
Sat Oct 24, 2020 7:42 pm
Forum: Balancing Chemical Reactions
Topic: combustion
Replies: 4
Views: 57

Re: combustion

I think it indicates that the reaction is to be heated.
by Xinyu Li 1C
Sat Oct 24, 2020 7:39 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity and Electronegativity
Replies: 9
Views: 84

Re: Electron Affinity and Electronegativity

Electronegativity: how well an atom can attract electrons toward itself

Electron affinity: amount of energy released when an electron is added to a molecule or atom
by Xinyu Li 1C
Sat Oct 24, 2020 7:36 pm
Forum: Student Social/Study Group
Topic: Chem Community Questions
Replies: 6
Views: 74

Re: Chem Community Questions

They are due at 11:59 PM PST/PDT every Sunday :)
by Xinyu Li 1C
Sat Oct 24, 2020 7:22 pm
Forum: Properties of Light
Topic: Sapling HW question 12
Replies: 3
Views: 36

Re: Sapling HW question 12

1. Calculate the energy of electron in ground state and 5th energy level. E_{n}=-\frac{hR}{n^{2}} h = 6.626*10^{-34} R = 3.29*10^{15} n = energy level 2. Calculate the energy emitted. \Delta E=E_{final}-E_{initial} \Delta E = E_{1}-E_{5} 3. Calculate the wavelength from \Delta E \lambda =\frac{hc}{E...
by Xinyu Li 1C
Sat Oct 24, 2020 7:09 pm
Forum: Photoelectric Effect
Topic: Textbook 1B.3A problem
Replies: 2
Views: 43

Re: Textbook 1B.3A problem

The term "work function" refers to the minimum E required to remove an electron from a metal surface. Remember, longer wavelength = lower frequency = lower energy. So when the problem asks you to find the longest wavelength, you can just calculate the wavelength of the electromagnetic radi...
by Xinyu Li 1C
Sat Oct 24, 2020 6:36 pm
Forum: Properties of Electrons
Topic: Textbook problem Quantum World 1A 15
Replies: 3
Views: 39

Re: Textbook problem Quantum World 1A 15

The unit for wavelength in E= is meter (m), not nanometer (nm). Therefore, you'd need to convert 102.6 nm to m before plugging it into the equation.



Edit: formatting
by Xinyu Li 1C
Sat Oct 24, 2020 6:22 pm
Forum: Einstein Equation
Topic: Week 2-4 Sapling HW Quesiton 25
Replies: 6
Views: 101

Re: Week 2-4 Sapling HW Quesiton 25

From my understanding, E=hv is only used for calculating energy of photons whereas the de Broglie's equation is used for calculating energy of any moving particles with momentum.
by Xinyu Li 1C
Sat Oct 24, 2020 6:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Calculator
Replies: 3
Views: 20

Re: Calculator

I believe we are allowed to use a scientific calculator.

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