Search found 60 matches

Sun Jan 17, 2021 5:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K
Replies: 46
Views: 153

Re: Q and K

I understand the relationship between Q and K, but can someone tell me why/when we would want to measure the Q/when it would be important? You could measure Q in order to figure out what direction the reaction is going towards. When Q<K, the reaction favors the forward reaction/products and if Q>K,...
Sun Jan 17, 2021 5:20 pm
Forum: Student Social/Study Group
Topic: Comfort Movies
Replies: 108
Views: 242

Re: Comfort Movies

I like Studio Ghibli movies and Spiderman: Into the Spiderverse!
Sun Jan 17, 2021 5:19 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q > K, Q< K
Replies: 25
Views: 75

Re: Q > K, Q< K

When Q < K, the reaction will favor the forward reaction, so there will be more products formed. When Q > K, the reverse reaction is favored with more reactants forming
Sun Jan 17, 2021 5:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: shifts left or right
Replies: 20
Views: 42

Re: shifts left or right

A shift to the left means that reactants are favored while a shift to the right favors products.
Sun Jan 17, 2021 5:12 pm
Forum: Ideal Gases
Topic: Inverse Kc
Replies: 29
Views: 61

Re: Inverse Kc

You want to use the inverse of Kc when solving for the Kc of the reverse reaction.
Sun Jan 10, 2021 6:25 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 287

Re: Units of Temperature

Kelvin. You can convert celsius to kelvin with K = C + 273.15.
Sun Jan 10, 2021 6:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Counting Moles
Replies: 11
Views: 56

Re: Counting Moles

You only count gases since the question is asking abt pressure.
Sun Jan 10, 2021 6:15 pm
Forum: Student Social/Study Group
Topic: Study Habits
Replies: 91
Views: 246

Re: Study Habits

I found the assigned textbook problems on the syllabus to be really helpful in practicing my understanding. Also, try to space out your studying instead of a long intensive study session.
Sun Jan 10, 2021 6:09 pm
Forum: Student Social/Study Group
Topic: Chemistry Community
Replies: 29
Views: 82

Re: Chemistry Community

In an email, Professor Lavelle said 5 posts per week = 5 pts per week. I think the deadline is on sundays, but different TAs might have a different rules.
Sun Jan 10, 2021 6:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Equilibrium Concentrations
Replies: 10
Views: 40

Re: Calculating Equilibrium Concentrations

yeah, solids and liquids aren't included because their change in concentration is very small.
Tue Dec 15, 2020 3:54 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Square Planar vs. Tetrahedral
Replies: 15
Views: 123

Re: Square Planar vs. Tetrahedral

Tetrahedral shapes are AX4, so there are only 4 bonded atoms while square planar is AX4E2, so it has 2 more lone pairs.
Tue Dec 15, 2020 3:53 am
Forum: Lewis Acids & Bases
Topic: KA and pKA
Replies: 19
Views: 144

Re: KA and pKA

Ka is the acidity constant and pKa is the -log of Ka. Ka = [H+][A-]/[HA]. Both can be used to find out how strong an acid is. A higher Ka means a lower pKa and stronger acid while a lower Ka means a higher pKa and weaker acid.
Tue Dec 15, 2020 3:47 am
Forum: Determining Molecular Shape (VSEPR)
Topic: axial/equatorial
Replies: 5
Views: 45

Re: axial/equatorial

Equatorial are on the same horizontal plane as the central atom while axial are above/below that plane.
Tue Dec 15, 2020 3:46 am
Forum: Naming
Topic: Ligand use -ate
Replies: 18
Views: 108

Re: Ligand use -ate

You use ate when overall charge is negative.
Tue Dec 15, 2020 3:45 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer and Lyman Series
Replies: 6
Views: 61

Re: Balmer and Lyman Series

I remember that Lyman is around 100nm while Balmer is around 400-600nm, but knowing the energy levels is important for equations.
Sun Dec 06, 2020 5:25 pm
Forum: Administrative Questions and Class Announcements
Replies: 13
Views: 92

I think lecture videos should be working now.
Sun Dec 06, 2020 5:24 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: Differences between intermolecular forces
Replies: 3
Views: 32

Re: Differences between intermolecular forces

There's ion-ion, ion-dipole, dipole-dipole, dipole-induced dipole, and induced dipole-induced dipole. Ion-ion is between 2 ions (Na+ and Cl-). Ion-dipole is between an ion and something that's not an ion but has ionic characteristic (Cl and H2O). Dipole-dipole is between two non ions but they still ...
Sun Dec 06, 2020 5:14 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Memorization for final
Replies: 9
Views: 71

Re: Memorization for final

I think knowing the ligands might be something to memorize since I think we can only have the periodic table and formula sheet.
Sun Dec 06, 2020 5:12 pm
Forum: Administrative Questions and Class Announcements
Topic: CCLE fixed?
Replies: 19
Views: 98

Re: CCLE fixed?

My lecture videos are working right now, maybe try checking again or refreshing?
Sun Dec 06, 2020 5:10 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH formula?
Replies: 46
Views: 934

Re: pH formula?

pH = -log[H+]. I don't think we need to how it was derived.
Sun Nov 29, 2020 7:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 12
Views: 66

Re: Molecular Shape

Lone pairs affect molecular shape. They have more repulsion and change bond angles.
Sun Nov 29, 2020 7:25 pm
Forum: Student Social/Study Group
Topic: Week 8/9 Thoughts/Worries
Replies: 66
Views: 481

Re: Week 8/9 Thoughts/Worries

I also feel like it's going pretty well, but I'm learning new material now so I'm slightly nervous for that and for finals.
Sun Nov 29, 2020 7:22 pm
Forum: Student Social/Study Group
Topic: Tips for Staying Focused
Replies: 52
Views: 524

Re: Tips for Staying Focused

Don't forget to take breaks, so you don't get tired. Also, try not to be in a distracting environment (I avoid the living room bc the TV is on). I tend to study at night since that is when I feel the most focused personally. Taking notes and having a set goal for what I want to have studied also hel...
Sun Nov 29, 2020 7:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent
Replies: 9
Views: 62

Re: Bent

yep
Sun Nov 29, 2020 7:04 pm
Forum: Student Social/Study Group
Topic: Studying for Final Exam
Replies: 57
Views: 359

Re: Studying for Final Exam

I'm going to solve the textbook problems assigned to us, and I'm probably going to attend some workshops as well throughout weeks 9 and 10 to avoid cramming.
Sun Nov 22, 2020 3:28 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Character
Replies: 33
Views: 210

Re: Covalent Character

Look at electronegativity. A smaller electronegativity difference means more covalent character.
Sun Nov 22, 2020 3:27 pm
Forum: General Science Questions
Topic: # of chem posts
Replies: 27
Views: 323

Re: # of chem posts

You need 5 posts per week, so 35 posts are needed.
Sun Nov 22, 2020 3:23 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 7 Sapling
Replies: 12
Views: 125

Re: Week 7 Sapling

Week 7 and 8 are in the same sapling assignment, so it's due next sunday.
Sun Nov 22, 2020 3:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2 Scores
Replies: 28
Views: 201

Re: Midterm 2 Scores

I think we'll get them by this week since it took abt a week for midterm 1.
Sun Nov 22, 2020 3:20 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bond Lecture
Replies: 7
Views: 35

Re: Sigma and Pi Bond Lecture

lecture 22!
Sun Nov 15, 2020 5:25 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling week 5 & 6 #5
Replies: 20
Views: 123

Re: Sapling week 5 & 6 #5

C should have a formal charge of -2. Valence - free - bonding/2 = 4 - 4 - 4/2 = -2.
Sun Nov 15, 2020 5:23 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 2
Views: 24

Re: Electron Affinity

It's negative due to electron-electron repulsion. Adding the first electron makes group 16 elements an anion, so the second electron affinity is negative since the electron is trying to go into an already electron dense space, causing them to repel and need energy to add it.
Sun Nov 15, 2020 5:12 pm
Forum: Electronegativity
Topic: Sapling Question 13
Replies: 7
Views: 35

Re: Sapling Question 13

The electronegative N and O and the slightly positive Hs can all hydrogen bond. N has 1 lone pair, so it can form 1 H bond (2 Ns = 2 H bonds) while O has 2 lone pairs, so it can form 2 H bonds. Each H (4 Hs in urea) can have one H bond, so the total becomes 8 bonds.
Sun Nov 15, 2020 5:05 pm
Forum: Administrative Questions and Class Announcements
Topic: midterm 2 lecture content
Replies: 4
Views: 29

Re: midterm 2 lecture content

it's lectures 10-18.
Sun Nov 15, 2020 5:02 pm
Forum: Lewis Structures
Topic: Sapling hw 3
Replies: 11
Views: 83

Re: Sapling hw 3

N can't have an expanded octet since it's in period 2.
Sun Nov 08, 2020 4:23 pm
Forum: Lewis Structures
Topic: Lone Pairs Question
Replies: 22
Views: 119

Re: Lone Pairs Question

Lone pairs are the electrons that aren't in a covalent bond, so they aren't shared between atoms.
Sun Nov 08, 2020 4:20 pm
Forum: Resonance Structures
Topic: Valence Electrons [ENDORSED]
Replies: 43
Views: 256

Re: Valence Electrons[ENDORSED]

You can find VE quickly by counting which group it's in. There are 8 groups from left to right when you don't include the d-block/transition metals, and the group it's in corresponds to the element's valence electrons.
Sun Nov 08, 2020 4:14 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 LS7A and Chem14A at the same time right now. I think LS7A has more work because of launchpad, but it's manageable as long as you don't procrastinate a lot.
Sun Nov 08, 2020 4:11 pm
Forum: Ionic & Covalent Bonds
Topic: Size of Bonds
Replies: 28
Views: 99

Re: Size of Bonds

Double bonds have 2 shared pairs of electrons while single bonds only share 1 pair, so the greater number of electrons results in a stronger attraction to the nuclei, shomaking double bonds shorter.
Sun Nov 08, 2020 4:06 pm
Forum: Formal Charge and Oxidation Numbers
Topic: What do we use formal charges for?
Replies: 15
Views: 51

Re: What do we use formal charges for?

When there are multiple resonance structures, formal charge can be used to find the most stable structure. The most stable have a formal charge that is or is closest to 0.
Sun Nov 01, 2020 6:25 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Question 26 Sapling
Replies: 5
Views: 61

Re: Question 26 Sapling

You can use heisenberg's uncertainty principle where ΔxΔp >= h/4π. Δp = mΔv, so you can substitute that in and rearrange the equation for Δv which becomes Δv = h/(4πmΔx). Then, you can just plug in electron mass and Δx which is given to you.
Sun Nov 01, 2020 6:19 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 9
Views: 38

Re: Ionization Energy

Ionization energy decreases from top to bottom since the valence electrons are in shells that are further away from the nucleus and held less tightly, making them easier to remove. Ionization energy increases from left to right since nuclear charge is also increasing, making it more difficult to rem...
Sun Nov 01, 2020 6:11 pm
Forum: Student Social/Study Group
Topic: Sappling week 2-4 #22
Replies: 6
Views: 49

Re: Sappling week 2-4 #22

Kinetic energy is .5mv^2. You can use the constants sheet to get the mass of an electron, so you just need to find its velocity. You can use de Broglie's equation where λ = h / mv and rearrange it to get v = h / mλ and plug it into .5mv^2. Then, you just need to convert from Joules (since KE has uni...
Sun Nov 01, 2020 6:05 pm
Forum: DeBroglie Equation
Replies: 21
Views: 129

Avogadro's number means that 1 mole (mol) is equal to 6.0221 * 10^23 particles. Particles can refer to molecules/atoms/formula units. You usually use it when you need to convert moles to atoms/molecules. For example, the mass on the periodic table is molar mass so you would divide by avogadro's numb...
Sun Nov 01, 2020 6:02 pm
Forum: DeBroglie Equation
Topic: Sapling HW #17
Replies: 6
Views: 47

Re: Sapling HW #17

You can use the de Broglie equation, λ = h/p which becomes λ = h/mv. You already have velocity, and you can get fluorine's mass by converting its molar mass using avogadro's number to go from grams/mol to grams/molecule. Make sure you find molar mass of F2 when converting since it's a diatomic molec...
Sun Oct 25, 2020 5:47 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Module #18
Replies: 5
Views: 52

Re: Module #18

I got D. I used ΔxΔp≥h/4Π which can also be written as Δxmv≥h/4Π (p = mv) and manipulated it to get v. V = (h/4Π) / (Δxm). We were given that position (x) was 1% of the radius, so I found x by calculating .01 * (.05 * 10^-9) <-since you need to convert to meters. Mass of an electron is a constant, a...
Sun Oct 25, 2020 5:25 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E.23 Part A and C
Replies: 4
Views: 62

Re: E.23 Part A and C

You don't need to find the mass percentage. You're right that you find the molar mass of the molecules, but afterwards just use molar ratios. Divide the given masses (make sure they're in grams) by molar mass to get the moles of the molecule, then use the molar ratio between the atom and the molecul...
Sun Oct 25, 2020 5:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Rearranging uncertainty in velocity
Replies: 5
Views: 38

Re: Rearranging uncertainty in velocity

Since ΔP = M x ΔV, you can divide both sides by M to isolate ΔV, so ΔV= ΔP / M.
Sun Oct 25, 2020 5:18 pm
Forum: Administrative Questions and Class Announcements
Topic: Printouts for Midterm
Replies: 8
Views: 69

Re: Printouts for Midterm

We were sent an email with a periodic table sheet and constants/equations we can print out and use.
Sun Oct 25, 2020 5:10 pm
Forum: Einstein Equation
Topic: Textbook Problem 1A.3
Replies: 9
Views: 55

Re: Textbook Problem 1A.3

Speed of light in a vacuum is constant where c = 3.00 * 10^8. c can also be found by c = λ * v, so frequency and wavelength are inversely related.
Sun Oct 18, 2020 3:43 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 8
Views: 46

Re: Study Tips

I've been reading through the textbook sections listed on the syllabus and solving the problems as well.
Sun Oct 18, 2020 3:39 pm
Forum: Administrative Questions and Class Announcements
Topic: Will the midterm only consist of fundamental topics & 1A-1D?
Replies: 1
Views: 24

Re: Will the midterm only consist of fundamental topics & 1A-1D?

I think so. On his website, it said Midterm 1 is all the material through week 3 which is up to Q21 on Sapling and Topic 1D on the textbook.
Sun Oct 18, 2020 3:34 pm
Forum: Photoelectric Effect
Topic: Sapling Week 2,3,4 #9
Replies: 2
Views: 45

Re: Sapling Week 2,3,4 #9

Since we're looking for the longest wavelength possible, this means that work function should be the same as the photon's energy (there won't be excess energy/kinetic energy from the electrons because that would mean that it wouldn't be the longest wavelength possible). We know the formula E = hv gi...
Sun Oct 18, 2020 3:25 pm
Forum: Properties of Electrons
Topic: protons and electrons
Replies: 33
Views: 191

Re: protons and electrons

An electron has a much smaller mass than protons and neutrons which are about the same. An electron's mass is basically negligible while the other 2 have masses of around 1 amu/dalton.
Sun Oct 18, 2020 3:12 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1292

Re: How are you studying?

I'm using the fundamentals/problems posted on the syllabus as study materials. I take notes on the fundamentals, watch the audio-visual modules, and take notes on the lectures.
Sun Oct 11, 2020 5:46 pm
Forum: Limiting Reactant Calculations
Topic: Sapling HW 10
Replies: 9
Views: 127

Re: Sapling HW 10

You can use the molecular formulas to find the molar mass, but I just searched it up and got molar mass of butanone on the internet. You would only need to know the formulas for the 2-butanone and 3-methyl-3-hexanol since the other product is in excess. To approach the problem, first use the density...
Sun Oct 11, 2020 4:02 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: post video Q28
Replies: 2
Views: 36

Re: post video Q28

Wavelength is measured in meters so since you know how many wavelengths are in 1 meter from the problem, you can do wavelength = 1/1,650,763.73 and use that answer to find the region it falls under. Then for the photon question, you can use the formula E = hv.
Sun Oct 11, 2020 3:28 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular Formula
Replies: 3
Views: 37

Re: Molecular Formula

Once you find the empirical formula's molar mass, you can divide the mass of the molecular formula by the empirical formula to get the ratio. You can then use that number and multiply each element's subscript/number of atoms in the empirical formula by that number to get the molecular formula.
Sun Oct 11, 2020 3:25 pm
Forum: Molarity, Solutions, Dilutions
Topic: Formulas involved in Determining Solution Concentration
Replies: 8
Views: 86

Re: Formulas involved in Determining Solution Concentration

Try and note down what variables are being used in the problem. If there are 2 molarities or 2 volumes, you probably need to use M1V1 = M2V2. Another way to tell is that if a solution has been diluted/water was added, you probably need to use the same equation since number of moles (n) stays the sam...
Sun Oct 11, 2020 3:19 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Week 1 #8
Replies: 3
Views: 57

Re: Sapling Week 1 #8

Make sure you're using capital letters. I had that problem too, but you just need capitals.