## Search found 65 matches

Fri Jan 15, 2021 2:51 am
Forum: Ideal Gases
Topic: n/V = concentration
Replies: 19
Views: 73

### Re: n/V = concentration

Hello! We know molarity = moles of solute (mol) / volume of solution (L). When we rearrange the ideal gas law so that n/V, we realize that this is the same thing as mol/L, which is concentration.
Fri Jan 15, 2021 2:45 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H2O as a Gas
Replies: 53
Views: 372

### Re: H2O as a Gas

We don't include solids or liquids when solving ICE tables. When water is a gas, I believe we include it in the ICE table because the partial pressure of the gas will affect the overall equilibrium. Please correct me if I'm wrong!
Fri Jan 15, 2021 2:41 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure vs. concentration
Replies: 9
Views: 32

### Re: Pressure vs. concentration

I think you'll know whether to use Kp or Kc depending on the values given in the problem. If the problem gives molarity (mol.L-1) we use Kc and if they give values in atm/bar we use Kp.
Thu Jan 14, 2021 11:30 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chemical Equilibrium Outline
Replies: 3
Views: 53

### Re: Chemical Equilibrium Outline

I think these refer to the examples that Dr. Lavelle will present in lectures. In Chem 14A he talked about hemoglobin in the context of coordination compounds so he tried to incorporate these ideas into a biological context. When he lists these things I think he is referring to his discussion of th...
Wed Jan 13, 2021 3:58 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J.5
Replies: 5
Views: 21

### Re: 5J.5

I'm pretty sure it's a typo and there's supposed to be a 2H2 to balance the equation.
Wed Jan 13, 2021 3:34 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chemical Equilibrium Outline
Replies: 3
Views: 53

### Chemical Equilibrium Outline

Hi everyone! On the Chemical Equilbirum Outline, there was an objective that stated "Biological examples. For example: ATP hydrolysis; osmotic pressure". Could someone explain what this means?
Sun Jan 10, 2021 3:54 am
Forum: Administrative Questions and Class Announcements
Topic: FINAL EXAM QUESTIONS
Replies: 24
Views: 281

### Re: FINAL EXAM QUESTIONS

Based on the midterms and final we took in 14A, I think it's definitely a good idea to do the textbook problems listed on each outline. Rather than focusing on memorizing specific problems, I suggest doing multiple so that you know how to approach any type of problem that may be thrown at you on the...
Sun Jan 10, 2021 3:46 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Q
Replies: 53
Views: 157

### Re: K vs. Q

Hi Lilly! You are correct. The reaction quotient, Q, is used to represent the concentration/partial pressure of products divided by the concentration/partial pressure of reactants of the reaction at ANY time. The equilibrium constant, K, represents the reaction at equilibrium.
Sun Jan 10, 2021 3:40 am
Forum: Ideal Gases
Topic: PV=nRT and concentration
Replies: 27
Views: 96

### Re: PV=nRT and concentration

Molarity, or molar concentration, is defined by the number of moles of solute per liter of solution, mol/L. In the ideal gas law, PV = nRT, n is the number of moles and V is volume, so n/V can be rewritten as concentration (mol/L). I hope this explanation wasn't too confusing!
Sat Jan 09, 2021 1:49 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 278

### Re: Units of Temperature

When using the ideal gas law, write the temperature in Kelvin.
Sat Jan 09, 2021 1:46 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: terminology
Replies: 11
Views: 44

### Re: terminology

Hi Sera! When a reaction favors products, the reaction "shifts" to the right, and more products are being formed than reactants at equilibrium. When a reaction favors reactants, the reaction "shifts" to the left, meaning that more reactants are being formed than products at equil...
Sat Dec 12, 2020 5:22 pm
Forum: Student Social/Study Group
Topic: Finals Study Things
Replies: 27
Views: 178

### Re: Finals Study Things

thank u!! <3
Sat Dec 12, 2020 5:19 pm
Forum: Bronsted Acids & Bases
Topic: metal/nonmetal oxides
Replies: 3
Views: 20

### Re: metal/nonmetal oxides

Metal oxides are typically basic, nonmetal oxides are usually acidic, and metalloid oxides are usually amphoteric.
Thu Dec 10, 2020 7:51 pm
Forum: Naming
Topic: Naming quizlet
Replies: 41
Views: 259

### Re: Naming quizlet

Thank you! You're the best
Thu Dec 10, 2020 12:57 am
Forum: Bronsted Acids & Bases
Topic: Textbook J.17
Replies: 2
Views: 25

### Re: Textbook J.17

In part b, ClO- is actually a polyatomic ion called hypochlorite, so ClO- can be considered as a single unit and the Cl is not removed. Hypochlorite is an anion that is considered a weak base in water. In part c, the Cl- anion does not have an effect so it is treated as a spectator ion.
Thu Dec 10, 2020 12:49 am
Forum: Conjugate Acids & Bases
Topic: HW 6A.3 Part C
Replies: 2
Views: 55

### Re: HW 6A.3 Part C

I made the same mistake, but the problem states that H2PO4- is acidic in this scenario so we have to remove the H+ and it forms a conjugate base.
Sat Dec 05, 2020 12:50 pm
Forum: Lewis Structures
Topic: Lone Pair placement
Replies: 10
Views: 66

### Re: Lone Pair placement

Although the two lone pairs are drawn next to each other in a H2O Lewis structure, the electron repulsion pushes them away so that they aren't close together in a real molecule. Imagine each lone pair occupying a large region of electron density, resulting in them being further away.
Sat Dec 05, 2020 12:39 pm
Forum: Ionic & Covalent Bonds
Topic: Polar and Nonpolar
Replies: 28
Views: 172

### Re: Polar and Nonpolar

In order to consider if a molecule is polar or nonpolar, I always draw the Lewis structure first to see if the dipoles cancel out of it there are lone pairs.
Sat Dec 05, 2020 12:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: ligand names
Replies: 10
Views: 63

### Re: ligand names

I think my TA mentioned that we wouldn't be allowed to use the ligand sheet for the final. It would probably be best if you tried to memorize them. The more problems you do the easier it becomes to memorize the ligands!
Sat Dec 05, 2020 12:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Weekly discussion points
Replies: 13
Views: 108

### Re: Weekly discussion points

My TA said that if by the end of the quarter you don't have 50 posts, they might look at the posts you've already made to see how thorough they are, taking quality over quantity into consideration. Also, it probably won't hurt to have 50 posts by the end of week 10 just in case your TA does decide t...
Sat Dec 05, 2020 12:21 pm
Forum: General Science Questions
Topic: study methods/recs
Replies: 37
Views: 278

### Re: study methods/recs

I really recommend going to the UA workshops every week! I started attending them recently and I've found them to be super helpful. For the final, I think I'm going to review my notes and skim over past homework problems.
Tue Nov 24, 2020 4:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Names
Replies: 50
Views: 282

### Re: Shape Names

Reiterating what people have said before, we can say angular or bent when referring to the shape. I don't think it matters which one we use but I think the textbook refers to it as angular.
Tue Nov 24, 2020 4:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook Section 2E Exercise glitch
Replies: 3
Views: 33

### Re: Textbook Section 2E Exercise glitch

This happened to me as well, I logged out of Sapling and then signed in again and the issue was fixed. I'll also copy and paste the customer service email they sent: Install and use Google Chrome. If you already have Chrome installed continue to step 2, but if you just installed Chrome then skip to ...
Tue Nov 24, 2020 4:27 pm
Forum: Student Social/Study Group
Topic: How have your study habits changed?
Replies: 45
Views: 294

### Re: How have your study habits changed?

In high school, I would cram for tests the night before and basically teach myself all the content for the first time. I've tried to change my study habits by studying a little bit across several days before the exam so I don't get overwhelmed. I like to review homework/textbook problems I've done a...
Tue Nov 24, 2020 4:18 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 30
Views: 152

### Re: Polarity

A molecule can have polar bonds between atoms, but if they cancel out then there is no net dipole moment so the overall molecule isn't polar.
Tue Nov 24, 2020 4:08 pm
Forum: Student Social/Study Group
Topic: Exercising Our Minds and Bodies
Replies: 103
Views: 494

### Re: Exercising Our Minds and Bodies

I like working out to Blogilates videos. Cassey has a monthly calendar that lists different workouts to do each day which makes exercising interesting!
Wed Nov 18, 2020 11:03 pm
Forum: Ionic & Covalent Bonds
Topic: covalent dissociation energy learning goal
Replies: 4
Views: 36

### Re: covalent dissociation energy learning goal

What you stated for bond multiplicity and atomic radius is correct. As for unpaired electrons, I think unpaired electrons will repel each other in order to achieve a lower energy state and become more stable, so the more unpaired electrons, the lower the bond dissociation energy.
Wed Nov 18, 2020 10:55 pm
Forum: Student Social/Study Group
Topic: post midterm 2
Replies: 27
Views: 283

### Re: post midterm 2

Good luck to everyone about to take the midterm this week! I took mine today, and to wind down I took a nap and watched Saiki-K!
Wed Nov 18, 2020 10:51 pm
Forum: Student Social/Study Group
Replies: 110
Views: 1160

I'm comforted by the fact that other people are also worried about their grades. This quarter has been super difficult for a lot of people because of Zoom schooling and being stuck at home, but we're all going through similar experiences and we'll get through it together!
Wed Nov 18, 2020 10:43 pm
Forum: Student Social/Study Group
Topic: Post Midterm Blues
Replies: 71
Views: 602

### Re: Post Midterm Blues

This thread is so supportive! Don't feel discouraged about the midterm grades, this quarter has been really difficult for a lot of people because of online school and being stuck at home. You'll also have a lot of chances to make up points with Sapling homework and chem community!
Wed Nov 18, 2020 10:16 pm
Forum: Bond Lengths & Energies
Topic: Boiling/Melting Point
Replies: 20
Views: 142

### Re: Boiling/Melting Point

Hi Natalie! We look at intermolecular forces because the bonds between the molecules are being broken, not the bonds holding each molecule together. Compounds with stronger IMFs will have higher melting/boiling points.
Fri Nov 13, 2020 11:41 pm
Forum: Lewis Structures
Topic: Polyatomic Ions and Their Charges
Replies: 2
Views: 22

### Polyatomic Ions and Their Charges

Hey everyone, I was wondering if we need to memorize polyatomic ions and their charges for Midterm 2.
Fri Nov 13, 2020 11:16 pm
Forum: Ionic & Covalent Bonds
Topic: Electronegativity difference
Replies: 12
Views: 87

### Re: Electronegativity difference

Since electronegativity is calculated experimentally, if we ever needed to solve for the electronegativity difference we would be given a chart with the values. Also, Professor Lavelle said that elements with an electronegativity difference between 1.5 and 2 would require experimentation to study th...
Fri Nov 13, 2020 11:11 pm
Forum: Resonance Structures
Topic: structure of lower energy
Replies: 5
Views: 17

### Re: structure of lower energy

Yep! You calculate the formal charges for each atom in the structure. The structure with the least formal charges (the most zeros) will require lower energy.
Fri Nov 13, 2020 11:02 pm
Forum: Resonance Structures
Topic: Delocalized Electrons
Replies: 7
Views: 25

### Re: Delocalized Electrons

Hey Eliana! The textbook states that delocalization means that a shared electron pair is distributed over several pairs of atoms and cannot be identified with just one pair of atoms. Electrons that are shown in different positions in a set of resonance structures are said to be delocalized. In my ow...
Fri Nov 13, 2020 10:42 pm
Forum: Lewis Structures
Topic: textbook problem 2B #1
Replies: 3
Views: 43

### Re: textbook problem 2B #1

In the answer key, N is the central atom double-bonded to O and single-bonded to F. You can check if your structure is correct by counting the formal charges. The molecule with the least amount of formal charges is most likely the correct structure. The formal charges for the structure you originall...
Fri Nov 13, 2020 10:23 pm
Forum: Lewis Structures
Topic: textbook problem 2B #11
Replies: 3
Views: 36

### Re: textbook problem 2B #11

Adding on to the previous responses, after drawing the Lewis structure for a molecule, it's a good idea to check the formal charges of each atom. The molecule with the least amount of formal charges is most likely to be the structure we're looking for. When drawing Lewis structures, there will be so...
Sat Nov 07, 2020 1:59 pm
Forum: Student Social/Study Group
Topic: Favorite TV shows
Replies: 176
Views: 836

### Re: Favorite TV shows

Selling Sunset is a reality show on Netflix about selling real estate in LA. It ended up being really fun to watch! I've also been rewatching Criminal Minds recently.
Fri Nov 06, 2020 2:58 am
Forum: Administrative Questions and Class Announcements
Topic: Reviewing Answers for Midterm 1
Replies: 13
Views: 133

### Re: Reviewing Answers for Midterm 1

I hope we'll be able to go over the midterm with our TAs. I'm wondering if I made silly calculation mistakes or if I just completely misunderstood concepts.
Fri Nov 06, 2020 2:47 am
Forum: Student Social/Study Group
Topic: Veterans Day
Replies: 16
Views: 131

### Re: Veterans Day

My TA says we don't have our discussion session on Wednesday, but the powerpoints and practice problems will be posted on CCLE. I'm not sure about the lecture though.
Thu Nov 05, 2020 3:45 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: F orbitals?
Replies: 21
Views: 109

### Re: F orbitals?

Hi, To show which orbital each electron is in for the p orbital, we wrote it as 2px^2 2py^2 etc... and for d it was xy yz and zx, but I am just wondering what it would be for the f orbital? I don't think that we would have to know it, but just curious. :) Thanks Hey, I don't think we'll need to kno...
Thu Nov 05, 2020 3:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: energy in electron configurations
Replies: 7
Views: 55

### Re: energy in electron configurations

Hi Kaylee! I read that whenever you have the opportunity to complete a half d-shell or a full d-shell (going from 4 electrons to 5 or 9 electrons to 10), then you take 1 electron away from the s-shell and put it into the d-shell. I believe this is because a half or full d-shell is more stable and re...
Sat Oct 31, 2020 1:00 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration Shorthand Question
Replies: 5
Views: 44

### Re: Electron Configuration Shorthand Question

When a problem asks for shorthand electron configuration, I believe they are referring to noble gas configuration, which is why the shorthand of Si starts with the noble gas [Ne].
Sat Oct 31, 2020 12:41 am
Forum: Administrative Questions and Class Announcements
Topic: Audio-Visual Focus Topics
Replies: 14
Views: 100

### Re: Audio-Visual Focus Topics

I also really liked learning with the modules! I think it helped prime my brain for future lectures so it wouldn't be as overwhelming as learning each topic for the first time.
Fri Oct 30, 2020 2:01 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: position units
Replies: 19
Views: 112

### Re: position units

For the Heisenberg uncertainty equation, I believe you always use meters in order to keep the units consistent (since velocity is also written in meters/sec). This way they'll cancel out when calculating.
Fri Oct 30, 2020 1:39 am
Forum: Properties of Light
Topic: Midterm Question
Replies: 11
Views: 166

### Re: Midterm Question

I believe the midterm covers all the material from Outline #1 and I did the textbook exercises for Outline #2 up to 1B. I think it's recommended that we read the textbook up to 1D Section 2.
Fri Oct 30, 2020 1:31 am
Forum: SI Units, Unit Conversions
Topic: Angstrom
Replies: 6
Views: 66

### Re: Angstrom

Hey! Just wanted to add that if you want a brief review of exponents and unit conversions, I recommend looking at Appendix 1B and 1D in the textbook. It was a nice refresher :)
Fri Oct 30, 2020 1:21 am
Forum: Student Social/Study Group
Topic: How to relax
Replies: 113
Views: 586

### Re: How to relax

I like to cook or make myself a quick snack to relax and take a break from school work! I've also been watching new k-dramas on Netflix. :)
Fri Oct 23, 2020 7:54 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: clarification: Δx
Replies: 6
Views: 45

### Re: clarification: Δx

How I like to think about it is if the uncertainty is 10Å, then it is just 10 x10^-10 m, while if it gives you +/-10Å, it will be 10x10^-10 m in the positive direction and 10x10^-10 m in the negative direction as the uncertainty. Hope this helps! This was a helpful way of thinking about it, thank y...
Fri Oct 23, 2020 7:45 pm
Forum: Einstein Equation
Topic: m vs nm
Replies: 66
Views: 433

### Re: m vs nm

When doing calculations, I believe the quantities are supposed to be written in meters! However, since the midterm is multiple choice, you'll be able to see if the final answer is going to be m or nm.
Fri Oct 23, 2020 7:28 pm
Forum: Properties of Light
Topic: Units for wavelength/frequency
Replies: 18
Views: 93

### Re: Units for wavelength/frequency

The units for frequency are usually written in Hz (1s-1), and the unit written for wavelength is meters. However, in a lot of problems I see the wavelength written in nm. A tip is to write 10-9 behind the original number to convert from nm to m for easy calculations.
Fri Oct 23, 2020 7:21 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1266

### Re: How are you studying?

To study for the midterm, I'm going to refer to the outlines posted on Professor Lavelle's website and review the notes and past homework we've done. I think I'm going to look over the Sapling questions and redo any textbook problems I've found difficult in the past!
Thu Oct 22, 2020 4:02 am
Forum: Balancing Chemical Reactions
Topic: Formula Unit vs. Molecules
Replies: 3
Views: 54

### Re: Formula Unit vs. Molecules

Hey Juwan! A molecule is composed of two or more elements that are covalently bonded. For example, H2O or CO2 are molecules because a nonmetal element bonding with another nonmetal element forms covalent bonds. A formula unit refers to the ratio of ions in an ionic compound, such as the salt NaCl.
Sat Oct 17, 2020 3:00 am
Forum: Photoelectric Effect
Topic: Work Function
Replies: 6
Views: 44

### Re: Work Function

Yes! The work function, also known as the threshold energy, is the minimum amount of energy required to eject an electron from the surface.
Sat Oct 17, 2020 3:00 am
Forum: Photoelectric Effect
Topic: Work Function
Replies: 6
Views: 44

### Re: Work Function

Yes! The work function, also known as the threshold energy, is the minimum amount of energy required to eject an electron from the surface.
Sat Oct 17, 2020 2:51 am
Forum: Photoelectric Effect
Topic: Frequency vs. Intensity
Replies: 16
Views: 131

### Re: Frequency vs. Intensity

According to the equation E photon = h v , we see that the energy of a photon is directly proportional to the frequency of light. Therefore, if the frequency increases, the energy of the photon increases, allowing electrons to be ejected. However, increasing the intensity of light only increases the...
Sat Oct 17, 2020 2:40 am
Forum: Properties of Electrons
Topic: protons and electrons
Replies: 33
Views: 191

### Re: protons and electrons

I agree with the previous replies on this post. Protons and neutrons have approximately the same mass, 1.67 x 10-24 grams (1 amu), while electrons are much smaller.
Sat Oct 17, 2020 2:27 am
Forum: Properties of Light
Topic: Energy Levels
Replies: 11
Views: 92

### Re: Energy Levels

Can electrons jump up multiple energy levels at once or do they have to reach a certain stage before they can reach the next energy level afterwards? For example, if an electron was at energy level n = 1, could it jump up to n = 4, or would it have to pass/stop(?) through energy levels n = 2 and n ...
Sat Oct 17, 2020 2:14 am
Forum: SI Units, Unit Conversions
Topic: Mnemonic
Replies: 6
Views: 59

### Re: Mnemonic

lauren_tran_3J wrote:I remember it as K.H.D.U.D.C.M : King Henry Doesn't Usually Drink Chocolate Milk. Or Kilo, Hecto, Deca, Unit (for example: gram), Deci, Centi, Mili. Hope this helps!

This is super helpful, thank you!
Fri Oct 09, 2020 7:57 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.25
Replies: 2
Views: 40

### Re: G.25

Hey Daniela! Since doubling the volume decreases the concentration by half each time, and this process is repeated 90 times, the problem can be written as 1.0M x (0.5)90.
Fri Oct 09, 2020 7:47 pm
Forum: Molarity, Solutions, Dilutions
Topic: What does mmol stand for?
Replies: 33
Views: 329

### Re: What does mmol stand for?

Hey Abby! mmol stands for millimole; 1 mmol = 1 x 10-3 mole
Fri Oct 09, 2020 1:34 am
Forum: Balancing Chemical Reactions
Topic: Fundamental Exercise H7
Replies: 5
Views: 55

### Re: Fundamental Exercise H7

Hi Adam! Since a catalyst is a substance that increases the rate of chemical reaction without going under any chemical change itself, it does not affect the chemical equation. In the textbook, the catalyst name was written above the arrow in a chemical equation to indicate that a catalyst had been a...
Thu Oct 08, 2020 12:44 am
Forum: Molarity, Solutions, Dilutions
Topic: Molarity written with (aq)
Replies: 4
Views: 59

### Re: Molarity written with (aq)

Hey Savannah! I think writing (aq) after 0.123 M HCl(aq) is just to indicate that the HCl has been diluted with water to form an aqueous solution. I don't think you have to include the phase of matter in your final answer or calculations unless the problem specifies.
Thu Oct 08, 2020 12:02 am
Forum: SI Units, Unit Conversions
Topic: Formula Units
Replies: 9
Views: 107

### Re: Formula Units

Do you calculate formula units the same way we calculate number of atoms in a molecule from molar mass and avogadros number? Hi Mary! Since 1 mole always means 6.0221 x 10 23 of 'things', you can use Avogadro's number as a conversion factor so that there are 6.0221 x 10 23 formula units in 1 mole o...
Mon Oct 05, 2020 11:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: Units for Dilution Equation [ENDORSED]
Replies: 23
Views: 208

### Re: Units for Dilution Equation[ENDORSED]

When solving for a dilution problem (M initial V initial = M final V final ), it doesn't matter if you use mL or L as long as you keep the units consistent for V initial and V final . If you are solving for volume, and the problem specifies that you should use mL or L, then convert to those units. I...