Search found 51 matches

by Jeannine 1I
Thu Feb 07, 2019 9:41 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 109
Views: 2483

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

005199302 wrote:for #6, shouldn't the work be -12.4kJ?

w=-PxdV = (-122atm/L)(101.33J/atmL) = -12.4kJ


Were you able to solve 6a? I've tried doing it but keep getting 12.85 kJ, but I don't see where it went wrong.
by Jeannine 1I
Wed Feb 06, 2019 7:08 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 109
Views: 2483

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

For Worksheet 1 question 7, are the sig figs correct? Wouldn't it be 3 sig figs, not 4, because the lowest number given is 298 K? Or is it 4 sig figs because we don't use the temperature to solve this problem?
by Jeannine 1I
Thu Jan 31, 2019 11:10 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question on yesterday’s lecture
Replies: 2
Views: 24

Re: Question on yesterday’s lecture

That's a good question! I originally thought it was all in Chapter 8 of the 6th edition, but there are some concepts that I can't find. So, if it isn't in Chapter 8, I guess it would be in Chapter 9.
by Jeannine 1I
Thu Jan 31, 2019 11:07 am
Forum: Phase Changes & Related Calculations
Topic: What Does U and q stand for?
Replies: 9
Views: 59

Re: What Does U and q stand for?

is the overall change in internal energy of a system, and q is heat!
by Jeannine 1I
Thu Jan 31, 2019 11:02 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: increasing pressure, what happens to concentration?
Replies: 7
Views: 39

Re: increasing pressure, what happens to concentration?

You can imagine that when pressure increases, the gas molecules on both sides of the reaction move faster, and are therefore more likely to bump into each other. The side with more moles of gas will have more molecules that bump into each other, which will drive the reaction to shift towards the sid...
by Jeannine 1I
Thu Jan 31, 2019 10:49 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cv vs. Cp [ENDORSED]
Replies: 13
Views: 636

Re: Cv vs. Cp [ENDORSED]

Kenan Kherallah 2C wrote:Whats R?


I believe R refers to the universal gas constant!
by Jeannine 1I
Thu Jan 24, 2019 12:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Assuming K
Replies: 2
Views: 18

Assuming K

Let's say there's a question that asks you if a chemical reaction is at equilibrium, and it gives you a reaction and K-value but doesn't specify if the K is Kc or Kp. Then, it gives you the partial pressure concentrations of the reactants and products. Is it safe to assume then, that the K-value giv...
by Jeannine 1I
Wed Jan 23, 2019 9:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial Q
Replies: 3
Views: 52

Re: Initial Q

I am terrible at explaining, but here is the video I watched: https://www.youtube.com/watch?v=54n1XppP-lA and I got confused with the example at 25:46 when the initial concentrations of the products were not 0. The reason why the initial concentrations of the products are not 0, is because they giv...
by Jeannine 1I
Wed Jan 23, 2019 9:17 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Increase in Volume Effect on Equilibrium
Replies: 6
Views: 45

Increase in Volume Effect on Equilibrium

I understand that when you decrease volume, the side with more moles becomes more crowded and "bumps into each other" more often, which is why the reaction then favors the side with fewer moles. But can someone help me visualize why when you increase volume, the side with more moles is fav...
by Jeannine 1I
Tue Jan 22, 2019 9:45 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier and water
Replies: 3
Views: 32

Re: Le Chatelier and water

Since we don't include liquids or solids in K-values, adding water won't change the K-value.The only thing that would affect it is if the concentrations of the reactants or products are increased/decreased, but if the concentrations remain the same, adding water won't affect it.
by Jeannine 1I
Tue Jan 22, 2019 9:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Does [H3O+][OH-] always equal 10^-14?
Replies: 9
Views: 52

Re: Does [H3O+][OH-] always equal 10^-14?

I'm not sure what that problem is since I have the 6th edition, but I believe it is 10^-14 under lab conditions, which means the temperature is constant. Even then, I'm not sure if it is ALWAYS equal to 10^-14. I'd like to know too, it's a good question!
by Jeannine 1I
Tue Jan 15, 2019 11:05 pm
Forum: General Science Questions
Topic: Rounding/ Significant Figures
Replies: 2
Views: 28

Re: Rounding/ Significant Figures

Remember that when looking at a problem, you use the number with the least amount of sig figs for your answer. So in the problem you're talking about, are you sure there wasn't a number given somewhere that only had 1 significant figure? At least from the problems I've looked at, the solution manual...
by Jeannine 1I
Fri Jan 11, 2019 4:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding a liquid
Replies: 7
Views: 37

Re: Adding a liquid

I believe that adding a liquid will not affect the K because it will stay the same on both the reactants and products sides.
by Jeannine 1I
Fri Jan 11, 2019 1:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What do you do if all products are pure substances?
Replies: 2
Views: 13

Re: What do you do if all products are pure substances?

Yes, you would only include the gases in the , and the numerator would be 1 since the equilibrium constant for partial pressure is the concentrations of partial pressure of products over partial pressure of reactants:

by Jeannine 1I
Thu Jan 10, 2019 4:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition, 11.7?
Replies: 4
Views: 63

Re: 6th edition, 11.7?

Thanks that's really helpful. Just wanted to know why would 5/17 be used for the calculation of partial pressure instead of 6/11 from the earlier part B? It's because you're looking for the equilibrium constant K, so you use the flask that's at equilibrium! The flask that's before the one with 5/17...
by Jeannine 1I
Sat Dec 08, 2018 8:00 pm
Forum: Naming
Topic: Ligand Names
Replies: 4
Views: 72

Re: Ligand Names

I think using either will be fine! I have heard before that Lavelle will be using the old convention. Can someone confirm this please?
by Jeannine 1I
Thu Dec 06, 2018 10:11 pm
Forum: Bronsted Acids & Bases
Topic: donating or accepting proton
Replies: 2
Views: 23

Re: donating or accepting proton

Yes, I think that's a good way to think about it! The H+ counts as a proton.
by Jeannine 1I
Thu Dec 06, 2018 10:09 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power: Size vs. Charge
Replies: 3
Views: 46

Re: Polarizing Power: Size vs. Charge

It helps me to know what the trend of sizes are for cations. They generally decrease across a period, and increase down a group (due to the addition of another shell). From there, you can tell that the smaller the cation, the greater its polarizing power. Hope that helps(:
by Jeannine 1I
Thu Dec 06, 2018 9:57 pm
Forum: Naming
Topic: Naming with bis-
Replies: 5
Views: 43

Re: Naming with bis-

what were the other names we had to remember besides bis when the other prefixes are already used in the name? We need to remember to use: bis- instead of di- tris- instead of tri- tetrakis- instead of tetra- pentakis- instead of penta- We use those names when the ligand already has di-, tri-, or t...
by Jeannine 1I
Fri Nov 30, 2018 5:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Pentagonal bipyramidal
Replies: 4
Views: 38

Re: Pentagonal bipyramidal

My TA told us that usually a central atom will at most form 6 bonds, with a total of 12 valence electrons in its outermost shell, so since pentagonal bipyramidal has 7 bonds to its central atom, I think it is a rarity.
by Jeannine 1I
Tue Nov 27, 2018 4:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3 Content
Replies: 3
Views: 84

Re: Test 3 Content

Rebeca_Ruiz_3D wrote:So just to be clear the test won’t cover anything from Monday’s lecture? Like coordination compounds?


Yes, the test will not cover anything from Monday's lecture!
by Jeannine 1I
Tue Nov 27, 2018 1:29 pm
Forum: Hybridization
Topic: hybridization
Replies: 3
Views: 36

Re: hybridization

sp and sp2 and so on are the general hybridization of atoms. When it says 2sp2 that refers to the second period orbitals. For example, if we are asked to label the bond between C and H in CH4, we would label it as \sigma (C2sp^{3}, H1s) . This is because Carbon has valence electrons in perio...
by Jeannine 1I
Tue Nov 27, 2018 1:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polarity vs. nonpolarity
Replies: 8
Views: 68

Re: polarity vs. nonpolarity

You do have to be careful when looking at dipole moments because some nonpolar molecules can have dipole moments, they just cancel out against other dipole moments. For a molecule to be polar it must have polar bonds with dipoles that don't cancel. Professor Lavelle also said it would be helpful to...
by Jeannine 1I
Tue Nov 27, 2018 11:00 am
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi bonds
Replies: 5
Views: 56

Re: Sigma and Pi bonds

They could also ask us to label all existing bonds in a molecule. For example, in we would label the bond (C2, H1s).
by Jeannine 1I
Tue Nov 27, 2018 10:09 am
Forum: Ionic & Covalent Bonds
Topic: Covalent character and Electronegativity
Replies: 2
Views: 43

Re: Covalent character and Electronegativity

According to electronegativity trends, Cs has a lower electronegativity value than K, so the difference between Cs and Cl is greater than the EN difference between K and Cl. In this case though, the difference is so great that both KCl and CsCl will be ionic, with CsCl having greater ionic characte...
by Jeannine 1I
Mon Nov 26, 2018 11:52 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent character and Electronegativity
Replies: 2
Views: 43

Covalent character and Electronegativity

How does electronegativity relate to greater covalent character when comparing 2 molecules?
For example, between KCl and CsCl, which one has the greater covalent character? And why? Does electronegativity explain it?
by Jeannine 1I
Mon Nov 19, 2018 9:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSPER Formula
Replies: 7
Views: 81

Re: VSPER Formula

The VSEPR formula refers to AX(sub n)E(sub m), where A is the central atom, X is the atoms attached to the central atom (so n would be the number of atoms attached), and E refers to electron lone pairs (so m would be the number of lone pairs attached to the central atom). For example, in H20, the VS...
by Jeannine 1I
Sat Nov 17, 2018 12:22 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral
Replies: 4
Views: 41

Re: Octahedral

Do the bond angles of the octahedral shape (90 degrees) ever change (because of things like electron pairs)? I believe if there is only one electron pair (AX5E), it will slightly push the other 4 bonded atoms further away from it, so that the angle between the central atom, the opposite atom from t...
by Jeannine 1I
Thu Nov 15, 2018 12:07 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing structures
Replies: 4
Views: 36

Re: Drawing structures

Yes, if you were to draw the VSEPR model of NH3, given that it has a lone pair, you would draw N as the central atom with a lone electron pair attached, one H with a regular line, one H with the stripes, and one H with the triangular wedge! The striped lines means the H atom is seen in the back, whi...
by Jeannine 1I
Wed Nov 14, 2018 11:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Bond Angles
Replies: 1
Views: 29

Re: Determining Bond Angles

I think knowing their 3-Dimensional geometry definitely helps determine their bond angles! I would generally say though, that the most common angles are 90, 109.5,120, and 180. It's usually either those angles, or slightly less than those angles (when lone pairs are involved). Thinking about what th...
by Jeannine 1I
Fri Nov 09, 2018 9:14 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization Energies
Replies: 13
Views: 109

Re: Ionization Energies

How would you determine these trends for diagonal (non-adjacent) elements? For example, between Carbon and Sulfur. I think between those two, carbon would have a higher ionization energy because sulfur is in period 3, which means it has another shell around the nucleus. The extra shell shields vale...
by Jeannine 1I
Fri Nov 09, 2018 8:33 pm
Forum: Electronegativity
Topic: Electronegativity Difference from 1.5-2
Replies: 1
Views: 43

Electronegativity Difference from 1.5-2

I know the general rule for categorizing ionic vs covalent bonds, is knowing the difference in electronegativities of the atoms involved, and if it's less than 1.5 it's covalent, and if it's greater than 2 it's ionic. What exactly is the bonding type, or what happens between the atoms, when the elec...
by Jeannine 1I
Fri Nov 09, 2018 4:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral Shape Question
Replies: 3
Views: 32

Re: Tetrahedral Shape Question

Yes! Because electrons in the real world are 3-dimensional, the electrons maximize their repulsions to each other, and do their best to have as much space between each other as possible. This results in the tetrahedral shape Dr. Lavelle mentioned in class. As for drawing it out, I'm not too sure, bu...
by Jeannine 1I
Wed Oct 31, 2018 7:04 pm
Forum: Ionic & Covalent Bonds
Topic: Problem 3.5
Replies: 1
Views: 30

Re: Problem 3.5

The ground state electron configuration for Cu would be [Ar]4s^1 3d^10. You would think it would be [Ar]4s^2 3d^9, but a full d-orbital is more favorable than a full s-orbital. This means one electron in the s-orbital will jump to the d-orbital in order for that orbital to be full. So in Cu+, the el...
by Jeannine 1I
Wed Oct 31, 2018 6:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron removal from orbitals question
Replies: 3
Views: 51

Re: Electron removal from orbitals question

When you remove an electron from an atom that has a p-orbital (and no d-orbital), you remove it first from p and then from s. However, if you remove an electron from an atom that has a d-orbital, you remove it first from the s-orbital.
by Jeannine 1I
Wed Oct 31, 2018 6:34 pm
Forum: Trends in The Periodic Table
Topic: Electron affinity
Replies: 2
Views: 48

Re: Electron affinity

I was also very confused by the book definition, but my TA explained electron affinity by saying it's basically how badly an atom wants an electron. The atoms that need only a few more electrons to have a full shell, want electrons much more than those that need many more electrons to fill in their ...
by Jeannine 1I
Wed Oct 24, 2018 11:25 pm
Forum: DeBroglie Equation
Topic: De Broglie module #35
Replies: 3
Views: 110

Re: De Broglie module #35

I think it's true that technically all matter has wavelike properties, but I believe in one of his lectures, Mr. Lavelle mentioned that anything smaller than 10^-18 would be so small that it most likely would not display wavelike properties.
by Jeannine 1I
Wed Oct 24, 2018 11:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Indeterminacy Question
Replies: 3
Views: 121

Re: Indeterminacy Question

Yes, I would think so! Since the equation involves a greater than or equal to sign, it would make sense that they ask for minimum of something, and not maximum.
by Jeannine 1I
Wed Oct 24, 2018 11:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Answers to module questions?
Replies: 2
Views: 64

Re: Answers to module questions?

If you answer all the questions on the post-modules, the whole thing is scored, and although it doesn't tell you what the correct answers are (for the ones you got wrong), it's still useful to know! And there's always the option of retaking it and choosing different answers until you get 100% of the...
by Jeannine 1I
Sun Oct 21, 2018 11:41 am
Forum: Properties of Light
Topic: HW 1.3 (6th edition)
Replies: 1
Views: 45

HW 1.3 (6th edition)

Question 1.3 asks, "What happens when frequency of electromagnetic radiation decreases?" and the answer is "the extent of the change in the electrical field at a given point decreases." Would someone be able to explain to me what the answer to this means, or how this relationship...
by Jeannine 1I
Sun Oct 21, 2018 10:45 am
Forum: Properties of Light
Topic: Equations
Replies: 6
Views: 64

Re: Equations

Yes, for every test we will be given a sheet of equations and the periodic table!
by Jeannine 1I
Thu Oct 18, 2018 11:05 pm
Forum: *Black Body Radiation
Topic: Black Body
Replies: 9
Views: 171

Re: Black Body

I believe he mentioned in class that we don't need to know about black bodies, so I wouldn't worry too much about studying them. It's also not on the course outline!
by Jeannine 1I
Tue Oct 16, 2018 9:37 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Question 1.15 sixth edition
Replies: 10
Views: 108

Re: Question 1.15 sixth edition

why is the energy level of 102.6 nm 1? My reasoning for why n1=1, is that the 102.6 nm is a part of the Lyman series, and a general rule in the Lyman series is the first energy level (n1) is always equal to 1, so n1=1. I'm not sure if that line where 102.6 nm is is n1, but that was just my reasonin...
by Jeannine 1I
Sat Oct 13, 2018 10:25 pm
Forum: Properties of Light
Topic: Units for a Joule [ENDORSED]
Replies: 3
Views: 46

Re: Units for a Joule [ENDORSED]

A "Joule" is a unit of energy, and is named after the man who discovered it. I think we just use the term "joule" as a shorter way to say 1 kg*m^2/s^2, and it lets people know automatically that we're referring to energy. I hope that helps at least a bit haha(: !
by Jeannine 1I
Sat Oct 13, 2018 9:31 pm
Forum: Balancing Chemical Reactions
Topic: Test 1 and Future Tests
Replies: 5
Views: 121

Re: Test 1 and Future Tests

What I end up doing to show my work for balancing equations, is count the number of moles on each side and write them out. For example, if there are 12 total carbon atoms on both sides, I'd write C: 12 on each side! I hoped it would show them that I checked my work.
by Jeannine 1I
Sat Oct 13, 2018 9:14 pm
Forum: Properties of Light
Topic: HW 1.7A
Replies: 3
Views: 396

Re: HW 1.7A

I got the same answer of 4.23 x 10^-7, and since nanometers is in 10^-9, I just moved over the decimal so that it would be 10^-9. The answer then becomes 423 x 10^-9, which is the same thing as 423 nanometers. I hope this helps!(:
by Jeannine 1I
Sat Oct 06, 2018 10:41 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.13
Replies: 1
Views: 38

Re: G.13

You're right, it should be 4 L of water as the final volume! Did you check to see if the final answer is correct? Maybe it was a typo, or they really did solve it incorrectly. The answer should be 1.0 x 10^-2 mol of N!
by Jeannine 1I
Sat Oct 06, 2018 12:10 am
Forum: Administrative Questions and Class Announcements
Topic: Number of questions on test one [ENDORSED]
Replies: 39
Views: 16698

Re: Number of questions on test one [ENDORSED]

I attended a chemistry study session where I was told there would only be about 3-4 questions, but most likely with multiple parts. I was also told that really studying and understanding what is listed in Outline 1 would help us on the test! I don't know how strict they'll be on grading though:/
by Jeannine 1I
Wed Oct 03, 2018 9:00 pm
Forum: Significant Figures
Topic: E23C Sig Figs
Replies: 2
Views: 39

Re: E23C Sig Figs

In general, you use the given information to figure out how many sig figs you need in your answer. So yes, in this case you base it off the 25.2 kg in the question, which means your answer will also include 3 sig figs!
by Jeannine 1I
Wed Oct 03, 2018 8:55 pm
Forum: Empirical & Molecular Formulas
Topic: Homework
Replies: 2
Views: 64

Re: Homework

My chem TA told us to include our Bruin ID number and our discussion session! I'm not sure if that applies to all classes though.
by Jeannine 1I
Tue Oct 02, 2018 8:50 pm
Forum: Balancing Chemical Reactions
Topic: Balancing equations (Problem H21 6th edition)
Replies: 3
Views: 60

Balancing equations (Problem H21 6th edition)

In this equation, we need to balance the equation C10H15N + O2 -----> CO2 + H2O + CH4N2O, and the answer to that is 2 C10H15N + 26 O2 -----> 19 CO2 + 13 H2O + CH4N2O. I ended up with the correct answer, but it took me a while to figure it out. Does anyone know a faster way to balance out equations, ...

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