Search found 62 matches

by Lucy Wang 2J
Mon Jan 18, 2021 9:15 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: textbook 5I.11
Replies: 2
Views: 16

textbook 5I.11

A reaction vessel of volume 0.500 L at 700. K contains 1.20 mmol SO2(g), 0.50 mmol O2(g), and 0.10 mmol SO3(g). At 700. K, Kc 5 1.7 3 106 for the equilibrium 2 SO2(g) 1 O2(g) ∆ 2 SO3(g). (a) Calculate the reaction quotient Qc. I calculated Qc=(.1)^2/[(.5)(1.2)^2]=.0139, however the answer key says t...
by Lucy Wang 2J
Sun Jan 17, 2021 10:45 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature and Kc
Replies: 5
Views: 19

Re: Temperature and Kc

when a reaction is endothermic, meaning energy is required for the reactants to go to products, if a reaction is heated this will favor the forward reaction/the formation of products so Kc will increase. when a reaction is exothermic, meaning energy is released when the reactants go to products, if ...
by Lucy Wang 2J
Sun Jan 17, 2021 10:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 #10
Replies: 8
Views: 28

Re: Sapling Week 1 #10

To solve for the equilibrium constant, Kc, you do [products]/[reactants]. So for this it would be (2.28)^2/(0.463)
by Lucy Wang 2J
Sun Jan 17, 2021 10:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: composition of the reaction mixture
Replies: 2
Views: 17

Re: composition of the reaction mixture

not necessarily, the composition of a reaction mixture is the reaction quotient, Q, which gives the concentration values for an expression that may not necessarily be at equilibrium yet.
by Lucy Wang 2J
Sun Jan 17, 2021 10:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #10
Replies: 4
Views: 18

Re: Sapling #10

I think you need to factor the equation to be a quadratic so it will be Ax^2 + Bx + C = 0 and then use the quadratic formula x=[B +/- sqrt(B^2-4AC)]/2A. From this, you will get two answers and you need to eliminate the one that would give you a negative concentration value. Then you will have your x...
by Lucy Wang 2J
Fri Jan 15, 2021 1:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When x is negligible in Equilibrium constant
Replies: 34
Views: 98

Re: When x is negligible in Equilibrium constant

Hi!

I think Professor Lavelle said that in order for x to negligible, the value must be smaller that 10^-3 but to be safe under 10^-4.
by Lucy Wang 2J
Mon Jan 11, 2021 12:21 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Coefficients for eq constant
Replies: 9
Views: 26

Re: Coefficients for eq constant

you would raise it to the power of that coefficient
by Lucy Wang 2J
Mon Jan 11, 2021 12:18 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Temp
Replies: 9
Views: 42

Re: Change in Temp

yes when enthalpy is positive it's an endothermic reaction and when it is negative the reaction is exothermic
by Lucy Wang 2J
Sun Jan 10, 2021 11:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables
Replies: 11
Views: 54

Re: ICE Tables

you can use ICE tables to figure out the molar concentration of the products and reactants at equilibrium and the change in the molar concentration
by Lucy Wang 2J
Sun Jan 10, 2021 11:31 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K on and reactant/product concentrations
Replies: 8
Views: 27

Q and K on and reactant/product concentrations

during lecture 2, Professor Lavelle said that if Q<K during a reaction, then [R]>[P] and the forward reaction is favored. however, isn't it possible for Q<K but for [P] to be greater than [R]?
by Lucy Wang 2J
Sun Jan 10, 2021 11:14 pm
Forum: Ideal Gases
Topic: Inert Gases
Replies: 7
Views: 33

Re: Inert Gases

an inert gas is just a gas that does not react in the reaction
by Lucy Wang 2J
Sun Dec 06, 2020 2:57 pm
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 3
Views: 48

Re: Final

There will be 30 questions on the final, each worth 6 points. I think quantum will be covered the most on the final since we spent the most time on it. The distribution is based on how long we spent on each topic.
by Lucy Wang 2J
Sun Dec 06, 2020 2:56 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sapling Week 10: #13 and #14
Replies: 2
Views: 40

Re: Sapling Week 10: #13 and #14

If a species is more predominant that means that is the majority in the solution. For an acidic solution, the predominant species will be charged and for a basic solution, the predominant species is neutral.
by Lucy Wang 2J
Sun Dec 06, 2020 2:47 pm
Forum: Naming
Topic: Naming Coordination Compounds
Replies: 5
Views: 66

Re: Naming Coordination Compounds

first you list the ligand names in alphabetical order with (Greek Prefix), then the transition metal cation name (Roman Numeral) and then if there are anions, then you put the anion name, with a Greek Prefix and then the hydrate
by Lucy Wang 2J
Sun Dec 06, 2020 2:41 pm
Forum: Lewis Acids & Bases
Topic: week 10 sapling #1
Replies: 5
Views: 57

week 10 sapling #1

In aqueous solution, classify these compounds as strong acids, weak acids, strong bases or weak bases.

How do you tell if an acid is strong or not?
by Lucy Wang 2J
Sun Dec 06, 2020 2:37 pm
Forum: Bronsted Acids & Bases
Topic: bronsted vs. lewis acid
Replies: 10
Views: 75

bronsted vs. lewis acid

I was wondering if someone could explain the difference between a bronsted and a lewis acid. What's the difference between them? Is it possible for an acid to be both a bronsted and lewis acid?
by Lucy Wang 2J
Sun Nov 29, 2020 11:20 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Shape
Replies: 5
Views: 51

Re: Seesaw Shape

The seesaw shape applies to when there are 5 areas of electron density. One area is a lone pair and the other 4 are bonds. When this happens, it leads to a seesaw structure.
by Lucy Wang 2J
Sun Nov 29, 2020 11:17 am
Forum: Hybridization
Topic: Lecture #23
Replies: 13
Views: 115

Re: Lecture #23

Yes the electrons are delocalized and a pi bond is formed above and below the ring.
by Lucy Wang 2J
Sun Nov 29, 2020 11:14 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: formation of coordination compounds
Replies: 3
Views: 47

formation of coordination compounds

In lecture #24, Professor Lavelle mentioned that to form salts, KCN or NaCl or NH3 would replace water's position in the ligand. Is there a reason water is so easily replaceable in a ligand solution?
by Lucy Wang 2J
Sun Nov 29, 2020 11:06 am
Forum: Hybridization
Topic: hybridization orbitals
Replies: 5
Views: 49

Re: hybridization orbitals

it depends on its ground state electron configuration. Since C ends at 2p. the hybridization orbital is 2sp
by Lucy Wang 2J
Sun Nov 29, 2020 10:58 am
Forum: Sigma & Pi Bonds
Topic: sapling #18
Replies: 1
Views: 68

sapling #18

Select the correct statement about the relative positions of the hydrogen atoms in the three structures. ->The hydrogen atoms of H2CCH2 and H2CCCCH2 lie in the same plane. The hydrogen atoms of H2CCCH2 and H2CCCCH2 lie in the same plane. The hydrogen atoms of H2CCH2 and H2CCCH2 lie in the same plane...
by Lucy Wang 2J
Sun Nov 29, 2020 10:37 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelate Stability
Replies: 3
Views: 34

Re: Chelate Stability

i think multidentate ligands are more stable because they have more bonds so its more difficult to break but I'm not sure how easy it is to form multidentate ligands versus unidentate ligands
by Lucy Wang 2J
Wed Nov 18, 2020 6:07 pm
Forum: Trends in The Periodic Table
Topic: Metallic Character
Replies: 7
Views: 72

Re: Metallic Character

Metallic character is greatest at the bottom left corner of the periodic table. The answer is in increasing order so P has the least metallic character and Na has the most. This follows and makes sense with the trend of metallic character across the periodic table.
by Lucy Wang 2J
Wed Nov 18, 2020 5:23 pm
Forum: Lewis Structures
Topic: Identifying Radicals
Replies: 4
Views: 46

Re: Identifying Radicals

Hi!
Yes, all molecules that have an odd number of electrons are radicals.
by Lucy Wang 2J
Wed Nov 18, 2020 5:19 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: Hydrogen Bonding
Replies: 5
Views: 40

Re: Hydrogen Bonding

if a N, O or F atom has 2 lone pairs, then hypothetically yes it could form two hydrogen bonds, one for each lone pair.
by Lucy Wang 2J
Sun Nov 15, 2020 9:46 pm
Forum: Trends in The Periodic Table
Topic: Ion Trends
Replies: 18
Views: 93

Re: Ion Trends

I think you should know trends for ionization energy, electronegativity, atomic radius.

i'm not really sure about any others
by Lucy Wang 2J
Sun Nov 15, 2020 9:44 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Section 1D #25
Replies: 2
Views: 43

Re: Section 1D #25

The subshells possible for a certain shell is l=0,1,...n-1.
so for n=2, l=0, 1. However since for l=2 for d, the subshell 2d cannot exist.
Hope this helps!
by Lucy Wang 2J
Sun Nov 15, 2020 9:41 pm
Forum: Resonance Structures
Topic: bookwork 2C.15
Replies: 2
Views: 23

Re: bookwork 2C.15

The lewis structure that has more formal charges that are closer to zero are lower energy and more stable.
by Lucy Wang 2J
Sun Nov 15, 2020 9:39 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Sapling 9
Replies: 6
Views: 80

Re: Oxidation Sapling 9

The sum of the oxidation numbers of the atoms in the perchlorate ion must equal the charge on the ion, -1. When oxygen is bonded to a nonmetal other than flourine, it has an oxidation number of -2. Because there are four oxygen atoms in the ion, chlorine must have an oxidation number of +7 to equal ...
by Lucy Wang 2J
Sun Nov 15, 2020 9:26 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polar vs nonpolar
Replies: 3
Views: 36

Re: polar vs nonpolar

If a molecule is polar, that means the charge distribution will be unequal. For example, in the molecule HF it would be polar because F is much more electronegative than H and therefore will have a stronger pull on the electrons. Making the F side of the molecule slightly more negative than the H si...
by Lucy Wang 2J
Sun Nov 15, 2020 3:11 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: Sapling question Hydrogen Bonding
Replies: 1
Views: 25

Re: Sapling question Hydrogen Bonding

Hey! In order for there to be hydrogen bonding, there needs to either be a Hydrogen bonded to a highly electronegative atom (N, O, F) or a lone pair of a highly electronegative atom (N, O, F). So for this problem, theoretically there are 8 sites where hydrogen bonds can be formed with this molecule....
by Lucy Wang 2J
Sun Nov 08, 2020 9:54 pm
Forum: Einstein Equation
Topic: E=pc vs E=hv
Replies: 15
Views: 150

Re: E=pc vs E=hv

Hey!
My understanding is that E=hv is only used for light/photons. However, E=pc is used for these that have mass, like electrons.
by Lucy Wang 2J
Sun Nov 08, 2020 9:51 pm
Forum: Lewis Structures
Topic: Valence Shell electrons
Replies: 2
Views: 37

Valence Shell electrons

So my understanding is that valence shells must have 8 electrons. And these are represented by the s2p6. However, what does the d and f orbital represent then? Do these also fill valence shells?
by Lucy Wang 2J
Sun Nov 08, 2020 9:48 pm
Forum: Lewis Structures
Topic: nitrate lewis structure
Replies: 7
Views: 57

Re: nitrate lewis structure

I think it has to do with formal charge. If two of the oxygen had a double bond, then the nitrogen would have 5 bonds which is not very stable.
by Lucy Wang 2J
Sun Nov 08, 2020 9:39 pm
Forum: Lewis Structures
Topic: Lewis acids and bases
Replies: 10
Views: 71

Lewis acids and bases

how can we tell the difference between a molecule that is an acid or a base? do they react differently in chemical reactions?
by Lucy Wang 2J
Sun Nov 08, 2020 9:05 pm
Forum: Student Social/Study Group
Topic: Midterm 2
Replies: 28
Views: 170

Re: Midterm 2

I would say to do the textbook homework problems and attend the step up learning sessions. Don't wait until the last minute to do these questions, you should try to do these along with the lectures that pertain to the textbook problems. For me, it helps to reinforce my understanding of what Prof.Lav...
by Lucy Wang 2J
Fri Oct 30, 2020 5:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Sapling homework
Replies: 2
Views: 47

Re: Sapling homework

The question is basically asking how many electrons could have these criteria. so for the first one, n=3 The 3 shell has 3s, 3p, 3d and in each of these subshells they can contain 2, 6, 10 electrons respectively. Then add them together and the answer is 18. For the second question, n=4, l=2 This is ...
by Lucy Wang 2J
Fri Oct 30, 2020 5:40 pm
Forum: Trends in The Periodic Table
Topic: ionization trend
Replies: 3
Views: 40

Re: ionization trend

Hi Brett, I'm not completely sure but my understanding is that in order to conduct electricity, electrons need to be able to to be transferred relatively easily from atom to atom as free electrons. And when the ionization energy for an atom is low, this means that the energy needed to remove an elec...
by Lucy Wang 2J
Fri Oct 30, 2020 5:36 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Finding Electrons with Quantum Numbers
Replies: 3
Views: 29

Re: Finding Electrons with Quantum Numbers

Hi Quinton, So for the first question since n=4 AND l=2, this is referring to electrons that are in the 4d subshell only. The value of l for the electrons from the 4s or 4p subshells do not equal 2 so they don't apply to this question. I think the answer should be 10. For the second question, when n...
by Lucy Wang 2J
Fri Oct 30, 2020 4:53 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: SAPLING #20
Replies: 4
Views: 53

SAPLING #20

Identify the reasons why oxygen has a lower first ionization energy than both nitrogen and flourine.

So I understand why oxygen has a lower first ionization energy than oxygen but can someone explain why for nitrogen?
by Lucy Wang 2J
Tue Oct 27, 2020 1:30 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: atomic spectroscopy vs. molecular spectroscopy
Replies: 2
Views: 30

atomic spectroscopy vs. molecular spectroscopy

can someone explain the point on the Unit 2: Outline that says"with respect to electron transitions that give rise to a UV or visible spectrum: understand the difference between electronic transitions in atomic orbitals and electronic transitions in molecular orbitals" or if u could point ...
by Lucy Wang 2J
Fri Oct 23, 2020 4:38 pm
Forum: DeBroglie Equation
Topic: Sapling Question 22
Replies: 3
Views: 55

Re: Sapling Question 22

The reason you must use de Broglie's equation for this problem is because it is talking about an electron. The equation c=wv only applies to photons since c is the speed of light. When you use that equation for an electron, your answer will be incorrect. However, de Broglie's equation can be used fo...
by Lucy Wang 2J
Fri Oct 23, 2020 4:34 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing Electron Configuration
Replies: 2
Views: 25

Re: Writing Electron Configuration

For an excited state electron configuration, the electrons won't necessarily be in the "correct" (groundstate) order. For example Carbon has 6 electrons. A ground state configuration would be 1s2, 2s2, 3s2. But if one of the electrons were to be excited, then the excited-state electron con...
by Lucy Wang 2J
Fri Oct 23, 2020 4:30 pm
Forum: *Shrodinger Equation
Topic: Clarification Needed..
Replies: 3
Views: 62

Re: Clarification Needed..

I asked my TA about this and I think he was just explaining how they got the equation but for this class we won't necessarily need to know how to derive it. I think the wave is to represent the probability that you will find an electron there. So at the peaks, it has the greatest probability and whe...
by Lucy Wang 2J
Fri Oct 23, 2020 4:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Energy Levels in the same Shell
Replies: 2
Views: 20

Re: Energy Levels in the same Shell

Hey! I'm not 100% sure why it is that they have lower energy but I don't think we need to know why for now, just know that the order of increasing orbitals is s, p, d, f.
by Lucy Wang 2J
Fri Oct 23, 2020 4:22 pm
Forum: Properties of Light
Topic: Sapling Homework week 2 problem 5
Replies: 11
Views: 107

Re: Sapling Homework week 2 problem 5

Hey! I think you are doing it correct but you just need to convert from cm to m before you find Energy (J).
by Lucy Wang 2J
Fri Oct 23, 2020 4:12 pm
Forum: Trends in The Periodic Table
Topic: Shielding Effect
Replies: 2
Views: 34

Re: Shielding Effect

Hey! So I don't think the electrons are necessarily lined up right next to each other. We never know the exact location of the electron, we only know that they are located in their orbitals which are high probability areas, like the s-orbital(sphere). Even though we don't know the exact location, th...
by Lucy Wang 2J
Fri Oct 23, 2020 4:04 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1B.9 Question
Replies: 2
Views: 27

Re: 1B.9 Question

I solved it by using the equation E=(hc)/wavelength to get 4.73 x 10^-19 Joules/photon. Then in order to get the # of photons, I divided 64J by 4.73 x 10^-19 J/photon to get the number of individual protons (1.35 x 10^20 photons). Then to convert the photons to moles use Avogadro's number to get 2.2...
by Lucy Wang 2J
Fri Oct 16, 2020 2:42 pm
Forum: Properties of Electrons
Topic: calculating the frequency of Light
Replies: 4
Views: 23

Re: calculating the frequency of Light

Hey! I posted a reply to this in Lec 7. Question [ENDORESED] but I've attached it below. I hope it helps! The negative sign simply is to show that this is the amount of energy LOST by the electron. We changed it to a positive sign to show the amount of energy being ABSORBED by the photon or turned i...
by Lucy Wang 2J
Fri Oct 16, 2020 2:39 pm
Forum: Properties of Electrons
Topic: calculating the frequency of light
Replies: 4
Views: 41

Re: calculating the frequency of light

The -1/16 is denoting the energy for when the n=4. In the equation, E = (hR)/n^2, so when n=4, it would be (-1/16)*hR. The -1/4 is showing when n=2.
by Lucy Wang 2J
Fri Oct 16, 2020 2:37 pm
Forum: SI Units, Unit Conversions
Topic: 10^?
Replies: 2
Views: 53

Re: 10^?

i think the easiest way would just be to plug the equation, as it's written, into your calculator! If you are having trouble figuring out which 10^?, then I would recommend switching to scientific notation rather than flo. It would probably be easiest just to look up how to do this for your specific...
by Lucy Wang 2J
Fri Oct 16, 2020 2:33 pm
Forum: Properties of Electrons
Topic: Electron Transition
Replies: 7
Views: 36

Re: Electron Transition

electron transition refers to when an electron changes energy levels in an atom/molecule. For example an electron can be excited during a photoelectric experiment and jump from energy level n=1 to n=3
by Lucy Wang 2J
Fri Oct 16, 2020 2:12 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lecture 7 Question [ENDORSED]
Replies: 4
Views: 76

Re: Lecture 7 Question [ENDORSED]

The negative sign simply is to show that this is the amount of energy LOST by the electron. We changed it to a positive sign to show the amount of energy being ABSORBED by the photon or turned into light. This works because according to the conservation of energy, energy cannot be created or destroy...
by Lucy Wang 2J
Fri Oct 16, 2020 2:06 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectroscopy N?
Replies: 3
Views: 44

Re: Atomic Spectroscopy N?

I think to find the change in energy, you do the final energy - initial energy.
by Lucy Wang 2J
Fri Oct 09, 2020 3:07 pm
Forum: Limiting Reactant Calculations
Topic: Actual yield
Replies: 20
Views: 194

Re: Actual yield

You should be able to calculate the theoretical yield. As for the actual yield, I think this is usually given to you or maybe as a percentage of the theoretical yield, so that you would be able to solve for the actual yield.
by Lucy Wang 2J
Fri Oct 09, 2020 3:05 pm
Forum: Administrative Questions and Class Announcements
Topic: Exam Regulations
Replies: 7
Views: 64

Re: Exam Regulations

I think they will all be closed book.
by Lucy Wang 2J
Fri Oct 09, 2020 3:04 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: HW E.15
Replies: 4
Views: 47

HW E.15

E.15 The molar mass of the metal hydroxide M(OH)2 is 74.10g*mol -1. What is the molar mass of the sulfide of this metal?

What does it mean the sulfide of this metal? Am I supposed to convert it to something else?
by Lucy Wang 2J
Fri Oct 09, 2020 3:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Petition to Bring Music Back To Lectures [ENDORSED]
Replies: 34
Views: 539

Re: Petition to Bring Music to Back To Lectures [ENDORSED]

Yes! I agree! We need the music back! It helps to make it feel like a real lecture in the classroom
by Lucy Wang 2J
Fri Oct 09, 2020 2:59 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.13
Replies: 3
Views: 64

Re: G.13

So in the first solution, there are 0.20 moles of NH4NO3. When the florist dilutes it by adding 3.0L of water, the molarity of the solution is .20 mol/ 4 L = .05 Molarity. From there, the florist pours 100ml, or 0.1 L, of this diluted solution into each plant. So the number of moles of NH4NO3 being ...
by Lucy Wang 2J
Fri Oct 09, 2020 2:46 pm
Forum: Properties of Light
Topic: Amplitude and Velocity Relationship
Replies: 3
Views: 33

Re: Amplitude and Velocity Relationship

My understanding is that amplitude does not affect wave velocity. However, amplitude has more to do with the energy or intensity of the light? I'm not 100% sure though, anyone can feel free to correct me.
by Lucy Wang 2J
Thu Oct 08, 2020 5:48 pm
Forum: DeBroglie Equation
Topic: Question about post-module assessment
Replies: 5
Views: 95

Re: Question about post-module assessment

hey! could you be more specific about where this problem is from?
by Lucy Wang 2J
Thu Oct 08, 2020 5:46 pm
Forum: Balancing Chemical Reactions
Topic: WK 1 Sapling #10
Replies: 7
Views: 87

Re: WK 1 Sapling #10

Yeah thats what I did and it worked for me! Since it is a 1:1 ration, I just used the number moles of 2-butanone and multiplied it by the molar mass of 3-methyl 3-hexanol to get the theoretical yield of the product in grams.

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