Search found 64 matches

by Charlene D 3I
Sun Jan 17, 2021 4:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: sapling week #1 Question 6
Replies: 4
Views: 21

Re: sapling week #1 Question 6

It looks like your exponent for H2 is 2 when it should be 3 because of the coefficient of H2 in the reaction! (:
by Charlene D 3I
Sun Jan 17, 2021 3:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 1 Sapling 3
Replies: 11
Views: 47

Re: Week 1 Sapling 3

Try square rooting both sides of the equation! This should simplify things and make solving for x easier.
by Charlene D 3I
Sun Jan 17, 2021 3:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Help on #5 Sapling Homework
Replies: 1
Views: 23

Re: Help on #5 Sapling Homework

Hi Jessica, You can use the pH to solve for [OH-] which u can then plug into the Kb equation,[BH+][OH−]/[B]. I assumed that the reaction started with 0M of product so this [OH-] value is also equal to the change in x in our ICE table. Since there are equal parts moles of each product, [BH+] = [OH−],...
by Charlene D 3I
Sun Jan 17, 2021 3:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Applying 5J.11 b to other problems
Replies: 1
Views: 9

Applying 5J.11 b to other problems

Hello, In this problem you are asked state what happens when temperature increases in the reaction of X 2 (g) turns into 2X(g) where X is a halogen. The answer key concludes that because it requires energy to break the X-X bond we should think of it as endothermic. I'm wondering if there are other r...
by Charlene D 3I
Thu Jan 14, 2021 3:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Long term vs short term changes in conc.
Replies: 6
Views: 28

Long term vs short term changes in conc.

When asked to find the effects of adding more product or reactant to a reaction, will we be told whether we're analyzing changes in the long or short term or should we assume that it is one way or the other? And just for clarification: say we had one reactant in an equation. if it's in the short ter...
by Charlene D 3I
Sun Jan 10, 2021 1:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling #5 on finding k
Replies: 2
Views: 24

Re: Sapling #5 on finding k

Hi! I approached this problem by rearranging the given reactions and using the following knowledge. 1) know that when you are adding/combining reactions together the K values are multiplied. ie) rxn1 + rxn2 has a K value of K1*K2. 2) the K of a reverse reaction is just 1/K 3) If a molecule has the s...
by Charlene D 3I
Sat Jan 09, 2021 4:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Conceptual Understanding of Decrease in Volume
Replies: 3
Views: 22

Conceptual Understanding of Decrease in Volume

I'm wondering why a decrease in volume when moles of gas are not equal for reactants and products causes a shift. What is happening at the molecular level to cause this?
by Charlene D 3I
Sat Jan 09, 2021 3:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Impacts of Increasing Pressure
Replies: 4
Views: 13

Impacts of Increasing Pressure

If there's equal moles on each side of a reaction, and the pressure increases is it safe to say that the equilibrium doesn't shift and assume that it's not in a vessel? I'm wondering because in lecture it was pretty apparent that it's the decreasing volume and resulting conc. change not increasing p...
by Charlene D 3I
Fri Jan 08, 2021 6:27 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5.61 f. textbook problem explanation
Replies: 1
Views: 12

5.61 f. textbook problem explanation

Hello! The question asks what happens when water is added to the photosynthesis chemical reaction. I understand that water does not affect the equilibrium concentration bc it's a pure liquid, but I'm curious about the book answer's explanation. It says "As long as the glucose solution is dilute...
by Charlene D 3I
Wed Jan 06, 2021 5:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: #29 Chem Equilibrium Pt. 2 Module
Replies: 2
Views: 28

#29 Chem Equilibrium Pt. 2 Module

the problem states: A researcher fills a 1.00L reaction vessel with 1.84 x 10^-4 mol of BrCl gas and heats it to 500K. At equilibrium, only 18.3% of BrCl gas remains. Calculate the equilibrium constant, assuming the following reaction is taking place 2BrCl (g) -> Br 2 (g) + Cl 2 (g). I'm wondering i...
by Charlene D 3I
Thu Dec 10, 2020 11:10 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs Lewis Acids and Bases
Replies: 8
Views: 59

Bronsted vs Lewis Acids and Bases

When asked to simply identify the acid or base in a reaction, how do I distinguish between the type of acid/base? I know in some cases the terms can be used interchangeably, but are there examples when it would be incorrect to call a bronsted base/acid a lewis, or vice verse?
Thank you!
by Charlene D 3I
Thu Dec 10, 2020 10:52 pm
Forum: Conjugate Acids & Bases
Topic: Sapling #13/#14
Replies: 3
Views: 54

Re: Sapling #13/#14

Thank you so much! That makes everything a lot clearer! Though I do have one residual question, what does the pKa stand for? Like, I know the equation is the charged particle concentration over intact molecules, but what does it mean in the context of this topic? If that's a little vague, let me kn...
by Charlene D 3I
Thu Dec 10, 2020 11:41 am
Forum: Bronsted Acids & Bases
Topic: More Strong Bases?
Replies: 1
Views: 9

More Strong Bases?

Is there a reason Be(OH)2 and Mg(OH) aren't included in the Macmillan textbook list of strong bases when they are group 1 and 2 hydroxides? I noticed there were no oxides listed either... Is there a more comprehensive list I should look at and memorize? here is the list i'm referring to: https://sit...
by Charlene D 3I
Tue Dec 08, 2020 11:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: determining shape of complex
Replies: 4
Views: 55

determining shape of complex

My notes seem to contradict each other so I would like some clarification.
Does the number of ligands or the number of bonds determine the shape of a complex?
Thanks in advance.
by Charlene D 3I
Tue Dec 08, 2020 9:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: tetrahedral vs octahedral correction lec 24
Replies: 2
Views: 13

tetrahedral vs octahedral correction lec 24

I'm sorry if this was already posted but I couldn't find anyone else who mentioned it. While reviewing my notes and rewatching lecture 24, i noticed that Lavelle said that a coordination compound with 4 bonds is either "octahedral or square planar." Just to make sure, he meant tetrahedral ...
by Charlene D 3I
Thu Dec 03, 2020 10:10 pm
Forum: Hybridization
Topic: 2.45 b Textbook problem
Replies: 3
Views: 39

2.45 b Textbook problem

For the double bonds on the molecule H2C=CHCHO, can someone explain how to "identify the composition of the bonds and the hybridization of each lone pair" ? Sorry I don't think I completely understand the diff between identifying the composition of the bonds and the hybridization of each L...
by Charlene D 3I
Thu Dec 03, 2020 9:17 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxalato Bonding Sites
Replies: 2
Views: 12

Oxalato Bonding Sites

Can someone explain the chemistry behind the fact that the oxygen atoms with a lone pair and double bonds are NOT bonding sites but the oxygens with a lone pair and single bonds ARE bonding sites?
Thank you (:
by Charlene D 3I
Thu Dec 03, 2020 9:03 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: List of Polydentate Ligands
Replies: 3
Views: 45

List of Polydentate Ligands

Hi! I'm wondering if anyone can let me know which of the ligands on the sheet are polydentate and how many bonding sites they each have?
If you found a resource that could be good, too!
Thank you in advance.
by Charlene D 3I
Thu Dec 03, 2020 8:39 pm
Forum: Lewis Structures
Topic: Varying Arrangements of Structure
Replies: 5
Views: 63

Re: Varying Arrangements of Structure

Yes thank you I meant CH2Cl2! Thank you all for the help.
by Charlene D 3I
Mon Nov 30, 2020 7:21 pm
Forum: Lewis Structures
Topic: Varying Arrangements of Structure
Replies: 5
Views: 63

Varying Arrangements of Structure

When drawing molecules like C2HCl2 that can have multiple atom arrangements, how do I know whether like atoms are draw opposite or next to each other? Is there a difference?
Do these arrangements lead to the same tetrahedral VSEPR structure?
Thank you!
by Charlene D 3I
Mon Nov 30, 2020 12:01 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Formula Order
Replies: 2
Views: 30

Formula Order

When coming up with a formula for a coordination compound from the name, do the cations always come before the brackets and do the anions always go after? I am referring to the ions that aren't inside the coordination sphere.
Thank you!
by Charlene D 3I
Sun Nov 29, 2020 10:51 pm
Forum: Hybridization
Topic: Contributions to Hybridization for different bonds
Replies: 1
Views: 21

Contributions to Hybridization for different bonds

Conceptually, why do single, double, and triple bonds contribute the same to hybridization? Why is it that the number of electrons between two atoms does not affect the blending of two orbitals? Thank you!
by Charlene D 3I
Thu Nov 26, 2020 12:38 pm
Forum: Biological Examples
Topic: Cisplatin example clarification
Replies: 2
Views: 44

Cisplatin example clarification

In the diagram that shows cisplatin interacting with the GC base, it appears that the one cisplatin molecule attaches to two Guanine N^7 sites. If this is the case, wouldn't that mean that there's a lone electron left on the nitrogen of each GC base? What happens to that lone electron on Nitrogen? P...
by Charlene D 3I
Thu Nov 26, 2020 12:37 pm
Forum: Administrative Questions and Class Announcements
Topic: how to access saved drafts
Replies: 2
Views: 28

Re: how to access saved drafts

Marylyn Makar 1D wrote:Hi! You can find your saved drafts by clicking on your name in the upper right hand corner and then click user control panel. Then click overview and on the left hand side click manage drafts. Hope that helps!

Thank you this was helpful! Do you know how I can post a draft straight from that section?
by Charlene D 3I
Wed Nov 25, 2020 1:47 pm
Forum: Administrative Questions and Class Announcements
Topic: how to access saved drafts
Replies: 2
Views: 28

how to access saved drafts

Hello,
I'm wondering where I can access a draft I saved on Chem Community?
It might be right in front of my nose, but I couldn't find it from searching or in the quick links.
Thank you!
by Charlene D 3I
Wed Nov 25, 2020 1:39 pm
Forum: Biological Examples
Topic: Cisplatin and G-C base interactions
Replies: 1
Views: 36

Cisplatin and G-C base interactions

Hi, This is referring to lecture 24's cisplatin example. I am wondering how the Cl atom is taken off of the cisplatin in order for the Platinum to bond with the guanine N^7 position. Is it due to the forces from the nitrogen's lone pair? I'm just curious how this interaction happens in the first pla...
by Charlene D 3I
Mon Nov 23, 2020 6:04 pm
Forum: Hybridization
Topic: Carbon rotation and breaking of bonds
Replies: 3
Views: 19

Carbon rotation and breaking of bonds

Hi,
In today's lecture (#23) Dr. Lavelle stated that when the Carbons on ethene rotate their pi-bond breaks. When this happens, does the sigma bond between Cs stay in-tact or does it also break?
Thank you!
by Charlene D 3I
Sun Nov 22, 2020 3:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorizing Shape Names
Replies: 12
Views: 63

Memorizing Shape Names

Hi I'm wondering if any of y'all have helpful mneumonics or memory tricks for remembering the name of a molecule and its corresponding shape.
Thank you, I appreciate it! (:
by Charlene D 3I
Sun Nov 22, 2020 3:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle of Molecule
Replies: 7
Views: 42

Bond Angle of Molecule

Hi for one of the sapling problems, it asks for the smallest bond angle in a molecule with two bonds and two lone pairs. In my notes (which could be wrong) and for my answer I wrote 104.5 degrees and got it correct, but the solution explanation uses approximately or slightly less than 109.5 degrees....
by Charlene D 3I
Wed Nov 18, 2020 10:19 pm
Forum: Resonance Structures
Topic: 2.7 Resonance of N5 cation
Replies: 2
Views: 33

2.7 Resonance of N5 cation

The question asks you to find the resonance structures of the N5 + cation. Is there a strategy that you all use to find all the possible arrangements of a structure like this? I normally add single bonds then try to rearrange electrons then add double and triple bonds if I'm electron deficient. And ...
by Charlene D 3I
Wed Nov 18, 2020 10:03 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: H-Bonding clarification
Replies: 7
Views: 96

H-Bonding clarification

In addition to a lone pair on the N, O, or F that an H is bonding to, Does the N,O, or F that's already connected to the H have to have a lone pair on it in order for an H-bond to form or
is it just the N, O, or F that the H is bonding TO that needs to have a lone pair?

Thank you!
by Charlene D 3I
Mon Nov 16, 2020 10:52 pm
Forum: Resonance Structures
Topic: Dominant Contribution to Resonance Hybrid
Replies: 4
Views: 53

Dominant Contribution to Resonance Hybrid

I'm wondering what is means for a structure to be the dominant contributor to a resonance hybrid?
Why is it that the structure with the lowest energy / is most stable is the most likely to make a contribution?
This is from 2c.17 of the homework btw.
Thank you!
by Charlene D 3I
Sun Nov 15, 2020 5:01 pm
Forum: Dipole Moments
Topic: Sapling #13 Hydrogen Bonds
Replies: 5
Views: 50

Re: Sapling #13 Hydrogen Bonds

hi Jill!
I believe that as long as the Hydrogen (from the H2O) is bonding with an N, O, or F and the H is attached to an N, O, or F with a lone pair (which it is bc it's attached to the O in H20), it counts as an H-bond.
I hope this helps!
by Charlene D 3I
Tue Nov 10, 2020 10:55 pm
Forum: Lewis Structures
Topic: Lewis Structure for NO+
Replies: 3
Views: 41

Lewis Structure for NO+

When drawing the lewis structure for NO+ why does the Oxygen atom have the positive charge / why is there a triple bond? Is this more favorable than having a double bond with Nitrogen holding the positive charge?
Thank you!
by Charlene D 3I
Mon Nov 09, 2020 10:28 am
Forum: Ionic & Covalent Bonds
Topic: deltas in covalent bonds
Replies: 3
Views: 22

deltas in covalent bonds

Just a clarification on lecture #16, When Dr. Lavelle drew the structure of CO he added deltas. The type of delta corresponds to the relative level of electronegativity right? With delta positive on the less electronegative atom and the delta negative on the more electronegative atom? How are deltas...
by Charlene D 3I
Sun Nov 08, 2020 10:34 pm
Forum: Lewis Structures
Topic: Bond Character
Replies: 6
Views: 82

Re: Bond Character

I read some other posts and it seems that ample behavior is when the expected and measured bond lengths are close enough to each other and overwhelming is when the values are very close or the same. However, I too would like more context. Ie) is there a general value that distinguishes "ample&q...
by Charlene D 3I
Sun Nov 08, 2020 10:06 pm
Forum: Quantum Numbers and The H-Atom
Topic: Pz Py Pz
Replies: 5
Views: 42

Re: Pz Py Pz

Hi Nina,
I believe the subscripts refer to the axis that each p-orbital lies on.
ie) px is on the x-axis
by Charlene D 3I
Sun Nov 08, 2020 4:13 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Covalent character vs. Ionic character
Replies: 4
Views: 47

Re: Covalent character vs. Ionic character

Hi Valerie, I had the same question, however after attending a UA session I got a better understanding. Here are some of my main takeaways. Ionic bonds: electrons are transferred between atoms, electronegativity difference greater than 2, more soluble in water Covalent bonds: electrons are shared be...
by Charlene D 3I
Sat Nov 07, 2020 6:45 pm
Forum: Resonance Structures
Topic: Overall Structure of Ion - Sapling #4, W5
Replies: 3
Views: 24

Overall Structure of Ion - Sapling #4, W5

The question is:
Which of the Lewis structures would be expected to contribute the least to the overall structure of the carbamate ion?
I am unsure how to approach this question. What makes characteristics make a structure less likely to contribute to the structure of an ion?
Thank you!
by Charlene D 3I
Sat Nov 07, 2020 6:35 pm
Forum: Resonance Structures
Topic: Sapling HW Question 4
Replies: 5
Views: 46

Re: Sapling HW Question 4

Oh wait nevermind. I realized the C and O bonds are single bonds.
by Charlene D 3I
Sat Nov 07, 2020 6:30 pm
Forum: Resonance Structures
Topic: Sapling HW Question 4
Replies: 5
Views: 46

Re: Sapling HW Question 4

For question number 4 in the Sapling HW, I am asked to to draw the three major resonance structures for a carbamate ion. One is given, and. I was able to come up with one that had a double bond between the N and the C but I am not sure wha the third one would be. Maybe someone has some guidance on ...
by Charlene D 3I
Sun Nov 01, 2020 6:19 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Question 26 Sapling
Replies: 5
Views: 60

Re: Question 26 Sapling

Hi!
You can convert the uncertainty of position to meters, then plug that value in for delta x in the Heisenberg Indeterminacy equation. From there you can solve for delta V using the mass of an electron.
Let me know if you need any more clarification!
by Charlene D 3I
Fri Oct 30, 2020 12:05 pm
Forum: Ionic & Covalent Bonds
Topic: Inert vs Noble Gas
Replies: 4
Views: 44

Inert vs Noble Gas

In today's lecture (12), during the ionic bonds section it was stated that main group metals form the same e- configuration as their preceding "inert-gas" atom whereas p-block non-metals gain p valence e- until they reach "noble gas" configuration. I am wondering what the differe...
by Charlene D 3I
Fri Oct 30, 2020 11:43 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Sapling Learning Week 2,3, and 4 Homework Question 26
Replies: 3
Views: 57

Re: Sapling Learning Week 2,3, and 4 Homework Question 26

I believe you would use Heisenberg's Indeterminacy equation (m*Δv)* Δx = h/(4pi). where m is the mass of a helium atom (its atomic mass in kg), Δv is uncertainty in velocity converted to meters per second and Δx is the uncertainty in position converted to meters. note: it is an equals sign and not g...
by Charlene D 3I
Thu Oct 29, 2020 9:11 pm
Forum: Properties of Light
Topic: Textbook Question Number 1A 3 c
Replies: 3
Views: 60

Re: Textbook Question Number 1A 3 c

If you think about the wave like a function on a graph, the "extent of change" would refer to the slope. A wave with a lower frequency would have a smaller slope, or extent of change, than a wave with a higher frequency. This question is definitely hard to visualize, but I hope this helps...
by Charlene D 3I
Thu Oct 29, 2020 3:56 pm
Forum: Einstein Equation
Topic: Sapling Week 4 #23
Replies: 3
Views: 118

Sapling Week 4 #23

The electron affinity is the difference in energy between the incident photons and the energy of the ejected electrons. Determine the electron affinity of thulium in units of electron volts per atom. Note: I didn't include all the values bc I have a conceptual question. So after finding the differen...
by Charlene D 3I
Sun Oct 25, 2020 4:18 pm
Forum: Limiting Reactant Calculations
Topic: using the molar ratio to find LR?
Replies: 3
Views: 49

using the molar ratio to find LR?

Hi,
When finding the limiting reactant of a reaction, do you all normally convert the mols of reactant to the mols of a product or keep the mols in terms of the reactant? I have seen it done both ways.
Thank you!
by Charlene D 3I
Sun Oct 25, 2020 4:09 pm
Forum: Limiting Reactant Calculations
Topic: Textbook G.25
Replies: 4
Views: 59

Re: Textbook G.25

Hi Chanel,
This confused me as well. I think the textbook said "no substance" because the answer you got is very small and therefore insignificant and has no effect on a patient.
i hope this helped.
by Charlene D 3I
Sat Oct 24, 2020 5:35 pm
Forum: Einstein Equation
Topic: Sapling Homework - electron affinity
Replies: 5
Views: 82

Re: Sapling Homework - electron affinity

Yeah I couldn't get the right answer for the second part either. I wonder if there is anything wrong with my conversions. @Samantha, could you explain your steps for the first part and how you got 1.003? I used E=hc/lambda and converted nm to m as well as J to eV, but I still didn't get to 1.003. Th...
by Charlene D 3I
Fri Oct 23, 2020 5:09 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm length
Replies: 4
Views: 43

Re: Midterm length

I was told it would be around 20 questions and that we should have more than enough time to work on all the problems.
by Charlene D 3I
Tue Oct 20, 2020 11:28 pm
Forum: Photoelectric Effect
Topic: Sapling Hw #5
Replies: 3
Views: 82

Re: Sapling Hw #5

Even though your set-up and thought process is correct, I believe there is an error in your final answer. It should be 3.24 x 10^20 <-- with a positive exponent.
I had a small error the first time I did this question as well, but I hope this helped. (:
by Charlene D 3I
Sun Oct 18, 2020 1:11 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 10/16 Lecture Demo on Atomic Spectra
Replies: 5
Views: 33

Re: 10/16 Lecture Demo on Atomic Spectra

Oh my bad. I didn't actually answer your question directly, but yeah I don't think there was any gas in the bottom. I think it was displayed so we could compare it to how gases emit specific and different wavelengths of light.
by Charlene D 3I
Sun Oct 18, 2020 1:00 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 10/16 Lecture Demo on Atomic Spectra
Replies: 5
Views: 33

Re: 10/16 Lecture Demo on Atomic Spectra

Hi Emily!
I believe it was white light / visible light.
from top to bottom: helium, neon, mercury, white light.
by Charlene D 3I
Sun Oct 18, 2020 12:55 pm
Forum: Photoelectric Effect
Topic: 1B.15a DeBroglie or KE equation
Replies: 3
Views: 57

Re: 1B.15a DeBroglie or KE equation

Okay that makes sense thank you!
by Charlene D 3I
Fri Oct 16, 2020 6:10 pm
Forum: Photoelectric Effect
Topic: 1B.15a DeBroglie or KE equation
Replies: 3
Views: 57

1B.15a DeBroglie or KE equation

The velocity of an electron emitted from a metallic surface by a photon is 3.6x10^3 km/s. What is the wavelength of the ejected electron? For this problem I used KE=(1/2)(mv^2) after converting km/s to m/s and using the mass of an electron. I then used lambda=(hc)/KE to find wavelength. However I di...
by Charlene D 3I
Fri Oct 16, 2020 12:22 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lec 7 - electron energy value
Replies: 1
Views: 56

Lec 7 - electron energy value

In the lecture Dr. Lavelle gave an example of an electron that was at energy level n=20 and the energy of the electron was 0 because it wasn't interacting with the nucleus. I understand why the energy between the electron and nucleus would be insignificant from a high energy level. However I would l...
by Charlene D 3I
Wed Oct 14, 2020 9:33 pm
Forum: Student Social/Study Group
Topic: iPad vs Paper notes
Replies: 32
Views: 265

iPad vs Paper notes

Hi! I've noticed that many students use iPads for note taking and doing problems (especially for STEM classes). The idea of organizing everything from one subject area into a convenient digital folder seems nicer than my current notebook set up where one topic is dispersed throughout my notebook fro...
by Charlene D 3I
Wed Oct 14, 2020 8:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: E23 Confused
Replies: 4
Views: 87

Re: E23 Confused

Hi Ruth! The you are given the grams of CuBr2, which you can then convert to mols of CuBr2 using the molar mass. Because molar mass corresponds to the amount of grams in one mole of CuBr2, you can simply multiply the mols of CuBr2 by the molar ratio of 1 mol Cu : 1 mol CuBr2 to find mols of Cu^2+ io...
by Charlene D 3I
Sun Oct 11, 2020 3:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: atomic spectra post video Q29
Replies: 2
Views: 29

Re: atomic spectra post video Q29

The 11J of energy is the total energy emitted in 1.0 second. If you know the energy of one photon you can find the number of photons generated in 1.0 second by dividing total energy by energy of one photon.
Hope this helped!
by Charlene D 3I
Fri Oct 09, 2020 11:38 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: G13 Question
Replies: 7
Views: 110

Re: G13 Question

Hi Charlene! You are correct that the number of moles of NH4NO3 stay the same before and after the reaction, but in this problem you are finding the moles of Nitrogen atoms as opposed to the moles of NH4NO3. Therefore you would have to multiply the moles of NH4NO3 by 2 (there are two moles of Nitro...
by Charlene D 3I
Fri Oct 09, 2020 11:32 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Frequency and Wavelength cannot be negative
Replies: 1
Views: 34

Re: Frequency and Wavelength cannot be negative

I believe that in the worked example of the video module for Atomic Spectra, Lavelle took the absolute value of the change in E before plugging it into the difference in energy = h x frequency equation. Therefore I would follow this method. Hope this helps!
by Charlene D 3I
Wed Oct 07, 2020 1:41 pm
Forum: Photoelectric Effect
Topic: Module Question 29
Replies: 5
Views: 215

Re: Module Question 29

Does anyone know why we don't add the kinetic energy to the energy to remove e-? I thought that to find the energy needed to eject the e- we had to add the work function to the kinetic energy. The work function is equivalent to the required energy per mol needed to eject the e- Therefore we can jus...
by Charlene D 3I
Wed Oct 07, 2020 12:54 pm
Forum: Photoelectric Effect
Topic: Photoelectric effect [ENDORSED]
Replies: 6
Views: 620

Re: Photoelectric effect [ENDORSED]

ShreyaKannan1B wrote:
Camille 4I wrote:Where did you get the number 4.200x10^-19 from?


Yeah I don't get that either.

I believe he got that number from the next question (#32) that's related to this one. However the problem can be solved without this information.
by Charlene D 3I
Tue Oct 06, 2020 11:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: G13 Question
Replies: 7
Views: 110

Re: G13 Question

For this question I eventually got the correct answer, but I'm still having trouble understanding it conceptually. If you have the same amount of moles in a solution before and after dilution, why can't you use the number of moles in NH4NO3 (calculated using the initial Volume and initial molarity),...

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