Search found 107 matches
- Wed Mar 11, 2020 12:32 am
- Forum: Administrative Questions and Class Announcements
- Topic: What is the plan for the final?
- Replies: 16
- Views: 1003
Re: What is the plan for the final?
Will there be a time limit for the exam?
- Tue Mar 10, 2020 4:49 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Tuesday Night Covel UA Sessions
- Replies: 2
- Views: 246
Tuesday Night Covel UA Sessions
Will the UA sessions in Covel 210 still be going on tonight?
- Tue Mar 10, 2020 3:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: practice test
- Replies: 2
- Views: 299
Re: practice test
As always, homework problems are the most reliable source of practice for the exam so definitely make sure that you have done all the problems before the final!
- Tue Mar 10, 2020 2:57 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Calculation for pre-exponential factor A
- Replies: 3
- Views: 301
Re: Calculation for pre-exponential factor A
Even though the assigned reading goes into this calculation in-depth, I doubt that we will have to know how to calculate it as he hasn't gone over it in lecture and there have been no homework problems that deal with the topic.
- Tue Mar 10, 2020 2:55 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final exam content
- Replies: 15
- Views: 1141
Re: Final exam content
Usually, at least one question from the homework will appear nearly word for word on Lavelle's midterms and finals.
- Tue Mar 10, 2020 2:52 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Intermediate
- Replies: 3
- Views: 480
Re: Intermediate
For the image above, it's good to know that only one intermediate will be formed since the reaction profile indicates a 2 step process and the intermediate will be created in the first step and used as a reactant for the second step.
- Tue Mar 10, 2020 2:50 pm
- Forum: *Enzyme Kinetics
- Topic: K and Catalyst
- Replies: 3
- Views: 411
Re: K and Catalyst
To add on to the previous post, the presence of a catalyst will also not affect equilibrium concentrations or enthalpy!
- Tue Mar 03, 2020 5:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Sapling Learning
- Replies: 6
- Views: 549
Re: Sapling Learning
How do I access Sapling Learning? I tried accessing it on a link he sent in one of his emails, but it required a payment method. The instructions said there was a way to avoid payment but I didn't see it. Upon buying the textbook for the course, you should have also received a pamphlet with a Sapli...
- Tue Mar 03, 2020 5:13 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: A Reactivity Epiphany
- Replies: 2
- Views: 503
Re: A Reactivity Epiphany
nicolely2F wrote:We will be given a sheet with all the half-reactions and standard potentials needed, though, right?
Yes, those will definitely be provided!
- Tue Mar 03, 2020 5:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum and Granite
- Replies: 4
- Views: 333
Re: Platinum and Granite
We use platinum and graphite as the electrode in our cell diagrams when there are no conducting solids present for the given half-reaction.
- Tue Mar 03, 2020 5:11 pm
- Forum: Van't Hoff Equation
- Topic: Equation Sheet
- Replies: 18
- Views: 1020
Re: Equation Sheet
I don't believe that it is.
- Tue Mar 03, 2020 5:10 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: 6O.1
- Replies: 2
- Views: 272
6O.1
A 1.0 m NiSO4(aq) solution was electrolyzed by using inert electrodes. Write (a) the cathode reaction; (b) the anode reaction. (c) With no overpotential at the electrodes, what is the minimum potential that must be supplied to the cell for the onset of electrolysis? When presented with these kinds o...
- Wed Feb 26, 2020 6:46 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Cell Potential
- Replies: 3
- Views: 261
Re: Standard Cell Potential
In addition, a substance is in standard conditions when it has a molarity of 1M (aq), when it has a partial pressure of 1 bar (g), or when it can be considered a pure liquid or solid.
- Wed Feb 26, 2020 6:44 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Work
- Replies: 4
- Views: 336
Re: Work
The Gibbs free energy of a redox reaction can be linked to its cell potential and Gibbs free energy can be interpreted as the maximum non-expansion work a specific reaction can do.
- Wed Feb 26, 2020 6:41 pm
- Forum: Balancing Redox Reactions
- Topic: common oxidation numbers
- Replies: 3
- Views: 270
Re: common oxidation numbers
A general rule of thumb is that H will be +1 and O and S will be -2.
- Wed Feb 26, 2020 6:40 pm
- Forum: Balancing Redox Reactions
- Topic: balancing in acidic solutions
- Replies: 4
- Views: 372
Re: balancing in acidic solutions
H+ and H3O+ are essentially the same thing so you could theoretically use them interchangeably. However, since H3O+ is more useful for when we are dealing with proton transfer, H+ would be the more efficient one to use.
- Wed Feb 26, 2020 6:38 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2 Topics
- Replies: 5
- Views: 842
Test 2 Topics
Will test 2 cover concepts like rust/corrosion and pH meters? Some of the later homework questions deal with these topics but Lavelle has not gone over them during lecture.
- Tue Feb 25, 2020 1:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L 5d
- Replies: 2
- Views: 188
Re: 6L 5d
I don't believe the cell potential for the Au+ -> Au3+ + 2e- half reaction, the one that I expected, is given in the back of the book either. I'm commenting down below so I can return to this post when more answers have been posted.
- Thu Feb 20, 2020 2:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode to the Right Rule
- Replies: 6
- Views: 446
Re: Cathode to the Right Rule
A word of caution: an UA told me that the book is really inconsistent with the visual diagram conventions so I would always double check!
- Thu Feb 20, 2020 2:20 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing/reducing agent
- Replies: 7
- Views: 494
Oxidizing/reducing agent
Can someone please explain to me what an oxidizing/reducing agent is? From the homework problems, it seems as if the compound losing electrons is the reducing agent and the compound gaining electrons is the oxidizing agent but that sounds incorrect to me.
- Wed Feb 19, 2020 11:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2 Material
- Replies: 16
- Views: 983
Re: Test 2 Material
I believe Lavelle has said that he will be finished lecturing for Test 2 material after Monday next week.
- Wed Feb 19, 2020 11:38 pm
- Forum: Administrative Questions and Class Announcements
- Topic: HW7
- Replies: 14
- Views: 792
Re: HW7
Essentially all problems in the textbook up to what Lavelle has covered so far can be fair game!
- Wed Feb 19, 2020 11:37 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation number of Ozone
- Replies: 10
- Views: 698
Oxidation number of Ozone
Is the overall oxidation number for ozone 0? How could this occur if the oxygen atom is commonly regarded to have an oxidation number of -2?
- Thu Feb 13, 2020 8:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Review session powerpoints
- Replies: 4
- Views: 259
- Thu Feb 13, 2020 8:10 pm
- Forum: Administrative Questions and Class Announcements
- Topic: grading curve
- Replies: 10
- Views: 643
Re: grading curve
Seeing as the class average was about a B+ for CHEM 14A, I would not expect a sizeable curve.
- Thu Feb 13, 2020 8:09 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm grading
- Replies: 8
- Views: 396
Re: Midterm grading
Jessica Esparza 2H wrote:It is uniform graders. Does anyone know if it'll take about a week like last time?
Yes they should be handing back the midterm at the end of lectures about a week from now!
- Thu Feb 13, 2020 8:08 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2
- Replies: 1
- Views: 123
Re: Test 2
The second test will likely cover the end of outline 4 and outline 5!
- Thu Feb 13, 2020 8:07 pm
- Forum: Calculating Work of Expansion
- Topic: Last Question on the Midterm [ENDORSED]
- Replies: 5
- Views: 477
Re: Last Question on the Midterm [ENDORSED]
I'm not sure about the exact details of the question, but the answers for the midterms should be posted soon on Lavelle's website complete with step by step solutions and a point breakdown!
- Thu Feb 06, 2020 1:58 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: 4H.9
- Replies: 1
- Views: 117
4H.9
Container A is filled with 1.0 mol of the atoms of an ideal monatomic gas. Container B has 1.0 mol of atoms bound together as diatomic molecules that are not vibrationally active. Container C has 1.0 mol of atoms bound together as diatomic molecules that are vibrationally active. The containers all ...
- Mon Feb 03, 2020 10:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Lyndon Bui Workshops
- Replies: 7
- Views: 467
Re: Lyndon Bui Workshops
He has not posted it yet! But I would definitely be on the lookout as he should be uploading it soon.
- Mon Feb 03, 2020 5:19 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Thermodynamics Laws
- Replies: 4
- Views: 132
Re: Thermodynamics Laws
The first law of thermodynamics is the change in internal energy = heat + work and the second law is delta S = q/T.
- Mon Feb 03, 2020 5:17 pm
- Forum: Phase Changes & Related Calculations
- Topic: phase changes, temperature constant?
- Replies: 11
- Views: 577
Re: phase changes, temperature constant?
In addition, you can think of the temperature remaining the same due to all the added heat being used to break the bonds between molecules of a substance.
- Mon Feb 03, 2020 5:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: intensive/extensive
- Replies: 4
- Views: 146
Re: intensive/extensive
I think it would be good to remember that entropy is an extensive property!
- Mon Feb 03, 2020 5:14 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Midterm Review
- Replies: 7
- Views: 370
Re: Midterm Review
He typically posts a worksheet on chemistry community! He'll probably let us know what to type in the search bar to find it in the following days.
- Thu Jan 30, 2020 9:51 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Material
- Replies: 13
- Views: 664
Re: Midterm Material
An UA told me that we were going to cover material up to Outline 4. There are usually a bunch of review sessions that are held by BOTH lavelle and the UA's so definitely be on the lookout for those!
- Thu Jan 30, 2020 9:50 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Enthalpy at Constant Pressure
- Replies: 2
- Views: 126
Re: Enthalpy at Constant Pressure
Enthalpy at constant pressure is referring to essentially an open system with an air pressure of 1.0 atm. With an open system, the gas has the ability to push the air on top of the beaker out of the way, therefore performing work onto it.
- Mon Jan 27, 2020 7:53 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 11
- Views: 340
Re: Hess's Law
In order to use Hess's Law to solve for the change in enthalpy, you will have to know the changes in enthalpy for intermediate reactions that occur with the reactants given to form the end product.
- Mon Jan 27, 2020 7:50 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Last Lecture Week 3 Lec 3
- Replies: 1
- Views: 68
Re: Last Lecture Week 3 Lec 3
Are you referring to the example dealing with the combustion of methane? If so, I don't believe that we needed to calculate the mass, but rather the change in enthalpy by adding up the sum of the standard enthalpies of formation for the products and subtracting the sum from the standard enthalpies o...
- Mon Jan 27, 2020 7:45 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: q and deltaH
- Replies: 3
- Views: 94
Re: q and deltaH
During the lecture, Lavelle instructed us that q(p)=delta H!
- Mon Jan 20, 2020 5:05 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: 6B 9
- Replies: 1
- Views: 36
Re: 6B 9
Yes I had that issue too! I believe it's an error on the solution manual.
- Mon Jan 20, 2020 5:04 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Directionality of Acid/Base Equations
- Replies: 4
- Views: 119
Re: Directionality of Acid/Base Equations
For the purposes of this course, acid/base reactions are reversible only with weak acids or bases.
- Mon Jan 20, 2020 5:03 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH Examples
- Replies: 3
- Views: 271
Re: pH Examples
I think it would be a good idea for you to memorize the chemical formula just in case! It's relatively straight forward.
- Mon Jan 20, 2020 5:00 pm
- Forum: Ideal Gases
- Topic: Acid and Bases
- Replies: 16
- Views: 499
Re: Acid and Bases
pH measures the amount of H3O+ ions produced due to the reaction. The more H30+ ions a reaction can produce, the more acidic it is. It might also be helpful to remember that pH and the concentration of H3O+ ions are inversely related.
- Mon Jan 20, 2020 4:57 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: "Quick Way" for predicting response to changes in volume/pressure
- Replies: 3
- Views: 154
Re: "Quick Way" for predicting response to changes in volume/pressure
To add on, this system works this way due to Le Chatelier's principle since favoring the side of the reaction with less moles of gas when pressure is applied means that there will be less molecules ultimately bouncing off the walls of the container and creating additional pressure.
- Mon Jan 13, 2020 6:58 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier
- Replies: 3
- Views: 102
Re: Le Chatelier
Increasing the total pressure of the system will cause equilibrium to shift to the side with fewer moles Changing the pressure of a system will not change the equilibrium constant k itself, but it will cause a net increase in the equilibrium concentration of the side of a reaction with less moles d...
- Mon Jan 13, 2020 6:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc and Kp
- Replies: 8
- Views: 268
Re: Kc and Kp
but can't you also use Kc for gases? so the phases don't really tell you anything but just go off of what you're given? You can also use Kc for gases since a lot of the reactions we deal with have heterogeneous equilibria. If the units for the amount of gas are in L/mol, use concentration and if th...
- Mon Jan 13, 2020 6:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc and Kp
- Replies: 8
- Views: 268
Re: Kc and Kp
Solids and liquids aren't included in the equilibrium constant because there's no such thing as the "concentration" of a solid and liquids (solvents) can usually be expected to have nearly the same concentration on both sides of the equation so they would cancel out to 1 anyways if we divi...
- Mon Jan 13, 2020 6:48 pm
- Forum: Ideal Gases
- Topic: R constant
- Replies: 6
- Views: 242
Re: R constant
Lavelle gives you 4 different values for the R constant on his formula sheet during tests. Whichever one you use depends on the units given in the problem.
- Mon Jan 13, 2020 6:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Are Lectures Bruincasted?
- Replies: 10
- Views: 358
Re: Are Lectures Bruincasted?
None of Lavelle's lectures are recorded during the quarter with the exception of his lecture series on early chemical equilibria posted on his website.
- Mon Jan 13, 2020 6:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ATP Hydrolysis
- Replies: 2
- Views: 93
Re: ATP Hydrolysis
I don't believe that Lavelle has gone over that topic in lecture yet but seeing as it's listed on the outline and not mentioned in the books, I'd advise you to make a habit of attending his lectures as oftentimes he likes to emphasize specific concepts about biological examples such as this that may...
- Wed Jan 08, 2020 9:16 pm
- Forum: Ideal Gases
- Topic: PV=nRT equation manipulation
- Replies: 13
- Views: 683
Re: PV=nRT equation manipulation
We move elements of the equation around to solve for P and the concentration so we can convert the partial pressure of a gas to its concentration. Being able to do so will be helpful when we deal with heterogenous equilibria.
- Wed Jan 08, 2020 9:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5.35
- Replies: 4
- Views: 199
5.35
The following plot shows how the partial pressures of reactant and products vary with time for the decomposition of compound A into compounds B and C. All three compounds are gases. Use this plot to do the following: (a) Write a balanced chemical equation for the reaction. (b) Calculate the equilibr...
- Wed Jan 08, 2020 9:04 pm
- Forum: Ideal Gases
- Topic: Units for Pressure
- Replies: 6
- Views: 162
Re: Units for Pressure
In one of Lavelle's video lectures he asserted that we will treat 1 bar as equal to 1 atmosphere for the purposes of this course.
- Wed Jan 08, 2020 9:02 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Sapling Learning
- Replies: 9
- Views: 483
Re: Sapling Learning
Sapling learning assignments did not account for any portion of our grade last quarter for 14A!
- Wed Jan 08, 2020 10:39 am
- Forum: Ideal Gases
- Topic: Equilibrium
- Replies: 7
- Views: 207
Re: Equilibrium
Q is known as the reaction quotient and K is known as the equilibrium constant. One important thing to note is that K stays constant for a specific reaction at a specific temperature while Q does not have a predetermined value.
- Tue Dec 03, 2019 5:47 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Plane
- Replies: 2
- Views: 172
Re: Plane
Generally, only molecules arranged in planar arrangements, such as linear, trigonal planar, square planar, and perhaps t-shaped (please correct me if I am incorrect) contained atoms that are considered to be on one plane.
- Tue Dec 03, 2019 5:46 pm
- Forum: Lewis Acids & Bases
- Topic: Cations and Anions
- Replies: 3
- Views: 205
Re: Cations and Anions
Additionally, there are instances of acidic anions (when the reactant is polyprotic). The book goes into this in detail and there’s a chart of that lists the few times this occurs.
- Tue Dec 03, 2019 5:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Early Quantum Review Session
- Replies: 3
- Views: 110
Re: Early Quantum Review Session
I left 30 minutes in but keep us updated on whether or not he shows!
- Tue Dec 03, 2019 4:44 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: HW 6D11
- Replies: 7
- Views: 643
Re: HW 6D11
I just stumbled upon this section in my lecture notes and to add on to what everyone has been saying, Lavelle clarified that the hydrated metal cation will release H+ ions to form hydronium ions with water until the overall charge of the ion becomes neutral. When this happens, any anions attached to...
- Mon Dec 02, 2019 10:00 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: HW 6D11
- Replies: 7
- Views: 643
Re: HW 6D11
"When copper(II) nitrate dissociates in water, it forms Cu2+ and NO3-. Cu2+ is acidic since it is a transition metal, and NO3- is neutral because its the base of a strong acid, so it's relatively weak and doesn't do anything (spectator ion)." Lavelle gave this answer when answering another...
- Mon Dec 02, 2019 8:24 pm
- Forum: Bronsted Acids & Bases
- Topic: Fundamentals J.13c
- Replies: 2
- Views: 150
Fundamentals J.13c
2HI(aq) + CaO(s) --> CaI2(aq) + H2O(l)
Can someone explain the chemical reaction that is going on here and why CaO is a base? I understand why HI functions as an acid since it can pretty easily give off the H+ ion, but I'm not sure how these reactants form those products.
Can someone explain the chemical reaction that is going on here and why CaO is a base? I understand why HI functions as an acid since it can pretty easily give off the H+ ion, but I'm not sure how these reactants form those products.
- Mon Nov 25, 2019 1:40 pm
- Forum: Bronsted Acids & Bases
- Topic: Ions and Bronsted Acids and Bases
- Replies: 1
- Views: 134
Re: Ions and Bronsted Acids and Bases
I think it would be helpful to memorize the charges for the common polyatomic ions since it's not guaranteed that Lavelle would provide them on the final; it could save you a lot of time with the oxidation number calculations for coordination compunds if these ions show up as ligands as well.
- Mon Nov 25, 2019 1:36 pm
- Forum: Bronsted Acids & Bases
- Topic: Why do acids and bases react?
- Replies: 3
- Views: 238
Re: Why do acids and bases react?
Assuming that HBr + K+(OH)- --> KBr + H2O is your intended reaction, this reaction is an example of a neutralization reaction, which you could read more about in Fundamentals J.3. The H+ ion dissociates with the Br in the presence of a metal hydroxide (KOH-) since HBr is a strong acid and KOH- is a ...
- Mon Nov 25, 2019 1:29 pm
- Forum: Bronsted Acids & Bases
- Topic: Difference between Bronsted Acids and Bases
- Replies: 1
- Views: 135
Re: Difference between Bronsted Acids and Bases
Bronsted acids are defined as proton donors while Bronsted bases are defined as proton acceptors. In this case, the NH3 is a Bronsted base since a H+ ion (really just a proton) could bond to the N as it has an extra unoccupied bonding site. I'm not sure if you could make the generalization that mole...
- Mon Nov 25, 2019 1:08 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Displacement of Water Molecules in Aqueous Solution
- Replies: 1
- Views: 139
Displacement of Water Molecules in Aqueous Solution
Can someone explain to me how molecules such as NH3 displace the water molecules bonded to a metal ion in an aqueous solution during a chemical reaction?
- Mon Nov 25, 2019 12:58 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: edta
- Replies: 1
- Views: 160
edta
Would the edta ligand form an octahedral complex when it bonds with a metal ion since it is hexadentate and has the coordination number 6? If so, would the entire ligand have to wrap around the metal ion? Additionally, why are the points of attachment for the edta ligand only on the N atoms and the ...
- Fri Nov 22, 2019 9:53 pm
- Forum: Bond Lengths & Energies
- Topic: Dissociation Bond Length
- Replies: 3
- Views: 472
Re: Dissociation Bond Length
I think the exact bond length and dissociation energy for a molecule is something that has to be experimentally determined. He might ask you to compare the bond lengths of certain molecules, but general rules concering atomic radii should be able to help you compare their lengths qualitatively.
- Wed Nov 20, 2019 6:06 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Bond angles in Trigonal Bipyramidal
- Replies: 4
- Views: 525
Bond angles in Trigonal Bipyramidal
Does a trigonal bypryramidal shape have bond angles of 90, 120, AND 180? I have 180 degrees written down in my notes as well but the book seems to exclude it and only states the angles of 90 and 120.
- Tue Nov 19, 2019 7:46 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: Dipole-Dipole Interactions in Nonpolar Molecules
- Replies: 1
- Views: 103
Dipole-Dipole Interactions in Nonpolar Molecules
Can nonpolar molecules still have dipole-dipole interactions even though they have a net dipole of zero?
- Tue Nov 19, 2019 7:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Cylindrical Symmetry
- Replies: 1
- Views: 152
Cylindrical Symmetry
What exactly does "cylindrical symmetry around the internuclear axis" mean? I understand that it has something to do with allowing the molecule to rotate while still maintaining an overlap of the bonding orbitals, but I'm having a difficult time visualizing "cylindrical symmetry".
- Tue Nov 19, 2019 7:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Effect of lone pair on bond angles
- Replies: 2
- Views: 185
Effect of lone pair on bond angles
Is there any way to reason why the bond angle between NH3 is larger than the bond angle of SO3(2-)? I believe Lavelle sort of touched on why it makes sense for one to have a bond angle of 107 degrees and the other to have one of 106 degrees but I didn't manage to catch his explanation.
- Wed Nov 13, 2019 8:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 15
- Views: 816
Re: Test 2
Ghadir Seder 4F wrote:Whats the first topic that lavelle lectured about after our midterm?
I believe the first lecture after the midterm on last Friday went in further detail in regards to principles of chemical bonding, more specifically induced dipole-induced dipole bonding and hydrogen bonding.
- Wed Nov 13, 2019 8:12 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Memorizing and Recognizing Molecular Shapes
- Replies: 4
- Views: 227
Re: Memorizing and Recognizing Molecular Shapes
I think that we are expected to recognize the shapes of simple molecules up to octahedral, as Lavelle didn't go over pentagonal bipyramidal in class. I wouldn't be surprised if a question on the bond angle between a specific trio of atoms came up on the test, so memorizing those would also be helpful.
- Wed Nov 13, 2019 8:09 pm
- Forum: Dipole Moments
- Topic: Do lone pairs repel more?
- Replies: 5
- Views: 257
Re: Do lone pairs repel more?
Yes! Lone pairs also have a stronger degree of repulsion since there's only one positive force that counteracts the energy of a lone pair, namely the nucleus of the atom to which the lone pair belongs to while bonded pairs have 2 positive nuclei in between them which act as 2 positive forces that co...
- Wed Nov 13, 2019 8:06 pm
- Forum: Bond Lengths & Energies
- Topic: Interaction Potential Energy equation
- Replies: 7
- Views: 454
Re: Interaction Potential Energy equation
I think this equation was referenced by Lavelle to emphasize the importance of the distance between two bonded atoms and their charges in determining the strength of a bond and whether the resulting compound is a solid, liquid, or gas. I think the more generalized equation, the one listed on the las...
- Mon Nov 11, 2019 2:36 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: Test 2
- Replies: 6
- Views: 227
Re: Test 2
I believe Test 2 will test on the topics posted on Outline 4 and will include topics like induced dipole-induced dipole bonding that were omitted from the midterm and on Chapters 2E-2F, which Lavelle should be able to cover within the next three lectures.
- Tue Nov 05, 2019 7:23 pm
- Forum: Octet Exceptions
- Topic: Naming molecules
- Replies: 2
- Views: 170
Re: Naming molecules
I don't think Lavelle expects us to know how which molecular formula corresponds to which molecular name but I think starting to look at a list of common polyatomic ions (there's only around 10-20 of them) and studying prefixes and suffixes would be a good place to start studying.
- Tue Nov 05, 2019 7:21 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Oxidation state for Midterm
- Replies: 1
- Views: 96
Re: Oxidation state for Midterm
I don't believe it is part of Lavelle's outline but I would recommend studying it as it's not a hard concept to grasp and can help you immensely in drawing lewis structures.
- Tue Nov 05, 2019 7:18 pm
- Forum: Properties of Light
- Topic: Good Luck On Midterm
- Replies: 1
- Views: 231
Re: Good Luck On Midterm
Thanks for the support! Good luck to you as well tomorrow :) I would also recommend double checking the location of your midterm since everyone gets split up.
- Tue Nov 05, 2019 7:15 pm
- Forum: Bond Lengths & Energies
- Topic: de Broglie threshold
- Replies: 4
- Views: 340
Re: de Broglie threshold
Wavelike properties fail to be detected past 10^-15m. For reference, an electron has a wavelength of 10^-12 m and an Angstrom is 10^-10m.
- Tue Nov 05, 2019 2:50 pm
- Forum: Photoelectric Effect
- Topic: Why does the photoelectric effect not eject light?
- Replies: 1
- Views: 220
Why does the photoelectric effect not eject light?
Through my studies for the midterm, I came across the detail that passing an electric current through hydrogen gas causes electromagnetic radiation of a certain frequency to be emitted as an electron goes from a higher to a lower energy level. Given this, why does an electron, and not electromagneti...
- Thu Oct 31, 2019 8:11 pm
- Forum: Trends in The Periodic Table
- Topic: Electronegativity Trend
- Replies: 2
- Views: 112
Re: Electronegativity Trend
Electronegativity follows the same general trend as ionization energy, increasing as you go up and to the right!
- Thu Oct 31, 2019 8:08 pm
- Forum: Electronegativity
- Topic: 2D.1
- Replies: 4
- Views: 290
Re: 2D.1
I believe you have mistakenly replaced indium with tellerium in your final answer. The correct answer is In<Sn<Sb<Se, which you should have arrived at based on your thought process if you didn't switch up the two elements
- Thu Oct 31, 2019 8:04 pm
- Forum: Lewis Structures
- Topic: Angstrom Measurements on Lewis Structures
- Replies: 3
- Views: 234
Re: Angstrom Measurements on Lewis Structures
Angstrom is a non-SI unit that is preferred in calculating bond lengths; one angstrom is equivalent to 10^-10 m. I believe it would be wise for you to memorize the conversion between angstrom and meters as this is an unit that will probably show up repeatedly in future chemistry courses.
- Thu Oct 31, 2019 8:01 pm
- Forum: Photoelectric Effect
- Topic: Ionization Energy vs Threshold Energy
- Replies: 4
- Views: 304
Re: Ionization Energy vs Threshold Energy
Threshold energy and ionization energy both have to do with the minimum energy required to remove an electron from an element but threshold energy refers to the energy needed to remove an electron from a metal (photoelectric effect) while ionization energy has to do with the energy needed to remove ...
- Tue Oct 29, 2019 5:27 pm
- Forum: Trends in The Periodic Table
- Topic: Energy of Noble Gases
- Replies: 2
- Views: 132
Re: Energy of Noble Gases
Noble gases are the least reactive and most stable out of all the elements in their period, but I'm uncertain as to whether this puts them at a lower energy level since their valence electrons are still filling the p subshells, which are higher in energy than the s subshells. Fulfilling hunds rule c...
- Wed Oct 23, 2019 4:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: What topic are we on?
- Replies: 11
- Views: 509
Re: What topic are we on?
I think this week was more focused on building upon prior concepts in the Quantum World unit as we have barely delved into the new unit so I would do my homework on the questions in Outline 2! However, if you'd like to move ahead I'm sure the questions on Outline 3 are fair game as well.
- Wed Oct 23, 2019 4:40 pm
- Forum: Resonance Structures
- Topic: Bond types
- Replies: 2
- Views: 69
Re: Bond types
A triple bond is most stable since the bonds have shorter lengths, thereby holding the electrons more tightly together.
- Wed Oct 23, 2019 4:36 pm
- Forum: Lewis Structures
- Topic: Exceptions
- Replies: 3
- Views: 71
Re: Exceptions
I believe that it would just be far more reasonable for these atoms to gain/lose electrons to fulfill the 1s shell rather than gaining all those excess electrons to fill the entire 2nd shell.
- Wed Oct 23, 2019 4:31 pm
- Forum: Ionic & Covalent Bonds
- Topic: Lewis Structures
- Replies: 3
- Views: 133
Re: Lewis Structures
The element with the lowest ionization energy is the central atom since it takes the least amount of energy for an electron to detach from the atom. This means that it can more readily form bond(s) with other atoms.
- Wed Oct 23, 2019 4:27 pm
- Forum: Lewis Structures
- Topic: Valence e in d block
- Replies: 5
- Views: 331
Re: Valence e in d block
Writing out the d block elements' electric configurations would help you immensely in counting their valence electrons! Just remember to only count electrons in the outermost shell. The electron configuration of Zinc is formally [Ar] 3d¹⁰4s², but you should only focus on the electrons in the outermo...
- Tue Oct 22, 2019 4:56 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration of Tantalum
- Replies: 1
- Views: 217
Electron Configuration of Tantalum
I didn't realize that the homework problems list specifically told us to skip this problem (1E.21 c) so I went ahead and tried to figure out the electron configuration of tantalum and arrived at Xe 4f7 5d10 6s2, which is far from the correct answer. I'm curious as to whether there's a fundamental pr...
- Wed Oct 16, 2019 4:43 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron spin
- Replies: 8
- Views: 253
Re: Electron spin
Since there are two possible electrons that can have the same n,l, and m quantum numbers, we use +1/2 and -1/2 spin to distinguish them. For that reason, there can only be 2 spin states.
- Wed Oct 16, 2019 4:32 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Difference Between Ground and Excited States
- Replies: 3
- Views: 142
Re: Difference Between Ground and Excited States
The ground state can also be described as the lowest possible energy level that the atom can occupy and can be represented in a hydrogen atom when n=1 as -hR.
- Wed Oct 16, 2019 4:27 pm
- Forum: *Shrodinger Equation
- Topic: Equations for Quantum Topics
- Replies: 3
- Views: 125
Re: Equations for Quantum Topics
I think those 3 equations basically cover the fundamentals of quantum mechanics, but there are several other equations that form the intermediate steps of those equations such as c=λv, E=hv, E=pc, p=mv, E(n)=-hR/N^2, λ=h/p, and E(k)=1/2mv^2 that would be helpful to keep in mind.
- Wed Oct 16, 2019 4:19 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: X Y and Z
- Replies: 7
- Views: 242
Re: X Y and Z
In his lecture today, Lavelle emphasized that the plane the electron is found in is arbitrary and different textbooks associate different l values with different x,y, and z planes.
- Wed Oct 16, 2019 4:14 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Energy levels
- Replies: 3
- Views: 234
Re: Energy levels
I believe the 4d orbital has a higher energy level than the 5s orbital, but not the 5p orbital. The graph I linked below might be helpful. https://webs.anokaramsey.edu/chemistry/ ... iagram.PDF
- Thu Oct 10, 2019 12:57 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Test Equation Sheet
- Replies: 8
- Views: 439
Re: Test Equation Sheet
My TA actually handed out a copy of equations that Lavelle provides on the test sheet. For Test 1, the only relevant formula is that of Avogadro's constant. I imagine it will be much more helpful for tests later in the year as it includes a lot of fundamental constants and equations from the quantum...
- Wed Oct 09, 2019 9:30 pm
- Forum: SI Units, Unit Conversions
- Topic: Practice Problems?
- Replies: 11
- Views: 572
Re: Practice Problems?
My TA specifically referred us to review H7, L35, M9, and M15 during our discussion as they were considered the more complicated problems of the bunch. I would look over them before the test just in case!
- Wed Oct 09, 2019 9:24 pm
- Forum: SI Units, Unit Conversions
- Topic: Test 1
- Replies: 9
- Views: 455
Re: Test 1
The test covers topics beyond what was covered in the Audio-Visual focus topics! I believe a comprehensive list of concepts it will test us on are bullet pointed on Outline 1.