Search found 87 matches
- Sun Mar 17, 2019 4:03 am
- Forum: *Enzyme Kinetics
- Topic: final
- Replies: 2
- Views: 601
Re: final
Actually, correction: know how catalyst rules apply to enzyme rules and enzyme kinetics. After all, an enzyme is just an organic catalyst.
- Sat Mar 16, 2019 12:20 am
- Forum: Zero Order Reactions
- Topic: writing rate
- Replies: 2
- Views: 481
Re: writing rate
It does not matter. And also, if A is a reactant, you would put a negative sign in front of the d[A]/d[t] because the reactant is being used up.
- Sat Mar 16, 2019 12:19 am
- Forum: *Enzyme Kinetics
- Topic: final
- Replies: 2
- Views: 601
Re: final
Well, I would assume you do not really need to know enzyme kinetics given that it does not show up on the outline. I would just know that an enzyme is a catalyst.
- Sat Mar 16, 2019 12:18 am
- Forum: *Enzyme Kinetics
- Topic: what will we be given ?
- Replies: 3
- Views: 684
Re: what will we be given ?
I would assume it would depend on the equation. We would always be given enough information to figure out the answer.
- Sat Mar 16, 2019 12:17 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.13
- Replies: 1
- Views: 440
Re: 9.13
Because you would have to calculate the entropy due to the temperature change, the reversible equation can be used for the first part. You would have to consider each portion separately. So, first you would assume the the temperature as constant (isothermal), for the compression. Then, you would ass...
- Thu Mar 14, 2019 10:49 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Corrosion and Ion Selective Electrodes
- Replies: 4
- Views: 494
Re: Corrosion and Ion Selective Electrodes
The inert electrodes are written in cell potential diagrams when either electrode does not have a metal.
- Thu Mar 14, 2019 8:59 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Ranking species
- Replies: 3
- Views: 520
Re: Ranking species
It is also important to note that you have to identify when you have to flip the Ecell standard based off the question. Even though the reaction is given one way, the problem may be asking for the reverse of the reaction (like the oxidation when only the reduction is given). In those cases, you will...
- Thu Mar 14, 2019 8:56 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Pseudo Equlibrium
- Replies: 2
- Views: 244
Re: Pseudo Equlibrium
Tony Ong 3K wrote:Will the final have pseudo equilibrium constants on it where we have to calculate it?
I would assume there would always be a way to calculate it even if it is not given to us. But if it is given to us, that would also work.
- Thu Mar 14, 2019 2:43 am
- Forum: General Rate Laws
- Topic: elementary step
- Replies: 1
- Views: 200
Re: elementary step
As for water, water or any other molecule that is not the solvent, if it is part of a reaction, it can be in the rate law. However if the solvent is water, you do not include water in the rate law since you have excess amount of water so that the concentration of water does not contribute to the rea...
- Thu Mar 14, 2019 2:37 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Units of k
- Replies: 7
- Views: 1015
Re: Units of k
The units of the rate are always M/s. Therefore, you always want to find a way to make the units equal to M/s. So the units of K would always be in relation to the units of the concentration. For example, for a zero order reaction, the units of K would be M/s.
- Thu Mar 14, 2019 2:30 am
- Forum: Zero Order Reactions
- Topic: Zero order
- Replies: 10
- Views: 1609
Re: Zero order
so if I'm understanding this correctly... zero orders are just equal to the constant (k). how would we write them in the k[A][B]^2 thing or would be leave them out? Well, for a zero order reaction, since the rate law is fully independent of the concentration of the reactant, the rate law equation w...
- Tue Mar 12, 2019 7:13 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: writing elementary steps
- Replies: 1
- Views: 227
Re: writing elementary steps
For your second question, the [NO]^2 has to do with the concentration being squared not the formula so it would not be equivalent to N2O2.
- Tue Mar 12, 2019 7:12 pm
- Forum: Zero Order Reactions
- Topic: conceptual textbook question
- Replies: 1
- Views: 480
Re: conceptual textbook question
It just means that with respect to the triiode ions, the reaction rate is just the reaction constant.
- Tue Mar 12, 2019 7:11 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: reaction profile question
- Replies: 2
- Views: 296
Re: reaction profile question
The catalyst is introduced in the step with less activation energy since that is the purpose of the catalyst.
- Tue Mar 12, 2019 7:08 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: intermediates
- Replies: 1
- Views: 248
Re: intermediates
Anything that is not a final product is an intermediate. So if the product in the elementary reaction is not the same as the product of the overall reaction, then it is an elementary reaction.
- Tue Mar 12, 2019 7:07 pm
- Forum: Van't Hoff Equation
- Topic: Van't Hoff use
- Replies: 13
- Views: 2052
Re: Van't Hoff use
It would be used in a situation where you are trying to find a K value at a different temperature. For instance, on test 2, we were given the K value at one temp and we were asked to find the K value at a different temperature since the K value changes with temperature. In that situation, we would h...
- Tue Mar 12, 2019 5:37 pm
- Forum: Student Social/Study Group
- Topic: Studying for the Final
- Replies: 25
- Views: 2709
Re: Studying for the Final
Go over past final exam questions. additionally, previous midterm questions are quite helpful for standard potential questions.
- Tue Mar 12, 2019 12:19 am
- Forum: Ideal Gases
- Topic: ICE
- Replies: 8
- Views: 641
Re: ICE
The approximation can be utilized when solving ice problems if that condition is true.
- Tue Mar 12, 2019 12:17 am
- Forum: Zero Order Reactions
- Topic: zero order in rate law
- Replies: 7
- Views: 1198
Re: zero order in rate law
In the overall reaction law, the equation would just be the reaction constant.
- Tue Mar 12, 2019 12:07 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Intermediates
- Replies: 3
- Views: 355
Re: Intermediates
The intermediate is just that--the intermediate. It shows up only in the elementary reactions and is not in the final product.
- Sat Feb 23, 2019 9:35 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: What is residual entropy?
- Replies: 16
- Views: 4783
Re: What is residual entropy?
Residual entropy is the difference in entropy between a non-equilibrium state and crystal state of a substance close to absolute zero.
- Sat Feb 23, 2019 9:35 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: What is the difference between entropy and free energy?
- Replies: 2
- Views: 2728
Re: What is the difference between entropy and free energy?
I would add that Gibbs free energy is the maximum of reversible work that may be performed by a thermodynamic system at a constant temperature and pressure. Entropy is a thermodynamic function that describes the randomness and disorder of molecules based on the number of different arrangements avail...
- Sat Feb 23, 2019 9:33 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: test 3
- Replies: 10
- Views: 959
Re: test 3
I believe Gibbs free energy is 4J. Additionally, electrochemistry is 6K to 6M.
- Sat Feb 23, 2019 9:31 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 3
- Replies: 14
- Views: 2277
Re: Test 3
^Dr. Lavelle said that we should study based off the homework fro Gibbs Free energy as well as the electrochemistry material.
- Thu Feb 14, 2019 1:18 am
- Forum: General Science Questions
- Topic: Midterm Formulas
- Replies: 6
- Views: 953
Re: Midterm Formulas
Most formulas were provided on the midterm. I feel that even those that were not provided could have been figured out based off the ones given too us.
- Thu Feb 14, 2019 1:17 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Stability
- Replies: 5
- Views: 452
Re: Stability
If the equilibrium constant is larger than 1, that means product formation is favored. If the formation of something is favored, it usually means its the more stable molecule.
- Thu Feb 14, 2019 1:14 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Cv and Cp
- Replies: 3
- Views: 370
Re: Cv and Cp
Usually you will be given some information as to the conditions of the situation. Based of that, you should be able to figure out if it is constant pressure or constant volume.
- Thu Feb 14, 2019 1:09 am
- Forum: Calculating Work of Expansion
- Topic: Integrals
- Replies: 4
- Views: 528
Re: Integrals
Calculus is probably not required but its a good idea to understand the conceptual backing behind the formulas. That would include the calculus derivations.
- Sat Feb 09, 2019 2:48 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: midterm [ENDORSED]
- Replies: 4
- Views: 524
Re: midterm [ENDORSED]
Anjali_Kumar1F wrote:When is Lyndon going to post his midterm review ws??
He will probably post today or tomorrow before his midterm review session on Monday. I would recommend searching up the word "hotdog" to find his worksheet because Dr. Lavelle recommended that to be the name of his worksheet.
- Sun Feb 03, 2019 11:52 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Work done by expansion
- Replies: 3
- Views: 317
Re: Work done by expansion
When a gas expands against external pressure, it has to to transfer some of its energy over to the surroundings so it reduces its overall energy because of its negative work.
- Sun Feb 03, 2019 11:51 pm
- Forum: Phase Changes & Related Calculations
- Topic: Type of systems
- Replies: 12
- Views: 1290
Re: Type of systems
No. Isolated systems don't allow either energy transfers or matter transfers while closed systems still allow energy transfer. For example, closed systems could still absorb heat.
- Sun Feb 03, 2019 11:49 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Friday 02/01/2019 lecture
- Replies: 2
- Views: 325
Re: Friday 02/01/2019 lecture
What is your email?
- Sun Feb 03, 2019 11:45 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Midterm [ENDORSED]
- Replies: 49
- Views: 4710
Re: Midterm [ENDORSED]
Looking up and doing extra practice problems online also helps reinforce key concepts.
- Sat Feb 02, 2019 8:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat
- Replies: 6
- Views: 545
Re: Heat
For the reaction, q would be negative if that helps.
- Sat Feb 02, 2019 8:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: Negative work
- Replies: 11
- Views: 1014
Re: Negative work
Yes, if the force being applied is in the opposite direction of the displacement, the work will be negative.
- Sat Feb 02, 2019 8:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Review
- Replies: 14
- Views: 1175
Re: Midterm Review
Dr. Lavelle said in his email today that he will be announcing when the sessions will be most likely on Tuesday or Wednesday.
- Tue Jan 22, 2019 3:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Setting up Equilibrium Equations
- Replies: 2
- Views: 222
Re: Setting up Equilibrium Equations
I believe we do need to know how to set up the equation by ourself, however I believe the Ka or Kb value will be given to us or enough information will be given so we can find either value. To set up the equation, you first need to determine whether the molecule dissolved in water is a weak acid or ...
- Tue Jan 22, 2019 3:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: AlCl3 (aq)
- Replies: 1
- Views: 190
Re: AlCl3 (aq)
Since the Al is a cation, it is surrounded by water molecules. So the equation would be Al(H₂O)₆3+ + H₂O --> H₃O+ + Al (H₂O)₅OH2+
- Tue Jan 22, 2019 3:20 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework for Week 3
- Replies: 5
- Views: 471
Re: Homework for Week 3
I believe the Chem_Mod said that this week's homework should be from the Acids and Base Chapter and the material we just learned last week.
- Tue Jan 22, 2019 12:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: help with homework 12.57
- Replies: 2
- Views: 197
Re: help with homework 12.57
For part a, you're given that the pH of 0.10 M HCLO2 is 1.2. pH is -log[H3O+], so to solve for [H3O+] you have to do 10^-pH. In this case, it would be 10^-1.2=0.06 M H3O+. Then, you solve for the Ka (acidity constant), which is (0.06^2)/(0.1-0.06). The pKa is the -log of your Ka value. Part b is th...
- Sun Jan 20, 2019 4:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sig figs in pH
- Replies: 7
- Views: 792
Re: Sig figs in pH
For pH, the sig figs in the final answer are calculated based off the least amount of sig figs in the answer. Then that amount of sig figs is used after the decimal point.
- Sun Jan 20, 2019 3:11 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Removing products
- Replies: 10
- Views: 3888
Re: Removing products
Only Q should be affected because q is in terms of what is happening during the reaction. K is just the overall equilibrium constant and it should not change.
- Sun Jan 20, 2019 3:10 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5% rule
- Replies: 4
- Views: 1490
Re: 5% rule
As Dr. Lavelle said in lecture, less than 5% is the rule. You can check with the quadratic formula to confirm though.
- Sun Jan 20, 2019 3:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When x is small
- Replies: 4
- Views: 472
Re: When x is small
If the approximation is not within 5%, then the answer would not be valid. You would have to use the quadratic equation to figure out the value of x.
- Sun Jan 13, 2019 7:25 pm
- Forum: Student Social/Study Group
- Topic: New to Lavells's
- Replies: 1
- Views: 160
Re: New to Lavells's
Dr. Lavelle's tests in 14A were a good balance of computational and conceptual questions. 14A also did not cover deriving things like schrodinger's equation: rather it focused on the concept. Other than that, there really should not be any real difference.
- Sun Jan 13, 2019 7:18 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Quotient Meaning
- Replies: 2
- Views: 217
Re: Reaction Quotient Meaning
Well, the reaction quotient Q is supposed to come into play when we try to figure out which direction a reaction is likely to proceed, based of pressure or the concentrations of products and reactants.
- Sun Jan 13, 2019 7:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Tables
- Replies: 3
- Views: 297
Re: ICE Tables
I would assume so because in the reaction, the reactants become the products. Therefore it would make sense for there to be a negative x on the reactant side and a positive x on the products side.
- Sat Dec 08, 2018 11:44 pm
- Forum: Polyprotic Acids & Bases
- Topic: Polyprotics on Final
- Replies: 3
- Views: 607
Re: Polyprotics on Final
If it has more than h+ proton that can dissasociate.
- Fri Dec 07, 2018 1:01 am
- Forum: Bronsted Acids & Bases
- Topic: 7th ed 6A.9 c
- Replies: 1
- Views: 237
Re: 7th ed 6A.9 c
Proton transfers are shown by the transfer of a hydrogen proton. Here, there was no proton transfer. Instead, an OH bond was transferred from acetic acid and replaced with NH2. And the OH bonded with last H atom remaining.
- Fri Dec 07, 2018 12:47 am
- Forum: Amphoteric Compounds
- Topic: H2O as Amphotertic Compound
- Replies: 1
- Views: 177
Re: H2O as Amphotertic Compound
No, it is not the only amphoteric compound. Other examples are HCO3 and HSO4.
- Fri Dec 07, 2018 12:43 am
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam
- Replies: 22
- Views: 1561
Re: Final Exam
Based off past final exams, the final exam will be a cumulative. Think of it as the midterm but on steroids with the stuff that we just learned.
- Fri Dec 07, 2018 12:35 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Ka on final, 12.25 [ENDORSED]
- Replies: 3
- Views: 614
Re: Ka on final, 12.25 [ENDORSED]
BenJohnson1C wrote:Is this also true for the upcoming final? (fall 2018)
Calculating Ka values, based of what Dr. Lavelle has said, will not be on the final.
- Tue Nov 27, 2018 9:41 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: TEST 3
- Replies: 4
- Views: 796
Re: TEST 3
The only equations given are the ones on the sheet given on every test. The Formal charge equation is just FC = Valence - [Lone Pairs + (1/2 Bonding Pairs)]. It would behoove you to memorize it.
- Tue Nov 27, 2018 9:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam
- Replies: 22
- Views: 1561
Re: Final Exam
Based off previous finals, its cumulative. Even if Dr. Lavelle does not isolate a concept such as balancing equations, he may give us something where we have to balance the equation as a key step in another related problem. Basically blending concepts.
- Tue Nov 27, 2018 9:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent and Angular
- Replies: 5
- Views: 485
Re: Bent and Angular
Or you could be safe and write bent/angular on the test.
- Tue Nov 27, 2018 6:18 pm
- Forum: Electronegativity
- Topic: Electronegativity values
- Replies: 2
- Views: 658
Re: Electronegativity values
If you want to figure out the which has more ionic character for a specific molecule, just use the general trend to generally find the difference. We will not be expected to calculate the electronegativity difference unless the electronegativity values have been given to us. In the case of the probl...
- Tue Nov 27, 2018 6:12 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 3
- Replies: 38
- Views: 2495
Re: Test 3
Does this mean that the material covered in this past Monday's lecture won't be included? No it as stated on Dr. Lavelle's website, the test will only cover 3.12-3.16, 6.4-6.5, and 4.1-4.7 which do not include Monday's lecture. Hi guys. What do we need to know about Acids and Bases for Test 3? Need...
- Tue Nov 27, 2018 6:01 pm
- Forum: Hybridization
- Topic: Molecular Shape
- Replies: 2
- Views: 145
Re: Molecular Shape
When determining hybridizations, you have to take into account molecular shape. When looking at molecular shape, you have to look at both bonded pairs and lone pairs. Furthermore, you have to take into account all of the electron densities on the atom that you are looking at, usually the central ato...
- Fri Nov 23, 2018 8:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3
- Replies: 10
- Views: 937
Re: Test 3
A good way to study conceptually is just explaining the concepts to yourself without looking at your notes. For instance, writing the concepts on a whiteboard and explaining it to yourself as you go along writing.
- Thu Nov 22, 2018 4:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3 Question
- Replies: 4
- Views: 490
Re: Test 3 Question
Dr. Lavelle also posted on his website what the test would cover - Test 3 covers: End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details).
- Fri Nov 16, 2018 12:38 am
- Forum: Administrative Questions and Class Announcements
- Topic: Homework Due Week 7
- Replies: 10
- Views: 1173
Re: Homework Due Week 7
Soyoung Park 1H wrote:Is the test over both outlines 3 and 4?
The test will be up to whatever he covers during lecture until a couple days before the test. He will probably specify as we get closer to the test but presumable Outline 3 and 4, since they were not on the last test, will be covered on the next test.
- Fri Nov 16, 2018 12:37 am
- Forum: Resonance Structures
- Topic: 2.7
- Replies: 1
- Views: 221
Re: 2.7
Are you talking about the 6th edition 2.7 homework problem? The problem does not talk about resonance structures.
- Mon Nov 12, 2018 9:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 7th Ed. 2.7: Most important Lewis structure
- Replies: 2
- Views: 367
Re: 7th Ed. 2.7: Most important Lewis structure
The most important lewis structure would be the most stable, lowest energy lewis structure with the right bond angles.
- Mon Nov 12, 2018 9:44 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Electron Distortion
- Replies: 2
- Views: 316
Re: Electron Distortion
In addition to the aforementioned response, this post from 2016 may help: viewtopic.php?t=16153
- Mon Nov 12, 2018 9:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3
- Replies: 8
- Views: 1701
Re: Test 3
Every chapter builds on previous concepts we have learned. Whilst it may not be an explicitly cumulative test, there probably still will be concepts in the third test from prior tests (ie dimensional analysis, energy calculations).
- Mon Nov 12, 2018 9:41 pm
- Forum: Dipole Moments
- Topic: Interaction Potential Energy
- Replies: 3
- Views: 209
Re: Interaction Potential Energy
At the very least, its a good idea to know the general concept behind the Ep equation even if we are not using it for calculation questions. Also, general rule of thumb, whatever Dr. Lavelle goes over in class is fair game for the third test or the final exam.
- Fri Nov 02, 2018 1:44 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Degenerate orbitals
- Replies: 3
- Views: 362
Re: Degenerate orbitals
Degenerate orbital are just orbitals that have the same energy level and thus (for hydrogen atoms), the same energy.
- Fri Nov 02, 2018 1:41 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Test Question 1a
- Replies: 2
- Views: 386
Re: Test Question 1a
For this, you actually have to calc the mass of the nitrogen gas molecule. The way to do that is first find the molar mass of nitrogen (in this case of n2 bc nitrogen is diatomic). Once you have found the molar mass, divide the molar mass by avagadro's number to find how many gs each molecule weighs...
- Sun Oct 28, 2018 11:48 pm
- Forum: Lewis Structures
- Topic: Delocalized Electrons
- Replies: 5
- Views: 436
Re: Delocalized Electrons
Its a pretty general term actually. As far as I know, its just not associated with a single atom or a covalent bond.
- Sun Oct 28, 2018 11:44 pm
- Forum: Ionic & Covalent Bonds
- Topic: Interactions between ions
- Replies: 3
- Views: 359
Re: Interactions between ions
I don't think so. Just know everything Lavelle goes over in lecture.
- Sun Oct 28, 2018 11:39 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s state
- Replies: 2
- Views: 298
Re: 4s state
I am not 100% sure but I believe its because the Aufbau principle indicates that the 4s orbital fills before the 3d orbital and thus the energy is lower in the 4s.
- Wed Oct 24, 2018 10:29 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Homework questions 2.21 and 2.27
- Replies: 5
- Views: 3828
Re: Homework questions 2.21 and 2.27
it should be 5d. I think "6d" was prolly a typo.
Lina Petrossian 3D wrote:Isn't 2.27 part a) 5d instead of 6d?
- Tue Oct 23, 2018 3:51 pm
- Forum: Properties of Light
- Topic: calculating wavelength
- Replies: 10
- Views: 1123
Re: calculating wavelength
Dr. Lavelle mentioned that E = hv can only be used for light. However, De Broglie's equation of lambda=h/p can only be used for objects with "rest" mass and velocity. "Rest" mass basically means anything that has mass when stationary. why is rest in quotes.. is there a significa...
- Tue Oct 23, 2018 3:43 pm
- Forum: Photoelectric Effect
- Topic: Question 28B on Post Module Assessment for Photoelectric Effect
- Replies: 1
- Views: 267
Re: Question 28B on Post Module Assessment for Photoelectric Effect
So what you need to do is account for the per mol portion of the threshold energy. The energy given was in terms of how much energy is needed to eject 1 mole of electrons of that metal. You need to find how much energy is needed to eject one electron. This can be easily done by dividing by the conve...
- Sun Oct 21, 2018 11:32 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect Module Question 27
- Replies: 2
- Views: 410
Re: Photoelectric Effect Module Question 27
all you need to do is multiply the frequency by plancks constant. The correct answer if you just do hv is 1.99*10^-18 J.
- Sun Oct 21, 2018 6:43 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Quantum numbers
- Replies: 5
- Views: 558
Re: Quantum numbers
The way to figure it out from my understanding is that 4 is the energy level it is in (the principle quantam number n equals 4 in this case) and f is determined by what l is equal to. In this case, the value of l, which is 3, corresponds with the the l value for the f orbital. Thus the answer, if pu...
- Sat Oct 20, 2018 5:35 pm
- Forum: Properties of Light
- Topic: De Broglie's equation [ENDORSED]
- Replies: 7
- Views: 1140
Re: De Broglie's equation [ENDORSED]
Yes. De broglie's equation (lamba = h / p) is the equation that cannot be used for photons. However, c=lambda/v, E=hv, E = (hc)/lambda, and E=(1/2)mv^2 can all be used with light.
- Thu Oct 18, 2018 9:35 pm
- Forum: DeBroglie Equation
- Topic: problem 43 6th edition
- Replies: 4
- Views: 401
Re: problem 43 6th edition
The minimum uncertainty is change in velocity or delta (the triangle) v. In this case, delta v would be 1.65*10^5 m/s.
- Thu Oct 18, 2018 9:21 pm
- Forum: Properties of Light
- Topic: calculating wavelength
- Replies: 10
- Views: 1123
Re: calculating wavelength
Dr. Lavelle mentioned that E = hv can only be used for light. However, De Broglie's equation of lambda=h/p can only be used for objects with "rest" mass and velocity. "Rest" mass basically means anything that has mass when stationary.
- Thu Oct 18, 2018 9:19 pm
- Forum: Photoelectric Effect
- Topic: Energy Levels
- Replies: 2
- Views: 218
Re: Energy Levels
As energy levels increase, the separating space between them becomes smaller and smaller. At "very high" levels, this gives way to a continuous range of all allowed energies. To corroborate this, during office hours, Dr. Lavelle mentioned that the energy levels eventually become a continuu...
- Thu Oct 18, 2018 9:11 pm
- Forum: Properties of Light
- Topic: Test 2 [ENDORSED]
- Replies: 15
- Views: 1182
Re: Test 2 [ENDORSED]
I thought it was everything until the end of this week no? Like including quantum numbers which we should go over in final lecture of this week.
- Wed Oct 10, 2018 9:40 pm
- Forum: Balancing Chemical Reactions
- Topic: Seventh Edition- H21 [ENDORSED]
- Replies: 3
- Views: 503
Re: Seventh Edition- H21 [ENDORSED]
Don't get frustrated about it! It is really just a guess and check most of time and it does take some time. One tip that I have personally incorporated is starting with the least amount of total atoms for the elements in the equation. For instance, if there are 3 atoms of C vs 5 atoms of F I would s...
- Wed Oct 10, 2018 9:33 pm
- Forum: SI Units, Unit Conversions
- Topic: Scientific Notation
- Replies: 7
- Views: 631
Re: Scientific Notation
It matters for things like sig figs. For instance, if your answer was 1330. but you only had 3 sig figs to work with, you would put it into scientific notation ie 1.33 *10^3 because this way you have the same answer and you have the right amount of sig figs.
- Wed Oct 10, 2018 9:16 am
- Forum: SI Units, Unit Conversions
- Topic: Rounding Off of 5
- Replies: 7
- Views: 2459
Re: Rounding Off of 5
This is just a general rule of sig figs that we must use I believe. A lot of the documents on the website do indicate that we should round to the nearest even number. This is because we will be less precise if we just round up (we would overestimate) and if we just round down (we would underestimate...
- Thu Oct 04, 2018 11:07 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: HW L7
- Replies: 3
- Views: 238
Re: HW L7
You need to first convert tristearin and o2 (the reactants) to moles. Then using the molar ration of 2 moles of tristearin/163 moles O2, find how much of one reactant is necessary to full react with the other reactant. Then, you can find how much O2 you need to react full with tristearin. Once that ...
- Thu Oct 04, 2018 10:55 pm
- Forum: SI Units, Unit Conversions
- Topic: Scientific Notation
- Replies: 11
- Views: 1073
Re: Scientific Notation
Use scientific notation when dealing with very big numbers. Otherwise, it will be a lot more difficult to do multiplication and division without it. In addition, always round the number to the least amount of sig figs in the problem. This youtube vid on scientific notation really help me understand ...
- Thu Oct 04, 2018 10:47 pm
- Forum: Significant Figures
- Topic: Sig Figs
- Replies: 3
- Views: 239
Re: Sig Figs
Also, for sig fig rounding, if the last digit is above 5 round up (ie 2 sigfigs then 6.56 is 6.7) and if the last digit is below 5 round down (ie 2 sigfigs then 3.44 is 3.4).