Search found 100 matches
- Sun Mar 14, 2021 1:14 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Which R to use
- Replies: 42
- Views: 2859
Re: Which R to use
A great way to know which R to use is tracking units. Use 8.314 if J is in the final answer and 0.0821 if you want L atm in the final.
- Sun Mar 14, 2021 1:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 512218
Re: Saying Thank You to Dr. Lavelle
Just finished the final! Dr. Lavelle is so passionate about his work. It's been a great semester.
- Sun Mar 14, 2021 1:10 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Effect of catalyst
- Replies: 22
- Views: 2183
Re: Effect of catalyst
If you look at a diagram, you'll see that the starting and final potential energies are the same.
- Sun Mar 14, 2021 1:09 pm
- Forum: Student Social/Study Group
- Topic: Plans for Summer/school year
- Replies: 34
- Views: 1465
Re: Plans for Summer/school year
I'm taking ochem lab this summer cuz I heard it's easier online.
- Sun Mar 14, 2021 1:08 pm
- Forum: First Order Reactions
- Topic: Half-life independent from initial concentration
- Replies: 8
- Views: 1537
Re: Half-life independent from initial concentration
If you take a look at the half-life reactions for first order the concentration of A is missing from the equation so it is independent.
- Sun Mar 07, 2021 6:30 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Constants and Equations Sheet
- Replies: 6
- Views: 337
Re: Constants and Equations Sheet
It's the same sheet for all the exams i believe.
- Sun Mar 07, 2021 6:29 pm
- Forum: Zero Order Reactions
- Topic: graph for 1st, 2nd, and zero order reactions
- Replies: 8
- Views: 4981
Re: graph for 1st, 2nd, and zero order reactions
Different functions graphed will give a linear curve. From this, you can determine what order the reaction is.
- Sun Mar 07, 2021 6:28 pm
- Forum: General Rate Laws
- Topic: overall order of the rxn (sapling #7)
- Replies: 9
- Views: 574
Re: overall order of the rxn (sapling #7)
Try adding the individual orders.
- Sun Mar 07, 2021 6:26 pm
- Forum: Balancing Redox Reactions
- Topic: Resources for Redox Reactions
- Replies: 6
- Views: 417
Re: Resources for Redox Reactions
Khan academy has a lot of practice problems.
- Sun Mar 07, 2021 6:25 pm
- Forum: Student Social/Study Group
- Topic: Final
- Replies: 12
- Views: 568
Re: Final
I'm pretty sure the test will be proportional to the amounts on the syllabus. So there should be equal parts equilibrium and thermo.
- Sun Feb 28, 2021 8:08 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: anode vs. cathode
- Replies: 12
- Views: 690
Re: anode vs. cathode
Don't memorize left and right as this is not always true. Just remember that the anode is where oxidation occurs and the cathode is where reduction occurs
- Sun Feb 28, 2021 8:07 pm
- Forum: Balancing Redox Reactions
- Topic: hw #4
- Replies: 3
- Views: 227
Re: hw #4
Balance Chlorine first since it only appears once on both sides. You'll have to trial and error with the oxygens and hydrogens but a tip that'll help is that the HNO3 and NO2 will always be 1:1.
- Sun Feb 28, 2021 8:04 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Sapling #15
- Replies: 3
- Views: 232
Re: Sapling #15
Yes your E naught should be 0.47
- Sun Feb 28, 2021 8:03 pm
- Forum: Balancing Redox Reactions
- Topic: Determining Phases
- Replies: 28
- Views: 974
Re: Determining Phases
The original problem should tell you the phases. I don't think there will ever be a case where you have to determine phase just off your intuition.
- Sun Feb 28, 2021 8:02 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling Week 7/8 #7
- Replies: 10
- Views: 474
Re: Sapling Week 7/8 #7
You've mixed up the cathodes and anodes.
- Sun Feb 21, 2021 9:49 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: Residual Entropy
- Replies: 4
- Views: 291
Re: Residual Entropy
Residual entropy is caused solely by positional entropy.
- Sun Feb 21, 2021 9:48 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling week 7/8 #2
- Replies: 5
- Views: 1171
Re: Sapling week 7/8 #2
Combine and balance the reactions is what I did.
- Sun Feb 21, 2021 9:47 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Can someone explain to me why work of compression is always negative?
- Replies: 12
- Views: 5707
Re: Can someone explain to me why work of compression is always negative?
The negative is used to correct the equation. If volume is decreased then work is positive and work is done on the system. If volume is increased then work is negative and work is done by the system.
- Sun Feb 21, 2021 9:46 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: State function?
- Replies: 36
- Views: 1276
Re: State function?
This is a path function and depends on the way in which the reaction occurs.
- Sun Feb 21, 2021 9:46 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Bomb calorimeter
- Replies: 9
- Views: 497
Re: Bomb calorimeter
Bomb Calorimeters have constant volume.
- Sun Feb 14, 2021 11:08 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Can heat capacities be negative?
- Replies: 52
- Views: 13512
Re: Can heat capacities be negative?
here q is negative, not the heat capacity.
- Sun Feb 14, 2021 10:58 pm
- Forum: Calculating Work of Expansion
- Topic: irreversible vs reversible
- Replies: 14
- Views: 651
Re: irreversible vs reversible
With reversible, the internal and external pressures should be the same.
- Sun Feb 14, 2021 10:56 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Adiabatic System
- Replies: 9
- Views: 452
Re: Adiabatic System
Adiabatic means that no heat moves in or out.
- Sun Feb 14, 2021 10:56 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: When is the Gibbs Free Energy useful
- Replies: 4
- Views: 281
Re: When is the Gibbs Free Energy useful
It's useful in many situation with equilibriums to know if a reaction is spontaneous. If you take LS7A you'll see a large chunk of the first midterm focuses on Free energy within the cell.
- Sun Feb 14, 2021 10:53 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Pressure and Volume for Ideal Gases
- Replies: 2
- Views: 175
Re: Pressure and Volume for Ideal Gases
Typically heat capacities at constant pressure are higher than those at constant volume because some energy is needed to do work. We also know that Cpm is equal to Cvm + R which is another explanation.
- Sun Feb 07, 2021 10:06 pm
- Forum: Calculating Work of Expansion
- Topic: Week 3/4 Sapling Homework: #15
- Replies: 9
- Views: 466
Re: Week 3/4 Sapling Homework: #15
I think you can do either and they will be the same.
- Sun Feb 07, 2021 10:04 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Positive and Negative q Value
- Replies: 19
- Views: 12866
Re: Positive and Negative q Value
Negative means heat is releases from the system while positive means heat is put into the system.
- Sun Feb 07, 2021 10:03 pm
- Forum: Phase Changes & Related Calculations
- Topic: Vapor vs gas
- Replies: 121
- Views: 8848
Re: Vapor vs gas
They are the same.
- Sun Feb 07, 2021 10:03 pm
- Forum: Phase Changes & Related Calculations
- Topic: endothermic/exothermic
- Replies: 43
- Views: 4325
Re: endothermic/exothermic
Endothermic requires energy so from a ordered to disordered to state while exothermic releases energy so from a disordered to ordered state.
- Sun Feb 07, 2021 10:02 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Sapling week 3/4 Question 5
- Replies: 9
- Views: 331
Re: Sapling week 3/4 Question 5
You want to manipulate the constants and flip the equations until they add up to the net reaction.
- Sun Jan 31, 2021 10:16 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy vs heat
- Replies: 31
- Views: 2212
Re: Enthalpy vs heat
Enthalpy is essential a concept formed to get heat as a state function. In order to do so there is the condition that the system is under constant pressure so that the path is defined.
- Sun Jan 31, 2021 10:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: is HClO3 weak or strong? [ENDORSED]
- Replies: 49
- Views: 3964
Re: is HClO3 weak or strong? [ENDORSED]
Some consider it strong some consider it weak. It depends on the textbook.
- Sun Jan 31, 2021 10:13 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Work-/+
- Replies: 9
- Views: 361
Re: Work-/+
If the system does work onto the surrounding it is negative. If the surroundings do work upon the system it is positive.
- Sun Jan 31, 2021 10:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Kc
- Replies: 36
- Views: 1215
Re: K vs. Kc
K in the book is actually Kp or constant for pressure.
- Sun Jan 31, 2021 10:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Making X negligible
- Replies: 34
- Views: 1300
Re: Making X negligible
Typically, when K is very small or large and you aim to subtract x from the side in which the reaction is favored. Using the 5% rule is a way to check if your assumption was correct.
- Sun Jan 24, 2021 9:51 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert Gases and Le Chatelier's Principle
- Replies: 6
- Views: 479
Re: Inert Gases and Le Chatelier's Principle
The definition of an inert gas means that it chemically unreactive to the reaction at hand. Typically, if you add pressure through an inert gas, the volume does not change so the reaction will not shift. You have stated that the inert gas could be part of the reactants, but at that point it would ce...
- Sun Jan 24, 2021 9:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 #1
- Replies: 9
- Views: 383
Re: Sapling Week 2 #1
Set up an ICE table with the initial concentration of the acid. They put the change with the -x on the reactants side and the +x on the products side. Set up the equilibrium expression equation equal to the constant and solve. the x value you solved for with be the concentration of H+ so you just ne...
- Sun Jan 24, 2021 9:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to use ICE box
- Replies: 23
- Views: 775
Re: When to use ICE box
You use ICE box to organize the information you have. If they give you an initial concentration you can represent missing variables with x and make this equal to the equilibrium constant.
- Sun Jan 24, 2021 9:42 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law Specifics
- Replies: 2
- Views: 182
Re: Hess's Law Specifics
I believe those two are the only transformations.
- Sun Jan 24, 2021 9:42 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6A.23 Textbook Question
- Replies: 4
- Views: 217
Re: 6A.23 Textbook Question
Ba(OH)2 is a strong acid. Find the concentration of the original molecule. OH- should be that concentration times 2 since 2 OH- are released per molecules. And yes BA 2+ will be equal to the original Ba(OH)2 concentration.
- Sun Jan 17, 2021 6:25 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Getting two positive x values when using quadratic
- Replies: 43
- Views: 4585
Re: Getting two positive x values when using quadratic
One of the positive values will be larger than one of the initial concentrations for the ICE table which will be impossible.
- Sun Jan 17, 2021 6:24 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Acids, Bases, and Autoprotrolysis
- Replies: 7
- Views: 406
Re: Acids, Bases, and Autoprotrolysis
Yes, water is always autoionizing at a small rate.
- Sun Jan 17, 2021 6:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE table calculations and X
- Replies: 3
- Views: 181
Re: ICE table calculations and X
You can also approximate x if K is a very large number and the ice table requires you to subtract from the products side.
- Sun Jan 17, 2021 6:22 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Post Assessment Question 17 Part 4
- Replies: 4
- Views: 350
Re: Post Assessment Question 17 Part 4
Temperature increase means that the equilibrium shifts in the endothermic direction. You can think of heat/energy as a reactant or product and think of the shifts like you did with concentrations. A decrease in temp means the equilibrium shifts in the exothermic direction
- Sun Jan 17, 2021 6:19 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Using the ICE table
- Replies: 36
- Views: 1314
Re: Using the ICE table
Yes, the ICE table works for either.
- Sun Jan 10, 2021 8:14 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: adding heat
- Replies: 15
- Views: 476
Re: adding heat
Increasing temp. will move the reaction towards the endothermic side whilst decreasing temp will move the reaction toward the exothermic side.
- Sun Jan 10, 2021 8:12 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: aqueous solutions
- Replies: 9
- Views: 341
Re: aqueous solutions
no, all aqueous molecules must be included.
- Sun Jan 10, 2021 8:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: identifying solids and non homogeneous reactant/product
- Replies: 4
- Views: 252
Re: identifying solids and non homogeneous reactant/product
In heterogenous reactions, there are a mix of phases. Liquid and solids are not included in the expression. You'll know if it's solid or liquid because the balanced chemical equation will say so. In homogeneous reactions the phases are all the same, so either all aqueous or all gas. Leave out the so...
- Sun Jan 10, 2021 8:03 pm
- Forum: Ideal Gases
- Topic: Units for Pressure
- Replies: 41
- Views: 2398
Re: Units for Pressure
The constant uses atm so use atm to make sure the units cancel nicely.
- Sun Jan 10, 2021 8:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs P
- Replies: 6
- Views: 359
Re: K vs P
A reaction with solely gases can use Kc or Kp. You can convert between the two using the ideal gas equation.
- Sat Dec 12, 2020 10:09 pm
- Forum: Naming
- Topic: Cobalt vs Cobaltate
- Replies: 16
- Views: 1058
Re: Cobalt vs Cobaltate
If the overall coordination compound is an anion the metal gets an "ate" at the end.
- Sat Dec 12, 2020 10:08 pm
- Forum: Hybridization
- Topic: hybrid orbitals
- Replies: 4
- Views: 163
Re: hybrid orbitals
Good question. To be precise 2sp^3 is correct. A lot of questions just ask what type of hybridization scheme which is why sp^3 can also be correct.
- Sat Dec 12, 2020 10:05 pm
- Forum: General Science Questions
- Topic: bond angles
- Replies: 3
- Views: 216
Re: bond angles
No, saying slightly less than or less than is sufficient.
- Sat Dec 12, 2020 10:04 pm
- Forum: Hybridization
- Topic: exceptions ?
- Replies: 4
- Views: 323
Re: exceptions ?
To my knowledge there aren't really any exceptions. Be careful when saying number of bonds, as hybridization also include the number of lone pairs. So like oxygen in H2O is really sp3 hybridized.
- Sat Dec 12, 2020 10:02 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sapling 10
- Replies: 6
- Views: 344
Re: Sapling 10
Yes, you have to determine the strengths relative to one another. The strongest will have the lowest Ph.
- Sun Dec 06, 2020 4:14 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Salts cause acidity
- Replies: 5
- Views: 381
Re: Salts cause acidity
The salt must have an acidic ion within it such as NH4+
Re: Sapling 1
It's based on the name of the ligand so ammino and chloro.
- Sun Dec 06, 2020 4:11 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Oxidation # Question
- Replies: 4
- Views: 343
Re: Oxidation # Question
The total number of electrons an atom loses or gains in order to form a chemical bond.
- Sun Dec 06, 2020 4:10 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Identifying monodentate ligands
- Replies: 5
- Views: 257
Re: Identifying monodentate ligands
It's more intuition. You'll have to look at the geometry specifically and see if two bonds can be formed. Usually, they have more intermediate atoms for more flexibility.
- Sun Dec 06, 2020 4:06 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number With Atoms outside of Coordination Compound
- Replies: 8
- Views: 325
Re: Coordination Number With Atoms outside of Coordination Compound
Coordination # is solely the number of ligands. The extra atoms are part of the coordination compound.
- Sun Nov 29, 2020 6:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Knowing VESPR for final
- Replies: 5
- Views: 279
Re: Knowing VESPR for final
I"m sure you have to memorize them all. Try flash cards.
- Sat Nov 28, 2020 8:09 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity and Shape
- Replies: 13
- Views: 620
Re: Polarity and Shape
I see a lot of people saying drawing the Lewis structure with the dipoles to see if they cancel, and although this would probably work a lot of the times, I would caution against this. You have to remember that dipoles exist in 3-dimensional space and not 2 dimensional, so there's room for potential...
- Sat Nov 28, 2020 8:03 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Axial vs Equatorial
- Replies: 3
- Views: 223
Re: Axial vs Equatorial
The terms axial and equatorial are really only applicable to an electron arrangement of trigonal bipyramidal. In this case, the lone pair will always be on the equatorial since there is less repulsion (the equatorial lone pair has two 90 degree contacts while the axial has 3 90 degree contacts). I w...
- Sat Nov 28, 2020 7:57 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Sapling Q.20
- Replies: 8
- Views: 1271
Re: Sapling Q.20
There can exist polar dipoles between individual atoms, but the overall molecule would still be nonpolar if these dipoles are equal in magnitude and opposite in direction. "As" is surrounded by oxygens in a tetrahedral shape. The oxygens are all the same so it is nonpolar. There is a reson...
- Wed Nov 25, 2020 8:48 pm
- Forum: Hybridization
- Topic: Clarification on 11/23 Monday's Lecture
- Replies: 5
- Views: 186
Clarification on 11/23 Monday's Lecture
Dr.Lavelle keeps mentioning/writes on the board that Ethylene has sp3 hybridization (Time Stamp 29 minutes). Is this a typo on his part? I'm 99% sure the three sigma bonds are sp2.
- Fri Nov 20, 2020 9:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Net Vector
- Replies: 4
- Views: 113
Re: Net Vector
Net vector is just the sum of all the vectors. So you take the directions and magnitudes and they can either amplify or reduce each other.
- Fri Nov 20, 2020 9:35 pm
- Forum: Lewis Structures
- Topic: Question on Radical -- SAPLING BOOK (Mistake in Answer Key)
- Replies: 6
- Views: 341
Re: Question on Radical -- SAPLING BOOK (Mistake in Answer Key)
No2 is a radical. The book is correct. Nitrogen has a double bond with each oxygen and has one remaining electron that is unbonded.
- Fri Nov 20, 2020 9:26 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Lewis acids and bases
- Replies: 22
- Views: 1078
Re: Lewis acids and bases
Lewis acid accepts an electron pair while the base is the donor. Look for coordinate covalent bonds because one element/molecule is always donating an electron to form the bond.
- Fri Nov 20, 2020 9:24 pm
- Forum: Trends in The Periodic Table
- Topic: Metallic Character
- Replies: 8
- Views: 735
Re: Metallic Character
Metallic character is best at the bottom left of the group so an element like Na would have more metallic character since it is below Be on the periodic table.
- Fri Nov 20, 2020 9:21 pm
- Forum: Bond Lengths & Energies
- Topic: Boiling vs. Melting Point
- Replies: 15
- Views: 2487
Re: Boiling vs. Melting Point
The boiling point is from the liquid to gas phase while the melting point is from the solid to liquid phase.
- Sat Nov 14, 2020 7:34 pm
- Forum: Dipole Moments
- Topic: H-Bond acceptor
- Replies: 9
- Views: 398
Re: H-Bond acceptor
No, you need one hydrogen bonded to F, O, or N but the other F, O,N that bonds to that hydrogen doesn't need to be connected to hydrogen.
- Sat Nov 14, 2020 7:31 pm
- Forum: Coordinate Covalent Bonds
- Topic: Hydrogen bonding
- Replies: 15
- Views: 806
Re: Hydrogen bonding
Hydrogen bonds are not covalent since they are intermolecular forces and not intramolecular.
- Sat Nov 14, 2020 7:31 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 3d Exceptions
- Replies: 3
- Views: 274
Re: 3d Exceptions
Only move electrons to form d^5 and 10. There should usually be at least one 4s electron.
- Sat Nov 14, 2020 7:29 pm
- Forum: Bond Lengths & Energies
- Topic: Energy released
- Replies: 3
- Views: 175
Re: Energy released
Intramolecular forces in general have much more energy than intermolecular.
- Sat Nov 14, 2020 7:29 pm
- Forum: Octet Exceptions
- Topic: Expanded Octets
- Replies: 5
- Views: 811
Re: Expanded Octets
Elements beyond the n=2 principal number have expanded because their electrons can move to the d orbitals.
- Sat Nov 07, 2020 3:37 pm
- Forum: Ionic & Covalent Bonds
- Topic: Salts v. Ionic bonds
- Replies: 9
- Views: 284
Re: Salts v. Ionic bonds
Yes, salts are all classified as ionic bonds.
- Sat Nov 07, 2020 3:36 pm
- Forum: Resonance Structures
- Topic: Bond lengths
- Replies: 20
- Views: 668
Re: Bond lengths
No, Lewis structures are a simplified model. There's no need to show a shorter line.
- Sat Nov 07, 2020 3:36 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Sapling #2 weeks 5
- Replies: 3
- Views: 99
Re: Sapling #2 weeks 5
Start with drawing a single bond between Carbon and each oxygen. You intuitively should know that Carbon is going to form a double bond with one of the oxygen to fill its own octet. The two remaining Oxygens have only 7 electrons each and the ion has two additional electrons so that's where you put ...
- Sat Nov 07, 2020 3:31 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic radius when changing sub- shells
- Replies: 4
- Views: 202
Re: Atomic radius when changing sub- shells
It depends. If you're talking about trends, the atomic radius does decrease when you go from left to right across the periodic table. If you are talking about a specific atom, then going from 2s to 2p will increase the radius because 2p is slightly higher in energy than 2s in multielectron atoms.
- Sat Nov 07, 2020 3:29 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Ground state electron configuration
- Replies: 2
- Views: 91
Re: Ground state electron configuration
Ground state means to most stable form/least energy. The ground state of an ion is simply the electron configuration minus one electron.
- Fri Oct 30, 2020 6:02 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation for ions?
- Replies: 4
- Views: 618
Re: Rydberg Equation for ions?
It works for hydrogn-like ions like He positive. In order to account for the stronger nuclear charge due to more protons you multiple by Z^2. Z is the atomic number.
- Fri Oct 30, 2020 6:00 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: sapling #6
- Replies: 2
- Views: 124
Re: sapling #6
Use Rydberg's equation to find the frequency of the max energy transfer which is from 6 to 1 and the lowest energy transfer which is from 6 to 5. After finding the two frequencies convert them to wavelength using the light constant equation.
- Fri Oct 30, 2020 5:55 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Textbook Question 1B.27
- Replies: 3
- Views: 110
Re: Textbook Question 1B.27
The answer key is wrong, Dr.Lavelle specifically stated that the plus-minus signs include the range.
- Fri Oct 30, 2020 5:54 pm
- Forum: Properties of Light
- Topic: How to remember what v is in equations
- Replies: 46
- Views: 7092
Re: How to remember what v is in equations
A 100% sure-fire way to ensure that you aren't mixing the units up is by actually canceling out the units and making sure that both sides of the equation are equal. Velocity is m/s while frequency is only /s. Another way to intuitively gauge it is, when the particle in question has a mass it's usual...
- Thu Oct 29, 2020 7:26 pm
- Forum: Photoelectric Effect
- Topic: Kinetic Energy
- Replies: 10
- Views: 518
Kinetic Energy
I'm looking at a quizlet with this true or false
t/f higher frequency light always emits electrons with higher kinetic energies
I think it's true but the answer says it's false.
Is this a typo or am I missing something?
t/f higher frequency light always emits electrons with higher kinetic energies
I think it's true but the answer says it's false.
Is this a typo or am I missing something?
- Fri Oct 23, 2020 6:35 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Frequency Equation Question
- Replies: 5
- Views: 300
Re: Rydberg Frequency Equation Question
I had the same question. The Sapling HW seems to swap the definition of n1 and n2 back and forth. When I asked my TA, he said the Sapling question regarding emission was wrong. At this point, I think that n1 is always initial and n2 is always final regardless of whether energy is emitted or absorbed...
- Fri Oct 23, 2020 6:27 pm
- Forum: Properties of Electrons
- Topic: sapling homework question 6
- Replies: 3
- Views: 90
Re: sapling homework question 6
Your conversions to nanometers are off. Your exponents should still be negative, just to a lesser degree.
- Fri Oct 23, 2020 6:25 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Where should the Rydberg Equation be used?
- Replies: 11
- Views: 418
Re: Where should the Rydberg Equation be used?
Rydberg's equation is used solely with hydrogen.
- Fri Oct 23, 2020 6:22 pm
- Forum: Properties of Electrons
- Topic: Understanding energy transitions
- Replies: 4
- Views: 205
Re: Understanding energy transitions
Yes, so each energy transition releases a photon with a specific wavelength and frequency. Typically, the higher the energy photons have higher frequencies. Since c=wavelength * frequency, a higher frequency corresponds to a shorter wavelength and vice versa.
- Wed Oct 21, 2020 10:27 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic vs Molecular Spectroscopy
- Replies: 3
- Views: 75
Atomic vs Molecular Spectroscopy
• With respect to electron transitions that give rise to a UV or visible spectrum: understand the difference between electronic transitions in atomic orbitals (atomic spectroscopy) and electronic transitions in molecular orbitals (molecular spectroscopy). This was one of the bullets for the quantum ...
- Sat Oct 17, 2020 9:19 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra
- Replies: 5
- Views: 207
Re: Atomic Spectra
Vivian Chang 2H wrote:Hi!
You can manipulate the equation you mentioned to get v(frequency) = RH (1/n2^2 - 1/n1^2), where RH is Rydberg's constant, 3.29 x 10^15 s^/1.
In this equation, n1 is always the higher energy level and n2 is the lower energy level.
Isn't n1 the initial??
- Fri Oct 16, 2020 4:52 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Spectra Module #29
- Replies: 2
- Views: 59
Re: Atomic Spectra Module #29
Divide speed of light by the wavelenght to find the frequency of a photon. Then use E=hv for part 1.
For the next part divide 11J by the energy of a single photon.
For the next part divide 11J by the energy of a single photon.
- Fri Oct 16, 2020 4:48 pm
- Forum: Properties of Light
- Topic: Sapling Week 2/3 HW Question 6
- Replies: 7
- Views: 392
Re: Sapling Week 2/3 HW Question 6
Hi! I had my discussion today and we went over this type of problem. She said to look at what the wavelength is (434 nm) and then look at what series that would be in. In this case, it would be in the Balmer series and the ending energy level is always going to be n=2 for this series. I am not sure...
- Fri Oct 16, 2020 4:39 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation
- Replies: 2
- Views: 105
Re: Rydberg Equation
It depends. If you factor out a negative yes, but as you can see here there isn't
- Fri Oct 16, 2020 4:17 pm
- Forum: Photoelectric Effect
- Topic: Homework Question
- Replies: 2
- Views: 112
Re: Homework Question
I'm not exactly sure about the question, but I'll do what I can. The work function is the minimum energy required for a single electron to be ejected (with zero kinetic energy). If you have the total energy I believe you just divide the total energy by the work to get the maximum number of electrons.
- Mon Oct 05, 2020 6:47 pm
- Forum: Einstein Equation
- Topic: Wavelength and Kinetic Energy
- Replies: 3
- Views: 141
Re: Wavelength and Kinetic Energy
The GaN laser has 4.9 E-19 J so it is powerful enough to displace electrons. You got part A correct, but when you looked at the answer in the text you looked at the answer for part B. The kinetic energy of the displaced electron will be 2.10E-20 J. Part B is solved when you subtract the work-energy ...
- Mon Oct 05, 2020 6:30 pm
- Forum: Balancing Chemical Reactions
- Topic: Photoelectric Effect
- Replies: 4
- Views: 151
Re: Photoelectric Effect
No, intensity when thinking about particles is just the number of electrons. There is a minimum frequency/energy level that the photon must reach in order to displace an electron.
- Mon Oct 05, 2020 6:26 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Formula Units
- Replies: 5
- Views: 230
Re: Formula Units
MgSO4 · 7H2O Part a) asks for the number of oxygen atoms in the 5.15 grams. So, divide 5.15 by the molar mass of MgSO4 · 7H2O in order to find the number of moles of MgSO4 · 7H2O. There are 11 oxygen atoms per molecule of MgSO4 · 7H2O so multiply that number by 11 to get moles of oxygen. Then multip...
- Mon Oct 05, 2020 6:05 pm
- Forum: Balancing Chemical Reactions
- Topic: HW H.21
- Replies: 5
- Views: 193
Re: HW H.21
You're going to use O2 and not O because seeing a lone O without any bonding is unrealistic because it would be unstable.
Also here's the balanced equation:
2 C10H15N + 26 O2 -> CH4N2O + 19 CO2 + 13 H20
Also here's the balanced equation:
2 C10H15N + 26 O2 -> CH4N2O + 19 CO2 + 13 H20
- Mon Oct 05, 2020 5:47 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity Question from Lecture 10/5
- Replies: 5
- Views: 244
Re: Molarity Question from Lecture 10/5
The moles of each ELEMENT must remain the same on both sides, not the actual molecules themselves. For example, there are 4 Hydrogen moles on each side & there are 2 Oxygen on each side. The atoms just rearrange themselves.