Search found 64 matches
- Sat Mar 16, 2019 8:09 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: standard cell potentials
- Replies: 5
- Views: 389
Re: standard cell potentials
Yes when the cell potential is negative it means the reaction is nonspontaneous
- Fri Mar 15, 2019 9:44 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: vertical line in cell diagram
- Replies: 4
- Views: 459
Re: vertical line in cell diagram
I believe you only do it for solids or at least that's what Lavelle implied in lecture today.
- Wed Mar 13, 2019 3:28 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration cell
- Replies: 1
- Views: 210
Re: Concentration cell
In a concentration cell both the electrodes are of the same metal which is why E naught is equal to 0
- Wed Mar 13, 2019 3:26 pm
- Forum: Student Social/Study Group
- Topic: Studying for the Final
- Replies: 25
- Views: 2567
Re: Studying for the Final
The homework problems are the best way to prepare for the final!
- Mon Mar 11, 2019 10:30 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Constructing cell diagrams
- Replies: 2
- Views: 327
Re: Constructing cell diagrams
You don't put H2O but you include H+ in the cell diagrams
- Mon Mar 11, 2019 7:33 pm
- Forum: General Rate Laws
- Topic: Unique Rate Law
- Replies: 4
- Views: 451
Re: Unique Rate Law
I don't think there is a unique rate law. I think you mean the unique average rate which is when you take the rate of product or reactants and divide it by the coefficients of the species monitored.
- Mon Mar 11, 2019 7:03 pm
- Forum: General Science Questions
- Topic: Final
- Replies: 7
- Views: 1166
Re: Final
No there is no curve for the class.
- Sun Mar 10, 2019 7:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Final Exam
- Replies: 23
- Views: 1623
Re: Final Exam
Yes chemical equilibrium will be on the final
- Sun Mar 03, 2019 9:23 pm
- Forum: General Rate Laws
- Topic: Final Grades
- Replies: 3
- Views: 437
Re: Final Grades
I don't think there is a curve.
- Sun Mar 03, 2019 9:22 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Porous Disk and Salt Bridge
- Replies: 13
- Views: 1145
Re: Porous Disk and Salt Bridge
Since they both serve the same purpose, I don't think either one is more efficient than the other.
- Sun Mar 03, 2019 9:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion about Test questions
- Replies: 5
- Views: 613
Re: Discussion about Test questions
I think so since everyone has taken their test by now
- Sun Feb 24, 2019 5:06 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation
- Replies: 4
- Views: 535
Re: Oxidation
I don't think we need to know why it's called oxidation besides that it means the losing of electrons
- Sun Feb 24, 2019 4:49 pm
- Forum: Balancing Redox Reactions
- Topic: TEST
- Replies: 7
- Views: 812
Re: TEST
I'm pretty sure everything up until last Friday will be on the test and only the electrochemistry part of the textbook will be included on the test.
- Fri Feb 22, 2019 12:27 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electrode Potential
- Replies: 2
- Views: 268
Re: Electrode Potential
Electrode potential is an intensive property because voltage difference is the same and does not depend on how many times the reaction will occur. Even if the half reactions are multiplied by an integer, it won't affect the value of the electrode potential for the reaction.
- Fri Feb 22, 2019 12:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell potential and Gibbs free energy
- Replies: 2
- Views: 242
Re: Cell potential and Gibbs free energy
Cell potential has to be positive in order for the reaction to be spontaneous because in the equation deltaG = -nFEcell, in order for delta G to be spontaneous (negative), Ecell must be positive.
- Fri Feb 22, 2019 12:17 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation state of MnO4-
- Replies: 3
- Views: 368
Re: oxidation state of MnO4-
Oxygen has an oxidation state of -2 which means overall just counting the oxygens, there is an oxidation state of -8 (4 oxygens times -2), but since Mn has an oxidation state of -1 we want to find what value added to -8 would equal -1, which in this case is +7.
- Fri Feb 22, 2019 12:12 pm
- Forum: Balancing Redox Reactions
- Topic: standard reduction potential
- Replies: 2
- Views: 248
Re: standard reduction potential
I believe that the half reactions can be multiplied in order to achieve the balanced equation but that won't change the value of e°since that is an intensive property, so only sign changes for standard reduction potentials.
- Tue Feb 12, 2019 10:58 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: C
- Replies: 3
- Views: 285
Re: C
heat capacity of the system
- Tue Feb 12, 2019 10:56 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: n in degeneracy
- Replies: 8
- Views: 2485
Re: n in degeneracy
n would equal 1
- Tue Feb 12, 2019 10:51 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: Difference in entropy: N2 or CO
- Replies: 1
- Views: 738
Re: Difference in entropy: N2 or CO
I think it could be because the N2 molecule is in a more ordered form than the CO molecule is in so CO would have a higher entropy than N2
- Wed Feb 06, 2019 9:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Symbol inquiry
- Replies: 4
- Views: 492
Re: Symbol inquiry
The symbol U represents internal energy which is just the total store of energy in a system. Change in internal energy is equal to the work of a system.
- Wed Feb 06, 2019 8:16 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 6th Edition Hw #8.11 Reversible/Irreversible
- Replies: 2
- Views: 280
Re: 6th Edition Hw #8.11 Reversible/Irreversible
According to the textbook, a reversible process "is one that can be reversed by an infinitely small change in a variable." Whereas, a irreversible process is when it expands against an external pressure that differs by a finite amount from the pressure of the system.
- Sat Feb 02, 2019 10:51 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: constant pressure/volume vs specific/molar heat capacities
- Replies: 4
- Views: 373
Re: constant pressure/volume vs specific/molar heat capacities
Yeah writing down all the given information always helps.
- Sat Feb 02, 2019 3:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Week 5 Homework
- Replies: 4
- Views: 344
Re: Week 5 Homework
I would still work on Thermochemistry homework.
- Sat Feb 02, 2019 3:44 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat Curve
- Replies: 6
- Views: 562
Re: Heat Curve
I'm pretty sure we will be given the heat curve.
- Fri Feb 01, 2019 5:45 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Open, closed, or isolated systems
- Replies: 10
- Views: 38780
Re: Open, closed, or isolated systems
An example for an open system would be like an automobile engine or the human body. An example for a closed system would be putting an ice pack on an injury and for an isolated system would be a hot liquid inside a thermos bottle or a sealed vacuum flask.
- Sat Jan 19, 2019 4:46 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Need to always check for Q?
- Replies: 2
- Views: 315
Re: Need to always check for Q?
I agree you should just check for Q just to be on the safe side.
- Sat Jan 19, 2019 4:44 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: difficulties recognizing weak acids and bases
- Replies: 9
- Views: 1440
Re: difficulties recognizing weak acids and bases
Most likely yes you will be dealing with weak acids and bases.
- Sat Jan 19, 2019 4:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: units for equilibrium constants
- Replies: 1
- Views: 175
Re: units for equilibrium constants
No there aren't any units for equilibrium constants.
- Thu Jan 10, 2019 9:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: lavelle's email
- Replies: 1
- Views: 192
Re: lavelle's email
Lavelle's email is lavelle@chem.ucla.edu
- Thu Jan 10, 2019 9:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HW Problem 5H.1 [ENDORSED]
- Replies: 4
- Views: 328
Re: HW Problem 5H.1 [ENDORSED]
For part B, since you are technically working with the exponents, you'd have to square root the K to get the answer. Whereas, for part c the coefficients (which become exponents) are doubled so you would have to square the K.
- Thu Jan 10, 2019 9:52 pm
- Forum: Student Social/Study Group
- Topic: Outlines Included in Test 1
- Replies: 2
- Views: 171
Re: Outlines Included in Test 1
My TA said chemical the equilibrium outline and the acids/bases outlines will be on test 1.
- Fri Dec 07, 2018 9:24 pm
- Forum: General Science Questions
- Topic: hydrogen bonding
- Replies: 3
- Views: 546
Re: hydrogen bonding
Yes, hydrogen bonding only occurs between N,O, and F. If not, yes it would be dipole-dipole interactions since hydrogen bonding is a type of dipole-dipole interaction.
- Fri Dec 07, 2018 9:21 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 5
- Views: 742
Re: Electronegativity
Nitrogen is more electronegative than carbon
- Fri Dec 07, 2018 9:20 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric
- Replies: 4
- Views: 558
Re: Amphoteric
If a molecule is amphoteric, then it has to amphiprotic as well since amphoteric molecules can act as an acid or a base (example: water). Amphiprotic means that the atom can donate or accept H+ protons.
- Fri Dec 07, 2018 9:02 pm
- Forum: Bronsted Acids & Bases
- Topic: Oxoacids
- Replies: 2
- Views: 307
Re: Oxoacids
An oxoacid is normally an acid containing an oxygen with a hydrogen atom bonded to the oxygen and another element bonded to the oxygen.
- Sat Dec 01, 2018 5:24 pm
- Forum: Hybridization
- Topic: identifying hybridization of a central atom
- Replies: 4
- Views: 374
Re: identifying hybridization of a central atom
If the molecule is symmetrical, it is normally nonpolar. If it is asymmetrical its probably polar. Normally, lone pairs on the central atom can make the molecule polar.
- Sat Dec 01, 2018 5:21 pm
- Forum: Hybridization
- Topic: pi bonds
- Replies: 5
- Views: 481
Re: pi bonds
Yes, pi bonds are always in the p subshell since it is not a part of hybridization.
- Sat Dec 01, 2018 5:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar Molecules
- Replies: 12
- Views: 815
Re: Polar Molecules
Normally, if the structure is symmetrical, it is safe to assume it's nonpolar. However, if there are lone pairs on the central atom or the Lewis structure is unsymmetrical, it is most likely polar.
- Fri Nov 23, 2018 9:40 pm
- Forum: Hybridization
- Topic: Number of Hybrid Orbitals
- Replies: 3
- Views: 301
Re: Number of Hybrid Orbitals
Hybrid orbitals are simply orbitals created by combining atomic orbitals of the same atom and atomic orbitals depended on the electron density surrounding an atom. As a result, the total number of orbitals for forming bonds don't change, only a new set of orbitals are formed.
- Fri Nov 23, 2018 9:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AX2E2
- Replies: 2
- Views: 154
Re: AX2E2
AX2E2 is bent because any VSEPR notation that has an E and a numerical value after it means there are lone pair electrons and in this case there are 2 lone pairs of electrons. Lone pair electrons (even if not on the same plane) have a high electron density and have a component that will push the bon...
- Fri Nov 23, 2018 12:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework for week 9
- Replies: 11
- Views: 1084
Re: Homework for week 9
I honestly don't think it matters so whatever you feel like doing!
- Fri Nov 16, 2018 10:34 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 3
- Replies: 19
- Views: 1248
Re: Test 3
I think it would be best to memorize the VSEPR chart, but I also think as you do more homework problems, it becomes intuitive and easier to figure out which shape each molecule is.
- Fri Nov 16, 2018 10:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR- Polar vs Nonpolar
- Replies: 5
- Views: 235
Re: VSEPR- Polar vs Nonpolar
If the charge distribution of the VSEPR model is symmetric then it is nonpolar, but if it is not symmetric then it would be polar
- Fri Nov 16, 2018 10:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Fluorine bonds
- Replies: 3
- Views: 948
Re: Fluorine bonds
Fluorine is a halogen which means it is a group 17 element and all group 17 elements have 7 valence electrons so they only need 1 more valence electron to completely fill their outer valence shell and get their noble gas configuration so they're stable. This pattern follows for all elements in group...
- Fri Nov 09, 2018 8:47 pm
- Forum: Dipole Moments
- Topic: Dipole
- Replies: 8
- Views: 732
Re: Dipole
Symmetric molecules have dipole moments, but since the molecules are symmetric the dipole moments cancel out and the molecule is nonpolar. If a molecule is polar then it's Lewis structure is not symmetric so the dipole moment vectors don't cancel out.
- Fri Nov 09, 2018 7:53 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 8
- Views: 673
Re: Electronegativity
Electronegativity is the tendency of an atom to attract another atom's electrons (kind of like stealing another atom's electrons). The electronegativity trend increases from left to right on the periodic table as well as when you move up a group on the periodic table.
- Fri Nov 09, 2018 7:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs
- Replies: 4
- Views: 347
Re: Lone Pairs
The presence of lone pairs causes the repulsion between lone pairs and bond pairs to be greater than just the plain bond pairs which causes the deflection angle to be lower than the a bond pair.
- Fri Nov 02, 2018 11:15 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Elements we have to memorize for the Midterm
- Replies: 4
- Views: 654
Re: Elements we have to memorize for the Midterm
The periodic table that Dr. Lavelle has given us for all our tests so far has had the elements' names, so I'm pretty sure we don't have to memorize any elemental names.
- Fri Nov 02, 2018 11:10 pm
- Forum: Properties of Electrons
- Topic: Isoelectronicity
- Replies: 3
- Views: 993
Re: Isoelectronicity
Isoelectronicity is when elements/molecules have the same number of valence electrons and electron configurations. For example, Li+ and He are isoelectronic. Most isoelectronic elements also have similar chemical properties.
- Fri Nov 02, 2018 11:01 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: degeneracy of the a 4p orbital
- Replies: 9
- Views: 2077
Re: degeneracy of the a 4p orbital
the degeneracy of a 4p orbital would be 3
- Thu Oct 25, 2018 9:30 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Degeneracy
- Replies: 6
- Views: 549
Re: Degeneracy
It typically means that all the electron energy levels/ shells have the same energy. For example in the p orbitals, if the 2px, 2py, and 2pz orbitals all have the same energy level then the degeneracy is 3 for the 2p orbitals.
- Thu Oct 25, 2018 9:12 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity Trend
- Replies: 9
- Views: 1038
Re: Electron Affinity Trend
Most nonmetals have a higher electron affinity since they have more valence electrons than metals and can easily attract more electrons and fulfill their octet. Also, nonmetals' valence electron shell is closer to the nucleus thus making it harder to remove electrons and easier for those elements to...
- Thu Oct 25, 2018 9:02 pm
- Forum: Properties of Light
- Topic: Electromagnetic Spectrum
- Replies: 5
- Views: 562
Re: Electromagnetic Spectrum
No I believe it is not necessary. Most likely if you need it to solve a problem on your test the TA will have provided it to you on your formula/equation sheet.
- Fri Oct 19, 2018 10:49 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Relation of charge to electrostatic potential energy
- Replies: 1
- Views: 116
Re: Relation of charge to electrostatic potential energy
There is an absolute value around (q1)(q2) hence any large number whether positive or negative will end up producing a higher energy. When he says a larger negative charge would increase energy, he means a larger negative charge for the atom would end up increasing the overall energy produced.
- Fri Oct 19, 2018 10:36 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Shielding [ENDORSED]
- Replies: 15
- Views: 1994
Re: Shielding [ENDORSED]
Yes the 2p orbital does experience shielding from the 2s orbital since the 2s orbital is closer to the nucleus and can block out the charge from the electrons from the 2p orbital since they are farther away
- Fri Oct 19, 2018 10:30 pm
- Forum: *Particle in a Box
- Topic: Midterm
- Replies: 17
- Views: 4071
Re: Midterm
I believe the midterm will cover topics from Fundamentals, The Quantum World, and the Chemical Bonds.
- Thu Oct 11, 2018 9:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework Week 2
- Replies: 5
- Views: 448
Re: Homework Week 2
Yes! Dr. Lavelle said that the homework is meant to be flexible and meet your needs, so it's okay to do review chemistry questions because that's most likely what you'll be using to review for the test this week.
- Thu Oct 11, 2018 9:09 pm
- Forum: Properties of Light
- Topic: Black Body Radiation
- Replies: 4
- Views: 315
Re: Black Body Radiation
Black body radiation is a material that can absorb and emit all wavelengths of light.
- Thu Oct 11, 2018 9:00 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect Equation
- Replies: 3
- Views: 343
Re: Photoelectric Effect Equation
It's basically saying that one photon must have enough energy to remove one electron and if it doesn't than it cannot remove that electron. However, if it does have enough energy or more energy then it can remove the electron and the rest of the energy will become kinetic energy.
- Thu Oct 04, 2018 5:09 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity
- Replies: 3
- Views: 304
Re: Molarity
The volume is measured after you add the solute in the solvent and I think when they said molarity the want to know the concentration of the solute that you have within your solution. For example, it would ask you what is the concentration of NaCl is in a solution, they want to know how heavily conc...
- Tue Oct 02, 2018 6:49 pm
- Forum: SI Units, Unit Conversions
- Topic: Scientific Notation
- Replies: 11
- Views: 1042
Re: Scientific Notation
I don't think it is necessary for all problems. I think you only have to do scientific notation in order to round your answer to the proper amount of sig figs to meet the requirements for sig figs for certain problems. Also, if its a really large number then you might have to do scientific notation,...
- Tue Oct 02, 2018 1:38 pm
- Forum: Empirical & Molecular Formulas
- Topic: Correct Answer for Audio-Visual Focus-Topics Empirical and Molecular Formulas Pre-Module Assessment
- Replies: 3
- Views: 295
Re: Correct Answer for Audio-Visual Focus-Topics Empirical and Molecular Formulas Pre-Module Assessment
The correct answer for that question was CoF6
- Tue Oct 02, 2018 1:37 pm
- Forum: Empirical & Molecular Formulas
- Topic: Correct Answer for Audio-Visual Focus-Topics Empirical and Molecular Formulas Pre-Module Assessment
- Replies: 3
- Views: 295
Re: Correct Answer for Audio-Visual Focus-Topics Empirical and Molecular Formulas Pre-Module Assessment
The pre/post assessment only grades your work. It only tells you if you got it correct or not