Search found 63 matches
- Fri Mar 15, 2019 11:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Deriving
- Replies: 3
- Views: 690
Re: Deriving
If you really want to study this, if you read the book theres yellow sections called How to do, or somethig like that, and it explains step by step the derivations and connections between topics.
- Fri Mar 15, 2019 11:03 pm
- Forum: General Rate Laws
- Topic: rate laws
- Replies: 6
- Views: 654
Re: rate laws
I was told by my PLF that they are used only for elementary step rate laws
- Fri Mar 15, 2019 11:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Approximation & Cubic Equations on Final
- Replies: 2
- Views: 520
Re: Approximation & Cubic Equations on Final
Considering he didn't mention it, I assume it's fair game to include both.
- Fri Mar 15, 2019 11:00 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U
- Replies: 4
- Views: 712
Re: delta U
Internal Energy should always be q+w
- Fri Mar 15, 2019 10:48 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: kr
- Replies: 1
- Views: 483
Re: kr
Chem_Mod Re: Disregard liquid and solid reactants in rate law? "That is correct. 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 ex...
- Fri Mar 15, 2019 10:42 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isometric/Isochoric
- Replies: 11
- Views: 1411
Re: Isometric/Isochoric
In the book, it says that bomb calorimeters are usually metals, so they maintain the volume although pressure may increase. To make the bomb calorimeter an isolated system, it can also be submerged in water to make it isothermal.
- Fri Mar 15, 2019 10:37 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 4
- Views: 671
Re: Catalysts
No, since they are not part of the actual reaction.
- Fri Mar 15, 2019 10:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equillibrium Constant
- Replies: 1
- Views: 512
Equillibrium Constant
In the book I read that the equilibrium constant is changed if the reaction is changed by a multiple ( such as NH3 to 2NH3). How would the constant change? Also how would we find the Equilibrium constant if multiple reactions ( and their K values are given) but not the overall reaction.
- Fri Mar 15, 2019 10:26 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: What are the units for A?
- Replies: 1
- Views: 248
Re: What are the units for A?
I searched this up online, and it said the units for A are the same as the rate constant units. In other words the units of A depend on the rxn order.
- Fri Mar 15, 2019 10:18 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Deriving
- Replies: 3
- Views: 448
Re: Deriving
Considering it is moderately simple to derive, I would memorize how to derive the equations just in case.
- Fri Mar 15, 2019 10:14 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Catalysts
- Replies: 2
- Views: 354
Re: Catalysts
Catalysts show up in the beginning of the reaction and at the end. The substances that are consumed are called intermediates.
- Fri Mar 15, 2019 10:09 pm
- Forum: Student Social/Study Group
- Topic: class pictures
- Replies: 15
- Views: 4059
Re: class pictures
Here is a video, not the best quality though.
- Sun Mar 10, 2019 7:56 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Temperature
- Replies: 1
- Views: 251
Temperature
When doing calculations and temperature isn't given, can we assume standard condition. What is standard condition, beside being at room temperature?
- Sun Mar 10, 2019 7:54 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagram
- Replies: 6
- Views: 625
Cell diagram
When drawing a cell diagram, why is platinum or carbon i belive included in the diagram if it is not involved in the actual reaction.
- Sun Mar 10, 2019 7:47 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation vs Reduction Half Rxn
- Replies: 9
- Views: 1082
Re: Oxidation vs Reduction Half Rxn
Oxidation releases electrons (on right side of equation), reduction uses electrons (on left side of equation) in short terms.
- Fri Feb 08, 2019 5:55 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: 5
- Views: 540
Re: Residual Entropy
I honestly do not know what residual entropy is, but Dr. Lavelle mentioned rotational state, translational state, vibrational state, and an electron's state in the actual atom.
- Fri Feb 08, 2019 5:53 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Temperature and Entropy
- Replies: 1
- Views: 266
Temperature and Entropy
During lecture today it was said that as temperature increases, thermal motion increases, meaning that entropy increases. Using the equation S=q/T it is implied that entropy is inversely proportional to entropy. Can anyone explain this please?
- Fri Feb 08, 2019 5:48 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Entropy, Enthalpy, Free Energy.
- Replies: 2
- Views: 363
Re: Entropy, Enthalpy, Free Energy.
entropy is q(reversible)/T. q(p=reversible)= delta H (enthalpy) if pressure is constant.
- Sun Feb 03, 2019 8:02 pm
- Forum: Calculating Work of Expansion
- Topic: Varieties of Work (Table 4A.1 (7th Edition))
- Replies: 1
- Views: 201
Re: Varieties of Work (Table 4A.1 (7th Edition))
The methods we've used so far seem to be only on expansion. So for now we should only be required to know those theoretically.
- Sun Feb 03, 2019 7:58 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Calorimeters
- Replies: 2
- Views: 381
Calorimeters
Can someone explain the different types of calorimeters there are. I am lost on how to recognize what calorimeter to use and how to solve these types of problems.
- Sun Feb 03, 2019 7:56 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Recognizing delta u
- Replies: 2
- Views: 281
Recognizing delta u
While doing a problem how would we recognize what method to use. Like how would we know if we need to use delta u.
- Fri Jan 25, 2019 4:43 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: ignoring x
- Replies: 10
- Views: 914
Re: ignoring x
I was also told that you HAVE TO check the 5% rule, you cant just choose if you want to check. It's better to be safe than sorry.
- Fri Jan 25, 2019 4:40 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Accurate and estimation of bond enthalpy
- Replies: 3
- Views: 417
Accurate and estimation of bond enthalpy
During class today Dr Lavelle stated that all diatomic molecules bond enthalpies were accurate, and that all other bond enthalpies were averages. I was wondering if someone could explain what a diatomic molecule was. I also vaguely remember Dr. Lavelle stating that C2's bond enthalpy is composed of ...
- Fri Jan 25, 2019 4:20 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 6th edition, 4A3 pt c
- Replies: 2
- Views: 267
Re: 6th edition, 4A3 pt c
I was told by my T.A. that the 7th edition has more errors than the 6th. This has also happened to me, and the 7th edition is the one that tends to be wrong.
- Tue Jan 22, 2019 1:12 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test and acid/ base recognition
- Replies: 1
- Views: 168
Test and acid/ base recognition
On this weeks test, will we need to know what acids/bases are strong/weak out of memory, or will we be told or be given a Ka/ Kb.
- Tue Jan 22, 2019 1:08 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Temperature change
- Replies: 5
- Views: 594
Temperature change
I know that when you change a rxn's condition the reaction is moved from equilibrium, but I was wondering how an increase or decrease in temperature specifically effected a reaction.
- Tue Jan 22, 2019 1:03 am
- Forum: Ideal Gases
- Topic: ICE Table Values
- Replies: 9
- Views: 1315
Re: ICE Table Values
The ice table is used for finding out how much of a weak acid or base reacted. From the problems I've seen only bars and molarity were used, but I'm not completely positive.
- Sun Jan 13, 2019 11:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Actual Yield of Products
- Replies: 2
- Views: 252
Re: Actual Yield of Products
I don't believe that a reaction goes to completion if you keep adding reactants. On the contrary the reaction will keep shifting. I am not completely sure though.
- Sun Jan 13, 2019 11:43 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 511
Re: Le Chatelier's Principle
In short the reaction shifts to accommodate a change in the reaction. Such as a change in temperature or concentration.
- Sun Jan 13, 2019 11:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pure Solids and Liquids
- Replies: 2
- Views: 182
Pure Solids and Liquids
I'm slightly confused on how to identify a pure solid and liquid when looking a written reaction. Can anyone please explain how to identify these.
- Sun Dec 02, 2018 11:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grades
- Replies: 10
- Views: 1088
Re: Final Grades
Yeah I know that but like overall letter grade is what I'm asking.
- Sun Dec 02, 2018 11:44 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Ligands
- Replies: 2
- Views: 314
Re: Ligands
A ligand is just an ion/ molecule that is bonded to the central atom. You basically figure them out using the lewis structure I believe.
- Sun Dec 02, 2018 11:41 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Calculating
- Replies: 2
- Views: 323
Re: Calculating
Dr. lavelle went over it really briefly and said that ph=-log10[h30].
- Sun Dec 02, 2018 11:37 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grades
- Replies: 10
- Views: 1088
Final Grades
Hey so does anyone know how the grading in this class is done. Is the class curved or is there a specific rubric. I've been asking around but still can't seem to find out.
- Sun Nov 25, 2018 10:58 pm
- Forum: Hybridization
- Topic: Questions in Chapter
- Replies: 5
- Views: 505
Questions in Chapter
For some of the questions from this chapter, in the textbook, they give the names of molecules rather than formulas in the questions. For test 3 will we be expected to know any basic molecules yet by the name.
- Sun Nov 25, 2018 10:48 pm
- Forum: Photoelectric Effect
- Topic: Midterm Q3B
- Replies: 1
- Views: 3057
Re: Midterm Q3B
First I used the equation E=hv to find the energy of a photon. Then I used the kinetic energy equation E=(1/2)mv^2 to find the energy of a electron that is released. Then using the concept of conservation of energy I set the initial energy of a photon equal to the sum of the Ionization energy (AKA t...
- Sun Nov 25, 2018 10:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Unhybridized P orbital
- Replies: 2
- Views: 215
Unhybridized P orbital
In one of Dr. Lavelle's lectures he mentioned how a p orbital was left unhybridized. Can anyone explain this to me, and also would this unhybridized p orbital also contain electrons or not?
- Mon Nov 19, 2018 8:50 pm
- Forum: Hybridization
- Topic: Hybridized Orbitals
- Replies: 4
- Views: 406
Re: Hybridized Orbitals
If you look at the atoms normal electron configuration, it may be inaccurate to the number of bonds that the atom has in a certain molecule. The hybridized d must be included if a atom has more than 4 bonds (8 electrons), such as those that exceed the octet rule.
- Mon Nov 19, 2018 8:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular shape on test
- Replies: 5
- Views: 418
Molecular shape on test
For the final, and test 3, will we be expected to know how to draw molecules, using electron densities (including the hybridized and non-hybridized models).
- Mon Nov 19, 2018 8:34 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining bond type
- Replies: 4
- Views: 368
Re: Determining bond type
From my understanding, as of so far, there is always one sigma bond between two atoms and the rest are pi bonds between those same atoms.
- Sun Nov 11, 2018 12:00 am
- Forum: Electronegativity
- Topic: Electronegativity and Electron Affinity
- Replies: 4
- Views: 510
Re: Electronegativity and Electron Affinity
I'm honestly quite lost also but what i found online says that electron affinity is an experimentally measured value, while eletronegativity is given in relationship to the values of other atoms in the periodic table
- Sat Nov 10, 2018 11:46 pm
- Forum: Dipole Moments
- Topic: Polarity and Dipole moments
- Replies: 2
- Views: 331
Re: Polarity and Dipole moments
The overall polarity of a molecule can be considered the vector additions of the all the dipole moments. they can either cancel each other out or add up.
- Sat Nov 10, 2018 11:35 pm
- Forum: Ionic & Covalent Bonds
- Topic: delta positive delta negative
- Replies: 15
- Views: 2350
Re: delta positive delta negative
First draw the direction of the dipole. The dipole should point towards the more electronegative atom in a molecule. therefore the end that the dipole points at is delta negative, and the end where the dipole starts at is delta positive. It may be confusing but try drawing it out, it'll help.
- Sun Nov 04, 2018 12:32 pm
- Forum: Bond Lengths & Energies
- Topic: Bond order
- Replies: 4
- Views: 501
Re: Bond order
I am not completely positive but i believe bond order is the average bond length of the resonance hybrid. I am almost positive though that to calculate bond order you divide all the number of bonds between the central and outer atoms (sticks)and divide by the number of outer atoms that you used.
- Sun Nov 04, 2018 12:26 pm
- Forum: Lewis Structures
- Topic: Question 3.55 (Sixth Edition)
- Replies: 6
- Views: 655
Re: Question 3.55 (Sixth Edition)
When you draw the lewis structures other of the answers given also seem to be radicals.
- Sun Nov 04, 2018 12:25 pm
- Forum: Lewis Structures
- Topic: Question 3.55 (Sixth Edition)
- Replies: 6
- Views: 655
Re: Question 3.55 (Sixth Edition)
A radical is basically a molecule that has more than one unpaired electron. In this case the answer is OH since there can only be a single bond in OH, O must have 5 electrons, resulting in one being unpaired.
- Sun Nov 04, 2018 12:17 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron configuration when 4s and 3d
- Replies: 3
- Views: 441
Re: Electron configuration when 4s and 3d
From my understanding you fill the 4s before the 3d usually. Only when the 3d is an exception, such as when you are 1 e from completing the 3 d orbital, do you complete the 3d first, since youre ultimate goal is to get a more stable atom. But when you write down the electron configurations first mak...
- Sun Oct 28, 2018 7:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polyatomic Ions [ENDORSED]
- Replies: 4
- Views: 527
Re: Polyatomic Ions [ENDORSED]
At the beginning of the quarter Dr. Lavelle said we didn't have to know them now, but that later we would. My PLF also said that with time, after doing many problems, you would probably end up memorizing them anyways. Don't worry about it too much , but do try to memorize them.
- Sun Oct 28, 2018 7:23 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1E 25)
- Replies: 2
- Views: 179
Re: 1E 25)
I would assume that we would need to know the basic groups, just because it was covered in high school chem. It's better to be safe than sorry, so I'd say just memorize the groups. On one slide though, the one where the periodic table is color coated in 3 different colors, where I believe he did men...
- Sun Oct 28, 2018 6:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Peer learning Sessions
- Replies: 3
- Views: 435
Re: Peer learning Sessions
The peer learning that I am aware of is the one that AAP offers. To join that one, you have to be a part of AAP, but i also did a google search and found this https://www.lscore.ucla.edu/ls-core-peer-learning/ . If you aren't a part of AAP you can investigate the one that this page offers.
- Sun Oct 21, 2018 8:24 pm
- Forum: Properties of Electrons
- Topic: ml
- Replies: 5
- Views: 578
ml
On Friday's lecture Dr. Lavelle kept mentiong ml, can someone please explain what that is, as I am majorly lost. Also instead of doing a lowercase l can i use a cursive l, since one of the reasons i got lost was because i kept confusing the l with a 1.
- Sun Oct 21, 2018 8:17 pm
- Forum: Properties of Electrons
- Topic: Shortcuts
- Replies: 4
- Views: 496
Shortcuts
So I'm having a hard time remembering the electron configurations, such as as the orbital shapes. I was wondering if anyone had a shortcut or method of memorizing these.
- Sun Oct 21, 2018 8:11 pm
- Forum: DeBroglie Equation
- Topic: Remembering mass of electrons for tests
- Replies: 6
- Views: 601
Re: Remembering mass of electrons for tests
I assume we wouldn't, just because on the last exam we were given known values.
- Wed Oct 17, 2018 12:29 am
- Forum: Administrative Questions and Class Announcements
- Topic: Points
- Replies: 4
- Views: 453
Re: Points
Alright Thank You!!!! Also I'm almost certain that you cannot make up for a previous week, because what i do remember is Dr. Lavelle saying the max number of points per week was 3.
- Tue Oct 16, 2018 5:17 pm
- Forum: Properties of Electrons
- Topic: Detectable Electron Wavelength
- Replies: 2
- Views: 176
Re: Detectable Electron Wavelength
In the lecture the professor said that gammas rays were the lowest, for sure, measured wavelength at 10^-12, but that anything below 10^-15 was unlikely, and that anything below 10^-18 was undetectable. He said that on the quizzes and test though, the answers were going to be obviously small, at aro...
- Tue Oct 16, 2018 5:03 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Points
- Replies: 4
- Views: 453
Points
Would posting 3 times in a single day count towards the 3 posts per week that i must submit.
- Mon Oct 15, 2018 2:27 am
- Forum: Student Social/Study Group
- Topic: Percent Composition
- Replies: 3
- Views: 2496
Re: Percent Composition
When I was doing one of these questions myself the number wasn't adding up to 100%. Although significant figures may have caused you to get to 99% you can try truncating all your answers to see if you get 100%, if you rounded all your answers.
- Mon Oct 15, 2018 2:13 am
- Forum: Properties of Light
- Topic: Measurable Wavelengths
- Replies: 3
- Views: 204
Re: Measurable Wavelengths
Although Dr. Lavelle said the cutoff was 10 ^-18, he specifically said that we wouldnt have to worry about the cutoff since the answers would be obviously small, like 10^-30
- Mon Oct 15, 2018 1:59 am
- Forum: Student Social/Study Group
- Topic: Studying techniques
- Replies: 12
- Views: 853
Re: Studying techniques
It all depends on the person. What works best for me is either rewiting notes in different colors, which helps me remember things better, or even making a little song out of the study notes. You can also try flashcards!
- Mon Oct 15, 2018 1:57 am
- Forum: Administrative Questions and Class Announcements
- Topic: Writing in Pen
- Replies: 13
- Views: 1052
Re: Writing in Pen
You should definitely ask your TA. My TA for instance told us she didn't mind if we wrote with pencil. But its all up to the TA I guess.
- Mon Oct 08, 2018 6:08 pm
- Forum: Properties of Light
- Topic: Speed of light constant (c)
- Replies: 6
- Views: 526
Re: Speed of light constant (c)
I remember the professor mentioning that the real value was the one starting with 2.99, but that for convenience he used the one starting with 3.00.
- Mon Oct 08, 2018 6:05 pm
- Forum: Empirical & Molecular Formulas
- Topic: M19
- Replies: 3
- Views: 363
Re: M19
If you're talking about the homework problem it should give you the molar mass of caffeine, and the percent composition. so you would multiply each percentage by the total molar mass. I don't think we should be expected to know the formula for caffeine, considering it's so early in the year.
- Mon Oct 08, 2018 5:59 pm
- Forum: Empirical & Molecular Formulas
- Topic: when to multiply empirical formula [ENDORSED]
- Replies: 9
- Views: 4588
Re: when to multiply empirical formula [ENDORSED]
You would multiple all the coefficients by 7, since you can't have 3.5 as a coefficient. You can't use 3 or 4 because that wouldn't uphold the exact proportion of 3.5.