Search found 115 matches
- Sat Mar 14, 2020 8:55 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 427411
Re: Final Jitters
Drinking a nice warm beverage and getting adequate sleep would help greatly. I've found that to be very helpful on occasion.
- Tue Mar 10, 2020 11:30 am
- Forum: General Rate Laws
- Topic: molecularity
- Replies: 8
- Views: 622
Re: molecularity
AKatukota wrote:Is molecularity then just the amount of reactants that interact?
Yep! Unimolecular = 1 molecule
Bimolecular = 2 molecules need to collide to react
etc etc etc.
- Tue Mar 10, 2020 11:28 am
- Forum: Administrative Questions and Class Announcements
- Topic: ENDGAME Review Session
- Replies: 71
- Views: 5823
Re: ENDGAME Review Session
We cannot thank you enough for your service Lyndon! Thanks for making Chemistry something we can enjoy, and for making your review sessions something we could all look forward every quarter! Love you 3000 king
- Mon Mar 09, 2020 3:08 pm
- Forum: General Rate Laws
- Topic: molecularity
- Replies: 8
- Views: 622
Re: molecularity
As Naneeta says, they're uncommon. Dr. Lavelle specifically told us to focus on 0, 1, and 2 order reactions (zero order, unimolecular, and bimolecular). Zero order == nonmolecular?
- Mon Mar 09, 2020 3:06 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: boltzmann
- Replies: 1
- Views: 153
Re: boltzmann
what is the significance of the Boltzmann distribution? It plots the number of molecules against energy and shows how many molecules have a certain amount of kinetic energy at various stages of a reaction. At higher temperatures, there are more molecules with more kinetic energy than at lower tempe...
- Mon Mar 09, 2020 3:00 pm
- Forum: General Rate Laws
- Topic: Textbook question 7A.17
- Replies: 3
- Views: 334
Re: Textbook question 7A.17
That tripped me up too. It's the unit conversions that cause it to have 10^-12.
- Mon Mar 09, 2020 3:00 pm
- Forum: Student Social/Study Group
- Topic: Final
- Replies: 21
- Views: 1458
Re: Final
Mai V 4L wrote:Will the test focus more on the first or second half of the class? (take home final sounds kinda lit)
Final exam for this class is cumulative meaning it will cover the entirety of this quarter's material. In other words, it will focus on everything :)
- Mon Mar 09, 2020 2:57 pm
- Forum: First Order Reactions
- Topic: Deriving First Order Half Life Equation
- Replies: 3
- Views: 289
Re: Deriving First Order Half Life Equation
By replacing t with t1/2, you're basically freezing the equation at the moment when the half life of the reactant takes place. At this moment (t1/2), the original concentration is exactly half of its starting value which explains the replacing of [A0] with 0.5[A0].
- Mon Mar 09, 2020 2:56 pm
- Forum: *Enzyme Kinetics
- Topic: Lecture 3/6
- Replies: 3
- Views: 383
Re: Lecture 3/6
Kallista McCarty 1C wrote:I was not able to make it to lecture on Friday, can someone explain what was covered?
If you would like some notes from that lecture, reply with your email and I can send them over :)
- Mon Mar 09, 2020 2:55 pm
- Forum: Student Social/Study Group
- Topic: Test Bank
- Replies: 2
- Views: 393
Re: Test Bank
Pretty sure some of the exams should have the solutions already on them as they can be student submissions of old exams
- Mon Mar 09, 2020 2:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Solutions Manual Errors
- Replies: 6
- Views: 525
Re: Solutions Manual Errors
There are definitely other errors in the solutions manual that may take some time to dig out. At this point we could either confirm with others that we got the same answer, consult Dr. Lavelle himself or the TAs, or just simply ignore the answer and say as long as we did the process right, we're fine.
- Mon Mar 09, 2020 2:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam Material Distribution
- Replies: 6
- Views: 429
Re: Final Exam Material Distribution
Judging by the tests we have been given, there should be a large question for each of the major topics (maybe 1-2 depending on how broad the subject is). I would expect 1-2 solely on thermo, 1-2 on kinetics, and 1-2 on the things we learned at the beginning of the quarter with some other smaller mis...
- Sat Feb 29, 2020 12:35 pm
- Forum: Balancing Redox Reactions
- Topic: Homework redox reactions
- Replies: 2
- Views: 227
Re: Homework redox reactions
Helpful way to remember it that I have used is to realize that the names of the agent and the rxn are opposites. For example: the species present in reduction rxns are the oxidizing agents, and vice versa.
- Sat Feb 29, 2020 12:32 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6m5a
- Replies: 2
- Views: 211
Re: 6m5a
Weird setup, but keep in mind there are exceptions to the rules we are taught. Here is one of them :) doubt we will see this on our exam though as it is almost eerily specific
- Sat Feb 29, 2020 12:31 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2
- Replies: 19
- Views: 1029
Re: Test 2
Test 2 will cover all material from Focus 5 (material not on the midterm) to the end of electrochemistry. It will not have any overlapping material but most likely some concepts will carry over from thermodynamics as Focus 5 is still within the thermo outline.
- Sat Feb 29, 2020 12:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Spontaneous reactions
- Replies: 6
- Views: 492
Re: Spontaneous reactions
Spontaneous reactions have positive cell potentials, so going off of this logic it technically contributes to a "higher" net cell potential. But as Sarah said the E cell value should determine spontaneity, not the other way.
- Sat Feb 29, 2020 12:26 pm
- Forum: Van't Hoff Equation
- Topic: Derive [ENDORSED]
- Replies: 4
- Views: 593
Re: Derive [ENDORSED]
Agreed. My TA recommended us know the process derivation of course but he also said not to depend on just the derivation on the exams as they would take up time. Just focus on the final formula and we should be good
- Mon Feb 24, 2020 12:32 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic/Voltaic Cells
- Replies: 4
- Views: 311
Re: Galvanic/Voltaic Cells
Adding on to that, galvanic cells are spontaneous, meaning they have a positive net cell potential. Electrolytic cells are NOT spontaneous, which require electrical energy to run.
- Mon Feb 24, 2020 12:30 pm
- Forum: Balancing Redox Reactions
- Topic: Half reactions
- Replies: 17
- Views: 943
Re: Half reactions
Make sure the charges that are reduced matches the amount of charges that are oxidized.
- Mon Feb 24, 2020 12:29 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Ion-Selective Electrodes
- Replies: 2
- Views: 213
Re: Ion-Selective Electrodes
The glass bit is the pH meter which gauges the concentrations of products vs reactants and converts that in terms of [H+] to find the pH of the general reaction.
- Mon Feb 24, 2020 12:25 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Today in lecture, Dr. Lavelle
- Replies: 4
- Views: 346
Re: Today in lecture, Dr. Lavelle
Thank you! Will add it to my chemistry jam list :))
- Mon Feb 24, 2020 12:24 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: gibbs free energy
- Replies: 15
- Views: 900
Re: gibbs free energy
As many have said above, Free Energy is the amount of energy available from a reaction or a process that can be used to do work. Delta G is change in this free energy, and Delta G naught is this value at equilibrium and standard conditions.
- Mon Feb 24, 2020 12:23 pm
- Forum: Balancing Redox Reactions
- Topic: OIL RIG
- Replies: 4
- Views: 347
Re: OIL RIG
OR you could think of it in terms of positive charge as follows:
REDUCING the positive charge == gaining electrons
OXIDIZING the charge == losing electrons to the addition of an Oxygen (this may not be correct, but is still helpful in remembering it nonetheless)
REDUCING the positive charge == gaining electrons
OXIDIZING the charge == losing electrons to the addition of an Oxygen (this may not be correct, but is still helpful in remembering it nonetheless)
- Mon Feb 17, 2020 4:24 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Delta G
- Replies: 6
- Views: 383
Re: Delta G
Thanks Mac! That was very helpful.
- Mon Feb 17, 2020 4:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Decreasing pressure
- Replies: 7
- Views: 615
Re: Decreasing pressure
To summarize, you can think of this in two ways: thinking about it in terms of concentration as Victoria Zheng--2F explained above, or the quicker way of gases occupying areas naturally as CameronDis2K and Natalie Benitez 1E have said. Whatever floats your boat!
- Mon Feb 17, 2020 4:20 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated Systems.
- Replies: 5
- Views: 502
Re: Isolated Systems.
Isolated systems cannot exchange heat or matter with the surroundings. They are closed in nature meaning they have constant pressure and volume (unless otherwise stated).
- Mon Feb 17, 2020 4:18 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Delta G
- Replies: 6
- Views: 383
Re: Delta G
But how are calculations different for each? and how will we tell when to use delta G or delta G naught in calculations?
- Mon Feb 17, 2020 4:16 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Constant R
- Replies: 15
- Views: 1102
Re: Constant R
As many have said, look at the units you need for a certain calculation and choose the R value accordingly. For example: you're given values in Liters, pressure, temperature, and mols, then you would use R = 0.08206 L*atm/K*mol
- Mon Feb 17, 2020 4:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Recommended Pathway for Chem Series
- Replies: 13
- Views: 1623
Re: Recommended Pathway for Chem Series
Best course of action would be to take 14A-D and BL with CL. I would try to aim to finish all of those sometime during your time at UCLA.
- Sun Feb 16, 2020 2:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: about the Midterm...
- Replies: 8
- Views: 608
Re: about the Midterm...
Same here! It just felt like the material we had focused on studying was not as heavily represented as we thought. There was a more general distribution of concepts as compared to the often-meticulous detail that the homework/practice problems entailed. Guess this just means we must consider studyin...
- Sat Feb 08, 2020 4:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion 4I
- Replies: 1
- Views: 135
Re: Discussion 4I
Hope you find them! Have you tried emailing your TAs or Dr. Lavelle? They might be able to spread the news further.
- Sat Feb 08, 2020 4:31 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible Process and Work
- Replies: 4
- Views: 196
Re: Reversible Process and Work
Reversible processes can be "turned" in any direction at the very slight perturbation of the system. The common one we went over in class was the slow isothermic expansion of gas in a piston chamber due to the addition of heat in gas which causes it to expand. Isothermic systems have tempe...
- Sat Feb 08, 2020 4:26 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam burns more than water
- Replies: 5
- Views: 263
Re: Steam burns more than water
Steam causes a larger energy change/transfer than water when it touches your skin. Larger energy transfer == more damage.
- Sat Feb 08, 2020 4:22 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeters
- Replies: 17
- Views: 1032
Re: Calorimeters
Constant volume as many have said. It's not really constant pressure because the reaction inside can keep changing the pressure.
- Sat Feb 08, 2020 4:21 pm
- Forum: Calculating Work of Expansion
- Topic: Integral for work
- Replies: 4
- Views: 177
Re: Integral for work
I would know why the equation exists. It exists in irreversible conditions (temperature constant, P and V changing at infinitesimally small intervals, so dw = -PdV. P becomes nRT/V, and if you take the integral of both sides you're left with w = -nRTln(V2/V1). It's just helpful to know in terms of l...
- Sun Feb 02, 2020 3:29 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Standard Enthalpy of Formation
- Replies: 4
- Views: 249
Re: Standard Enthalpy of Formation
They will be provided in the question or on a separate resource I believe. There are just so many values for standard enthalpy of formation it's unreasonable to memorize them all.
- Sun Feb 02, 2020 3:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 5 Homework
- Replies: 7
- Views: 274
Re: Week 5 Homework
Any problems from outlines covered recently in class are applicable though I believe it would be best if we do problems correlating with lecture material.
- Sun Feb 02, 2020 3:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Math Resources
- Replies: 8
- Views: 290
Re: Math Resources
As everyone has said, they're on his website. You'll also find many useful resources there besides the math ones!
- Sun Feb 02, 2020 3:24 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed system
- Replies: 5
- Views: 246
Re: Closed system
The defining characteristic of closed system is that there is no matter exchange between the system or its surroundings. Almost anything else is applicable (i.e. heat transfer, volume changes, etc). Traditionally volume changes are incurred via the depression/compression of a piston as many have sai...
- Sun Feb 02, 2020 3:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1 #5
- Replies: 7
- Views: 348
Re: Test 1 #5
Average grades aren't posted to us. Ask your TA or Dr. Lavelle for the averages!
- Mon Jan 27, 2020 12:29 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Methods to Calculate Enthalpies
- Replies: 6
- Views: 413
Re: Methods to Calculate Enthalpies
Depends on the information given and the setup of the question. For example: if multiple rxn equations are given with their respective enthalpy changes, then you might suspect Hess's Law. If bond energies are given, then you might use bond energies.
- Mon Jan 27, 2020 12:28 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy from DSC curves
- Replies: 1
- Views: 99
Re: Enthalpy from DSC curves
Yes, I would assume so eventually (maybe during today's lecture!)
- Mon Jan 27, 2020 12:27 am
- Forum: Phase Changes & Related Calculations
- Topic: Steam vs water
- Replies: 5
- Views: 209
Re: Steam vs water
Short answer: because steam has more phase changes than water, it releases more energy when it comes into contact with your skin. It transfers more energy to your skin resulting in greater damage.
- Mon Jan 27, 2020 12:26 am
- Forum: Phase Changes & Related Calculations
- Topic: Hess's Law
- Replies: 5
- Views: 180
Re: Hess's Law
Hess's Law encompasses all enthalpy changes that accompany a general reaction no matter how many intermediate steps said reaction has. Each individual change in enthalpy is taken into account.
- Mon Jan 27, 2020 12:25 am
- Forum: Phase Changes & Related Calculations
- Topic: Test 1
- Replies: 6
- Views: 248
Re: Test 1
Expect them to be returned this week or next week during discussion sections.
- Mon Jan 27, 2020 12:24 am
- Forum: Phase Changes & Related Calculations
- Topic: Steam Burns
- Replies: 9
- Views: 673
Re: Steam Burns
The energy change granted by the steam is higher (more energy is released) resulting in greater energy.
- Sun Jan 19, 2020 10:09 pm
- Forum: Ideal Gases
- Topic: homework #3
- Replies: 16
- Views: 970
Re: homework #3
Technically you're allowed to use problems from any material that is going to be on the exam, but like others have said it's better to remain on top of the lecture material as homework problems.
- Sun Jan 19, 2020 9:11 pm
- Forum: General Science Questions
- Topic: test 1
- Replies: 8
- Views: 330
Re: test 1
Test is during your discussion period this week, so it will occur at different times for every discussion section.
- Sun Jan 19, 2020 9:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% rule
- Replies: 8
- Views: 286
Re: 5% rule
If the equilibrium concentration divided by the initial reactant concentration is less than 0.05, then the equilibrium constant is valid. Basically this means: the change in concentration of product can be ignored while solving the equilibrium constant equation as long as it is less than 5% of the i...
- Sun Jan 19, 2020 9:02 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: X was ignored
- Replies: 27
- Views: 1196
Re: X was ignored
X value was ignored because the K value was so small, meaning the amount of product formed compared to the reactants was very small. This means that the amount of products (x) can technically be ignored as a change factor which is why you can eliminate it.
- Fri Jan 17, 2020 11:46 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Tips for Test
- Replies: 23
- Views: 1201
Re: Tips for Test
I study by doing homework problems and reading the textbook. Just make sure you're well adapted to the situations that might arise and you will be fine.
- Thu Jan 09, 2020 11:39 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Effect of Inert Gases
- Replies: 9
- Views: 356
Re: Effect of Inert Gases
As stated already, inert gases are exempt as they are stable and seldom interact with species involved in reactions. You can think of them as "pure" substances like liquids and solids which are also exempt from the equilibrium constant.
- Thu Jan 09, 2020 11:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Meaning of equilibrium constant
- Replies: 5
- Views: 265
Re: Meaning of equilibrium constant
When K is in the intermediate region, neither forward nor reverse reactions are favored. You can say the rxn is in an "intermediate" stage
- Thu Jan 09, 2020 11:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Q Values
- Replies: 5
- Views: 219
Re: K and Q Values
Recap: Q can be thought as the products-to-reactants constant at any time of the reaction. If Q < K, this means that the [products]/[reactants] ration at this time is smaller than the ratio at equilibrium; i.e. the [reactants] at this time are greater. Thus, the forward reaction will be favored as t...
- Thu Jan 09, 2020 11:30 pm
- Forum: Student Social/Study Group
- Topic: Chemistry Community Confessions
- Replies: 2
- Views: 270
Chemistry Community Confessions
I just had a random thought: since it's Week 1 and we've barely started, how about we set up an anonymous Chemistry confessions forum like the UCLA/UC Berkeley Facebook Confessions pages? Personally I think it would be a fun way to get to know each other more. Thoughts on this?
- Wed Jan 08, 2020 5:49 pm
- Forum: Student Social/Study Group
- Topic: Discussion Sections
- Replies: 7
- Views: 460
Discussion Sections
Just got an email about discussion sections and thought I would confirm with you guys.
Are there going to be discussion sections this week for Chem 14B?
Are there going to be discussion sections this week for Chem 14B?
- Sat Dec 07, 2019 8:48 pm
- Forum: Amphoteric Compounds
- Topic: Amphoteric vs amphiprotic
- Replies: 4
- Views: 430
Re: Amphoteric vs amphiprotic
Amphoteric means the compound can act as an acid or base, whereas amphiprotic means that the compound can donate and accept protons.
Building on to this, amphiprotic compounds are always amphoteric by definition.
Building on to this, amphiprotic compounds are always amphoteric by definition.
- Sat Dec 07, 2019 8:47 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Ka. Kb, Kw
- Replies: 4
- Views: 1397
Re: Ka. Kb, Kw
What is the difference between Ka, Kb, and Kw? Also, what is the difference between Ka1 and Ka2? Do we need to calculate Ka and Kb in the final? Ka * Kb = Kw = 1.0 x 10^-14 pKa + pKb = pKw = 14 Ka1 and Ka2 only appear in polyprotic acids (i.e. H2so4). Ka1 is the dissociation constant when 0 H+ are l...
- Sat Dec 07, 2019 8:43 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pKA values
- Replies: 4
- Views: 396
Re: pKA values
pKa is the negative log of the Ka value. Right now it's used in comparing acid strength as many have stated above.
- Sat Dec 07, 2019 8:43 pm
- Forum: Lewis Acids & Bases
- Topic: Bronsted vs Lewis Acid
- Replies: 1
- Views: 197
Re: Bronsted vs Lewis Acid
Acids are by definition both Bronsted and Lewis. The two different "types" are just different ways of looking at acid function. Acids traditionally combine with water molecules and result in the loss of an H+ proton, which binds to water to form the acidic H3O+ hydronium ion. However, this...
- Sat Dec 07, 2019 8:40 pm
- Forum: Biological Examples
- Topic: Vitamin B12
- Replies: 2
- Views: 158
Re: Vitamin B12
Vitamin B12 has a center of Cobalt with 5 Nitrogen ligands and one CH2. It has an overall octahedral shape centered at Cobalt. According to the book, the cobalt prevents pernicious anemia and mental illnesses, and classmates have said it also participates in synthesis of DNA and myelin, metabolism o...
- Sat Dec 07, 2019 8:37 pm
- Forum: Naming
- Topic: Abbreviations
- Replies: 6
- Views: 642
Re: Abbreviations
Yes, we're allowed to use abbreviations (Lyndon and many TAs have confirmed this). en, edta, and ox (for oxalato) are all allowed.
- Sat Dec 07, 2019 8:36 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: H20
- Replies: 4
- Views: 283
Re: H20
Think of polydentate molecules having two different bonding sites on two different atoms. As mentioned above, "spacer" atoms are need to give the atoms adequate space to bind more than once. The two electron LP's on the oxygen of H2O do not provide enough space to form two bonds to a centr...
- Sun Dec 01, 2019 3:34 pm
- Forum: Industrial Examples
- Topic: What do we need to know?
- Replies: 15
- Views: 1644
Re: What do we need to know?
I would review all the biological examples Dr. Lavelle has reviewed in class. As seen by Test 2, he might pull up something from his lectures that we considered to be unimportant or just another example.
- Sun Dec 01, 2019 3:33 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: hw problem
- Replies: 1
- Views: 82
Re: hw problem
Coordination numbers are basically the amount of bonding sites the central atom has. Take into account some ligands are polydentate and bind at more than one place. Can't give you the exact methods to solve this problem as I don't have my materials with me at the moment, but hope my reply helped.
- Sun Dec 01, 2019 3:30 pm
- Forum: Student Social/Study Group
- Topic: Final Topics
- Replies: 4
- Views: 285
Re: Final Topics
I would just focus on the topics we've been taught in class. I don't think we've learned about the specifics behind molecular and atomic spectroscopy. We've learned that mass spectroscopy, however, gives you the exact masses of molecular compounds to help in making molecular formulas.
- Sun Dec 01, 2019 3:26 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Water
- Replies: 5
- Views: 366
Re: Water
I believe Ka only focuses on the formation of acids (i.e. HCl -> Cl- + H+) so thus water won't really apply here.
- Sun Dec 01, 2019 3:23 pm
- Forum: Naming
- Topic: Roman Numeral
- Replies: 13
- Views: 971
Re: Roman Numeral
As many have said above, it represents the (usually positive) charge of the atom it's coupled with. Usually only transition metals have this notation.
- Sun Dec 01, 2019 3:22 pm
- Forum: Naming
- Topic: Final Exam?
- Replies: 20
- Views: 1206
Re: Final Exam?
Thanks for the info! I would brush up on everything you can't remember off the top of your head and reinforce those topics via hw questions.
- Sun Dec 01, 2019 3:21 pm
- Forum: Student Social/Study Group
- Topic: Final topics
- Replies: 10
- Views: 575
Final topics
Quick question: does the final cover all topics throughout the entire school year? Or does it only cover material taught after the midterm?
- Sat Nov 23, 2019 11:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shaped v. Trigonal pyramid
- Replies: 9
- Views: 577
Re: T-shaped v. Trigonal pyramid
I second the use of a visual aid to determine molecular shape. Sometimes I find it's helpful to visualize a molecule as if each electron density corresponds to a X value in the "AXE" VSEPR notation, then removing X's based on the number of lone pairs there are until the true molecular shap...
- Sat Nov 23, 2019 11:19 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acids
- Replies: 13
- Views: 1617
Re: Acids
Dr. Lavelle will most likely give us an idea on which specific acids we should know but the most common acids (shown above) are a good place to start!
- Sat Nov 23, 2019 11:18 pm
- Forum: Biological Examples
- Topic: Biological Importance
- Replies: 6
- Views: 389
Re: Biological Importance
I second the statement above about the effect of pH on protein functionality. I would assume everything in the lectures that Dr. Lavelle goes into detail about is fair game.
- Sat Nov 23, 2019 11:15 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 427411
Re: Final Jitters
Get a good night's sleep. Always helps to give your mind some proper rest
- Sat Nov 23, 2019 11:14 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: ligand
- Replies: 3
- Views: 282
Re: ligand
Ligands are basically "anything" that attaches to a metal atom to form a coordination compound. Ligands can be neutral in charge or negatively charged.
- Sat Nov 23, 2019 11:13 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Diethelyne tri-amine
- Replies: 1
- Views: 99
Re: Diethelyne tri-amine
Think of this as a more convenient shorthand configuration. The bonding of the Hydrogens on either side of the Carbon is there at the molecular level but it's written as CH2 instead of H-C-H etc to save time and space.
- Sun Nov 17, 2019 5:35 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Preferential
- Replies: 3
- Views: 149
Re: Preferential
Molecular shape is based on the arrangement of atoms and areas of electron density. Higher or lower Ionization Energies or Electronegativities of atoms will not affect structure.
- Sun Nov 17, 2019 5:31 pm
- Forum: Dipole Moments
- Topic: Polarity
- Replies: 7
- Views: 489
Re: Polarity
It's a symmetric molecule and has even distributions of electron density; thus, it is nonpolar.
- Sun Nov 17, 2019 5:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Do we have to memorize the names of shapes and/or the bond angles?
- Replies: 7
- Views: 538
Re: Do we have to memorize the names of shapes and/or the bond angles?
Yes, we need to memorize the names of the molecular shapes and the rough bond angles. I.e. trigonal planar = shape. 120 degrees = bond angle. OR i.e. trigonal pyramidal = shape, < 109.5 degrees = angle.
- Sun Nov 17, 2019 5:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.13
- Replies: 1
- Views: 119
Re: 2E.13
I would try to visualize this in 3 dimensions. If there were no lone pairs, the molecule would have a trigonal bipyramidal shape with 180 degree bond angle through the axis and 120 degrees equatorial. But because there are 3 lone pairs, you remove the three equatorial atoms, causing enough repulsion...
- Sun Nov 17, 2019 5:20 pm
- Forum: Student Social/Study Group
- Topic: test 2
- Replies: 8
- Views: 436
Re: test 2
50
- Sun Nov 17, 2019 5:19 pm
- Forum: SI Units, Unit Conversions
- Topic: Memorizing Conversions
- Replies: 25
- Views: 1404
Re: Memorizing Conversions
It's great to memorize the general conversion factors. pm (picometers, 10^-12) and nm (nanometers, 10^-9) are given but it's great to have a handle on the other prefixes in case they pop up in questions.
- Mon Nov 11, 2019 2:52 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3917890
Re: Post All Chemistry Jokes Here
An excited electron in this sense may be deadly
- Sun Nov 03, 2019 10:43 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: How to know where a double bond should go?
- Replies: 10
- Views: 1236
Re: How to know where a double bond should go?
Check the atoms' octets as well as the formal charge. More electronegative atoms would prefer negative formal charges and thus form more stable structures if this is accomplished via bond rearrangement.
- Sun Nov 03, 2019 10:30 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron configuration for D block
- Replies: 3
- Views: 232
Re: Electron configuration for D block
Venus is correct. But in any case, the 4s orbitals fill first before the 3d orbitals. In copper and chromium, the pre-existing electron from 4s2 fills up a spot in the lower energy 3d5 and 3d10 orbitals, resulting in 4s1 configuration.
- Sun Nov 03, 2019 10:27 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Ms and ML
- Replies: 6
- Views: 2082
Re: Ms and ML
Not really sure why ms has -1/2 and +1/2 specifically but the positive and negative values are there to represent opposite electron spins.
- Sun Nov 03, 2019 10:25 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron configuration for D block
- Replies: 3
- Views: 232
Re: Electron configuration for D block
The empty 3d block is higher in energy than the 4s block. Because electrons fill up lower energy shells first, the 4s fills before the 3d orbitals. But once one electron is present in the 3d orbitals, it drops to a lower energy than the 4s. This is why an atom with filled 4s and 3d orbitals has 4s e...
- Sun Nov 03, 2019 10:21 pm
- Forum: Octet Exceptions
- Topic: Expanded Valence Shells
- Replies: 6
- Views: 228
Re: Expanded Valence Shells
Theoretically speaking, all atoms in the 3rd energy level can break the octet rule because of their unused 3d orbitals that can accommodate extra electrons; however, in nature, only a few atoms consistently do this.
- Sun Nov 03, 2019 10:18 pm
- Forum: Electronegativity
- Topic: definitions
- Replies: 8
- Views: 506
Re: definitions
We will not need to know how to calculate the exact values in ionization energy or electronegativity; however, we will need to know what they mean and their respective periodic trends. We'll also need to know how they apply to bonding (i.e. the atom with the highest electronegativity prefers a negat...
- Sun Nov 03, 2019 10:16 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Formal names for each letter
- Replies: 5
- Views: 330
Re: Formal names for each letter
n = principal number
l = orbital angular momentum number
ml = magnetic number
I would just try and hard-code it into my mind. I don't think the full names of the quantum numbers matter very much though--I'm sure the graders will know what you mean if you just use n, l, ml, and ms.
l = orbital angular momentum number
ml = magnetic number
I would just try and hard-code it into my mind. I don't think the full names of the quantum numbers matter very much though--I'm sure the graders will know what you mean if you just use n, l, ml, and ms.
- Sun Oct 27, 2019 5:21 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization and Electron Affinity
- Replies: 5
- Views: 342
Re: Ionization and Electron Affinity
Adding on to the posts above, I find it helpful to remember the two separately by thinking of Electron Affinity (energy released when an element gains an electron) as the "affinity" or "attraction" that an elements have for an electron. This increases across a row and decreases d...
- Sun Oct 27, 2019 5:17 pm
- Forum: Resonance Structures
- Topic: Expanded Octets
- Replies: 4
- Views: 256
Re: Expanded Octets
Expanded octets (otherwise known as exceptions to the octet rule) exist starting with elements with 4s and 3d orbitals. Due to the nature and arrangement of orbitals, the 4s orbitals fill up before the 3d ones do. This allows additional electrons to be added into the empty 3d orbitals, allowing thes...
- Sun Oct 27, 2019 5:13 pm
- Forum: Student Social/Study Group
- Topic: Miderm Review
- Replies: 10
- Views: 670
Re: Miderm Review
I personally have not tried Sapling for myself yet, but I've heard some students are disappointed with what it offers. It's apparently just the same information you can find from the textbook and Dr. Lavelle's webpage. Still open to anything though! I'll give it a look and update my post if I find a...
- Sun Oct 27, 2019 5:11 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Determining # for Formal Charge
- Replies: 2
- Views: 186
Re: Determining # for Formal Charge
Formal Charge for an element in a compound/molecule is calculated with this formula: FC = # of Valence electrons - (# of lone pair electrons + (#of shared electrons / 2) ) = V - (L + S/2). The S value refers to the # of shared electrons; i.e. the amount of electrons present in bonds. Remember that s...
- Sun Oct 27, 2019 5:03 pm
- Forum: Student Social/Study Group
- Topic: Study Tips
- Replies: 58
- Views: 4764
Re: Study Tips
I would personally focus on exposing myself to as many problems as possible to get used to applying the information we've learned in lectures in multitudes of ways. External resources (Professor Lavelle's webpage, Youtube, Khanacademy) can help clarify information, but the true essence of understand...
- Sun Oct 27, 2019 4:56 pm
- Forum: Resonance Structures
- Topic: Bond lenghts.
- Replies: 11
- Views: 433
Re: Bond lenghts.
We haven't been taught how exactly to obtain measurements for bond lengths as of now. Professor Lavelle specified the different lengths to prove that double and triple bonds have higher attraction and thus shorter lengths than single bonds, and the bonds for resonance structures have lengths between...
- Sun Oct 27, 2019 4:52 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 16
- Views: 794
Re: Valence Electrons
Valence electrons of a specific element are based on the position the element is inside its period (row). For example, Oxygen is the 6th element in its period (not counting elements in d and f blocks), which means it has 6 valence electrons. Chlorine is the 7th element in its period so it has 7 vale...
- Sat Oct 19, 2019 11:23 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: 1D.17
- Replies: 1
- Views: 82
Re: 1D.17
Question: 1D.15: What are the principal and orbital angular momentum quantum numbers for each of the following orbitals:(a)6p,(b)3d,(c)2p,(d)5f?
principal # n = energy level
Angular momentum # l = 0,1,2,3,.... n-1
a) 6p: n = 6, l = 1
b) 3d: n = 3, l = 2
c) 2p: n = 2, l = 1
d) 5f: n = 5, l = 3
principal # n = energy level
Angular momentum # l = 0,1,2,3,.... n-1
a) 6p: n = 6, l = 1
b) 3d: n = 3, l = 2
c) 2p: n = 2, l = 1
d) 5f: n = 5, l = 3
- Sat Oct 19, 2019 11:18 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 1D.19
- Replies: 6
- Views: 213
Re: 1D.19
Below always holds true:
s: 1 orbital
p: 3 orbitals
d: 5 orbitals
f: 7 orbitals
g: 9 orbitals
s: 1 orbital
p: 3 orbitals
d: 5 orbitals
f: 7 orbitals
g: 9 orbitals
- Sat Oct 19, 2019 11:16 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Unit for Avogadro's Number
- Replies: 10
- Views: 2229
Re: Unit for Avogadro's Number
Avogadro's number is used to convert mols to virtually any unit. Think of it as the number of "something" in one mole of this "something". It can be the amount of atoms in 1 mole of atoms, or even the amount of jelly beans in one mole of jelly beans.