Search found 49 matches
- Mon Mar 20, 2017 11:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14C
- Replies: 3
- Views: 972
Re: Chem 14C
Do you know if the Organic Chemistry Course Reader we got for Chem 14B can be used for Chem 14C? Like, are there topics in our current Organics Course Reader that are covered in chem 14C? We will be learning a lot of new topics in Chem 14C, which is why we have new materials. You could use the cour...
- Sat Mar 18, 2017 5:16 am
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 621698
Re: Saying Thank You to Dr. Lavelle
Dr. Lavelle, I truly appreciate how you went above and beyond to provide all your students so many resources to help us succeed in the course. Whether it was taking the time to make a course reader or setting up countless hours of office hours and peer learning sessions, you have made an outstanding...
- Fri Mar 17, 2017 2:26 pm
- Forum: General Science Questions
- Topic: Final
- Replies: 9
- Views: 2285
Re: Final
Do we know any of the subjects that will not be covered on the exam? Because it would be much easier to study if we knew what to focus on & the things we won't need. I would go over everything that he has talked about in class and is in the course reader. Anything that has been assigned or disc...
- Tue Mar 14, 2017 6:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final content
- Replies: 4
- Views: 1044
Re: Final content
Anything Dr. Lavelle has gone over in class is fair game for the final, so whatever proofs he has discussed or covered in class could be on the final.
- Sun Mar 12, 2017 8:47 pm
- Forum: *Chem3D
- Topic: Shape of Organic Molecules
- Replies: 2
- Views: 1428
Re: Shape of Organic Molecules
The stable conformation will not always be what happens in nature because of thermal collisions. As we increase the temperature, you will see the equilibrium constant between the a less stable conformation (gauche) and the most stable conformation (anti) will decrease, meaning that as the temperatur...
- Thu Mar 09, 2017 8:30 pm
- Forum: Student Social/Study Group
- Topic: Book
- Replies: 2
- Views: 799
Re: Book
No, it is different.
- Thu Mar 09, 2017 6:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 3
- Replies: 2
- Views: 666
Re: Quiz 3
Quiz 3 covers from page 74 to page 96 in the course reader.
- Wed Mar 08, 2017 6:01 am
- Forum: *Nucleophilic Substitution
- Topic: Reaction profile for SN2 reaction
- Replies: 2
- Views: 1849
Re: Reaction profile for SN2 reaction
They would have to specify, but exergonic is much more common than endergonic so if they do not I would draw it the exergonic way.
- Wed Mar 08, 2017 5:58 am
- Forum: General Science Questions
- Topic: Types of energy profiles
- Replies: 5
- Views: 1354
Re: Types of energy profiles
I believe we look at the delta G of the transition states relative to the reactants, even for the second step. However, when you are calculating activation energy of the second step you look at the the transition state relative to the intermediates. My TA said that some chemists look at delta G of t...
- Fri Mar 03, 2017 11:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 3 Prep answers
- Replies: 6
- Views: 1315
Re: Quiz 3 Prep answers
I'm sure he will post the answers within the next couple days, so that we have a couple days to look over the solutions before the quiz.
- Fri Mar 03, 2017 6:53 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Steady State vs. Pre-Equilibrium Approach
- Replies: 2
- Views: 998
Re: Steady State vs. Pre-Equilibrium Approach
When the methods are done correctly, you will get the same answer with either method. Lavelle said that we are not tested on the steady-state approximation, we use the pre-equilibrium method in this class. In the pre-equilibrium method, we assume that the reactants and intermediates are in equilibri...
- Wed Mar 01, 2017 6:14 am
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz #3
- Replies: 6
- Views: 1396
Re: Quiz #3
I believe so. Lavelle will likely make an announcement on Friday about Quiz 3 and all the topics it will cover as he normally does before an upcoming quiz.
- Fri Feb 24, 2017 8:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 14CL
- Replies: 6
- Views: 1843
Re: 14CL
I believe Chem 14C and Chem 14Cl can be taken together. It is up to your own personal preference.
- Wed Feb 22, 2017 6:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Winter 2017
- Replies: 87
- Views: 21234
Re: Midterm Winter 2017
I believe the average was a 74% on the Midterm.
- Mon Feb 20, 2017 11:18 pm
- Forum: General Rate Laws
- Topic: Units of K
- Replies: 4
- Views: 27381
Re: Units of K
For a zero order, the units of k are M/s, or mol*L^-1*s^-1. For first order, the units are 1/s or s^-1. For second order, the units are 1/M*s or L*mol^-1*s^-1. You will notice that there is a pattern here. Every time the order is increase by one we divide by M or mols/L. So therefore, for a third or...
- Sun Feb 19, 2017 9:15 am
- Forum: Student Social/Study Group
- Topic: Quiz 2 Preparation
- Replies: 2
- Views: 849
- Fri Feb 17, 2017 6:51 am
- Forum: Balancing Redox Reactions
- Topic: Balancing (Acidic vs. Basic Balancing)
- Replies: 3
- Views: 761
Re: Balancing (Acidic vs. Basic Balancing)
The problem should always specify whether the reaction should be balanced in acidic or basic solution.
- Thu Feb 16, 2017 10:41 pm
- Forum: Student Social/Study Group
- Topic: Peer Learning Sessions
- Replies: 2
- Views: 698
Re: Peer Learning Sessions
Lavelle has a list of all the office hours and the peer learning sessions on the Chem 14B website. The peer learning sessions are very helpful. I definitely recommend going to one if you can!
- Mon Feb 13, 2017 9:35 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Specific Heat Capacity
- Replies: 2
- Views: 653
Re: Specific Heat Capacity
For this problem, you would be given the heat capacity for Cu, it is in the Appendix of the textbook.
- Fri Feb 10, 2017 2:38 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G vs Delta G0
- Replies: 5
- Views: 7887
Re: Delta G vs Delta G0
You would just solve using the first equation. To solve the second equation, you would need the reaction quotient Q.
- Mon Feb 06, 2017 7:26 am
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 1 Results
- Replies: 2
- Views: 732
Re: Quiz 1 Results
The quizzes are usually returned by your TA in your discussion section a week after the quiz. So, you will likely get your quiz back in this week's discussion section.
- Thu Feb 02, 2017 5:51 am
- Forum: Administrative Questions and Class Announcements
- Topic: Fall 2016 Finals Still Available?
- Replies: 5
- Views: 1271
Re: Fall 2016 Finals Still Available?
Won't the finals be available until Week 10 of the quarter?
- Tue Jan 31, 2017 6:49 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Quiz 1 Preparation #5
- Replies: 1
- Views: 584
Re: Quiz 1 Preparation #5
You are trying to create the reaction that the problem is asking for. So, you have to flip and multiply some of the equations and therefore, their corresponding enthalpies in order to get the enthalpy for the equation the problem is asking for when you add all of the equations and enthalpies up. Hes...
- Fri Jan 27, 2017 12:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz Topics
- Replies: 10
- Views: 1914
Re: Quiz Topics
I do not believe they will be posting answers for the practice quiz in the course reader in order to encourage students to work together and attend peer learning sessions or office hours, so they can figure out the correct answers.
- Mon Jan 23, 2017 9:04 am
- Forum: Student Social/Study Group
- Topic: Quiz 1 Prep
- Replies: 8
- Views: 1585
Re: Quiz 1 Prep
I'm interested as well. Please let me know what day and time you all are planning on meeting up!
- Thu Jan 19, 2017 6:18 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated Systems [ENDORSED]
- Replies: 2
- Views: 749
Re: Isolated Systems [ENDORSED]
Another example of an isolated system could be an very well insulated container, such as a thermos. An isolated system is anything that cannot exchange heat or mass with its surroundings.
- Tue Jan 17, 2017 3:32 am
- Forum: Phase Changes & Related Calculations
- Topic: Boiling Points at Altitude [ENDORSED]
- Replies: 2
- Views: 687
Re: Boiling Points at Altitude [ENDORSED]
Pressure drops as you gain elevation. Therefore, less heat is required to make the vapor pressure equal to the atmospheric pressure. So, the boiling point is lower at higher altitude. For example, water boils at a lower temperature in Denver than it may in Los Angeles.
- Sat Jan 14, 2017 8:10 am
- Forum: General Science Questions
- Topic: Intro to Organic Chemistry
- Replies: 9
- Views: 1953
Re: Intro to Organic Chemistry
I believe we will be using it later in the quarter when we begin learning about Organic Chemistry. It is a replacement for the organic chemistry textbook, but it is not a replacement for the actual textbook that we need to have for the rest of the class.
- Wed Jan 11, 2017 9:11 am
- Forum: Administrative Questions and Class Announcements
- Topic: Random Enrollment Checks
- Replies: 9
- Views: 2037
Re: Random Enrollment Checks
Yes, I also believe the enrollment checks are just to ensure that there are not people from other lectures attending a different lecture and taking up seats. I do not think you could be penalized for not coming to class because the class does not give points for attendance, as it is more of an expec...
- Tue Jan 10, 2017 11:40 am
- Forum: Student Social/Study Group
- Topic: chem 14B workbook
- Replies: 7
- Views: 1566
Re: chem 14B workbook
Yes, the only books I got from the course reader store was the actual course reader and the introduction to organic chemistry booklet.
- Fri Dec 02, 2016 4:33 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Difference between pka and Ka
- Replies: 1
- Views: 553
Re: Difference between pka and Ka
pKa is the -log(Ka). The smaller the value of Ka, the larger the value of pKa. The larger the value of pKa, the weaker the acid.
- Wed Nov 30, 2016 7:29 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: finding final pH
- Replies: 2
- Views: 770
Re: finding final pH
We do this because pOH+pH=14. So, if the the question is asking us to find the pH and we have found the pOH we can just subtract the number we have found (pOH) from 14 in order to find pH.
- Wed Nov 23, 2016 7:48 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: d-block electron configurations
- Replies: 2
- Views: 1036
Re: d-block electron configurations
You only need to memorize the elements that have 4 or 9 valence electrons in the d-orbital. Since they are one away from a half-filled or filled shell, they will take 1 away from the 4s shell because it is lower energy to have a half-filled or filled d-orbital. The other d-block elements have a &quo...
- Tue Nov 22, 2016 10:16 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Higher/lower energy in a MO diagram?
- Replies: 4
- Views: 1337
Re: Higher/lower energy in a MO diagram?
I believe the amount of distance you draw between them is due to the difference is electronegativity. So if one of the atoms is much less electronegative, it will be much higher than the one that is much more electronegative. On the other hand, if the difference in electronegativity between the two ...
- Sat Nov 19, 2016 9:46 am
- Forum: Sigma & Pi Bonds
- Topic: Bond Strength [ENDORSED]
- Replies: 2
- Views: 1334
Re: Bond Strength [ENDORSED]
It isn't saying that a double bond is weaker than a single bond, because it is not. Think of it like the pi bond within the double is weaker than the sigma bond. You are not looking at a pi bond + a sigma bond (a double bond) vs. just a sigma bond (single bond). I hope that is more clear.
- Wed Nov 16, 2016 9:57 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Heteronuclear Diatomic Molecules: Electronegativity
- Replies: 1
- Views: 537
Re: Heteronuclear Diatomic Molecules: Electronegativity
I believe this is due to lone pairs of electrons being more stable on more electronegative elements leading them to be lower in energy.
- Fri Nov 11, 2016 10:43 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14B and 14BL [ENDORSED]
- Replies: 12
- Views: 5655
Re: Chem 14B and 14BL [ENDORSED]
I'm planning on taking Chem 14B next quarter and then taking 14BL the next quarter after that. Would you recommend doing this or waiting until the end of the 14 series to take the labs?
- Thu Nov 10, 2016 5:40 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: HOMO to LUMO Concept
- Replies: 3
- Views: 1127
Re: HOMO to LUMO Concept
When you draw your molecular orbital diagram, your lowest molecular orbital that has no electrons in it is the LUMO. Your highest molecular orbital that is occupied by electrons is your HOMO. The HOMO and LUMO orbitals are the most important orbitals for reactivity.
- Thu Nov 03, 2016 9:17 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration for Fe 3+
- Replies: 5
- Views: 46564
Re: Electron Configuration for Fe 3+
You take electrons out of the 4s orbital, before you take them out of the 3d orbital, because it is lower energy to have them in the 3d orbital in comparison to the 4s.
- Fri Oct 28, 2016 1:30 pm
- Forum: Trends in The Periodic Table
- Topic: Periods 15 and 14 relationship
- Replies: 2
- Views: 682
Re: Periods 15 and 14 relationship
If you draw the electron configuration for each and specifically look at the 2p orbital you will see that Nitrogen has a half-filled p-shell, which is more stable than Carbon which is one away from a half filled p-shell. Carbon wants the electron more than Nitrogen to attain the stability.
- Thu Oct 27, 2016 6:49 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: How to figure out formal charge? [ENDORSED]
- Replies: 6
- Views: 1895
Re: How to figure out formal charge? [ENDORSED]
When calculating formal charge it is easiest just to take the number of valence electrons and subtract the number of bonds (same thing as the number of bonded electrons/2) and subtract the number of lone pair electrons. The resulting number is your formal charge. Do this for each of the atoms of you...
- Fri Oct 21, 2016 6:38 am
- Forum: Student Social/Study Group
- Topic: Hedrick Summit Study Group Chem 14A
- Replies: 29
- Views: 4262
Re: Hedrick Summit Study Group Chem 14A
I would like to join this study group if it is still active!
- Fri Oct 21, 2016 5:57 am
- Forum: Empirical & Molecular Formulas
- Topic: Writing Formulas
- Replies: 6
- Views: 1466
Re: Writing Formulas
To remember polyatomic ions, I have always used this mnemonic: Nick the Camel ate a Clam Supper in Pheonix with Ale. Nick = N for Nitrogen, the word has 3 consonants so there are 3 oxygens, and 1 vowel so a charge of -1. Therefore, Nitrate = NO3-1 Camel = C for Carbon, 3 consonants and 2 vowels, so ...
- Sat Oct 15, 2016 11:07 pm
- Forum: Hybridization
- Topic: Memorization Tricks
- Replies: 9
- Views: 5392
Re: Memorization Tricks
Another good acronym is Kings Hate Dragons Because Dragons Can't Make Money for Kilo, Hecto, Deca, Base, Deci, Centi, Milli, and Micro.
- Wed Oct 12, 2016 10:05 pm
- Forum: Balancing Chemical Reactions
- Topic: Diatomic Molecules
- Replies: 4
- Views: 2377
Re: Diatomic Molecules
The mnemonic device I use for diatomic molecules is HOBr FINCl (pronounced hobber finkle). It has helped me remember that the diatomic elements are Hydrogen, Oxygen, Bromine, Fluorine, Iodine, Nitrogen, and Chlorine. Diatomic elements have to be memorized, so it is a good idea to find memorization s...
- Fri Oct 07, 2016 10:03 pm
- Forum: Empirical & Molecular Formulas
- Topic: empirical formulas [ENDORSED]
- Replies: 1
- Views: 637
Re: empirical formulas [ENDORSED]
The empirical formula gives you the proportions of the elements present in a compound. The empirical formula can be used to calculate the percent composition of a compound. When working out reactions of a compound, its proportions are important to know.
- Wed Oct 05, 2016 12:50 pm
- Forum: *Black Body Radiation
- Topic: Black body [ENDORSED]
- Replies: 3
- Views: 1220
Re: Black body [ENDORSED]
A black body is something that absorbs all of the electromagnetic radiation incident upon it. It is an idealized emitter and absorber of energy. It is good concept to know because it may help you understand how other objects absorb/emit electromagnetic radiation better.
- Thu Sep 29, 2016 3:59 pm
- Forum: Student Social/Study Group
- Topic: Chemistry Joke
- Replies: 13
- Views: 2986
Re: Chemistry Joke
You would think that atoms bonding with other atoms would mean they're being friendly, but really they steal each other's electrons.
How ionic!
How ionic!
- Wed Sep 28, 2016 10:27 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reactant Calculations
- Replies: 1
- Views: 970
Re: Limiting Reactant Calculations
For this problem, I believe you can just ignore the physical conditions since they are not extreme. The only reason 1 atm and 25 degrees C are given in the problem is so the reader knows that the reaction is not put under extreme conditions, such as extremely high temperatures, which could cause H2S...