Search found 51 matches

by ELu 1J
Mon Mar 16, 2020 4:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Voltaic Cells
Replies: 3
Views: 91

Re: Voltaic Cells

Yes, they are the same thing. Both are different from concentration cells.
by ELu 1J
Sat Mar 14, 2020 10:09 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Lyndon Review: 1D
Replies: 5
Views: 140

Re: Lyndon Review: 1D

I believe the Ecell doesn't change. Wasn't there a similar problem on test#2? I wasn't able to get my test back so someone please correct me if I'm wrong.
by ELu 1J
Sat Mar 14, 2020 10:08 am
Forum: Administrative Questions and Class Announcements
Topic: Thanks From the UA’s!
Replies: 5
Views: 285

Re: Thanks From the UA’s!

Awww! This is so sweet <3 Thank you for all that you guys do
by ELu 1J
Thu Mar 12, 2020 9:12 am
Forum: *Enzyme Kinetics
Topic: How to distinguish the intermediates and catalysts?
Replies: 8
Views: 120

Re: How to distinguish the intermediates and catalysts?

You'll find that intermediates are the product of the first reaction step and then the reactant of the second reaction step - that is why it's called an intermediate because it ties the two steps together for the overall reaction. For a catalyst, it appears as a reactant and is not consumed in the r...
by ELu 1J
Thu Mar 12, 2020 9:10 am
Forum: Administrative Questions and Class Announcements
Topic: FinalReview Sessions
Replies: 3
Views: 152

Re: FinalReview Sessions

I believe their worksheet is under "Endgame". I don't think they've posted the answer key yet though.
by ELu 1J
Tue Mar 10, 2020 4:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Take Home Final?
Replies: 2
Views: 152

Take Home Final?

Due to Emily Carter's new email about UCLA switching to online classes, will our final be a take home final or do we still need to be present on campus on Sunday to take the Chem 14B final? I just wanted to confirm. Thanks!!
by ELu 1J
Mon Mar 09, 2020 10:50 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: How to determine slow step?
Replies: 9
Views: 119

How to determine slow step?

How do you know if a step is slow or fast in a reaction mechanism?
by ELu 1J
Tue Mar 03, 2020 4:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidizing Power
Replies: 3
Views: 63

Re: Oxidizing Power

If something has oxidizing power, it itself is being reduced. If something has HIGH oxidizing power, the potential for itself to be reduced is also HIGH. Therefore, it's standard reduction potential is high.
by ELu 1J
Tue Mar 03, 2020 4:28 pm
Forum: First Order Reactions
Topic: 1st, 2nd, and 0 Order Reactions
Replies: 2
Views: 68

Re: 1st, 2nd, and 0 Order Reactions

The difference between the three reactions is essentially the varying number of molecules needed to collide and react with each other for the reaction to proceed. You can calculate whether a reaction is 1st, 2nd, or 0th order by determining the orders of the individual reactants themselves, which ca...
by ELu 1J
Tue Mar 03, 2020 4:25 pm
Forum: Balancing Redox Reactions
Topic: Number of Electrons Being Transferred
Replies: 5
Views: 81

Re: Number of Electrons Being Transferred

If a substance is going from Fe3+ to Fe2+, you know it gained 1 electron because the charge/oxidation # went up by 1. Then you balance the two half reactions to make sure both transfer the same amount of electrons.
by ELu 1J
Tue Mar 03, 2020 4:23 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Reducing Power
Replies: 3
Views: 84

Re: Reducing Power

Reducing power is like the ability to give away electrons. A stronger reducing agent with stronger reducing power is more likely to give an electron to another compound.
by ELu 1J
Wed Feb 26, 2020 4:28 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potential
Replies: 3
Views: 46

Re: Standard Cell Potential

Standard electric potential is the electric potential of a galvanic cell measured under standard conditions. How to calculate: E(cell) = E(cathode) - E(anode). You can get E(cathode) and E(anode) from the half reactions that happen at the cathode and anode.
by ELu 1J
Wed Feb 26, 2020 4:24 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8196
Views: 1429877

Re: Post All Chemistry Jokes Here

Are you made up of 12 protons? Because you're sodium fine
by ELu 1J
Mon Feb 24, 2020 5:30 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Electrolytic Cells
Replies: 3
Views: 51

Re: Electrolytic Cells

I believe because of the positive electric potential and also the salt bridge.
by ELu 1J
Mon Feb 24, 2020 5:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework Problems from Outline 5 or 6 this week?
Replies: 2
Views: 145

Homework Problems from Outline 5 or 6 this week?

For this week, since Dr. Lavelle just finished going over electrochemistry today, do we complete homework problems from outline #5 or outline #6? Thanks!
by ELu 1J
Sat Feb 22, 2020 5:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Curve?
Replies: 5
Views: 71

Curve?

I was just wondering if Dr. Lavelle has curved exams in the past or just giving the class an additional 10 points at the end of the quarter? Does anyone know his pattern of curving? Thanks :)
by ELu 1J
Sat Feb 22, 2020 5:14 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8196
Views: 1429877

Re: Post All Chemistry Jokes Here

Instead of "LOL", Helium atoms text "HeHe" instead :)
by ELu 1J
Sat Feb 22, 2020 5:13 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8196
Views: 1429877

Re: Post All Chemistry Jokes Here

Atom A said, "I lost an electron"
Atom B asked, "Are you sure?"
Atom A said "Yeah, I'm positive"
Atom B said, "Well, you better keep an ion (eye on) them"
by ELu 1J
Sat Feb 22, 2020 5:12 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8196
Views: 1429877

Re: Post All Chemistry Jokes Here

A man was frozen to absolute zero. But don't worry - he's 0K now :D
by ELu 1J
Tue Feb 18, 2020 10:06 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Study Advice
Replies: 73
Views: 3948

Re: Study Advice

Lyndron Bui and Michael Zalgari's sessions are helpful!
by ELu 1J
Tue Feb 18, 2020 10:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Grade [ENDORSED]
Replies: 1
Views: 133

Midterm Grade [ENDORSED]

Dr. Lavelle said midterm grades would be coming out today (Tuesday, 2/18). Does anyone see their grade on myUCLA yet or is it posted somewhere else? Thanks!
by ELu 1J
Mon Feb 10, 2020 9:49 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Change due to Changes in Temperature
Replies: 2
Views: 40

Entropy Change due to Changes in Temperature

For the ratio fo T2/T1 in the ln for the entropy change equation, do they always have to be in kelvin or can the ratio be in celsius as well? I noticed a discrepancy in this. Thanks!
by ELu 1J
Mon Feb 10, 2020 9:47 pm
Forum: Administrative Questions and Class Announcements
Topic: Correct Calculator for Midterm
Replies: 2
Views: 144

Correct Calculator for Midterm

I just wanted to double check that a TI-30XIIS calculator is okay for the midterm? It isn't able to graph or record information. Thanks!
by ELu 1J
Mon Feb 10, 2020 9:46 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Free energy
Replies: 6
Views: 128

Re: Free energy

Standard free energy is measured in a lab under standard conditions (usually is denoted with a degree symbol). Delta G can be measured in a situation that isn't in standard conditions like in a biological system. So would we need to know anything more than just the sources of error/ comparison betw...
by ELu 1J
Sat Feb 08, 2020 8:53 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 67
Views: 2913

Re: Pizza Rolls REVIEW Session DOWNLOAD HERE

Is the Sunday review session only for going over the practice questions and then the one on Monday is content-based review?
by ELu 1J
Sat Feb 08, 2020 3:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
Replies: 67
Views: 2913

Re: Pizza Rolls REVIEW Session

Are you only going over the answers at the Sunday review session or the Monday one as well? Thank you so much :)))
by ELu 1J
Thu Feb 06, 2020 9:07 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Keeping equations straight
Replies: 2
Views: 35

Re: Keeping equations straight

I like to take a blank piece of printer paper and write down equations based on category. Also, for internal energy = heat + work, it's helpful for me to work out when there is constant volume, delta V = 0 and thus there is no work done so internal energy = work instead of simply memorizing internal...
by ELu 1J
Thu Feb 06, 2020 9:05 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: chen discussion [ENDORSED]
Replies: 5
Views: 101

Re: chen discussion [ENDORSED]

Diana_Diep2I wrote:When do we use C and when do we use R?

C = 3/2R at constant volume and C = 5/2R at constant pressure.
by ELu 1J
Thu Feb 06, 2020 9:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: reversible vs irreversible work
Replies: 4
Views: 59

Re: reversible vs irreversible work

A reversible system is usually one where the reactants and products fluctuate slowly to reach equilibrium.
by ELu 1J
Thu Feb 06, 2020 9:02 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Free energy
Replies: 6
Views: 128

Re: Free energy

Standard free energy is measured in a lab under standard conditions (usually is denoted with a degree symbol). Delta G can be measured in a situation that isn't in standard conditions like in a biological system.
by ELu 1J
Sun Feb 02, 2020 2:01 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: degeneracy
Replies: 3
Views: 55

Re: degeneracy

The equation to calculate degeneracy is W = x^n where x = # of states (in this case is 2) and n = # of particles (in this case is 3). Therefore, w = 2^3 = 8.
by ELu 1J
Sun Feb 02, 2020 12:58 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 5 Homework
Replies: 7
Views: 100

Week 5 Homework

For Week 5's homework, do we do problems from outline #4 again?
by ELu 1J
Thu Jan 30, 2020 9:49 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Material
Replies: 13
Views: 150

Midterm Material

What material is going to be covered for the midterm? Are there usually review sessions beforehand that are taught by Dr. Lavelle or the TAs?
by ELu 1J
Wed Jan 29, 2020 1:33 pm
Forum: General Science Questions
Topic: Sig Figs
Replies: 3
Views: 196

Sig Figs

When you have conversion factors in your calculations, do you also take the sig figs of those numbers into account? For example, 1L = 1000mL, would you take the sig figs into account when calculating the rest of the problem? Thanks!
by ELu 1J
Sun Jan 26, 2020 9:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Week 4 Homework
Replies: 11
Views: 117

Re: Week 4 Homework

Just wanted to comment so I can follow this post :)
by ELu 1J
Thu Jan 23, 2020 10:59 pm
Forum: Phase Changes & Related Calculations
Topic: Celsius and Kelvin
Replies: 11
Views: 86

Re: Celsius and Kelvin

You always have to convert between kelvins and celsius. It's better to do K = 273.15 + C because it is more exact.
by ELu 1J
Thu Jan 23, 2020 10:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Best Way To Study?
Replies: 13
Views: 153

Re: Best Way To Study?

Thank you all for so many helpful suggestions! I will definitely start looking into going to the UA sessions because I forgot those existed :)
by ELu 1J
Wed Jan 22, 2020 9:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 8
Views: 85

Re: Autoprotolysis

Daria Azizad 1K wrote:
ELu 1J wrote:It occurs naturally and emphasizes the amphoteric nature of water (the ability to both give and accept a proton).

The ability to accept and donate a proton is amphiprotic, while amphoteric is the ability to react with both acids and bases. :)


Oh my bad - thank you for the correction :)
by ELu 1J
Wed Jan 22, 2020 9:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Best Way To Study?
Replies: 13
Views: 153

Best Way To Study?

Hi, here's a question for those who have had Lavelle previously: what method of studying for exams did you find most effective? Doing all of the assigned textbook problems or sapling problems or other things? Thanks for sharing :)
by ELu 1J
Tue Jan 14, 2020 8:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium concentration with gases
Replies: 7
Views: 77

Re: equilibrium concentration with gases

Yes, because the context of the problem is moles, that is what leads you to calculate Kc instead of Kp even though all substances are in gas phase.
by ELu 1J
Tue Jan 14, 2020 8:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Are Lectures Bruincasted?
Replies: 10
Views: 156

Re: Are Lectures Bruincasted?

Where can you view modules?
by ELu 1J
Tue Jan 14, 2020 8:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Hw 5J.11
Replies: 2
Views: 32

Re: Hw 5J.11

I think you just have to memorize that if delta H is negative, the reaction is exothermic and if delta H is positive, the reaction is endothermic.
by ELu 1J
Tue Jan 14, 2020 8:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endothermic and exothermic reactions
Replies: 11
Views: 664

Re: Endothermic and exothermic reactions

I've heard someone explain it like this before: think of heat as either another reactant or product. If the reaction is endothermic, the system absorbs heat and heat is considered a reactant. Say you heat up the system, you're adding heat (a "reactant"), which means the reaction will favor...
by ELu 1J
Tue Jan 14, 2020 8:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis
Replies: 8
Views: 85

Re: Autoprotolysis

It occurs naturally and emphasizes the amphoteric nature of water (the ability to both give and accept a proton).
by ELu 1J
Mon Jan 13, 2020 4:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Are Lectures Bruincasted?
Replies: 10
Views: 156

Are Lectures Bruincasted?

I was wondering if Dr. Lavelle's lectures are bruincasted and if so, where may I find them? Thanks!
by ELu 1J
Sun Jan 12, 2020 1:36 pm
Forum: Administrative Questions and Class Announcements
Topic: General HW question
Replies: 9
Views: 103

Re: General HW question

I thought it was graded based on the correctness of our 5 problems we turned in.
by ELu 1J
Sun Jan 12, 2020 1:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 1 date
Replies: 4
Views: 51

Re: Test 1 date

It's during your discussion during week 3 (1/20-1/24).
by ELu 1J
Sat Jan 11, 2020 2:48 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changes in Pressure
Replies: 3
Views: 75

Re: Changes in Pressure

I think he was talking about how if the pressure is increased for a particular reaction, it isn't an adequate explanation to say that it will cause a shift to the right because there are more moles of reactants than products. Instead, the correct explanation would be that an increase in pressure wou...
by ELu 1J
Wed Jan 08, 2020 9:16 pm
Forum: Ideal Gases
Topic: PV=nRT equation manipulation
Replies: 13
Views: 232

Re: PV=nRT equation manipulation

I think the purpose is just based on the context of the problem. The problem could give the initial concentration of a gas but then ask you to find the partial pressure at equilibrium or something that requires you to be able to convert one to another when the substance is a gas.
by ELu 1J
Wed Jan 08, 2020 9:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 5G.1b
Replies: 1
Views: 34

Problem 5G.1b

5G.1 State whether the following statements are true or false. If false, explain why. (b) An equilibrium reaction is not affected by increasing the concentrations of products. I just wanted to clarify that the statement is saying that the concentration of the products is increased AFTER the reaction...

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