Search found 36 matches

by Ziyan Peng 3A
Tue Feb 23, 2021 8:03 am
Forum: Student Social/Study Group
Topic: Fave food
Replies: 99
Views: 204

Re: Fave food

I love salt & vinegar goldfish crackers
by Ziyan Peng 3A
Tue Feb 23, 2021 6:15 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: State property
Replies: 19
Views: 45

Re: State property

A state function does not depend on the path taken while properties like work and heat describe the path taken.
by Ziyan Peng 3A
Sun Feb 14, 2021 11:42 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy change involved in phase change of water
Replies: 3
Views: 12

Entropy change involved in phase change of water

In the example that Dr. Lavelle gave at the end of the lecture on Tuesday of Week 6, he mentions as water is melting, H2O(l) occupies more positions and thus have a higher degeneracy and entropy than H2O(s). I am having a harder time to digest - isn't ice less dense than water thus giving it a highe...
by Ziyan Peng 3A
Sun Feb 14, 2021 11:33 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: Degeneracy at maximum
Replies: 2
Views: 18

Re: Degeneracy at maximum

since degeneracy is defined as the number of ways of achieving given energy of the state, as stated in lecture, and the isolated system has the greatest amount of possible states at equilibrium, thus the degeneracy is at maximum. Thinking about the gas expanding in the container which Dr. Lavelle ta...
by Ziyan Peng 3A
Sun Feb 14, 2021 11:24 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Intensive vs. Extensive Property
Replies: 8
Views: 20

Re: Intensive vs. Extensive Property

an intensive property is not related to the amount of matter (e.g. specific heat capacity, which is already adjusted to per unit of mass and temperature, with its unit being kJ ºC g^-1), versus extensive properties which depend on amount of particles (e.g. entropy, and therefore we take into account...
by Ziyan Peng 3A
Sun Feb 14, 2021 11:17 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: qrev
Replies: 22
Views: 91

Re: qrev

qrev stands for heat in reversible processes (which we use for isothermal reversible expansion of ideal gas), as opposed to q in general which can refer to both irreversible and reversible processes
by Ziyan Peng 3A
Sun Feb 14, 2021 11:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs K
Replies: 9
Views: 28

Re: Kc vs K

I echo what everyone and especially what Megan is saying! Kp is always for pressure and Kc for molar, and K is just the general concept of the equilibrium constant
by Ziyan Peng 3A
Sun Feb 14, 2021 11:09 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Which R to use
Replies: 26
Views: 61

Re: Which R to use

one thing that's really helped me is looking at the units! in this case 8.314 :)
by Ziyan Peng 3A
Sun Feb 07, 2021 3:49 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 24
Views: 79

Re: Systems

Isolated system because as far as we know matter and energy in our universe are contained in here.
by Ziyan Peng 3A
Sun Feb 07, 2021 3:42 pm
Forum: Phase Changes & Related Calculations
Topic: Vapor vs gas
Replies: 91
Views: 238

Re: Vapor vs gas

Yes they are the same. Think about how water vapour is just another way of saying H2O(s), or the gas form of water.
by Ziyan Peng 3A
Sun Feb 07, 2021 3:41 pm
Forum: Phase Changes & Related Calculations
Topic: Define Phase Change
Replies: 76
Views: 217

Re: Define Phase Change

A phase change is when the state of the matter (solid/liquid/gas) is changed. For example it could be ice melting, which is from solid to liquid.
by Ziyan Peng 3A
Sun Feb 07, 2021 3:39 pm
Forum: Ideal Gases
Topic: R ideal gas constant
Replies: 25
Views: 62

Re: R ideal gas constant

I agree with what everyone here is saying! Notice how the units for the two units as seen on the equation sheet are different. What R value to use depends on what other units (e.g. for pressure) we are using in the specific question.
by Ziyan Peng 3A
Sun Feb 07, 2021 3:36 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem Community Grade Error
Replies: 15
Views: 102

Re: Chem Community Grade Error

I was wondering about that too but I think it just has not been updated to include your posts from week 5 yet. I'm pretty sure the 22 posts were just tallied from weeks 1-4 and the 25 posts that it is out of are supposed to be done by the end of week 5 :)
by Ziyan Peng 3A
Sun Jan 31, 2021 6:53 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: State Function
Replies: 22
Views: 50

Re: State Function

I echo with what everyone has been saying here that because work typically describes the path taken to to get to a state, it is not a state function (which is the same regardless of the path taken).
by Ziyan Peng 3A
Sun Jan 31, 2021 6:50 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Strong Acids/Bases
Replies: 19
Views: 128

Re: Strong Acids/Bases

This chart attached helped me a lot when I was studying! Hope it helps :)
by Ziyan Peng 3A
Sun Jan 31, 2021 6:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Would an aq agent be included in K?
Replies: 27
Views: 82

Re: Would an aq agent be included in K?

Yea! Think of acid and base reactions we wouldn't get Ka & Kb if we didn't include the aq agents :)
by Ziyan Peng 3A
Sun Jan 31, 2021 6:43 pm
Forum: Student Social/Study Group
Topic: Go treat yourself after MT1!
Replies: 75
Views: 302

Re: Go treat yourself after MT1!

Same as literally everyone here haha I had not been caught up with sleep until after this midterm this week :)) So proud of all of us!
by Ziyan Peng 3A
Sun Jan 31, 2021 6:40 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: How Does Temperature Affect the Equilibrium Constant?
Replies: 25
Views: 76

Re: How Does Temperature Affect the Equilibrium Constant?

Raising temperature makes K higher in endothermic reactions and lower in exothermic reactions.

Think of it in terms of the reaction curves: raising temperature pushes the reaction towards the products, which are higher energy than reactants, in endothermic reactions, and vice versa.
by Ziyan Peng 3A
Sun Jan 31, 2021 6:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Making X negligible
Replies: 34
Views: 97

Re: Making X negligible

first you typically look at if K ≤ 10^-4, and if the question satisfies that you go ahead with neglecting x in the denominator, but you double check afterwards to see if x value < 5% of the initial concentration.
by Ziyan Peng 3A
Sun Jan 31, 2021 6:28 pm
Forum: Student Social/Study Group
Topic: Favorite Music
Replies: 104
Views: 286

Re: Favorite Music

Indie rap and alternative R&B, R&B songs with electronic-esque beats really hit different!! Masego, Kali Uchis, Galimatias, Weston Estate, Savannah Ré, Riz La Vie, and of course Jhené Aiko :)) If you use Apple Music like me I highly recommend the Baseline playlist and Northern Vibes playlist...
by Ziyan Peng 3A
Sun Jan 24, 2021 12:58 pm
Forum: Phase Changes & Related Calculations
Topic: State Property
Replies: 43
Views: 131

Re: State Property

In a simple analogy, when you are trying to get somewhere and the Maps app on your phone tell you it is 2 kilometres away by straight line distance , but when you start navigation and find out that the actual path to go around the blocks adds up to 2.5 kilometres. The straight line distance 2km is l...
by Ziyan Peng 3A
Sun Jan 24, 2021 12:49 pm
Forum: Phase Changes & Related Calculations
Topic: Steam causing severe burns
Replies: 19
Views: 86

Re: Steam causing severe burns

I agree with these responses! Unless you are very determined to hurt yourself, your biological reflexes tell you to pull your hand away from, say a pot of boiling water. With the little amount of vapour whose heat is also partially lost to the air, especially if your hand isn't directly on top of th...
by Ziyan Peng 3A
Sun Jan 24, 2021 12:42 pm
Forum: Student Social/Study Group
Topic: Comfort Movies
Replies: 128
Views: 343

Re: Comfort Movies

not a movie but The Office is the epitome of comfort shows :))
by Ziyan Peng 3A
Sun Jan 24, 2021 12:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE Tables
Replies: 32
Views: 77

Re: ICE Tables

Coefficients! This is because x in and of itself represents some amount of molarity and in the C part of the ICE chart we are trying to quantify the amount of change. These changes should be proportional to the stoichiometry of the reaction, therefore the coefficients before x.
by Ziyan Peng 3A
Sun Jan 24, 2021 12:30 pm
Forum: Phase Changes & Related Calculations
Topic: Endothermic v. Exothermic
Replies: 103
Views: 311

Re: Endothermic v. Exothermic

Yes. You can also make sense of this by thinking about enthalpy being a state property. As long as the amount of heat is greater than the system began with, it is definitely endothermic, and vice versa for exothermic reactions.
by Ziyan Peng 3A
Sun Jan 17, 2021 7:42 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: midterms [ENDORSED]
Replies: 10
Views: 335

Re: midterms [ENDORSED]

Chem_Mod wrote:No class that day due to midterm. :-)


Hello :) Are there any accommodations in place for international students for the midterm like there is for the final? Thanks in advance!
by Ziyan Peng 3A
Fri Jan 15, 2021 9:07 am
Forum: Student Social/Study Group
Topic: Exam Changes
Replies: 12
Views: 78

Re: Exam Changes

Does anyone know if there is any sort of accommodations for students located in very different time zones? I am 16 hours ahead of LA time and having the exam during lecture time does not seem very friendly with my schedule :(
by Ziyan Peng 3A
Fri Jan 15, 2021 9:00 am
Forum: General Science Questions
Topic: Calculating Ka from pKa
Replies: 7
Views: 54

Re: Calculating Ka from pKa

Ka=10^(-pKa), just like how [H3O+]=10^(-pH) and how [OH-]=10^(-pOH). I find grouping these together easier to remember, especially if you don't want to run the math through your head every time like me :)
by Ziyan Peng 3A
Fri Jan 15, 2021 8:57 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8753
Views: 1489542

Re: Post All Chemistry Jokes Here

Chemistry puts the cation in education.
by Ziyan Peng 3A
Fri Jan 15, 2021 8:43 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pKA and pH
Replies: 8
Views: 67

Re: pKA and pH

I was a little confused in the beginning as well but thinking about the equations really helped me differentiate between the two concepts: pKa is equal to the product concentrations (which includes H3O+) multiplied together over reactant concentration, but pH is just the negative log of H3O+ concent...
by Ziyan Peng 3A
Fri Jan 15, 2021 8:38 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKA, pKB, KA, KB
Replies: 7
Views: 52

Re: pKA, pKB, KA, KB

I agree and a stronger Kb would translate into higher product concentrations in the basicity constant equation, meaning that the equilibrium lies to the right (more dissociation), indicating that it would bee a stronger base. Since pKb is the negative log of Kb (thus Kb=10^(-pKb), this would mean th...
by Ziyan Peng 3A
Fri Jan 08, 2021 10:16 am
Forum: Administrative Questions and Class Announcements
Topic: Chemistry Posts in 14B
Replies: 153
Views: 2283

Re: Chemistry Posts in 14B

Akemi Karamitsos 1E wrote:What is the last day in the week to get in our 5 posts? Is there a set "due date"?


I'm assuming that it's by midnight Sunday like the Sapling assignments but someone please correct me if it's not :)
by Ziyan Peng 3A
Fri Jan 08, 2021 10:13 am
Forum: Student Social/Study Group
Topic: Study Habits
Replies: 96
Views: 321

Re: Study Habits

I think it would be helpful to go to the UA sessions earlier because I really only went for the review sessions and I think if I had gone earlier there would have been less stress when it came time for the final Hi! What do we usually do at the UA sessions? I have not taken them with Dr. Lavelle an...
by Ziyan Peng 3A
Fri Jan 08, 2021 10:06 am
Forum: Student Social/Study Group
Topic: Topics we need to know from chem 14a for chem 14b
Replies: 6
Views: 41

Re: Topics we need to know from chem 14a for chem 14b

^^! Adding on to that I remember Dr. Lavelle mentioning in the first lecture that he will briefly go over the fundamentals of any new topic that he talks about. I wouldn't worry too much about spending a ton of time reviewing chem 14a material especially if you feel like you digested the content wel...
by Ziyan Peng 3A
Fri Jan 08, 2021 10:00 am
Forum: Administrative Questions and Class Announcements
Topic: Accessing the E-textbook [ENDORSED]
Replies: 107
Views: 7267

Re: Accessing the E-textbook [ENDORSED]

Hi! Does anyone know when Dr. Lavelle says the Sapling assignments are due midnight Sunday of the week is he referring to Sunday as the first day of the week? Like is the Week 1 Assignment due on 11:59pm on Jan 10th or 17th? Thanks in advance :)
by Ziyan Peng 3A
Fri Jan 08, 2021 9:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Favoring
Replies: 6
Views: 72

Re: Favoring

Hi! I thought that this infographic I found was quite clear in explaining this. Hope this is of help to you :)

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