Search found 76 matches
- Mon Feb 10, 2020 2:09 pm
- Forum: Student Social/Study Group
- Topic: Midterm Topics
- Replies: 12
- Views: 663
Re: Midterm Topics
Up to the first page of Outline 4: Thermodynamics.
- Mon Feb 10, 2020 2:06 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U
- Replies: 7
- Views: 386
Re: Delta U
Delta U=0 for Isothermal compression or expansion (at constant temperature).
- Mon Feb 10, 2020 1:59 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: H and Q
- Replies: 4
- Views: 328
Re: H and Q
At constant pressure w=-p delta V. Since delta H=delta U + p delta V=q+w+delta V=q+(-p delta V)+p delta V. So delta H=q.
- Mon Feb 10, 2020 1:52 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Spontaneous vs Favorable
- Replies: 8
- Views: 394
Re: Spontaneous vs Favorable
I think they have the same meaning and when a reaction is spontaneous it is favorable; and when a reaction is favorable it should occur spontaneously.
- Mon Feb 10, 2020 1:48 pm
- Forum: Student Social/Study Group
- Topic: Test 1 Solution
- Replies: 6
- Views: 504
Re: Test 1 Solution
Thank you!! I will ask TAs for help!
- Mon Feb 03, 2020 1:34 am
- Forum: Calculating Work of Expansion
- Topic: Reversible process
- Replies: 2
- Views: 189
Re: Reversible process
Because work is defined as the energy transferred from one type to another whenever a force is applied causing an object to move a distance.Work would be the area under the graph on a force-displacement graph.
- Mon Feb 03, 2020 1:27 am
- Forum: Calculating Work of Expansion
- Topic: Midterm Question Involving Integrals
- Replies: 3
- Views: 233
Re: Midterm Question Involving Integrals
Have the same questions!
- Mon Feb 03, 2020 1:21 am
- Forum: Student Social/Study Group
- Topic: Test 1 Solution
- Replies: 6
- Views: 504
Test 1 Solution
Was the answer key for test 1 posted? Will it be posted before the midterm? I didn’t do well and really need to review it for the midterm.
- Mon Feb 03, 2020 1:18 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: qp = ΔH?
- Replies: 5
- Views: 310
Re: qp = ΔH?
At constant pressure
- Mon Feb 03, 2020 1:16 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Energy of a system
- Replies: 5
- Views: 332
Re: Energy of a system
If Delta H is negative, the reaction is exothermic, heat released; if Delta H is positive, the reaction is endothermic, heat absorbed.
- Mon Feb 03, 2020 1:12 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 7
- Views: 458
Re: Hess's Law
Ex: Delta H for CS2(l) + 3 O2(g) → CO2(g) + 2 SO2(g)? Given: C(s) + O2(g) → CO2(g); ΔHf = -393.5 kJ/mol S(s) + O2(g) → SO2(g); ΔHf = -296.8 kJ/mol C(s) + 2 S(s) → CS2(l); ΔHf = 87.9 kJ/mol Solve: C(s) + O2(g) → CO2(g), ΔHf = -393.5 kJ/mol 2 S(s) + 2 O2(g) → 2 SO2(g), ΔHf = 2(-326.8 kJ/mol) CS2(l) → ...
- Wed Jan 29, 2020 12:21 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible vs irreversible
- Replies: 6
- Views: 919
Re: Reversible vs irreversible
In irreversible reactions, the reactants convert to products and the products cannot convert back to the reactants. An example of an irreversible reaction is combustion. In reversible reactions, the forward and reverse reactions occur simultaneously.
- Wed Jan 29, 2020 12:15 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Useful Summary of Thermodynamic Definitions
- Replies: 55
- Views: 18254
Re: Useful Summary of Thermodynamic Definitions
Thank you for the definitions! So helpful!
- Tue Jan 28, 2020 10:50 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: System vs Surroundings
- Replies: 14
- Views: 1993
Re: System vs Surroundings
“The system is the part of the universe we wish to focus our attention on. In the world of chemistry, the system is the chemical reaction. For example: 2H2 + O2 ---> 2H2O The system consists of those molecules which are reacting. The surroundings are everything else; the rest of the universe. For ex...
- Tue Jan 28, 2020 10:46 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Order of homework for Thermochem unit
- Replies: 6
- Views: 292
Re: Order of homework for Thermochem unit
I think you could either skip the sections and do what we covered in lectures or read through the textbook and do the problems that we haven’t covered beforehand since all materials on the learning objectives will be on the midterms.
- Mon Jan 20, 2020 7:41 pm
- Forum: Student Social/Study Group
- Topic: Curve?
- Replies: 50
- Views: 5813
Re: Curve?
I think it depends on the class average at the end of the quarter.
- Mon Jan 20, 2020 7:38 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Effect of Increasing Temperature on an Equilibrium System
- Replies: 4
- Views: 368
Re: Effect of Increasing Temperature on an Equilibrium System
Thank you for asking and thank you for the explanations!
- Mon Jan 20, 2020 7:34 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Inert Gas
- Replies: 9
- Views: 511
Re: Adding Inert Gas
If the pressure of the reaction increased by adding inert gas(noble gas) there will be no effect on P&R concentration and no effect on the reaction.
- Mon Jan 20, 2020 7:22 pm
- Forum: Student Social/Study Group
- Topic: Test 1
- Replies: 9
- Views: 528
Re: Test 1
There isn’t any past exam questions for practicing unfortunately but the homework problems should definitely help.
- Mon Jan 20, 2020 7:15 pm
- Forum: Ideal Gases
- Topic: homework #3
- Replies: 16
- Views: 777
Re: homework #3
I think either “acid and base equilibria” or the topic that we are going to cover in Wednesday’s lecture should be fine.
- Mon Jan 20, 2020 7:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH Examples
- Replies: 3
- Views: 264
Re: pH Examples
I would recommend to at least get familiar with most of them.
- Mon Jan 20, 2020 7:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE table and X
- Replies: 6
- Views: 265
Re: ICE table and X
You can approximate when K is less than 10^-3.
- Mon Jan 20, 2020 7:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Converting K to Kc
- Replies: 4
- Views: 252
Re: Converting K to Kc
K can be Kc (for concentration) or Kp (dealing with gas given the partial pressure). PV=nRT can be used to convert between Kc and Kp.
- Mon Jan 20, 2020 7:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pKa of conjugate acid relating to strength of base
- Replies: 2
- Views: 198
Re: pKa of conjugate acid relating to strength of base
We need pka to solve for pkb, and then we can rank the bases in order of strength. The larger the pka value : the smaller the pkb, the weaker the acid, and the stronger the conjugate base. Therefore ethylamine is the strongest base.
- Mon Jan 20, 2020 6:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Van’t Hoff Equation
- Replies: 4
- Views: 188
Re: Van’t Hoff Equation
I do not think we went over this concept in class so probably no need to worry about it.
- Mon Jan 20, 2020 6:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE tables
- Replies: 5
- Views: 150
Re: ICE tables
It is normally used to calculate the equilibrium constant K of a reaction. Or when K is given, it can be used to calculate one or more of the concentrations in the table that are unknown.
- Sun Dec 08, 2019 12:17 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration
- Replies: 8
- Views: 694
Re: Electron Configuration
You should put 3d before 4s since when 3d is filled it has lower energy than 4s.
- Sat Dec 07, 2019 11:31 pm
- Forum: Student Social/Study Group
- Topic: Equilibrium
- Replies: 3
- Views: 126
Equilibrium
Last minute questions....How much do we need to know about the equilibrium for the upcoming final? :( I am so stressed out...
- Sat Dec 07, 2019 11:27 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: pH sig figs
- Replies: 11
- Views: 598
Re: pH sig figs
Yes for PH sic figs count after the decimal
- Sat Dec 07, 2019 11:16 pm
- Forum: Student Social/Study Group
- Topic: Studying for Final
- Replies: 7
- Views: 662
Re: Studying for Final
Anyone know where to find any past exam questions for practicing? Really need to work on some actual problems!
- Sat Dec 07, 2019 2:00 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Ka Kb on the Final
- Replies: 2
- Views: 106
Ka Kb on the Final
Just want to make sure... How much do we need to know about Ka, Kb, pKa and pKb for the upcoming final? Do we need to know how to calculate them? My TA mentioned in the section that we do not need to worry too much about them for this class since they will appear again in 14B...but they are on the s...
- Sun Dec 01, 2019 10:23 pm
- Forum: Lewis Acids & Bases
- Topic: Weak vs. Strong
- Replies: 8
- Views: 670
Re: Weak vs. Strong
Weak acids will have a higher pH value(lower concentration of hydrogen ions) than strong acids At the same concentration.
- Sun Dec 01, 2019 10:16 pm
- Forum: Lewis Acids & Bases
- Topic: Donating Proton vs Accepting Electron
- Replies: 4
- Views: 261
Re: Donating Proton vs Accepting Electron
They both talk about the same thing just with two different concepts, one based one proton and on based on electron. As an acid donates a proton, it can be also viewed as accepting an electron.
- Sun Dec 01, 2019 10:01 pm
- Forum: Lewis Acids & Bases
- Topic: Relative acidity
- Replies: 4
- Views: 267
Re: Relative acidity
Strong acids are fully ionised but weak acids are only partly ionised in solution. At the same concentration, weak acids have a higher pH value(lower concentration of hydrogen ions) than strong acids.
- Sun Dec 01, 2019 9:58 pm
- Forum: Lewis Acids & Bases
- Topic: Final
- Replies: 4
- Views: 295
Re: Final
I have the same question. I assume there will be more questions on week 6-10 materials but not sure.
- Sun Nov 24, 2019 7:22 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Shape
- Replies: 31
- Views: 2751
Re: Bent Shape
One or two I believe
- Sun Nov 24, 2019 7:13 pm
- Forum: Hybridization
- Topic: dsp3 vs sp3d
- Replies: 4
- Views: 286
Re: dsp3 vs sp3d
I think they are the same. Just depends on personal preferences.
- Sun Nov 24, 2019 7:08 pm
- Forum: Hybridization
- Topic: stability in hybridization
- Replies: 4
- Views: 270
Re: stability in hybridization
The sp2 bond would actually be more stable~
- Sun Nov 24, 2019 7:04 pm
- Forum: Hybridization
- Topic: Sigma and Pi bonds
- Replies: 13
- Views: 620
Re: Sigma and Pi bonds
I think you can just label the bonds with their names and draw them normally.
- Sun Nov 24, 2019 6:51 pm
- Forum: Hybridization
- Topic: Lone pairs
- Replies: 9
- Views: 533
Re: Lone pairs
I think since they will affect the shape of the molecules, they will also contribute in hybridization.
- Sun Nov 24, 2019 6:48 pm
- Forum: Hybridization
- Topic: d-orbitals
- Replies: 7
- Views: 605
Re: d-orbitals
Yes, they do. There are five d orbitals, referred to as dz2, dxy, dxz, dyz , and dx2-y2. The d orbitals are what give transition metals their special properties.
- Sun Nov 17, 2019 11:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Resonance and VSEPR
- Replies: 9
- Views: 526
Re: Resonance and VSEPR
No. I don’t think resonance would have any effect on VESPR.
- Sun Nov 17, 2019 11:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion Strength
- Replies: 5
- Views: 367
Re: Repulsion Strength
It depends on the distance between them. Since lone pairs are the closest to each other, they have the greatest repulsion strength.
- Sun Nov 17, 2019 11:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing molecules
- Replies: 12
- Views: 642
Re: Drawing molecules
I don not think that we will be ask to draw the 3D models but we should definitely know their shapes, names, and angles between the bonds in each structure.
- Sun Nov 17, 2019 11:30 pm
- Forum: Hybridization
- Topic: Pi and Sigma Bonds
- Replies: 17
- Views: 1173
Re: Pi and Sigma Bonds
One sigma bond for single, double, triple bond. One pi bond for double bond, and two pi bonds for triple bonds.
- Sun Nov 17, 2019 11:26 pm
- Forum: Hybridization
- Topic: test 2
- Replies: 8
- Views: 442
Re: test 2
According to our TA, Hybridization will not be on test 2. But the structures, shape, angles, and pi vs sigma bonds....will be on there.
- Mon Nov 11, 2019 8:40 am
- Forum: Hybridization
- Topic: Noble Configuration vs. Full
- Replies: 7
- Views: 304
Re: Noble Configuration vs. Full
I believe it should say in the question which one to use. If not specified, either way should be fine.
- Mon Nov 11, 2019 8:34 am
- Forum: Hybridization
- Topic: Determining how many electron densities
- Replies: 5
- Views: 567
Re: Determining how many electron densities
Yes! Lone pairs do count toward the number of electron densities! The F atom should have four regions of electron density.
- Mon Nov 11, 2019 8:28 am
- Forum: Hybridization
- Topic: dsp3 vs. sp3d
- Replies: 3
- Views: 543
- Mon Nov 11, 2019 8:26 am
- Forum: Hybridization
- Topic: The D Orbital
- Replies: 4
- Views: 596
Re: The D Orbital
KatherineValdez_4B wrote:so when you reach a d-orbital does it go before or after the previous s-orbital?
I believe both dsp3 or sp3d are okay but sp3d is preferred?
Here is the answer:
viewtopic.php?t=1256
- Mon Nov 11, 2019 8:10 am
- Forum: Hybridization
- Topic: Hybrid Orbitals
- Replies: 6
- Views: 655
Re: Hybrid Orbitals
Only the orbitals need to be included so the answer should be sp sp2 sp3...
- Sun Nov 03, 2019 7:41 pm
- Forum: Dipole Moments
- Topic: Induced Dipole
- Replies: 5
- Views: 201
Re: Induced Dipole
In induced dipole, or London force, the dipole is created by the movement of electrons, causing a temporary dipole because one end is more negative than the other.
- Sun Nov 03, 2019 7:26 pm
- Forum: Ionic & Covalent Bonds
- Topic: coulomb potential energy and Madelung constant, as well as lattice energy
- Replies: 4
- Views: 457
Re: coulomb potential energy and Madelung constant, as well as lattice energy
I hope these will not be on the test or I would definitely fail.:(
- Sun Nov 03, 2019 7:24 pm
- Forum: Ionic & Covalent Bonds
- Topic: Strength and Length
- Replies: 18
- Views: 799
Re: Strength and Length
Longer bonds are easier to break. Shorter bonds are stronger since the attractions between the elements are stronger. Single bond is longer than double bond, and double bond is longer than triple bond. Therefore, single bond is weaker than double bond, and double bond is weaker than triple bond.
- Sun Nov 03, 2019 7:18 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic vs Covalent
- Replies: 14
- Views: 810
Re: Ionic vs Covalent
ionic bond is usually between a metal and a nonmetal. Elements in ionic bonds donate and accept electrons (become ions) while in covalent bonds they share electrons.
- Sun Nov 03, 2019 7:17 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic and Covalent
- Replies: 5
- Views: 215
Re: Ionic and Covalent
Elements in ionic bond donate and accept electrons while elements in covalent bond share electrons. The difference in electronegativity is also higher for ionic bond. Ionic bond is usually between a metal and a nonmetal.
- Mon Oct 28, 2019 9:06 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Octet Rules
- Replies: 8
- Views: 482
Re: Octet Rules
It just means that most elements prefer to have 8 valence electrons in order to stay stable. But many can have more or less than 8 especially when they bond to other elements.
- Mon Oct 28, 2019 9:01 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Useful YouTube videos?
- Replies: 6
- Views: 232
Re: Useful YouTube videos?
Thanks for asking!! I found this helpful as well!
- Mon Oct 28, 2019 9:00 pm
- Forum: Properties of Light
- Topic: Constant for Speed of Light
- Replies: 14
- Views: 531
Re: Constant for Speed of Light
2.998*10^8 m/s is definitely more accurate, but 3.0*10^8 m/s is also not wrong for sure. If we can use a calculator then using the more accurate one is definitely more recommend.
- Mon Oct 28, 2019 8:54 pm
- Forum: Properties of Light
- Topic: Midterm formulas
- Replies: 6
- Views: 432
Re: Midterm formulas
Yes, I believe we will get formula sheet and periodic table just like we had for the test.
- Fri Oct 25, 2019 2:09 am
- Forum: Administrative Questions and Class Announcements
- Topic: Homework week 4
- Replies: 4
- Views: 227
Re: Homework week 4
Since we haven’t really covered anything about chemical bonding in class, I believe that we should still do hw from the quantum world this week.
- Fri Oct 18, 2019 2:34 am
- Forum: *Shrodinger Equation
- Topic: Nodal Planes
- Replies: 6
- Views: 322
Re: Nodal Planes
N,L,M L determines shape/angular momentum
N=1, L=0 s
N=2, L=0 s, 1 p
N=3, L=0 s, 1 p, 2 d
N=4, L=0 s, 1 p, 2 d, 3 f
N=1, L=0 s
N=2, L=0 s, 1 p
N=3, L=0 s, 1 p, 2 d
N=4, L=0 s, 1 p, 2 d, 3 f
- Fri Oct 18, 2019 2:26 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Drawing Orbitals
- Replies: 5
- Views: 241
Re: Drawing Orbitals
You do not need to know how to draw! Although it might be really helpful if you can picture the orbitals in your head.
- Fri Oct 18, 2019 2:24 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Advice for studying
- Replies: 92
- Views: 6226
Re: Advice for studying
Step Up session is definitely recommended! For me I think it is easier to just go and listen than read through the textbook~
- Fri Oct 18, 2019 2:21 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Spin State
- Replies: 17
- Views: 336
Re: Spin State
There's no universal notion of "up" or "down", they just represent the two directions. +/- is just for you to distinguish the difference between the two paired electrons. I believe it does not really matter which is which.
- Fri Oct 18, 2019 2:09 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: G orbital
- Replies: 6
- Views: 387
Re: G orbital
It is possible that n can be larger and so that g orbital could exist, but since the electrons are so far away from the nucleus, the elements will be extremely unstable and will probably not exist under normal conditions. I don’t think we need to know that for the this class since it’s not even on t...
- Mon Oct 14, 2019 12:11 am
- Forum: Administrative Questions and Class Announcements
- Topic: How to find my posts
- Replies: 163
- Views: 159015
Re: How to find my posts
Anybody knows whether Prof will post his lecture PowerPoint online or not? Where can I find it? I really need them for revising my notes! Thx
- Sun Oct 13, 2019 11:50 pm
- Forum: *Particle in a Box
- Topic: Particle in A box
- Replies: 8
- Views: 865
Re: Particle in A box
Yeah I don’t think we need to know it for the text but it was really helpful at least for me to understand the concepts in this chapter.
- Tue Oct 08, 2019 11:37 am
- Forum: Properties of Light
- Topic: Posts Per Week
- Replies: 6
- Views: 199
Re: Posts Per Week
Our TA said in the discussion that you can post/reply from Monday to Sunday to get the points for the week.
- Tue Oct 08, 2019 11:33 am
- Forum: Properties of Light
- Topic: Light intensity
- Replies: 10
- Views: 355
Re: Light intensity
I think intensity is effected by amplitude. Higher amplitude will result in higher intensity which will cause the light to be brighter. But Plz correct me if I am wrong!
- Tue Oct 08, 2019 11:23 am
- Forum: *Black Body Radiation
- Topic: Black Body
- Replies: 5
- Views: 273
Re: Black Body
I think professor mentioned in class that the perfect black body that can absorb all frequencies of light does not currently exist. Cuz if we can still see it, it must has reflected some sort of frequencies which are able to be detected by our eyes, or it will just be invisible. Plz correct me if I ...
- Fri Oct 04, 2019 12:01 am
- Forum: Limiting Reactant Calculations
- Topic: Study Strategies/Youtube Videos
- Replies: 14
- Views: 515
Re: Study Strategies/Youtube Videos
Textbook has a lot of readings and sometimes it is hard to distinguish what is really important from all the various concepts. However, the resources that the professor provided are extremely helpful for the course and homework. Highly recommend going over them and using textbook as a supplementary ...
- Thu Oct 03, 2019 2:18 am
- Forum: Student Social/Study Group
- Topic: Study Group Fall 2019
- Replies: 32
- Views: 2656
Re: Study Group Fall 2019
Study group will be so helpful! I felt like I’ve forgotten everything about chem:)
- Thu Oct 03, 2019 2:09 am
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student [ENDORSED]
- Replies: 297
- Views: 374367
Re: Advice from a Medical Student [ENDORSED]
Thank you so much for sharing these. I am a 2nd year right now and was so stressed about being a premed student. I felt like I have so much to do, to get prepared but don’t even know how to start. Your advices are so helpful! I should really make a plan for myself.
- Thu Oct 03, 2019 1:57 am
- Forum: SI Units, Unit Conversions
- Topic: Homework 2
- Replies: 7
- Views: 299
Re: Homework 2
I am not sure but I believe we will choose 5 questions for all the homework assignments in the future( from the weekly assigned topics) to turn in, but more practice is always highly recommend!
- Thu Oct 03, 2019 1:48 am
- Forum: SI Units, Unit Conversions
- Topic: Calculator Question
- Replies: 13
- Views: 669
Re: Calculator Question
As long as it is not a graphing calculator you will be all good I guess. Mine was TI36x pro, and I’ve used it for many other classes that say “ no graphing calculator” in their syllabus. :) however I am not 100% sure, I hope it will work for this class!