## Search found 66 matches

Sat Mar 16, 2019 5:28 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Final [ENDORSED]
Replies: 9
Views: 358

### Re: Final[ENDORSED]

Just to be sure, steady state is not included in finals right?
Sat Mar 16, 2019 5:26 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst
Replies: 14
Views: 405

### Re: Nernst

josephperez_2C wrote:Just making sure, n could never equal 0 since there is always a transfer of electrons right?

Yes I think so
Sat Mar 16, 2019 5:24 pm
Forum: Administrative Questions and Class Announcements
Topic: LYNDON'S PORK RAMEN REVIEW
Replies: 37
Views: 5390

### Re: LYNDON'S PORK RAMEN REVIEW

Tysm Lyndon! Can someone post the answer plss tyyy~
Wed Mar 06, 2019 3:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Corrosion
Replies: 3
Views: 181

### Re: Corrosion

Also if it is not in the syllabus, then I don’t think we need to know it.
Wed Mar 06, 2019 3:22 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Arrhenius Equation
Replies: 1
Views: 151

### Re: Arrhenius Equation

A represents the number of collisions multiplied by the frequency in which they are in the correct orientation, which gives us A the frequency factor.
Wed Mar 06, 2019 3:20 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Volume and Temperature
Replies: 2
Views: 104

### Re: Volume and Temperature

The entropy increases as the temperature increases, hope that helps.
Thu Feb 28, 2019 11:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: H+ in cell diagrams
Replies: 5
Views: 277

### H+ in cell diagrams

Can anyone explain when do we add H+ in cell diagrams?
eg.
Pt I Fe3+, Fe2+ II H+, MnO4-, Mn2+ I Pt
Thu Feb 28, 2019 8:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Organization of cell diagrams
Replies: 9
Views: 258

### Re: Organization of cell diagrams

Aurbal Popal wrote:Also, to add on to her question, you do not need to put Pt on both sides of the cell diagram if there is a solid on the other side, right?

THAT'S RIGHT
Wed Feb 27, 2019 3:21 pm
Forum: Balancing Redox Reactions
Topic: Oxidized vs oxidizing agent
Replies: 6
Views: 171

### Re: Oxidized vs oxidizing agent

I usually just remember one as an opposite of another. If something is being oxidized, then it is the reducing agent.
Wed Feb 27, 2019 3:16 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt (s) [ENDORSED]
Replies: 8
Views: 381

### Re: Pt (s)[ENDORSED]

I think we also add Pt when both species of the same kind are in the same solution, say Fe2+ and Fe3+
Wed Feb 27, 2019 3:14 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagram
Replies: 1
Views: 83

### Cell diagram

In some of the HW problem solutions, the cell diagram shows Fe2+, Fe3+ II ..., instead of Fe2+ I Fe3+ II...
Is there a difference between using , and I ?
Thu Feb 21, 2019 1:04 pm
Forum: Balancing Redox Reactions
Topic: Half Reactions
Replies: 1
Views: 97

### Re: Half Reactions

For acidic reactions, we balance out the O by adding H2O and balance out the H by adding H+.
For basic reactions, we balance out O by adding H2O and balance out H by adding OH-.
Thu Feb 21, 2019 1:00 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8199
Views: 1430058

### Re: Post All Chemistry Jokes Here

If I steal your electrons would I be legally charged?
Thu Feb 21, 2019 12:59 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8199
Views: 1430058

### Re: Post All Chemistry Jokes Here

Did you know that you can cool yourself to -273.15˚C and still be 0 K?
Tue Feb 12, 2019 10:19 pm
Forum: Administrative Questions and Class Announcements
Replies: 179
Views: 12857

Karyn Nguyen 1K wrote:For worksheet 4, is the answer for 6a wrong? I did (3/2)(31.9 mol)(8.314 J/Kmol)(311.15 K) = 124 kJ. When I didn't convert the temperature from C to K I got 15.1 kJ which is the answer given in the key.

We don’t have to convert it to kelvin as it is change in temperature (38-0)
Tue Feb 12, 2019 10:16 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isothermal and reversible
Replies: 2
Views: 154

### Isothermal and reversible

Doe isothermal expansion ALWAYS mean reversible expansion?
Or is it possible to have isothermal, irreversible expansion as well?
Tue Feb 12, 2019 9:36 pm
Forum: Administrative Questions and Class Announcements
Replies: 179
Views: 12857

Quick question for Worksheet 1 ques8:

When I2 is added, neither products nor reactants is favored as I2 is a solid.
What happens when I2 is removed, does the reaction not shift too?
Mon Feb 11, 2019 5:39 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U and deltaH
Replies: 1
Views: 94

### Delta U and deltaH

Can someone explain how is deltaU = deltaH -p* deltaV
Mon Feb 11, 2019 5:37 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Replies: 1
Views: 114

I understand that q=0 in adiabatic situations, but why does w=Cv* deltaT? ( I thought that w is suppose to be work due to expansion of gas)
Thu Feb 07, 2019 11:50 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible vs irreversible
Replies: 3
Views: 161

### Re: Reversible vs irreversible

In thermodynamics, a reversible process is a process whose direction can be "reversed" by inducing infinitesimal changes to some property of the system via its surroundings. Throughout the entire reversible process, the system is in thermodynamic equilibrium with its surroundings. Having b...
Thu Feb 07, 2019 11:44 am
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 and Entropy
Replies: 1
Views: 114

### Re: Degeneracy and Entropy

Increasing degeneracy results in an increase in entropy of the system. This is shown by the Boltzmann equation: S=kB*ln(W), where w is the degeneracy and S is entropy. Therefore, an increase in w increases the value of S, which is entropy. This also makes sense because degeneracy is the number of wa...
Thu Feb 07, 2019 11:38 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Degeneracy
Replies: 2
Views: 131

### Re: Degeneracy

How do we calculate degeneracy caused by heat then?
Thu Feb 07, 2019 11:36 am
Forum: Calculating Work of Expansion
Topic: Ideal gas expansion
Replies: 4
Views: 141

### Re: Ideal gas expansion

I understand that q=0 as there is no net heat change. But why isn’t W a negative value as the system has done work to expand?
Thu Feb 07, 2019 11:32 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Difference in Entropy Due to Temperature Change
Replies: 2
Views: 157

### Re: Difference in Entropy Due to Temperature Change

For the second equation S=Cln(T2/T1), is q constant then?
Sat Feb 02, 2019 7:58 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Heat vs. Temp
Replies: 9
Views: 469

### Re: Heat vs. Temp

So is it correct to say that heat is directly proportional to temperature?
Sat Feb 02, 2019 7:57 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Review
Replies: 14
Views: 542

### Re: Midterm Review

For last quarter there were many review sessions by both TAs and Lavelle :)
Sat Feb 02, 2019 7:55 pm
Forum: Student Social/Study Group
Topic: Absent on 1/30; in need of notes
Replies: 4
Views: 234

### Re: Absent on 1/30; in need of notes

I can send you the notes what’s your email?
Sat Feb 02, 2019 7:53 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpy equations
Replies: 6
Views: 211

### Re: bond enthalpy equations

Yes drawing out the structures really worked for me
Tue Jan 22, 2019 8:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q reaction quotient
Replies: 2
Views: 106

### Q reaction quotient

When asked for Q reaction quotient, should we give in terms of pressure or concentration when the chemical equation contains both liquid and gases?
Sat Jan 19, 2019 9:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka vs. Kb
Replies: 12
Views: 718

### Re: Ka vs. Kb

And Kp is the pressure constant?
Sat Jan 19, 2019 9:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Studying for First Discussion Test
Replies: 10
Views: 385

### Re: Studying for First Discussion Test

I will be doing all the homework problems and going through lecture notes. GOODLUCK everybody!
Sat Jan 19, 2019 9:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Studying for First Discussion Test
Replies: 10
Views: 385

### Re: Studying for First Discussion Test

Anyone knows if Karen is still giving out worksheets for this class?
Fri Jan 11, 2019 10:49 am
Forum: General Science Questions
Topic: Week 1 Homework
Replies: 5
Views: 228

### Re: Week 1 Homework

Can we submit our hw during discussion?
Fri Jan 11, 2019 10:47 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K, Kc and Kp
Replies: 8
Views: 205

### Re: K, Kc and Kp

The K values are only affected by the change in temperature.
Mon Jan 07, 2019 4:44 pm
Forum: General Science Questions
Topic: Chem textbook
Replies: 3
Views: 224

### Chem textbook

Hi does anyone know what book is this?

CHEMICAL PRINCIPLES (LOOSE-LEAF) & SSM (NEW COPIES W/24MO SAPLING & ETEXT ACCESS)

Cause it was listed as REQUIRED in the UCLA textbook page for Chem 14B but I don’t think it’s the textbook itself coz that was listed separately.

Tqsm!
Sat Dec 08, 2018 3:57 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 11347

### Re: FINAL PRACTICE - Lyndon's Churro Review Session[ENDORSED]

Thank you! Does anyone know which other TAs or UAs post worksheets as well (besides Lyndon and Karen)?
Sat Dec 08, 2018 3:53 pm
Forum: Administrative Questions and Class Announcements
Replies: 135
Views: 31485

Thanks Karen for the helpful worksheets!
Thu Nov 29, 2018 2:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular orientation
Replies: 2
Views: 116

### Re: Molecular orientation

Thanks! That was really helpful! But what about COOH though... is it one of the few exemptions?
Wed Nov 28, 2018 8:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular orientation
Replies: 2
Views: 116

### Molecular orientation

Is it safe to assume that the sequence of the chemical formula is a correct representation of the molecular structure itself?

Example: the molecular structure of CNO- is in the sequence C-N-O since the formula is CNO-
Wed Nov 28, 2018 8:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electron Geometry and Molecular Geometry
Replies: 2
Views: 188

### Electron Geometry and Molecular Geometry

When the question asks for the shape, can I just give the molecular geometry, or do I have to give both electron and molecular geometry?
Wed Nov 28, 2018 8:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape and Lewis Structure
Replies: 1
Views: 66

### Shape and Lewis Structure

When the question asks for the Lewis Structure, would I be penalized if I draw out the shape instead (as the shape is just a more “advanced” version of Lewis Structure?
Fri Nov 16, 2018 1:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Distance from Central Atom
Replies: 8
Views: 223

### Re: Distance from Central Atom

Then does a non-wedge bond indicate that the bond goes sideways?
Fri Nov 16, 2018 1:03 pm
Forum: Student Social/Study Group
Topic: curve?
Replies: 20
Views: 1705

### Re: curve?

Is it true that he will curve if the class finals average is too low?
Fri Nov 16, 2018 1:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: CH 4 HW 4.41 6TH EDITION
Replies: 3
Views: 128

### Re: CH 4 HW 4.41 6TH EDITION

Is the CN bond usually a triple bond?
Thu Nov 08, 2018 9:23 pm
Forum: Lewis Structures
Topic: Placement of Elements?
Replies: 5
Views: 248

### Re: Placement of Elements?

I don't think it matters.
Thu Nov 08, 2018 9:21 pm
Forum: Sigma & Pi Bonds
Topic: Easy way of remembering the difference
Replies: 6
Views: 291

### Re: Easy way of remembering the difference

I believe that they only happen in covalent bonds as ionic bonds are a complete transfer of electrons without any sharing.
Thu Nov 08, 2018 9:19 pm
Forum: Student Social/Study Group
Topic: Homework 6
Replies: 5
Views: 268

### Re: Homework 6

Yes I did some from the past sections and some on the newer topics too.
Thu Nov 08, 2018 9:18 pm
Forum: Electronegativity
Topic: Covalent Bonds
Replies: 2
Views: 176

### Re: Covalent Bonds

Yes, for the reasons above AlCl3 is actually ionic with covalent character.
Thu Nov 08, 2018 9:16 pm
Forum: Octet Exceptions
Topic: Octet vs formal charge
Replies: 16
Views: 1091

### Re: Octet vs formal charge

Also make sure that for elements that do not have expanded d orbitals (Period 2 and above) do not exceed their octet shell.
Thu Nov 08, 2018 9:08 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8199
Views: 1430058

### Re: Post All Chemistry Jokes Here

Not quite chem related but..
Why do many pre-med students want to donate their bodies to research after they die?

Because that is the only way for them to get into med school.
Sun Nov 04, 2018 8:51 pm
Forum: Ionic & Covalent Bonds
Topic: Chem Midterm
Replies: 13
Views: 526

### Re: Chem Midterm

Do we need a blue book for the test?
Sat Nov 03, 2018 2:35 pm
Forum: Bond Lengths & Energies
Topic: Lengths of Bonds
Replies: 9
Views: 263

### Re: Lengths of Bonds

Thank you!
Thu Nov 01, 2018 7:08 pm
Forum: Bond Lengths & Energies
Topic: Lengths of Bonds
Replies: 9
Views: 263

### Re: Lengths of Bonds

Btw does anyone know why is that when calculating the bond length of say BiF4, we only sum up the bond length of Bi and F, instead of summing the lengths of Bi and 4Fs?
Thu Nov 01, 2018 7:06 pm
Forum: Bond Lengths & Energies
Topic: Lengths of Bonds
Replies: 9
Views: 263

### Re: Lengths of Bonds

Cause the electron density is higher?
Thu Oct 25, 2018 1:42 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Homework Ch.2 Question 15, 6th Edition
Replies: 6
Views: 219

### Re: Homework Ch.2 Question 15, 6th Edition

605122791 wrote:But the textbook says that

= n-1-l
Which should give us
=3-1-1
=1

For b) the number of radial nodes
Thu Oct 25, 2018 1:41 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Homework Ch.2 Question 15, 6th Edition
Replies: 6
Views: 219

### Re: Homework Ch.2 Question 15, 6th Edition

But the textbook says that

= n-1-l
Which should give us
=3-1-1
=1

Thu Oct 25, 2018 1:39 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Homework Ch.2 Question 15, 6th Edition
Replies: 6
Views: 219

### Re: Homework Ch.2 Question 15, 6th Edition

The answer given in the solution manual is
a) 1 nodal plane
Thu Oct 18, 2018 12:00 am
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 69
Views: 24884

### Re: formula units[ENDORSED]

Yes, which is the Avogadro Number.
Wed Oct 17, 2018 11:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Using different letters for variables
Replies: 1
Views: 48

### Using different letters for variables

Hi, I was wondering if I am allowed to use different letters when writing down a formula.. eg.for c = v x lamda can I write v = f x lamda instead? I find it confusing as some of the letters in the new equations, means a totally different thing form what I have used to learn. So, would I get penalize...
Wed Oct 17, 2018 11:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 221
Views: 115702

### Re: Advice from a Medical Student[ENDORSED]

Wed Oct 10, 2018 11:13 pm
Forum: SI Units, Unit Conversions
Topic: Ways to remember prefixes
Replies: 7
Views: 1885

### Re: Ways to remember prefixes

I used the Tune of Happy Birthday song!

Tera Giga Mega
Kilo Hecto Deca
Deci Centi Milli Micro
Nano Pico Hepto
Wed Oct 10, 2018 11:12 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 80
Views: 3871

### Re: How does grading for discussion posts work?

My TA said it’s dued by Friday midnight
Wed Oct 10, 2018 11:11 pm
Forum: Properties of Light
Topic: Telling color by wavelength
Replies: 3
Views: 105

### Re: Telling color by wavelength

Thanks so much for the chart!
Fri Oct 05, 2018 4:00 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 80
Views: 3871

### Re: How does grading for discussion posts work?

Hi guys. May I know what’s included in our test next week?

Is it the whole of the Fundamental section, or just the sections mentioned in Outline 1?

Thanks!
Fri Oct 05, 2018 3:55 pm
Forum: SI Units, Unit Conversions
Topic: SI Units on tests
Replies: 5
Views: 289

### Re: SI Units on tests

Is the conversion between US units and SI units given in the tests?

Thanks!
Fri Oct 05, 2018 3:48 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 133
Views: 17383

### Re: All students read this sig fig post[ENDORSED]

Hi is it ok to not bother about significant figures in the beginning of calculations (by writing down more than the required sf.), and only round it to the correct number of sf. in the last equation?