Search found 48 matches

by Claire_Zhou_1A
Sat Mar 18, 2017 3:10 pm
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: 2013 Final Q8C
Replies: 1
Views: 465

2013 Final Q8C

For this question, I don't understand how we can determine it's in chair conformation based on the newman projection. Could someone explain to me? Thanks!
by Claire_Zhou_1A
Sun Mar 12, 2017 1:07 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: ch15 #51
Replies: 3
Views: 368

ch15 #51

For #51, the question is write the rate law for the formation of NOBr step 1 NO + Br2 → NOBr2 (slow) step 2 NOBr2 + NO → NOBr + NOBr (fast) the answer says because the first step is the rate-determining step so the rate of formation of NOBr=k[NO][Br2]. I thought according to step 1 rate of formation...
by Claire_Zhou_1A
Mon Mar 06, 2017 7:28 pm
Forum: *Ketones
Topic: course reader pg 61 naming example
Replies: 1
Views: 493

course reader pg 61 naming example

At the bottom of pg 61 the third structure is named 4-Methylcyclohexa-2,5-dienone. I don't understand why it isn't 4-Methylcyclohex-2,5-dienone, that is why should we write hexa- instead of hex-.
by Claire_Zhou_1A
Mon Mar 06, 2017 6:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 3 Winter 2017
Replies: 183
Views: 15893

Re: Quiz 3 Winter 2017

For question #8, what does the forth statement mean by "the Br- ion attacks at the same face of the bromonium ion"? Is it trying to say that the Br- attacks the same carbon attached by another Br?
by Claire_Zhou_1A
Sun Mar 05, 2017 7:42 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Activation energy, enthalpy of activation, and free gibbs energy of activation
Replies: 1
Views: 775

Activation energy, enthalpy of activation, and free gibbs energy of activation

According to the textbook, suppose there's a two step electrophilic addition reaction, for the second step, Ea and △H°++ are both comparing transition state 2 to the intermediate, while △G°++ is comparing transition state 2 with reactants. So should we follow the textbook or compare with reactants i...
by Claire_Zhou_1A
Sat Mar 04, 2017 1:08 pm
Forum: *Cycloalkanes
Topic: HW CH1 #16 [ENDORSED]
Replies: 1
Views: 331

HW CH1 #16 [ENDORSED]

So the question asks the name of a compound. Sorry I can't find a picture. It's a clyclopentane with two methyl groups attached to a carbon atom and an isopropane attached to the carbon next to it. The name should be 2-isopropyl-1,1-dimethylcyclopentane. What confuses me is that "iso" is c...
by Claire_Zhou_1A
Mon Feb 20, 2017 1:03 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: kinetics vs. thermodynamics control
Replies: 1
Views: 205

kinetics vs. thermodynamics control

I read some previous posts about this question, but I feel I still don't understand the difference clearly. So does kinetics control means the the direction that an equilibrium favors depends on the relative rates of forward and reverse reaction? And thermodynamics control means depending on the gib...
by Claire_Zhou_1A
Wed Feb 15, 2017 10:27 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: How to write electrode reactions from a cell diagram & write a cell diagram from overall reaction?
Replies: 2
Views: 431

How to write electrode reactions from a cell diagram & write a cell diagram from overall reaction?

So generally I know how to write electrode reactions based on cell diagrams and vice versa. But I don't know how to do these two problems: · the cell diagram given is Pt(s)|O2(g)|H+(aq)||OH-(aq)|O2(g)|Pt(s) and write a cell diagram · the overall reaction is 2Ag(s) + Br2(g)→2AgBr(s) I think what conf...
by Claire_Zhou_1A
Thu Feb 09, 2017 10:40 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: 2016 WINTER MIDTERM Q8A
Replies: 1
Views: 331

2016 WINTER MIDTERM Q8A

The question is: A standard electrochemical cell is made by placing a silver electrode into a 1M Ag+ solution and a cadmium electrode into a 1A Cd2+ solution. What is the redox reaction and what is the maximum potential produced by this cell? So the E° for Cd(s) → Cd2+ + 2e- is 0.4V (the reverse of ...
by Claire_Zhou_1A
Sun Feb 05, 2017 10:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating standard cell potentials
Replies: 2
Views: 226

Re: Calculating standard cell potentials

E° does not always equal to 0. I think E°cell is equal to the E°(cathode) - E°(anode). Only the E°cell of a concentration cell at standard state equals 0.
by Claire_Zhou_1A
Sun Jan 29, 2017 9:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz 1 Preparation Answers
Replies: 130
Views: 13728

Re: Quiz 1 Preparation Answers

I read previous replies and still confused about #9. Could someone explain to me? I know that △S(system) is 0 because it's a state function, but why is △S(surroundings)>0? Also, w and q are not state functions, but the processes in the question seem to be the opposite, shouldn't the q for each step ...
by Claire_Zhou_1A
Sun Jan 29, 2017 2:36 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Units of H, S, and G
Replies: 1
Views: 276

Units of H, S, and G

I just want to confirm all the units. For H, △H is j or kj. △H°is still j or kj. △Hf° is kj/mol or j/mol. For S, △S is j/k. △Sm° and △Sf° are both j/k/mol. For G, △G is j or kj. △Gm° and △Gf° are both j/mol or kj/mol. All the △H, △S, and △G for phase transition are defined per mole. Please correct m...
by Claire_Zhou_1A
Sun Jan 29, 2017 2:24 pm
Forum: Calculating Work of Expansion
Topic: quiz prep #3
Replies: 1
Views: 209

quiz prep #3

So the question is "if 2mol of an ideal gas at 300K and 3.00 atm expands isothermally and reversibly from 6L to 18L and has a final pressure of 1.20 atm, what is w, q, and △U? I know because it's isothermal and reversible I should use w = -nRT*In(V2/V1). Since the volume changes the pressure mu...
by Claire_Zhou_1A
Sun Jan 29, 2017 2:16 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Quiz Prep 1 #9
Replies: 2
Views: 376

Re: Quiz Prep 1 #9

I'm not sure if my answers are correct... I think q and w are both 0 since the gas goes back to original state w and △U are both zero and it follows q is 0. △S(system) is zero because the gas goes back to original state and then △S(surroundings) is 0. Therefore, △G is also 0. W is not 0 since it's n...
by Claire_Zhou_1A
Sun Jan 29, 2017 12:52 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7606
Views: 1018973

Re: Post All Chemistry Jokes Here

avengers unite
by Claire_Zhou_1A
Tue Jan 17, 2017 7:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: CH8 HW#99
Replies: 3
Views: 388

CH8 HW#99

So the question is a piece of zinc metal of mass 8.5g is dropped into an apparatus containing 800ml of 0.5M HCl(aq). If the initial temperature of the solution is 25℃, what is the final temperature of the solution? I don't understand how to solve for the reaction enthalpy and the solution says "...
by Claire_Zhou_1A
Sat Jan 14, 2017 11:17 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Definition of bond enthalpy
Replies: 1
Views: 235

Definition of bond enthalpy

So I read on the textbook that bond enthalpy is the difference between standard molar enthalpy of molecules and its fragments in gas phase. Is this the same as the energy required to break the bond?
by Claire_Zhou_1A
Sat Dec 03, 2016 7:08 am
Forum: Hybridization
Topic: Fall 2015 final [ENDORSED]
Replies: 2
Views: 410

Re: Fall 2015 final [ENDORSED]

Could anyone help with this question?
by Claire_Zhou_1A
Sat Dec 03, 2016 7:07 am
Forum: Naming
Topic: Naming ligands and writing ligands alphabetically? [ENDORSED]
Replies: 4
Views: 473

Re: Naming ligands and writing ligands alphabetically? [ENDORSED]

So alphabetical order doesn't matter when writing the formula?
by Claire_Zhou_1A
Fri Dec 02, 2016 10:26 pm
Forum: Biological Examples
Topic: final 2015 Q5A [ENDORSED]
Replies: 1
Views: 420

final 2015 Q5A [ENDORSED]

Could someone explain to me why is the Corrin-DMB ligand has a charge of -1? There's a line in the answer "the upper-left coordinated N is -1 while the other N are neutral", but why do I feel the upper left N is 0 and others are +1?
by Claire_Zhou_1A
Fri Dec 02, 2016 8:39 pm
Forum: Naming
Topic: Naming ligands and writing ligands alphabetically? [ENDORSED]
Replies: 4
Views: 473

Naming ligands and writing ligands alphabetically? [ENDORSED]

Is the alphabetical order refering to the name of ligands? For example if we have something like [Fe(NH3)(H2O)], should we write ammine-aqua-iron because "ammine" is before "aqua"? And about writing the formula alphabetically, NH3 before H2O is also because "ammine" is ...
by Claire_Zhou_1A
Fri Dec 02, 2016 7:24 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid strength pattern
Replies: 3
Views: 419

Re: Acid strength pattern

I'm still confused why the strength of the bond is NH3>H2O>HF....
by Claire_Zhou_1A
Fri Dec 02, 2016 4:20 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: About writing molecular orbitals
Replies: 3
Views: 423

About writing molecular orbitals

Can we write the π orbitals separately like (π2px)² and (π2py)² or do we have to write it in a combined form like (π2p)4 ? I know we are supposed to write in a combined form if the two atoms are different in a molecule.
by Claire_Zhou_1A
Fri Dec 02, 2016 4:13 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid strength pattern
Replies: 3
Views: 419

Acid strength pattern

So the course reader says the acid strength is determined by the strength of the bond of HX. I read the section in the textbook and it concludes patterns for across a period, down a group, oxoacid, and carboxylic acid. The textbook says across a period, the acid strength depends on the polarity, the...
by Claire_Zhou_1A
Fri Dec 02, 2016 4:04 pm
Forum: Hybridization
Topic: Fall 2015 final [ENDORSED]
Replies: 2
Views: 410

Fall 2015 final [ENDORSED]

So I'm a little confused about question Q4B. The question is asking about the hybridization for all carbon and nitrogen atoms in CH3CN. I know the hybridization for the first C is sp3, for the second C is sp, and for N is sp. What I don't understand is how exactly are electron arranged in the hybrid...
by Claire_Zhou_1A
Fri Dec 02, 2016 3:58 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ch12 hw 115
Replies: 2
Views: 425

Re: ch12 hw 115

Thank you!
by Claire_Zhou_1A
Sat Nov 26, 2016 12:53 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ch12 hw 115
Replies: 2
Views: 425

ch12 hw 115

So the question is a. Nitrous acid and carbonic acids are both weak acids in water. Will either of them act as a strong acid in acetic acid? b. Will ammonia act as a strong or weak base in acetic acid? I read the explanation in the solution manual but I don't really understand what it's saying. Coul...
by Claire_Zhou_1A
Fri Nov 18, 2016 9:12 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW 11.67
Replies: 3
Views: 341

Re: HW 11.67

I'm not sure about how to do that... but I think the concentration of Cl2 can only be 2.0 because the initial concentration of H2 is 1.0 and if H2 if pushed to 0, Cl2 is 2.0 (concentration can't be negative).
by Claire_Zhou_1A
Sat Nov 12, 2016 1:24 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Questions about coordination compound (mainly quiz 3 preparation)
Replies: 2
Views: 361

Questions about coordination compound (mainly quiz 3 preparation)

So I was reviewing coordination compound and several questions really confuse me. 1. When the coordination number is 4, how to determine the structure is square planar or tetrahedral? 2. There's a complex in quiz 3 preparation. It's [Cr(F)3(I)(H2O)2]. I'm not sure about its name since it doesn't hav...
by Claire_Zhou_1A
Thu Nov 10, 2016 2:24 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Heteronuclear diatomic molecular orbital
Replies: 2
Views: 301

Heteronuclear diatomic molecular orbital

So just a quick question... when a molecule consists of one atom with Z<8 and one atom with Z>8, why should we use the diagram of the atom with Z<8?
by Claire_Zhou_1A
Sun Nov 06, 2016 6:26 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7606
Views: 1018973

Re: Post All Chemistry Jokes Here

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by Claire_Zhou_1A
Sun Oct 30, 2016 11:54 am
Forum: Determining Molecular Shape (VSEPR)
Topic: The shape of SO2 and O3
Replies: 1
Views: 407

Re: The shape of SO2 and O3

Never mind. I just realized that a single e- is considered the same as a lone pair. So does angular and bent mean the same thing?
by Claire_Zhou_1A
Sun Oct 30, 2016 11:11 am
Forum: Determining Molecular Shape (VSEPR)
Topic: The shape of SO2 and O3
Replies: 1
Views: 407

The shape of SO2 and O3

I'm really confused about the shape of these two molecules. They both have the formula of AX2E, but according to the textbook O3 is angular and according to FALL 2015 midterm solutions SO2 is bent. I thought only molecules with a formula AX2E2 is bent. Could someone explain to me? Thanks!
by Claire_Zhou_1A
Sat Oct 29, 2016 9:08 am
Forum: Determining Molecular Shape (VSEPR)
Topic: The shape of I3- ion
Replies: 2
Views: 17054

Re: The shape of I3- ion

Thank you so much!
by Claire_Zhou_1A
Fri Oct 28, 2016 3:25 pm
Forum: Lewis Structures
Topic: CH3 HW questions
Replies: 3
Views: 397

Re: CH3 HW questions

Thanks!
by Claire_Zhou_1A
Fri Oct 28, 2016 3:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: The shape of I3- ion
Replies: 2
Views: 17054

The shape of I3- ion

This is an example in the textbook. I don't really understand why the shape of I3- ion should be linear. Could someone explain to me? Thanks!
by Claire_Zhou_1A
Mon Oct 24, 2016 9:45 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: e- configuration regarding 3d and 4s orbitals
Replies: 2
Views: 259

e- configuration regarding 3d and 4s orbitals

I'm just wondering which one should be written first in an exam.
by Claire_Zhou_1A
Mon Oct 24, 2016 9:40 pm
Forum: Lewis Structures
Topic: CH3 HW questions
Replies: 3
Views: 397

Re: CH3 HW questions

In the second line I mean one or two...
by Claire_Zhou_1A
Mon Oct 24, 2016 9:38 pm
Forum: Lewis Structures
Topic: CH3 HW questions
Replies: 3
Views: 397

CH3 HW questions

57.c So the question asks about the resonance structure of ClO4-. The answer suggests that there are three double bonds in the each resonance structure and therefore four resonance structures in total. I'm wondering why there is three double bonds in stead of one of two? Is it because formal charge ...
by Claire_Zhou_1A
Wed Oct 19, 2016 3:00 pm
Forum: Trends in The Periodic Table
Topic: Homework problem Ch2 67
Replies: 4
Views: 373

Re: Homework problem Ch2 67

Thanks!
by Claire_Zhou_1A
Sun Oct 16, 2016 12:54 pm
Forum: Trends in The Periodic Table
Topic: Homework problem Ch2 67
Replies: 4
Views: 373

Homework problem Ch2 67

I'm a little confused about the second question. The answer says C atom has a higher electron affinity than N atom. But the trend is the electron affinity is higher on the top right... Is it because that if C atom gains one more electron it would reach 2p3 structure and it's more stable? Could someo...
by Claire_Zhou_1A
Sun Oct 09, 2016 3:07 pm
Forum: Properties of Light
Topic: Hmwk Problem 1.9 [ENDORSED]
Replies: 6
Views: 541

Re: Hmwk Problem 1.9 [ENDORSED]

Never mind. I know now.
by Claire_Zhou_1A
Sun Oct 09, 2016 12:34 pm
Forum: Properties of Light
Topic: Hmwk Problem 1.9 [ENDORSED]
Replies: 6
Views: 541

Re: Hmwk Problem 1.9 [ENDORSED]

I'm still confused. How to differentiate between reading and suntan?
by Claire_Zhou_1A
Wed Sep 28, 2016 2:59 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect [ENDORSED]
Replies: 12
Views: 1446

Re: Photoelectric Effect [ENDORSED]

I think that light with larger wavelengths also has photon properties... It's just the light has low frequency since the wavelength is large and the energy of photon is too small to reach threshold energy. I don't know if I'm right.

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