Search found 48 matches
- Sat Mar 18, 2017 3:10 pm
- Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
- Topic: 2013 Final Q8C
- Replies: 1
- Views: 1175
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!
- Sun Mar 12, 2017 1:07 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: ch15 #51
- Replies: 3
- Views: 690
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...
- Mon Mar 06, 2017 7:28 pm
- Forum: *Ketones
- Topic: course reader pg 61 naming example
- Replies: 1
- Views: 1159
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-.
- Mon Mar 06, 2017 6:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 3 Winter 2017
- Replies: 183
- Views: 30109
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?
- 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: 1184
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...
- Sat Mar 04, 2017 1:08 pm
- Forum: *Cycloalkanes
- Topic: HW CH1 #16 [ENDORSED]
- Replies: 1
- Views: 590
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...
- Mon Feb 20, 2017 1:03 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: kinetics vs. thermodynamics control
- Replies: 1
- Views: 373
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...
- 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: 811
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...
- Thu Feb 09, 2017 10:40 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 2016 WINTER MIDTERM Q8A
- Replies: 1
- Views: 535
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 ...
- 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: 472
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.
- Sun Jan 29, 2017 9:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Quiz 1 Preparation Answers
- Replies: 130
- Views: 25836
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 ...
- Sun Jan 29, 2017 2:36 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Units of H, S, and G
- Replies: 1
- Views: 459
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...
- Sun Jan 29, 2017 2:24 pm
- Forum: Calculating Work of Expansion
- Topic: quiz prep #3
- Replies: 1
- Views: 391
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...
- 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: 723
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...
- Sun Jan 29, 2017 12:52 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3920015
Re: Post All Chemistry Jokes Here
avengers unite
- 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: 722
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 "...
- 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: 434
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?
- Sat Dec 03, 2016 7:08 am
- Forum: Hybridization
- Topic: Fall 2015 final [ENDORSED]
- Replies: 2
- Views: 991
Re: Fall 2015 final [ENDORSED]
Could anyone help with this question?
- Sat Dec 03, 2016 7:07 am
- Forum: Naming
- Topic: Naming ligands and writing ligands alphabetically? [ENDORSED]
- Replies: 4
- Views: 940
Re: Naming ligands and writing ligands alphabetically? [ENDORSED]
So alphabetical order doesn't matter when writing the formula?
- Fri Dec 02, 2016 10:26 pm
- Forum: Biological Examples
- Topic: final 2015 Q5A [ENDORSED]
- Replies: 1
- Views: 649
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?
- Fri Dec 02, 2016 8:39 pm
- Forum: Naming
- Topic: Naming ligands and writing ligands alphabetically? [ENDORSED]
- Replies: 4
- Views: 940
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 ...
- Fri Dec 02, 2016 8:31 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: About writing molecular orbitals
- Replies: 3
- Views: 747
- Fri Dec 02, 2016 7:24 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acid strength pattern
- Replies: 3
- Views: 787
Re: Acid strength pattern
I'm still confused why the strength of the bond is NH3>H2O>HF....
- Fri Dec 02, 2016 4:20 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: About writing molecular orbitals
- Replies: 3
- Views: 747
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.
- Fri Dec 02, 2016 4:13 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Acid strength pattern
- Replies: 3
- Views: 787
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...
- Fri Dec 02, 2016 4:04 pm
- Forum: Hybridization
- Topic: Fall 2015 final [ENDORSED]
- Replies: 2
- Views: 991
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...
- Fri Dec 02, 2016 3:58 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: ch12 hw 115
- Replies: 2
- Views: 574
Re: ch12 hw 115
Thank you!
- Sat Nov 26, 2016 12:53 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: ch12 hw 115
- Replies: 2
- Views: 574
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...
- Fri Nov 18, 2016 9:12 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HW 11.67
- Replies: 3
- Views: 592
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).
- Mon Nov 14, 2016 12:10 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Questions about coordination compound (mainly quiz 3 preparation)
- Replies: 2
- Views: 621
Re: Questions about coordination compound (mainly quiz 3 preparation)
Thank you! It's really helpful!
- 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: 621
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...
- Fri Nov 11, 2016 8:17 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Heteronuclear diatomic molecular orbital
- Replies: 2
- Views: 558
- Thu Nov 10, 2016 2:24 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Heteronuclear diatomic molecular orbital
- Replies: 2
- Views: 558
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?
- Sun Nov 06, 2016 6:26 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3920015
- Sun Oct 30, 2016 11:54 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: The shape of SO2 and O3
- Replies: 1
- Views: 1022
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?
- Sun Oct 30, 2016 11:11 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: The shape of SO2 and O3
- Replies: 1
- Views: 1022
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!
- Sat Oct 29, 2016 9:08 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: The shape of I3- ion
- Replies: 2
- Views: 32513
Re: The shape of I3- ion
Thank you so much!
- Fri Oct 28, 2016 3:25 pm
- Forum: Lewis Structures
- Topic: CH3 HW questions
- Replies: 3
- Views: 755
Re: CH3 HW questions
Thanks!
- Fri Oct 28, 2016 3:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: The shape of I3- ion
- Replies: 2
- Views: 32513
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!
- Mon Oct 24, 2016 11:01 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: e- configuration regarding 3d and 4s orbitals
- Replies: 2
- Views: 514
- 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: 514
e- configuration regarding 3d and 4s orbitals
I'm just wondering which one should be written first in an exam.
- Mon Oct 24, 2016 9:40 pm
- Forum: Lewis Structures
- Topic: CH3 HW questions
- Replies: 3
- Views: 755
Re: CH3 HW questions
In the second line I mean one or two...
- Mon Oct 24, 2016 9:38 pm
- Forum: Lewis Structures
- Topic: CH3 HW questions
- Replies: 3
- Views: 755
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 ...
- Wed Oct 19, 2016 3:00 pm
- Forum: Trends in The Periodic Table
- Topic: Homework problem Ch2 67
- Replies: 4
- Views: 712
Re: Homework problem Ch2 67
Thanks!
- Sun Oct 16, 2016 12:54 pm
- Forum: Trends in The Periodic Table
- Topic: Homework problem Ch2 67
- Replies: 4
- Views: 712
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...
- Sun Oct 09, 2016 3:07 pm
- Forum: Properties of Light
- Topic: Hmwk Problem 1.9 [ENDORSED]
- Replies: 6
- Views: 1134
Re: Hmwk Problem 1.9 [ENDORSED]
Never mind. I know now.
- Sun Oct 09, 2016 12:34 pm
- Forum: Properties of Light
- Topic: Hmwk Problem 1.9 [ENDORSED]
- Replies: 6
- Views: 1134
Re: Hmwk Problem 1.9 [ENDORSED]
I'm still confused. How to differentiate between reading and suntan?
- Wed Sep 28, 2016 2:59 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect [ENDORSED]
- Replies: 12
- Views: 2706
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.