CHEMISTRY COMMUNITY

Claire_Zhou_1A

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！

Claire_Zhou_1A

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...

Claire_Zhou_1A

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-.

Claire_Zhou_1A

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?

Claire_Zhou_1A

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...

Claire_Zhou_1A

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...

Claire_Zhou_1A

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...

Claire_Zhou_1A

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...

Claire_Zhou_1A

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 ...

Claire_Zhou_1A

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.

Claire_Zhou_1A

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 ...

Claire_Zhou_1A

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...

Claire_Zhou_1A

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...

Claire_Zhou_1A

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...

Claire_Zhou_1A

avengers unite

Claire_Zhou_1A

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 "...

Claire_Zhou_1A

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?

Claire_Zhou_1A

Could anyone help with this question?

Claire_Zhou_1A

So alphabetical order doesn't matter when writing the formula?

Claire_Zhou_1A

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?

Claire_Zhou_1A

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 ...

Claire_Zhou_1A

Thanks！

Claire_Zhou_1A

I'm still confused why the strength of the bond is NH3>H2O>HF....

Claire_Zhou_1A

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.

Claire_Zhou_1A

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...

Claire_Zhou_1A

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...

Claire_Zhou_1A

Thank you!

Claire_Zhou_1A

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...

Claire_Zhou_1A

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).

Claire_Zhou_1A

Thank you! It's really helpful!

Claire_Zhou_1A

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...

Claire_Zhou_1A

Thanks！

Claire_Zhou_1A

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?

Claire_Zhou_1A

Claire_Zhou_1A

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?

Claire_Zhou_1A

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!

Claire_Zhou_1A

Thank you so much!

Claire_Zhou_1A

Thanks!

Claire_Zhou_1A

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!

Claire_Zhou_1A

Thanks！

Claire_Zhou_1A

I'm just wondering which one should be written first in an exam.

Claire_Zhou_1A

In the second line I mean one or two...

Claire_Zhou_1A

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 ...

Claire_Zhou_1A

Thanks!

Claire_Zhou_1A

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...

Claire_Zhou_1A

Never mind. I know now.

Claire_Zhou_1A

I'm still confused. How to differentiate between reading and suntan?

Claire_Zhou_1A

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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