Search found 21 matches

by Joyce 3H
Sun Mar 15, 2015 9:07 am
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Cis/Trans and E/Z Configuration
Replies: 7
Views: 2004

Re: Cis/Trans and E/Z Configuration

Cis and trans appear only on alkene, cycloalkane, and cycloalkene, right?
Thank U!
by Joyce 3H
Sun Mar 15, 2015 9:05 am
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: 2011 final Q7A Why trans instead of cis?
Replies: 1
Views: 448

2011 final Q7A Why trans instead of cis?

In the cyclopentene, there're a alcohol group attached on C1 and a methyl group on C4. Between them ,there's a double bond on C2. So when naming cis or trans in ring, do we have to see across the double bond? Or just look at "axial" or "equatorial" to decide? Thank you for your h...
by Joyce 3H
Wed Feb 11, 2015 11:45 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Determining Entropy
Replies: 5
Views: 3289

Re: Determining Entropy

Two related questions: if the ideal monatomic and diatomic gas have same amount of molecules and are kept in the same volume container, then the diatomic gas has higher molar entropy right? And if it's provided that there's same moles of atoms for monatomic gas and some much more complicated gas(>di...
by Joyce 3H
Wed Feb 11, 2015 11:20 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity in dissolving process
Replies: 5
Views: 733

Re: Spontaneity in dissolving process

So, you mean that spontaneity is not equal to "favor"?
Then what's the criteria for "favor"? Is it just positive deltaS and negative deltaG? If it is, then the positive deltaS should be the deltaS(surrounding) or deltaS(system) or both or their sum deltaS(total)?
Thanks a lot!
by Joyce 3H
Wed Feb 11, 2015 8:16 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity in dissolving process
Replies: 5
Views: 733

Spontaneity in dissolving process

which measurement should we pay attention to, DeltaS(surrounding), deltaS(total), or delta(system), to decide whether the dissolving process is spontaneous or not?
(According to homework 8.87, it should be delta S( surrounding), why?)
Thank you!
by Joyce 3H
Sat Feb 07, 2015 5:29 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: HW prob 13.11d:Writing the half reactions for galvanic cells
Replies: 7
Views: 1106

Re: HW prob 13.11d:Writing the half reactions for galvanic c

One question on the answer: should we eliminate the coefficient 4 of all the reactants and products of the balanced reaction? Or it doesn't matter? Thank you!
by Joyce 3H
Sat Feb 07, 2015 4:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Course Reader page46 example of "Gold and Nitric Acid"
Replies: 1
Views: 278

Course Reader page46 example of "Gold and Nitric Acid"

Why NO3(2-) can be reduced to NO rather than NO2 or N2 in the half reaction? I believe it is somehow related to stability of the product but I am not sure how to explain it thoroughly.
Thank you in advance!
by Joyce 3H
Tue Jan 27, 2015 12:32 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: HW 8.87 (a) spontaneous process and entrophy
Replies: 1
Views: 334

HW 8.87 (a) spontaneous process and entrophy

The spontaneous process are accompanied by an increase in entrophy. Because the negative delta S(surrounding), the dissolving process is not favored. So I wonder the entrophy that is responsible for judging whether the process is spontaneous or not is specifically the delta S(surrounding) at all cas...
by Joyce 3H
Tue Jan 27, 2015 12:12 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: How is C60(g) --> C60(s) calculated? HW 7.109 (b)
Replies: 1
Views: 445

How is C60(g) --> C60(s) calculated? HW 7.109 (b)

Can someone explain how is the C60(g)--> C60(s) calculated? Or is there any standard data already exist?
Thank you!
by Joyce 3H
Tue Jan 27, 2015 12:04 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: standard formation enthalpy in Combustion
Replies: 1
Views: 352

standard formation enthalpy in Combustion

In calculating standard reaction enthalpy in combustion, which is exothermic reaction, why do we always use the standard formation enthalpy of liquid form of water instead of the gaseous one?
Thank you !
by Joyce 3H
Mon Dec 08, 2014 12:47 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: electron-related concept
Replies: 1
Views: 386

electron-related concept

Can someone help me clarify the relationship between electron delocalization power and electron withdrawing power? Quite confused by those two concepts~ Thank you so much!
by Joyce 3H
Mon Dec 08, 2014 12:36 pm
Forum: Amphoteric Compounds
Topic: (SO4)2-,(HSO4)-, H2SO4,
Replies: 3
Views: 5088

Re: (SO4)2-,(HSO4)-, H2SO4,

So HSO4- can act as both acid and base, and it's acidic at the same time? Well, another example similar to this is [H3PO4, H2PO4-, (HPO4)2-, (PO4)3-]. Is it true that both H2PO4- and (HPO4)2- can function just like HSO4-? Or only (HPO4)2- since H3PO4 is a very strong acid, which make it impossible t...
by Joyce 3H
Fri Dec 05, 2014 4:25 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: -CH3 electron donating property
Replies: 1
Views: 604

-CH3 electron donating property

Why do we say that -CH3 (in CH3COOH) has electron donating property and less electron withdrawing than -H (in HCOOH)? I mean from lewis structure, there's no electron left alone around C in -CH3 (electrons all form bonds), how can you say"electron donating property"? And what kind of struc...
by Joyce 3H
Fri Dec 05, 2014 4:14 pm
Forum: Amphoteric Compounds
Topic: (SO4)2-,(HSO4)-, H2SO4,
Replies: 3
Views: 5088

(SO4)2-,(HSO4)-, H2SO4,

(HSO4)- is a very special acidic molecule, and it can result in (SO4)2- instead of H2SO4 from the reaction with H2O. Why? Is it because H2SO4 is a strong acid compared to HSO4, and simply weak acid cannot result in strong acid. I am very confused about the point. Thank you so much in advance!
by Joyce 3H
Wed Nov 19, 2014 6:25 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endothermic and exdothermic
Replies: 1
Views: 404

endothermic and exdothermic

Exothermic reaction give off heat because it releases energy from forming bonds to achieve a more stable energy situation. Then why 6CO2(g)+6H2O(l)-->C6H12O6(aq)+6O2(g), a bond-making reaction, is a endothermic reaction?
Thank you in advance!
by Joyce 3H
Mon Nov 10, 2014 1:34 pm
Forum: Hybridization
Topic: Textbook 3.43
Replies: 2
Views: 497

Re: Textbook 3.43

Thank you ~big help!
by Joyce 3H
Sun Nov 09, 2014 11:27 pm
Forum: Hybridization
Topic: Textbook 3.43
Replies: 2
Views: 497

Textbook 3.43

"Noting that bond angle of sp3 hybridized atom is 109.5, that of sp2 hybridized atom is 120." The question is whether the bond angle between two hybridized orbitals increase or decrease as s-character of the hybridization increase. What does the s-character stand for? And what exactly the ...
by Joyce 3H
Fri Oct 31, 2014 5:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Ch. 3 #7 Question on number of electrons
Replies: 3
Views: 1180

Re: Ch. 3 #7 Question on number of electrons

But how come the shape is linear? Shouldn't it be something like angular?
by Joyce 3H
Fri Oct 17, 2014 5:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: The notation for Group 5 transition metals
Replies: 2
Views: 1214

The notation for Group 5 transition metals

It's Question 1.85 (c) of Chapter 1. It asks for notation for the valence-shell configuration of Group 5 transition metals. I think the answer (n-1)d^5 ns^2 is incorrect because apparently no element in Group 5 can apply that notation. And from my observation of the periodic table, there seems no ce...
by Joyce 3H
Sun Oct 12, 2014 5:32 pm
Forum: DeBroglie Equation
Topic: Photon has no rest mass, how do you calculate its momentum?
Replies: 2
Views: 391

Re: Photon has no rest mass, how do you calculate its moment

But isn't De Broglie‘s equation based on the momentum function p=mv, which in the first place doesn't apply to the "photon" situation?
by Joyce 3H
Fri Oct 10, 2014 2:02 pm
Forum: DeBroglie Equation
Topic: Particle-like properties and wave-like properties
Replies: 1
Views: 827

Particle-like properties and wave-like properties

Is it true that electron, neutron, and light all display particle-like properties and wave-like properties in experiment? And classical particles only display particle-like properties in experiment?

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