Search found 30 matches

by Wendy_Xie
Wed Mar 02, 2016 2:28 pm
Forum: *Identifying Primary, Secondary, Tertiary, Quaternary Carbons, Hydrogens, Nitrogens
Topic: Sec and tert - Alphabetical order
Replies: 2
Views: 566

Re: Sec and tert - Alphabetical order

In this case I won't use the common names but the IUPAC naming instead. This should solve such problems.
by Wendy_Xie
Wed Mar 02, 2016 2:25 pm
Forum: *Alkanes
Topic: Common Names
Replies: 1
Views: 368

Re: Common Names

I think we just need to remember the common names for reference. Basically you need to know what it is talking about when you see a compound in common names. If you do the naming yourself, I think it is up to you to use the common names or not. Personally I prefer the common names because it's short...
by Wendy_Xie
Wed Mar 02, 2016 2:23 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Cis and Trans in Large Compounds
Replies: 2
Views: 413

Re: Cis and Trans in Large Compounds

What do you mean by more than 4 carbons?
by Wendy_Xie
Fri Feb 05, 2016 11:50 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy change in reversible adiabatic expansion?
Replies: 1
Views: 297

Entropy change in reversible adiabatic expansion?

I understand that in reversible adiabatic expansion that
delta U=w=-nRTln(V2/V1)

But what is the entropy change?
By definition Entropy change=Q/T, can we say that because Q=0 in this case delta S=0 as well?

Thank you!
by Wendy_Xie
Thu Feb 04, 2016 2:46 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: HW 14.37 c
Replies: 1
Views: 229

HW 14.37 c

I constantly get -1.355267912 and I don't know why
by Wendy_Xie
Thu Feb 04, 2016 1:08 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: HW 14.27
Replies: 1
Views: 298

HW 14.27

Why can't we simply add U4+ + e- --->U3+ and U3+ + 3e- -----> U together to get the standard potential?
by Wendy_Xie
Mon Feb 01, 2016 8:07 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8205
Views: 1433221

Re: Chemistry Jokes

https://www.facebook.com/IFeakingLoveScience/videos/1208151935872482/
An interesting video about how elements react with each other
by Wendy_Xie
Mon Feb 01, 2016 10:33 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: H, S, and G at equilibrium
Replies: 1
Views: 306

Re: H, S, and G at equilibrium

Delta G is zero at equilibrium, and this is all we know. As for H S and G, as long as they make the value of delta G zero.
by Wendy_Xie
Wed Jan 20, 2016 12:09 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: What influence the degeneracy?
Replies: 1
Views: 438

What influence the degeneracy?

I feel like it's hard to understand the degeneracy. What factors influence degeneracy? So far I know volume is one, but what are some other factors?
Thank you!
by Wendy_Xie
Sat Jan 16, 2016 11:51 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Something wrong in HW 8.63
Replies: 3
Views: 663

Something wrong in HW 8.63

I think the correct answer should be -38.72 because the heat of formation of K2S should be 471.5 instead of 417.5?
by Wendy_Xie
Tue Jan 12, 2016 7:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy?
Replies: 1
Views: 338

Enthalpy?

“enthalpy is not a measure of the energy that a system possesses in the same fundamental sense as the internal energy. It is just a device that takes into account the effects of allowing the volume to change during heat transactions at constant pressure.” What does this mean?
by Wendy_Xie
Mon Jan 11, 2016 8:57 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 8.25
Replies: 1
Views: 356

Re: Question 8.25

+3.5 kJ indicates the heat absorbed by the calorimeter, and -3.5 indicates the heat released by the solution, as we are calculating the energy change of the calorimeter, it should be +3.5. 0.200M is important because there are same amount of KOH and HBr, only in this case can the solution be totally...
by Wendy_Xie
Mon Jan 11, 2016 8:52 am
Forum: Phase Changes & Related Calculations
Topic: HW 8.17 Work done in a phase change
Replies: 4
Views: 1204

Re: HW 8.17

Because of the phase change.
by Wendy_Xie
Thu Nov 19, 2015 11:12 am
Forum: Naming
Topic: monochloro?
Replies: 1
Views: 379

monochloro?

In a naming of a coordinate compound I saw something like "monochloro". Are we supposed to put mono before chloro? Or we just write chloro?
by Wendy_Xie
Thu Nov 19, 2015 11:10 am
Forum: Naming
Topic: Using H2O vs OH2
Replies: 1
Views: 384

Re: Using H2O vs OH2

I don't think it really matters. You can write it either way.
by Wendy_Xie
Thu Nov 19, 2015 10:51 am
Forum: Naming
Topic: Naming of Fe(CO)5
Replies: 1
Views: 463

Naming of Fe(CO)5

Should it be pentacarbonyliron(0) or pentacarbonylferrate(0) and why?
by Wendy_Xie
Thu Nov 19, 2015 10:27 am
Forum: Significant Figures
Topic: Sig Fig in Equilibrium
Replies: 2
Views: 617

Sig Fig in Equilibrium

When we are calculating the equilibrium constant or the concentration of the substance, how many sig figs are we supposed to keep?
by Wendy_Xie
Fri Nov 13, 2015 12:48 pm
Forum: Naming
Topic: useful resources
Replies: 1
Views: 204

useful resources

by Wendy_Xie
Sat Nov 07, 2015 1:35 am
Forum: Resonance Structures
Topic: Structure of O3
Replies: 1
Views: 363

Structure of O3

Why can't there be 2 double bonds in O3?
by Wendy_Xie
Sat Oct 31, 2015 11:06 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: MO? Bond Order?
Replies: 2
Views: 558

Re: MO? Bond Order?

If you understand the orbital of atom, which is just the s p d f things, then you will understand MO. MO is basically the same thing, it's just in a molecule instead of in an atom.

The larger the bond order is, the stronger and shorter the bond will be.
by Wendy_Xie
Sat Oct 31, 2015 11:04 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: MO theory, how do we know Z?
Replies: 2
Views: 421

Re: MO theory, how do we know Z?

For molecules which have two different atoms, if there is one that has the Z less than 8, then you use the one which sigma 2pz has higher energy level. You know Z just from the periodic table.
by Wendy_Xie
Sat Oct 31, 2015 11:02 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: What order do you fill bonds?
Replies: 3
Views: 507

Re: What order do you fill bonds?

You fill the lowest one first, in this case it's the sigma 2pz, and then you put one in pi 2py and another one in pi 2px in the same spinning direction, then you go back to pi 2py and fill it with another electron which spins in the opposite direction of the two you already put in, and another elect...
by Wendy_Xie
Fri Oct 30, 2015 2:21 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Ionization Energy based on Valence-Shell Configuration
Replies: 1
Views: 314

Re: Ionization Energy based on Valence-Shell Configuration

The electron configuration is related to the molecular orbital, so it shows how many electrons are there in bonding and anti-bonding. Once you know the number of electrons in bonding and anti-bonding, you can calculate the bond order, then you know the strength of the bond.(I don't know if this answ...
by Wendy_Xie
Fri Oct 30, 2015 2:19 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Determining Paramagnetism
Replies: 2
Views: 394

Re: Determining Paramagnetism

Well I just draw it in my mind... but it will be helpful if you write the electron configuration out(which is much less work).
by Wendy_Xie
Fri Oct 30, 2015 2:17 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Changes on Bond Order
Replies: 1
Views: 216

Re: Changes on Bond Order

It is similar to the question on workbook, which asks if we remove the electron in O2 and N2 then what will happen. If the electron removed is in anti bonding, then the bond order increases and the bond gets stronger; if it's in the bonding, then bond order decreases and it's get weaker.
by Wendy_Xie
Fri Oct 30, 2015 2:14 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Bond order conceptual
Replies: 1
Views: 267

Re: Bond order conceptual

It is the number of bond. For example the double bond between O2, the bond order is just 2. For N2, the bond order is 3, then it's just the triple bond. And for N2+, bond order is 2.5, then it just means it's something between double bond and triple bond.
by Wendy_Xie
Fri Oct 30, 2015 2:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Why Can't T-shaped Molecules be Trigonal Planar?
Replies: 3
Views: 2371

Re: Why Can't T-shaped Molecules be Trigonal Planar?

Consider the T-shape of AX3E2, if you put two lone pairs on the two opposite sides of the plane, then you will get six 90 angles between lone pairs and bonds. If you put the two lone pairs on the trigonal plane, the you will get one 120 angles between lone pairs and four 90 angles between lone pairs...
by Wendy_Xie
Fri Oct 30, 2015 12:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: ClO2+
Replies: 1
Views: 502

ClO2+

why is ClO2+ forming a double bond between Cl and O?
by Wendy_Xie
Fri Oct 23, 2015 9:15 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing power and size of ions
Replies: 1
Views: 5488

Polarizing power and size of ions

I saw a sentence goes like this:

Smaller, more highly charged ions have greater polarizing power.

The polarizability increases as the ion becomes larger and less electronegative.

Why it is like this?
by Wendy_Xie
Fri Oct 23, 2015 9:07 am
Forum: Electronegativity
Topic: How to determine electronegativity without the chart?
Replies: 2
Views: 656

Re: How to determine electronegativity without the chart?

I think everything we need to do is to remember the tendency. As if the two elements are too close, I don't think we will be tested on this.

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