CHEMISTRY COMMUNITY

StudentD2B

What does Dr. Lavelle mean in saying " Understand what is mean when kinetics rather than thermodynamics is controlling a reaction."

StudentD2B

Eº cell is the standard state cell potential, which means that the value was determined under standard states which include a concentration of 1 Molar (mole per liter) and an atmospheric pressure of 1. E cell is the non-standard state cell potential, which means that it is not determined under a con...

StudentD2B

technically k' is the rate of the reverse reaction. k is the rate of the forward reaction. K is the equilibrium constant. K=k/k'

StudentD2B

What exactly are you talking about? You can make an the approximation for x when the equilibrium constant is sufficiently small (10^-5) and with the 5% approximation

StudentD2B

a concentration cell is a limited form of a galvanic cell that has two equivalent half-cells of the same composition differing only in concentrations. He might have been talking about concentration cell corrosion which occurs when two or more areas of a metal surface are in contact with different co...

StudentD2B

Cp is the amount of heat required to raise the temperature of a substance of 1Kg mass by one degree celsius at constant pressure . Cv is the amount of heat required to raise the temperature of a substance of 1Kg mass by one degree celsius at constant volume . So use Cp when there is constant pressur...

StudentD2B

For a general reaction of the type aA + bB → cC + dD, the standard free-energy change and the equilibrium constant are related by the following equation: ΔG° = −RT lnK. Given the relationship between the standard free-energy change and the standard cell potential: ΔG° = −nFE°cell, we can write: −nFE...

StudentD2B

Find K for the first fast step, If the fast step is after the slow step, (ie. fast, slow, fast) you can ignore the second fast step completely because steps that follow the rate determining step take place as soon as the intermediate has been formed and have a negligible effect on the overall rate

StudentD2B

There are 4 different things you're looking at here:(1) Average Rate of Reaction, (2) Unique Average Rate of Reaction, (3) Instantaneous Rate of Reaction, (4) and Unique Instantaneous Rate of Reaction Average Rate of Reaction : The reaction rate calculated by measuring the change in concentration of...

StudentD2B

Yes! exactly.
Zeroth order - Rate =k
First Order - Rate =k[A]
Second Oder - Rate =k[A]^2

StudentD2B

In a way they matter for elementary reactions in that the formula of a species appears as many times as that species is required (ie: O2+O2+O2 = 3O2) Since elementary reactions match their chemical expression, if a reaction is elementary, the order of a reagent will match its stoichiometric coeffici...

StudentD2B

Are we going to need to know how to get an integrated rate law from a normal rate law on the final?

StudentD2B

In the 7th edition Focus 6C.3-4, when they reference HA, H-A, and A, what does the "A" stand for. Is it any acid or any acidic oxide or what?

StudentD2B

Also are we responsible for table 6C.4 "Contributions to the Enthalpy of Proton Transfer of Binary Acids*"

StudentD2B

How much are we going to have to know about entropy and enthalpy and Gibbs Free Energy for the final. It is mentioned quite a few times in the sections in the book (7th edition Focus 6B.1 and 6C.3 - 6C.4) There are also a bunch of equations we didn't cover in class, do we need to know how to use tho...

StudentD2B

How do you determine if a molecule has dipole dipole interactions? I know all atoms have London Dispersion, but I struggle with how exactly to know about dipole dipole

StudentD2B

Dipole moments can exist where polarity does not if they cancel each other out due to molecular geometry in a polyatomic molecule. For example CO2. The oxygen is more electronegative, but the C-O bonds are Both linear so they cancel each other out. If you have version 7 of the textbook there is a ch...

StudentD2B

All of outline 4 and the end of outline three, but I would brush up on all of outline three just to be safe

StudentD2B

Yes nonmetals are more electronegative than metals and this does have to do with their placement on the periodic table in that electronegativity increases up a group and left to right across a period. Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. E...

StudentD2B

When there is more than one central atom in a molecule the hybridization of each central atom is matched to the shape at that atom predicted by VSEPR

StudentD2B

Flourine because electronegativity increases up and to the right

StudentD2B

Not exactly. A pi bond has two electrons that lie on two lobes, one on each side of the internuclear axis, but is still only one bond. P-orbitals in a pi bond overlap in a side by side fashion. A sigma bond results from end-to end overlap (consequently because of this a sigma bond is stronger than a...

StudentD2B

Part of creating a Lewis Structure is finding the structure with the lowest formal charge so I would say that yes it is fairly important to use the correct Lewis structure since the Lewis structure will affect the outcome of the VSEPR

StudentD2B

As for the lone pairs on the oxygen I believe that the "Osp2" denotation is saying that the lone pairs on the oxygen are in one of the hybridized sp2 orbital. There are three: h_{1}=s + 2^{\frac{1}{2}}p_{y} h_{2}= s+(\frac{3}{2})^{\frac{1}{2}}p_{x}-(\frac{1}{2})^{\frac{1}{2...

StudentD2B

I believe the labeling is specifying the different types of hybridized orbitals that are participating in the bond. (sp, sp2, sp3, sp3d, or sp3d2). For example on the top right double bond between oxygen and carbon its saying that the sigma bond is between the hybridized sp2 orbital of the carbon an...

StudentD2B

Since water is polar, it has both negative and positive regions in the molecule, the reason this is good for dissolving ionic compounds is that the water molecule and the ionic compound attract each other and thus it dissolves in water, while nonpolar molecules repel away from water and don't disso...

StudentD2B

Nodal planes are areas where there is no possibility of electron density. In other words, it will be impossible to find electrons in nodal planes. Essentially for this class, I believe that all you need to know is that the p orbital has 1 nodal plane and the d orbital has 2 nodal planes. When I was...

StudentD2B

The molecule is linear, but since nitrogen is the least electronegative, it is the central atom. So the molecules are lined up N-N-O. Oxygen is much more electronegative than nitrogen making the molecule negatively charged on the oxygen side and therefore polar. Why is it lined up that way though. ...

StudentD2B

Thank you!!!!

StudentD2B

Could someone clarify what exactly a nodal plane is, how to find them, and what they cause? Im a little confused on the whole subject.

StudentD2B

Why is N20 Polar? If its a linear molecule with 2 nitrogens and 1 oxygen, shouldn't it be non-polar?

StudentD2B

Also to add onto the question i just posted, do my responses to other students questions count toward the total responses or is it only questions i post myself?

StudentD2B

How do i tell how many posts I've made on here

StudentD2B

Does anyne have like a tip or trick to remember all the specific bond angles or is repetition my best bet?

StudentD2B

Why does the polarity of water part of the reason why it is a good solvent for ionic compounds? More generally, what role does polarity have in things dissolving?

StudentD2B

How do you know if a dipole is permanent or not. For example in the case of c5h12 from page 190 of the 7th version of the text book. (in the margins of the actual text, not a question)

StudentD2B

Could someone explain why for 13D (I looked this up on the internet) the atoms have different electron configurations? I know that the electron configurations are: Neutral SC Atom: 1s2 2s2 2p6 3s2 3p6 3d1 4s2 SC2+ Ion: 1s2 2s2 2p6 3s2 3p6 3d1 Neutral K atom: 1s2 2s2 2p6 3s2 3p6 4s1 But could someone...

StudentD2B

Clearly I needed to look at this earlier than I did..

For 11b, would you subtract to n=3 from the n=1 or the n=1 from the n=3

StudentD2B

Jk final frequency I get 3.77 * 10^14. Why is this off

StudentD2B

Could someone explain 8b to me. Please tell me where I went wrong here. I found:
wavelength: 1.10 * 10^-9m
P=7.29 * 10^-43
V=8.00 * 10^-13
Work Function= 2.50 * 10^-19 J/atom
Kinetic Energy= 7.00 * 10^-55
Final Frequency= 5.94 * 10^-10

StudentD2B

Lina Petrossian 3D wrote:How do you go about solving the first problem?

https://wps.prenhall.com/wps/media/obje ... h0305.html

See for exact solution

StudentD2B

I tried the first problem and got it very very wrong. How would I solve it correctly?

StudentD2B

Why do you multiply by 10^5?

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