CHEMISTRY COMMUNITY

Daniel_Frees_1L

@Karina, I think you're right but these two specifically were labeled as acidic oxides on lavelles slide

Daniel_Frees_1L

I've gotten the same answer for 6B.5e) over and over and I'm convinced im doing the problem right. mg/L --> dimensional analysis to mol/L. OH- Molarity is the same because strong base. -log(M OH-) = -log(0.009714) = 2.012 = pOH. pH = 11.998. Does the answer key have a typo, or am I missing something?

Daniel_Frees_1L

@Joaquin I should've included that the products are given as well. (-->CH3CONH2 + H2O). The book says no proton is transferred. These problems we have to break up into ionic parts and then get rid of ions that are unchanged to find the net ionic equation. We then look at whether a H+ ion moved. I tr...

Daniel_Frees_1L

How do we find c) and d) to be amphoteric? Is it just memorization? Also, the answer in the book saying those are amphoteric goes against what we learned in class.

Daniel_Frees_1L

Same question here, that goes against what we learned in class too.

Daniel_Frees_1L

7th ed) I get how the final Lewis structure drawn in 6A.15 for CLO2- is the most stable resonance structure. However, the answer does not have the lowest energy resonance structure for SO2 on the reactants side. Is this because they wanted to match the resonance with the final structure? And would w...

Daniel_Frees_1L

Will we have any problems like 6A.9 on the final? If so, what is the process for writing net ionic equations (I get what they are, but not how to consistently know where to break up big compounds into two ions)? For example, for part C I thought I could break CH3COOH to CH3CO+ and OH- and then NH3 w...

Daniel_Frees_1L

I think it's important to add that they are able to release or take up multiple H+ because of the stability of their anion compounds.

Daniel_Frees_1L

They are both the same, but I think Lavelle writes them differently when he wants to make a point about where the - charge actually is. like H+ -OH coming together rather than H+ OH- coming together because the - charge goes next to the + and pulls the two into a bond.

Daniel_Frees_1L

@Samantha I think what she means is they do nothing to the pH of the solution. For K+ and Na+ the charge isn't high enough to pull charge on an O in H20 and lead to the release of an H+. Since the charge isn't high enough to do that they aren't causing acidity. For Br-, it does nothing because it is...

Daniel_Frees_1L

Its good to know the trends either way. Electronegativity, electron affinity both increase up and to the right. Atomic radius increases down and to the left

Daniel_Frees_1L

What are diamagnetism and paramagnetism? And do we need to know them for the test?

Daniel_Frees_1L

To clarify lone *pairs* count as regions of electron density. I don't know what a single electron would count as, but certainly the lone pair does not count as two regions because of its 2e-

Daniel_Frees_1L

I could be misunderstanding your question, but I believe Lavelle said he doesn't require any drawing of the orbitals or shapes in this class.

Daniel_Frees_1L

Also, I believe bonds always start with a sigma bond, and then pi bonds are added onto that with further bonding between the two atoms.

Daniel_Frees_1L

Dr. Lavelle said the easiest way to understand hybridization is to think about regions of electron density rather than bond number, so hybridize to the point where number of orbitals (sp3 = 4 regions) equals number of regions of density.

Daniel_Frees_1L

Just to add on to what Brian said, the reason why lone pairs cause more repulsion is because they are more diffuse than a bond between atoms.

Daniel_Frees_1L

Do we have to know the VSPER formulas themselves? Or just the final shape

Daniel_Frees_1L

Does anyone know how to find all the resonance structures on 2.7? I don't get how the answer chose which ones to put

Daniel_Frees_1L

Another way to look at this that might make more sense is that in a double bond two pairs of electrons are shared between atoms whereas a single bond has only one shared pair of electrons. With more electrons shared, the atoms have to pull closer together and are more 'dependent' on staying bonded w...

Daniel_Frees_1L

I totally zoned out when Dr. Lavelle explained this in class. I understood why molecules that are more polarizable had higher melting and boiling points (bc attraction) but I didn't catch why larger hydrocarbons are more polarizable than smaller ones. Can someone explain?

Daniel_Frees_1L

In addition to increased distance between the outer electrons and the nucleus, larger elements have more electron shielding which further reduces the pull of the nucleus on outer e-.

Daniel_Frees_1L

I know that the electron to take away when making an ion configuration (ie: Cr+) is typically the outermost electron, but are there any exceptions to this rule?

Daniel_Frees_1L

Do ions always form with such a configuration that there are the fewest possible unpaired e-? When doing problem 2A.21 part d I took silver's ground state configuration and removed 1 5s e- to make the Ag+ ion, and thus had [Kr] 4d9 5s1 as my electron configuration. The book says the answer is [Kr] 4...

Daniel_Frees_1L

I understand that s-block metals are usually more reactive than p-block metals because they are closer to a full valence shell, but is there a more technical explanation for this I should be aware of?

Daniel_Frees_1L

Question 1F.11 seems to pull on some exceptions to the trends we learned. How are we supposed to figure this question out, and in what detail are we supposed to understand exceptions to overall periodic table trends for the test?

Daniel_Frees_1L

The outline for test 2 says we should be able to 'Describe the factors affecting the energy of an electron in a many-electron atom.' I know that electron energy increases in multi-electron atoms when the electron is in a higher level shell, and when the sub shell goes from s->p->d (aka quantum numbe...

Daniel_Frees_1L

The Section 2 outline says we should be able to "List the allowed energy levels of a bound electron in terms of the quantum numbers n, l, and ml." Does this just mean we should understand how to fill orbitals and know what outer shell number (n), shape (l), and orientation (ml) are? ie: kn...

Daniel_Frees_1L

In our outline for test 2, it says "Understand the relationship between Schrodinger's equation (H ψ = E ψ), wave functions, and orbitals."

I'm not sure exactly what these means and I'm a little hazy on the relationship between the three. Can anyone help clarify?

Daniel_Frees_1L

psi squared is actually not the probability of finding an electron in a given orbital, it's just proportional to the probability. It's actually probability density (so probability density * volume = probability of finding an electron

Daniel_Frees_1L

To figure out how many orbitals are in a sub shell l: # = 2l +1

Daniel_Frees_1L

I understand the overall vague idea of the Shrodinger equation, but how will it apply to our tests? What about it is important to understanding our problems if we're not going to be using the equation?

Daniel_Frees_1L

Problem 1D.9 seems to touch on a lot of specific and weird aspects of orbitals we didn't cover in class. Will we need to know these things for the test? If so, is there another resource aside from the book that might make them easier to understand?

Daniel_Frees_1L

Does anyone know how to solve a problem like 1A.15 where we don't know the starting n or final n given wavelength of emitted photon? I tried playing around with the equations to solve and got close, but it seemed too messy and unclear. I'm sure there's a better way. Let me know, thanks

Daniel_Frees_1L

Hey, I must be missing something obvious but I keep getting 29 and 30 wrong on the quiz for the photoelectric effect module. 29 asks what the energy required to remove one electron from sodium is, and the problem tells us the work function for sodium is 1.506 *10^2 kj --> 1.506 * 10^5 J. Isn't that ...

Daniel_Frees_1L

Why is there no variable for intensity in the Energy equation for the photoelectric experiment? I understand that increasing intensity doesn't change electrons emitted when the frequency is too low to release electrons, but isn't it proportional to the electrons released when frequency is past the t...

Daniel_Frees_1L

Was anyone actually able to balance the third chemical equation in problem L.35? I got stuck after balancing Fe, then NA, then BR, then C, the oxygens would not balance. I even plugged the problem into a chemical equation balancer online after being stuck for a while and it said the equation cannot ...

Daniel_Frees_1L

@005 if it's like the other homework, it's due on next Friday's lecture the first week, and then before your discussion section each week after that

Daniel_Frees_1L

Knowing that oxygen has more atomic mass than nitrogen and hydrogen combined, you can estimate closer to 75% or greater. It just says don't use a calculation, not that you can't estimate using the atomic masses.

Daniel_Frees_1L

Given that the problem didn't specify the units to put our answer in, it probably doesn't actually matter whether you responded with m or km.

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