Search found 40 matches
- Sat Dec 08, 2018 1:22 pm
- Forum: Amphoteric Compounds
- Topic: 7th edition 6A.17
- Replies: 3
- Views: 367
Re: 7th edition 6A.17
@Karina, I think you're right but these two specifically were labeled as acidic oxides on lavelles slide
- Fri Dec 07, 2018 11:28 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: Error in 6B.5 e)?
- Replies: 2
- Views: 530
Error in 6B.5 e)?
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?
- Fri Dec 07, 2018 11:20 pm
- Forum: Bronsted Acids & Bases
- Topic: 6A.9
- Replies: 2
- Views: 363
Re: 6A.9
@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...
- Fri Dec 07, 2018 10:31 pm
- Forum: Amphoteric Compounds
- Topic: 6A.17 (admin?)
- Replies: 2
- Views: 517
6A.17 (admin?)
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.
- Fri Dec 07, 2018 10:28 pm
- Forum: Amphoteric Compounds
- Topic: 7th edition 6A.17
- Replies: 3
- Views: 367
Re: 7th edition 6A.17
Same question here, that goes against what we learned in class too.
- Fri Dec 07, 2018 9:25 pm
- Forum: Lewis Acids & Bases
- Topic: 6A.15
- Replies: 2
- Views: 366
6A.15
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...
- Fri Dec 07, 2018 7:32 pm
- Forum: Bronsted Acids & Bases
- Topic: 6A.9
- Replies: 2
- Views: 363
6A.9
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...
- Wed Dec 05, 2018 5:57 pm
- Forum: Polyprotic Acids & Bases
- Topic: Significance of Polyprotic Acids & Bases
- Replies: 6
- Views: 1005
Re: Significance of Polyprotic Acids & Bases
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.
- Wed Dec 05, 2018 5:55 pm
- Forum: Conjugate Acids & Bases
- Topic: OH- vs -OH
- Replies: 3
- Views: 430
Re: OH- vs -OH
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.
- Wed Dec 05, 2018 5:53 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: The pH of Solutions of Weak Acids and Bases 12.65
- Replies: 5
- Views: 638
Re: The pH of Solutions of Weak Acids and Bases 12.65
@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...
- Tue Nov 27, 2018 7:03 pm
- Forum: Electronegativity
- Topic: Electronegativity
- Replies: 4
- Views: 911
Re: Electronegativity
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
- Tue Nov 27, 2018 6:53 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: diamagnetism and paramagnetism
- Replies: 2
- Views: 346
diamagnetism and paramagnetism
What are diamagnetism and paramagnetism? And do we need to know them for the test?
- Tue Nov 27, 2018 6:52 pm
- Forum: Hybridization
- Topic: Lone Electrons and Hybridization
- Replies: 3
- Views: 560
Re: Lone Electrons and Hybridization
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-
- Tue Nov 20, 2018 12:31 pm
- Forum: Hybridization
- Topic: For the Test
- Replies: 3
- Views: 421
Re: For the Test
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.
- Tue Nov 20, 2018 12:28 pm
- Forum: Hybridization
- Topic: Pi and Sigma Bonds
- Replies: 4
- Views: 469
Re: Pi and Sigma Bonds
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.
- Tue Nov 20, 2018 12:25 pm
- Forum: Hybridization
- Topic: Tips
- Replies: 2
- Views: 361
Re: Tips
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.
- Thu Nov 15, 2018 10:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Trigonal Pyramidal
- Replies: 10
- Views: 487
Re: Trigonal Pyramidal
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.
- Thu Nov 15, 2018 10:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Memorizing the VSPER Models
- Replies: 4
- Views: 475
Re: Memorizing the VSPER Models
Do we have to know the VSPER formulas themselves? Or just the final shape
- Thu Nov 15, 2018 10:07 pm
- Forum: Resonance Structures
- Topic: 2.7
- Replies: 1
- Views: 239
2.7
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
- Wed Nov 07, 2018 5:21 pm
- Forum: Bond Lengths & Energies
- Topic: bond lengths and strengths
- Replies: 9
- Views: 942
Re: bond lengths and strengths
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...
- Wed Nov 07, 2018 5:19 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Why are larger hydrocarbons more solid?
- Replies: 2
- Views: 289
Why are larger hydrocarbons more solid?
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?
- Wed Nov 07, 2018 5:16 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Cause and Effect of Electrons in a Molecule
- Replies: 2
- Views: 295
Re: Cause and Effect of Electrons in a Molecule
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-.
- Sun Nov 04, 2018 6:38 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Which electron disappears for ion configurations
- Replies: 2
- Views: 404
Which electron disappears for ion configurations
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?
- Mon Oct 29, 2018 6:27 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ion formation and unpaired e-
- Replies: 2
- Views: 255
Ion formation and unpaired e-
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...
- Mon Oct 29, 2018 6:23 pm
- Forum: Trends in The Periodic Table
- Topic: 1f.19
- Replies: 1
- Views: 227
1f.19
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?
- Mon Oct 29, 2018 6:20 pm
- Forum: Trends in The Periodic Table
- Topic: 1f.11
- Replies: 1
- Views: 263
1f.11
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?
- Wed Oct 24, 2018 3:08 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Energy of Electron in many-electron atom
- Replies: 2
- Views: 126
Energy of Electron in many-electron atom
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...
- Wed Oct 24, 2018 3:05 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Test 2 outline
- Replies: 4
- Views: 753
Test 2 outline
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...
- Wed Oct 24, 2018 3:02 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation on Outline
- Replies: 2
- Views: 603
Shrodinger Equation on Outline
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?
I'm not sure exactly what these means and I'm a little hazy on the relationship between the three. Can anyone help clarify?
- Thu Oct 18, 2018 9:54 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Psi squared meaning
- Replies: 4
- Views: 2957
Re: Psi squared meaning
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
- Thu Oct 18, 2018 9:50 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Problem ID.11
- Replies: 3
- Views: 307
Re: Problem ID.11
To figure out how many orbitals are in a sub shell l: # = 2l +1
- Thu Oct 18, 2018 9:49 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger equation
- Replies: 2
- Views: 333
Re: Shrodinger equation
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?
- Thu Oct 18, 2018 9:47 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Problem 1D.9
- Replies: 3
- Views: 405
Problem 1D.9
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?
- Thu Oct 11, 2018 8:56 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Problem 1A.15
- Replies: 1
- Views: 105
Problem 1A.15
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
- Sun Oct 07, 2018 10:37 pm
- Forum: Properties of Light
- Topic: Quiz for PhotoElectric Effect Module
- Replies: 1
- Views: 77
Quiz for PhotoElectric Effect Module
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 ...
- Sun Oct 07, 2018 9:48 pm
- Forum: Properties of Light
- Topic: Photoelectric experiment- increasing intensity when frequency is high enough
- Replies: 1
- Views: 49
Photoelectric experiment- increasing intensity when frequency is high enough
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...
- Tue Oct 02, 2018 11:59 am
- Forum: Balancing Chemical Reactions
- Topic: Problem L.35
- Replies: 5
- Views: 357
Problem L.35
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 ...
- Fri Sep 28, 2018 8:50 pm
- Forum: SI Units, Unit Conversions
- Topic: How does grading for discussion posts work?
- Replies: 80
- Views: 8691
Re: How does grading for discussion posts work?
@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
- Fri Sep 28, 2018 8:46 pm
- Forum: Empirical & Molecular Formulas
- Topic: Percent Composition
- Replies: 5
- Views: 638
Re: Percent Composition
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.
- Fri Sep 28, 2018 8:42 pm
- Forum: SI Units, Unit Conversions
- Topic: Standard SI Unit, Question E1
- Replies: 3
- Views: 479
Re: Standard SI Unit, Question E1
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.