CHEMISTRY COMMUNITY

DanielHong2L

hello how does one decide whether a formula is a strong acid, weak acid, strong base, or weak base? for example how would i figure out what Ba(OH)2 is? thank you Strong Acid: Big size | Longer Bond Length | Weaker Bonds | Easily donates Proton -> Stronger Acid orrrrr if Resonance to stabilize acid ...

DanielHong2L

Just a bit confused but what does it mean when an acid/base is completely/partially ionized in water and how does this relate to how strong/weak an acid/base is? Stronger acids; donates more protons in solution, becomes completely ionized by loosing protons. Ionized in water = disassociated Stronge...

DanielHong2L

Cumulative; the more time / focus we had on one topic, the more prevalent it'll be is what Dr. Lavelle said I believe

DanielHong2L

Friday's "lecture" I believe is a bruincast review

DanielHong2L

Marylyn Makar 1D wrote:Hi! What's the difference between pH values and pKa values?

"p" = -log[]
Ka = [A-][H+] / [AH]
pKa = -log ^ number; pertains to acidity
- More acidic = higher Ka, lower pKa

H = [H30]
pH = -log[H30]
- Gives scale of concentration from acidic - alkaline-basic

Hope this helps a little!

DanielHong2L

hello how does one decide whether a formula is a strong acid, weak acid, strong base, or weak base? for example how would i figure out what Ba(OH)2 is? thank you Strong Acid: Big size | Longer Bond Length | Weaker Bonds | Easily donates Proton -> Stronger Acid orrrrr if Resonance to stabilize acid ...

DanielHong2L

Thank you! I'm having trouble with naming compounds so these videos are definitely going to help :D

DanielHong2L

Thank you! Definitely going into my review list plan :D

DanielHong2L

I understand why tetrahedral geometry is common for complexes w/ coordination number of 4.
However why is square planar geometry common and seesaw complex not?

They both have 4 "X's" or bonded atoms in naming their structure. Why is square planar favored over seesaw?

DanielHong2L

When discussing the myoglobin structure in today's lecture, it was mentioned that it is a tetradentate structure. I was confused on this description because I thought that there were 6 bonds because iron likes to be in an octahedral structure, but is this not correct? Could you expand on why myoglo...

DanielHong2L

Hi I understand(sorta) that the roman numerals are dependent on the charges (oxidation number). However, I was wondering if the direction of the charge (either positive or negative) affected the roman numeral. For example, would Iron +2 and Iron -2 both be considered Iron (II)? (assuming that both v...

DanielHong2L

I was having a bit of an issue understanding the differences between axial and equatorial bonds as well as how they impact the shape of molecules. Will certain atoms or lone pairs only be in one of the two positions and thus affect the shape? Axial: On the vertical axis Equatorial: On the plane Cer...

DanielHong2L

Txtbook problems for days and rewatching some of his lectures to keep the information fresh before tests.
I don't know if it will be changing for finals however.

DanielHong2L

To determine if the overall molecule is polar or non-polar it's non-polar if the bonds are non-polar but if the bonds are polar we have to know the molecule's shape and bond angles to see if the polar bonds cancel out and if they do then the molecule if non-polar, correct? Yeah you're right! If the...

DanielHong2L

Why does minimizing the number of 90 degree lone pair-bond interactions increase the stability of the molecule (eg in the seesaw VSEPR shape)? Is it because electron-electron repulsion is minimized in this configuration? If so, please explain in more detail. Thank you! Lone electron pairs because t...

DanielHong2L

Hello! I was a little bit confused with examples including unhybridized p-orbitals, regarding how many regions of electron density the carbon atoms have. For example, in ethene and benzene examples, Dr. Lavelle said in lecture that each carbon atom in these molecules has 3 regions of electron densi...

DanielHong2L

Also on drawing them, remember that the lowest formal charge should be the center atom.

I believe this is because the more relatively electronegative atoms (and thus the more ionization energy atoms) have a stronger hold on electrons so it'd be reflective of the true nature electron density.

DanielHong2L

Sameer Chowdhury 1C wrote:Hi, I was wondering when we could expect to get back our scores for the second midterm.

Like last time I would assume that it'd be by Thursday at max;
You could always ask in his discussion section tomorrow; he usually tells us when there

DanielHong2L

Polarizability pertains to the anion. It is a measure of how easily their electrons can be distorted (and moved into the shared region, which is on the internuclear axis between two atoms in a bond). Larger anions have more electrons that are not as closely held to the nucleus, so they are more pol...

DanielHong2L

What exactly is polarizability and polarizing power? I understand that polarizability has to do with an anion's ability to take away electrons (correct me if I'm wrong) But in the intermolecular energy equation, it uses the polarizability of two atoms and their polarizability which would mean that h...

DanielHong2L

What exactly is a dipole?

Is a dipole anything that is covalently bonded that has an imbalanced charge? Like anything that is polar?

DanielHong2L

There's also Dr. Lavelle's discussion section today where you could usually ask him questions you have!

DanielHong2L

Hello! So in today's lecture, there was a statement that said: repulsion strength: lone-lone pair > lone-bonding pair > bonding-bonding pair What exactly does this mean? I think I'm confused because I don't quite understand the concept of a lone-bonding pair or a bonding-bonding pair. Is it the sam...

DanielHong2L

Was Wednesday's lecture the last lecture that will be covered on midterm 2? Will Friday's Lecture (Nov13) be on midterm2 or is that new material for the final? According to my TA, the topics that are covered are: 1D (from quantum numbers), 1E, 1F, 2A, 2B, 2C, 2D, 3F.4, 3F.5 on the textbook So since...

DanielHong2L

How do you determine polarity of a molecule. Specifically what value would be considered polar or non polar? It's considered polar if there are even slight charges within the molecule. In Dr. Lavelle's discussion session, he talked about how to determine polarity / non polarity, one must know the l...

DanielHong2L

https://groupme.com/join_group/62288203/dSSkobMS groupme

DanielHong2L

What does it mean for bonds to be favorable? Are they more likely to occur when interacting? What does it mean in the context of in disassociation energy, or bond energies?

DanielHong2L

What's an oxidation number? How do you find it for a specific atom?

DanielHong2L

When you have two resonant structures (for example two structures of perchlorate ion, ClO4-), and one only has a -1 charge on chlorine and the other only has a -1 charge on oxygen, how do you know which one would be the more preferred (plausible) resonant structure? Both structures have only one -1...

DanielHong2L

Can someone please explain to me how to do this problem? I am a little confused about the ample and overwhelming bond character part. So the C-/=O bond of the given molecule has been given as 128 pm C-/=N bond of the given molecule has been given as 136pm And you are also given the values of the ex...

DanielHong2L

So to my understanding, in resonance structures, electrons that form double bonds are delocalized because they exist in multiple locations (equivalent electron density). But does this mean electrons involved in single bonding and lone pairs are not delocalized? Or are they also equally shared among...

DanielHong2L

Hi! Can anyone explain why delocalization of electrons lowers energy but also increases stability? Dr. Lavelle said it in his lecture for today (11/2), but I failed to understand why this occurs. Thanks for the help! Delocalization of the electrons increases the size of the molecule which makes it ...

DanielHong2L

Hi! Can anyone explain why delocalization of electrons lowers energy but also increases stability? Dr. Lavelle said it in his lecture for today (11/2), but I failed to understand why this occurs. Thanks for the help! Delocalization of the electrons increases the size of the molecule which makes it ...

DanielHong2L

LexyDenaburg_3A wrote:Can someone explain the main difference between ionic and covalent bonds?

Simply put

Ionic: give / take of electrons
Covalent: sharing of electron pairs

If you wanna know a bit more I'm happy to do so lmk

DanielHong2L

1B.27 A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at 5.00±5.0m⋅s−1. What is the minimum uncertainty in its position? Could someone explain why we don't convert 8.00kg to grams in this problem Thank you! I'm also confused in the uncertainty in position. I thought Dr. Lavelle e...

DanielHong2L

1B.27 A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at 5.00±5.0m⋅s−1. What is the minimum uncertainty in its position? Could someone explain why we don't convert 8.00kg to grams in this problem Thank you! I'm also confused in the uncertainty in position. I thought Dr. Lavelle e...

DanielHong2L

Is wavelength always converted into m or are there any instance where wavelength must be in nm? If the final answer is in nm then it should be in nanometers. The primary reason we convert it to m is to use formulas with constants which are oftentimes given in terms of m, kg, s... etc. Otherwise you...

DanielHong2L

Hi everyone! In Heisenberg problems, will there be instances where we're given a +/- with a percentage? For example, can the problem give us an uncertainty for position as 5.00 +- 1%, or would there always be an actual number after the +- sign? I understand that in theory, we would have to double i...

DanielHong2L

This question asked: If an electron (mass 9.11 x 10-31 kg) has an associated wavelength of 7.28 x 10-9 m, what is its speed? Is your answer reasonable, why? I calculated the speed to be 1.00x10^5 m/s, and I said this was not reasonable because the calculated speed is much slower than the speed of l...

DanielHong2L

Is the the Electrostatic potential equation (q1)(q2)/r solve anything beyond being a conceptual point Hi! Currently Dr. Lavelle has not yet used it for actual empirical calculations. And yes, currently it's a conceptual point to show how electrostatic potential is proportional to the magnitude of c...

DanielHong2L

I don't know why the first electron in an orbital is specifically spin-up, but I'm pretty sure they occupy different orbitals before filling them up because of the repulsion forces between them, so they'd want to be as far away as possible and thus occupy different orbitals. Also spin-up / spin-dow...

DanielHong2L

I am reviewing and am having a little trouble with this question. Practitioners of the branch of alternative medicine known as homeopathy claim that very dilute solutions of substances can have an effect. Is the claim plausible? To explore this question, suppose that you prepare a solution of a sup...

DanielHong2L

Should we be able to answer this question already? If so does anyone know the steps to solve it? Any help would be great. Thanks! What is the minimum uncertainty in an electron's velocity (Δvmin) if the position is known within 15 Å. What is the minimum uncertainty in a helium atom's velocity (Δvmi...

DanielHong2L

The Scrhodingers equation showed how to find the probability of an electron by squaring the sin graph. Where the sin graph peaked, the square of the sin graph will peak higher, meaning that there is a high probability of an electron being there. This connects to orbitals because you can predict whe...

DanielHong2L

I'm still kind of confused on this whole topic of scrhodingers as a base of orbital formation. Dr. Lavelle keeps talking about math functions and its relation to creating orbitals. Does the math function refer to psi? psi^2? the Hamiltonian (double derivative?)? Wave function (psi?) And what is plot...

DanielHong2L

A college student recently had a busy day. Each of the student’s activities on that day (reading, getting a dental x-ray, making popcorn in a microwave oven, and acquiring a suntan) involved radiation from a different part of the electromagnetic spectrum. Complete the following table and match each...

DanielHong2L

If I remember correctly, according to my TA and other folks, TI 84's can be used during exams.

DanielHong2L

This is a 3 part question from 28-30 28: light hitting sodium metal surface, velocity of ejected electron = 6.61*10^5 m/s In 28 you're given that the work function for sodium is 150.6kJ/mol 29 asks what is the energy reqruied to remove an electron from one sodium atom If the work function is also th...

DanielHong2L

KE = E(in) - E(threshold) Frequency = c/ wavelength v = (3*10^ m/s) / (194*10^-9m) v = 1.55*10^15 s^-1 E = vh E = 1.024*10^-18 J E(in) = 1.024*10^-18 J E(threshold) = 7.22*10^-19 J E(in) - E(threshold) = 3.03*10^-19J Probably loss of some sig figs here and there so -> 3.05*10^-19J Hopefully this hel...

DanielHong2L

So the syllabus states
for the Quantum World Unit that the problems are from 1A, B, D, E, & F. Just making sure, is it recommended that we still read over C or is it going to be material that is not needed/covered in class?

DanielHong2L

I would assume it'd be helpful to know the different equations but if you can derive the different equations from the MV(i) = MV (f) I don't see a particular need to memorize them directly

DanielHong2L

Yes; because empirical formula is a ratio of moles

DanielHong2L

You could also do your own chromatography at home! There's a type of paper called chromatography paper which you can use and see the different chemical components of a given marker / pen! I think it's called paper(ink)chromatography if you wanna search it up Basically, it's separating the black mark...

DanielHong2L

I was wondering which equation is supposed to be used to solve exercise E1? How would it result in an answer in the pm length unit. if a "." was 1 ag atom and 1 mole of Ag atoms has 6.0221*10^23 atoms and they're all lined up it would be ............... etc And if each of them has a radius...

DanielHong2L

I don't believe that there is a submit button; if you did the hw and it has checkmarks in the quetions it should be fine

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