CHEMISTRY COMMUNITY

FDeCastro_1B

Could you argue that BrO is the stronger base because it's protonated more completely than morphine?

FDeCastro_1B

Camille 4I wrote:How do we know that HBrO is the corresponding weak acid that creates the base BrO-?

I think it's the conjugate acid that receives a proton from the base. Hence why there is now an H in the formula.

FDeCastro_1B

Ionization energy and electronegativity both decrease down a group and increase across a period.

FDeCastro_1B

Can someone please explain how to go about answering this:

List the following carboxylic acids in order of increasing strength: CHCl2COOH, CH3COOH, and CH2ClCOOH.

FDeCastro_1B

ShravanPatel4G wrote:pOH = -log(.077) = 1.11
pH = 14-1.11 = 12.9

hope this helps!

Yes! Thank you.

FDeCastro_1B

Since 6B.2 isn't on the learning outcomes for Focus 6, will it not be on the final?

FDeCastro_1B

Just checking to see if I have the right answer since I can't find it online.

Calculate the pH of 0.077 m NaOH(aq).

FDeCastro_1B

My TA said it's because F has a smaller atomic radii

FDeCastro_1B

Hello, can someone explain this statement from the textbook? I'm not entirely sure as to what they mean by the formula for the molecular form. When the net ionic equation is written for the neutralization of a weak acid or a weak base, the formula for the molecular form of the weak acid or base is u...

FDeCastro_1B

Why is it that HF is considered a weak acid and not a strong acid when the definition of a strong acid is that almost every molecule or ion of that acid has lost its proton and HF seems to match that definition?

FDeCastro_1B

There's a test bank in SAC but last time I went for the midterm and they didn't have anything from Lavelle.

FDeCastro_1B

Will the class average be the "A"?

FDeCastro_1B

I noticed that Dr. Lavelle will be reviewing previous final questions during lecture on Friday. Will he be reviewing the same questions for every single one of his lectures? Or will they be different questions per lecture hour?

FDeCastro_1B

Mandeep Garcha 3C wrote:Lyndon's session is Friday December 6 at 7:30-10pm in Haines 39.

Make sure to have the "Marshmallow" practice sheet done so you're not completely lost during Lyndon's review session!

FDeCastro_1B

Can someone please explain how to find the oxidation number of a chemical compound?

Feel free to use K2[Ni(CN)4] as an example if it makes it any easier.

FDeCastro_1B

No, you do not need to show dashes and wedges. Though it'd be good to understand why that is.

FDeCastro_1B

Cavalli_1E wrote:Also does anyone know if material covered in today's (Monday) lecture will be on the test as well?

Only the slide on the types of bonds will be on test 2. Hybridization will not be on the test.

FDeCastro_1B

Vuong_4G wrote:
KTran 1I wrote:Will we need to have the specific bond angles for each molecular shape memorized for Test 2?

Yes you do.

Dr. Lavelle said we're not to memorize the specific bond angles. Only to know conceptually that lone pairs force bonding electrons closer together meaning bond angles are less than 109.5.

FDeCastro_1B

Is it preferred that the lone pair is equatorial or axial on seesaw?

FDeCastro_1B

Though it's part of the learning outcomes on the syllabus, hybridization won't be on Test 2. He'll take 5 minutes of next lecture to go over sigma and pi bonds which will be the last thing we have to know for Test 2. I assume we'll just continue on with hybridization after the test.

FDeCastro_1B

Are formal charges to be considered when drawing the Lewis structure to correctly name the VSEPR model?

FDeCastro_1B

Dashes and wedges are used to draw the structure of the molecule. We won't be asked to do this.

FDeCastro_1B

To find the shape you'll have to start with the Lewis structure of the ion. From there, you'll find the amount of bonded pairs there are around the central atom which will give you the shape of the atom (trigonal planar, tetrahedral, etc.). To find the expected bond angle you'll have to start with t...

FDeCastro_1B

I haven't officially heard anything from my TA or Dr. Lavelle about what is going to be on Test #2. I suggest just reviewing topics we've been learning about in the past lectures after the midterm.

FDeCastro_1B

CHI3 has a higher boiling point because the atomic size is bigger which leads to the increase of the atom's surface area.

FDeCastro_1B

I'm sure we'll be learning more about them in the next lectures.

FDeCastro_1B

The angular momentum is the l quantum number.

FDeCastro_1B

I don't think it's that we're not allowed to. Just that Lavelle would prefer that we use -hR/n1^2.

FDeCastro_1B

Can someone please explain how electronegativity determines the dipole moments? Which element gets which partial charge?

FDeCastro_1B

Sigma bonds are stronger than pi bonds.

FDeCastro_1B

In Dr. Lavelle's own words, "Midterm covers all material up to the end of Focus 2D in Outline 3 (Chemical Bonds)."

FDeCastro_1B

Yes, Lewis acids and bases.

FDeCastro_1B

The UA did that to half the number of shared electrons through the bond. I wouldn't attempt it on the final or worry about having to do it. Dr. Lavelle has not gone over it in lecture with us.

FDeCastro_1B

Lone pairs are the two dots next to the atom

FDeCastro_1B

From what I could gather in lecture, an expanded octet is when a central atom ends up with more than an octet.

FDeCastro_1B

I have never been told to write out px, py, or pz.I don't think we'll be required to.

FDeCastro_1B

Yes, there is always an octet formed.

FDeCastro_1B

In each second, a certain lamp produces 2.4x10^21 photons with a wavelength of 633 nm. How much power (in watts) is produced as radiation at this wavelength (1W=1 J.s^1)?

How do I go about solving this problem? I'm not sure where to start.

FDeCastro_1B

How many orbitals can have the following quantum numbers in an atom:(a)n=2,l=1;(b)n=4,l=2,ml=22; (c)n=2;(d)n=3,l=2,ml=11?

Can somebody please explain the process of answering this problem?

FDeCastro_1B

How many orbitals are present in the (a) 4p-subshell; (b) 3d-subshell; (c) 1s-subshell; (d) 4f-subshell of an atom?

I'm confused. This question is asking for the orbitals, but the solutions manual gives me the number of electrons in the orbitals. Am I missing something?

FDeCastro_1B

I'm not entirely sure as to why that question was asked either. The wavelength of a neutron and a proton would end up to be the same because they nearly have the same mass, just missing the mark by a couple sig figs.

FDeCastro_1B

If you look on the class website, there's actually an error in the solutions manual for that problem. They made delta v = 5 m/s rather than 10 m/s as it should be (the velocity given was 5 m/s +- 5 m/s, so that would range from 0-10 m/s). The correct answer for delta x = 6.7 x 10-37 m (hopefully yo...

FDeCastro_1B

What is the minimum uncertainty in the speed of an electron confined to within a lead atom of diameter 350. pm? Model the atom as a one-dimensional box with a length equal to the diameter of the actual atom. I used the Heisenbeg Indeterminacy Equation and still did not get the same answer as what's ...

FDeCastro_1B

In the hydrogen atomic spectrum, what is the wavelength of light associated with the n = 2 to n = 1 electron transition? I understand how to go about this question and the equations to use. However, I still end up getting an answer that isn't even one of the options. Can anybody please walk me throu...

FDeCastro_1B

Yes! E(photon) should always be greater than or equal to the work function in order to eject an electron.

FDeCastro_1B

Hi Ellis! This is Ariel. Here's a general list from my notes: c = λ ν -- Used to calculate wavelength/frequency E(photon) = h ν -- Used to calculate energy per single photon -- Bohr Frequency Condition: v = ∆E/h; used to calculate frequency E(photon) = Work Function/Threshold Energy + EK EK =(1/2)m...

FDeCastro_1B

I use Dr. Lavelle's problem solving guidelines:
1. What is the question?
2. What concepts do I know?
3. What model or equations do I know?
4. What is known? What is unknown?
5. Can I express unknown with respect to the known?

FDeCastro_1B

In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line.

How do I begin with this problem?

FDeCastro_1B

Can somebody please briefly explain the correlation between the wavelength and the electrons? Why can light sources with short wavelengths eject electrons while light sources with long wavelengths can't? And how do intensity and frequencies correlate as well?

FDeCastro_1B

Yes. So you'd have to multiply that whole chem equation (both sides) by 2 to get rid of the fraction.

FDeCastro_1B

formula for magnesium sulfate heptahydrate is MgSO4.7H2O to do all three problems, you have to find the formula mass of MgSO4.7H2O (which you can do by looking at the periodic table) which is 246.37 g/mol (a) you need to find the number of moles of the magnesium sulfate heptahydrate. you are given t...

FDeCastro_1B

My TA told our class that we're not expected to know the formulas ourselves. He said they'll provide them to us during the test. I'd email your TA to make sure though.

FDeCastro_1B

My TA said that we'll be given the formulas from the compound names we see on the test. Apparently naming compounds and writing its formulas will be introduced to us later on in the quarter.

FDeCastro_1B

Hello! I'm just wondering if we'll be heavily graded on whether or not we use sig figs correctly when giving our answers for next week's test in discussions?

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