CHEMISTRY COMMUNITY

Yadira Flores 1G

So will the review sessions usually in Hedrick Hall continue on Tuesday and Wednesday?

Yadira Flores 1G

You would subtract one.

Yadira Flores 1G

For the question overall why is it that they didn't specify whether they wanted the Lewis or Bronsted acid or base? Does it matter?

Yadira Flores 1G

We were told only to know three specific polydentates, correct?

Yadira Flores 1G

Yes looking at the difference in electronegativity will help to determine which which, if any, the dipole moment will move towards as well as if they will cancel. If they do, then it's non-polar and if they don't it's polar.
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Yadira Flores 1G

I think in general we have to be able to figure out the hybridization of compounds when they are given, and memorizing which hybridizations go with each VSEPR shape can only help.

Yadira Flores 1G

The 2 lone pairs on the I in the lewis structure does not allow for the shape to correspond to trigonal planar nor trigonal pyramidal. The VSEPR formula of AX3E2 corresponds to the t-shape.

Yadira Flores 1G

I think we're expected to be able to tell the VSEPR formula, the shape, the bond angles, hybridization, and the lewis structures based on the homework problems assigned to us.

Yadira Flores 1G

I think it has largely to do with the fact that your comparing electronegativities between H and F, and because F is the most electronegative element it should be the most electronegative. Also I checked the electronegativity chart because they are pretty close to one another and the difference is b...

Yadira Flores 1G

I think it's all the elements in group 13.

Yadira Flores 1G

I always begin by drawing each element in the order it was given. So for your first example Carbon is given first so I would draw the carbon with the O bonded to it, this being because H tends to only make one bond so it'd be unlikely all four would be in a linear form. So, I would have a carbon who...

Yadira Flores 1G

I would try and remember that Oxygen usually tends to make two bonds in order to acquire the formal charge of zero

Yadira Flores 1G

I'm still not getting how you would get the correct lewis structure for a. Can anyone explain?

Yadira Flores 1G

I think you would place the brackets around the whole compound too because the charge has to do with the entire compound.

Yadira Flores 1G

Why when doing the resonance structure can we not give Cl-N a double bond? Or can we?

Yadira Flores 1G

I remember him saying he's not one to emphasize remembering the names of molecules, more understanding the concept of their structures.

Yadira Flores 1G

If you calculate the formal charge for the lewis structures of the two you have you will also be able to see that the correct Lewis structure equals zero, meaning its the most stable, therefore the correct one. Hope that helps.

Yadira Flores 1G

I always think of the octet rule as, most, elements always wanting a full 8 electrons to be as stable as possible. They all want to be full like the noble gases.

Yadira Flores 1G

Expanded octet can only be used depending on the element's place on the periodic table, only if the element is after the 2nd row. F is on the second row, therefore cannot have an expanded octet.

Yadira Flores 1G

Electronegativity increases across because the element is closer to have a filled orbital. It then decreases down because the valence electrons are further away.

Yadira Flores 1G

I have the problem worked out, would it be possible for anyone to work out the steps? Just want to make sure I did it correctly.

Yadira Flores 1G

Why are suppose to use Avogadro's number for this problem?

Yadira Flores 1G

Also I always convert the given mL to L and do the calculations, unless it specifically states the answer is wanted in mL. Also, he posted the answers under the topic and the answer he gave had the final units in L.

Yadira Flores 1G

42. An excited hydrogen atom emits light with a frequency of 1.14 x 1014 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?

Can anyone explain the steps needed to solve this problem? I'm having trouble starting because only one n value was given.

Yadira Flores 1G

Pretty sure we're focusing on the position it has on the periodic table and not specifically by any value.

Yadira Flores 1G

I had a question about part a of this problem. The question states: "How many values of the quantum number l are possible when n=7? Since l=0,1,2,..n-l is my answer of seven correct? I'm just confused because I know l indicates the subshell and because we have not talked about those above l=3(f...

Yadira Flores 1G

I'm pretty sure because each electron has a different interaction based on each state, the +1/2 and -1/2 account for the spin up and spin down

Yadira Flores 1G

So for part c since we already know the 1.00 mol of Na would we just multiply by Avogadro's number and by the E we found in a? or just by Avogadro's number?

Yadira Flores 1G

What units would the final answer be in?

Yadira Flores 1G

Should homework questions that will be turned into our TA's this week be strictly from the list of Ch.1 questions Dr. Lavelle emailed us?

Yadira Flores 1G

You can also use the formula En= -hR/n^2 which Dr. Lavelle used in one of the previous lectures too right?

Yadira Flores 1G

I'm still having trouble with the conversion part of the question. Can anyone show me the steps for the conversion?

Yadira Flores 1G

I have tried to see if there's a way but I don't think it allows us to see the answers we got correct on any pre-assessments, only on the post-assessment does it show you.

Yadira Flores 1G

Yes, In discussion my TA suggested we know the order of increasing wavelengths which would also help in knowing the frequency since they are inverse of one another.

Yadira Flores 1G

You have to convert the picometers into meters before plugging it into the equation right?

Yadira Flores 1G

I think it's meaning that in order to have 'measurable wavelike properties' it has to be within the range of the electromagnetic spectrum.

Yadira Flores 1G

A quantum of light of wavelength is the minimum amount of energy which can be stored in an electromagnetic wave at that wavelength, which is Planck's constant h times the frequency. (E=hv)

Yadira Flores 1G

I am stuck on this problem too. I found the mol of C6H9Cl3 to be 0.004 and then continued by multiplying that my 3molAgNO3/1molC6H9Cl3 and got 0.012molAgNO3 so then I multiplied that by the molar mass 169.88g of AgNO3 but my answer isn't correct. Can anyone help?

Yadira Flores 1G

A solution is prepared by dissolving 55.1 g of KCl in approximately 75 mL of water and then adding water to a final volume of 125 mL. What is the molarity of KCl(aq) in this solution? Why isn't it correct to apply the M1V1=M2V2 to this specific problem?

Yadira Flores 1G

For the top answer in part b) when finding the limiting reagent I got 9.45mol for Al and 7.55mol for Cl2 but noticed that in the above posted answer they got 8.33mol. Did I make a calculation error?

Yadira Flores 1G

Im having trouble with part b of the question. I found the grams in the H2O molecule to be 2.992x10^-23 but don't know how to approach finding the molecule number.

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