CHEMISTRY COMMUNITY

Namie Fotion-1E

Yes, when you see H+ (aq) thats the same thing as hydronium

Namie Fotion-1E

I'm pretty sure we have to know the basics. Like if we are given that the concentration of an acid is 1.0 x 10^-9 we would know the pH is 9. Beyond that, I don't think professor Lavelle indicated we would have to know more.

Namie Fotion-1E

So this homework problem asked what hybridizations exist with pi and sigma bonds. The answers said that the sigma bonds for a C-C double bond was 2sp³, which I understand. But then it said that the pi bond is 2p. Why is that? Does the pi bond have to be the first orbital in 2p? Can it not be 2s?

Namie Fotion-1E

Hi! So trigonal planar is correct in that it is the general geometry of CLO2, but if you want to define its shape, the shape is bent due to the lone pair repulsion

Namie Fotion-1E

If a question asks you for the VSEPR formula, it is the formula written like: AXE
A stands for the central atom
X stands for number of electron regions
E stands for lone pairs of electrons

Namie Fotion-1E

The bent shape is due to the fact that lone pairs exert a higher electron repulsion than shared electrons, so the lone pair is pushing the two side atoms down

Namie Fotion-1E

So i thought dipole-dipole forces were the same thing as london forces, but in homework problem 6.1 it has dipole-dipole and london forces as two separate answers. And CBr₄ only has london forces and not dipole-dipole. Could someone explain the difference between the two?

Namie Fotion-1E

this question asks about drawing the Lewis structure for a hydrogen sulfite ion. I drew it correctly, but when looking in the solutions manual, it notes that there are only two resonance structures. Yet, can't the hydrogen attached to the oxygen be moved to any of the oxygens surrounding sulfur? So ...

Namie Fotion-1E

I noticed this too. It can be explained in a lecture by Professor Lavelle when he mentioned that group 13 elements, like B and Al, are exceptions to the octet rule and mostly have 6 electrons. He noted that these reactions are called "lewis acid-base reactions"

Namie Fotion-1E

Are all the homework problems from outline 3 going to be subjects on the test?

Namie Fotion-1E

Thank you so much for your response! It is interesting to see how you thought about it. I worked on this problem for a very long time and I was trying lots of different methods to see if I could make it work. I eventually settled on finding the ratio of the elements using the moles of N, H, and C I...

Namie Fotion-1E

So i assumed oxygen was present in the compound as well, so I started solving for oxygen. I took each of the masses of the products, divided by the molar mass of that product so I could get the moles, then I used another conversion factor (mole of one element/the mole of each product) to get the mol...

Namie Fotion-1E

I believe it would be the entire diameter because the electron can be within that entire diameter of an atom. It would not make physical sense for the electron to be limited to only half the atom.

Namie Fotion-1E

Once you find the uncertainty in velocity, you can plug that value into the formula for kinetic energy, KE= .5mv². Because your v was the uncertainty in v, the KE will be the uncertainty in kinetic energy

Namie Fotion-1E

I worked this out in the following attachment. Hope it helps.

Namie Fotion-1E

so n=number of shells l=the subshell
n and l are related by this: l is any integer from 0 to (n-1)
so if n=4, there would be 4 values of l, or 4 subshells
those values would be 0, 1, 2, 3
It would not be 4 because l maxes out at (n-1)
hope that helps!

Namie Fotion-1E

My T.A. just mentioned that we only really need to know the axes that each lie on. I think anything more than that won't be tested.

Namie Fotion-1E

Electrons in lower energy levels ex. n=1 have a lower energy than electrons at n=2,3,4,... because less energy had to be imputed into the electron. Electrons absorb energy in order to move to a higher energy level (absorbing photons) and they release energy when they fall to a lower energy level (em...

Namie Fotion-1E

I'm a little shaky on questions 2-4 and I don't want to provide incorrect explanations, but I can help clarify number 1. n represents the energy levels when we went over atomic spectrum. n=whatever number represents the energy state an electron is at currently. n=0 represents when the electron is pr...

Namie Fotion-1E

the speed of light equals the frequency times the wavelength for electromagnetic radiation. If the wavelength becomes larger, the frequency must become smaller and vice versa so that the product of the two can always equal approximately 3.00 x 10^8

Namie Fotion-1E

All the constants we have gone over as well as equations will be given to us on the front page of the test, like the first test. But you will need to know what the variables in the equations stand for and how to use them.

Namie Fotion-1E

Hm the only way I've been able to check which answers I got wrong was by completing the post-assessment. It'll let you review your answers at the end.

Namie Fotion-1E

I'm not sure if this is entirely accurate, so please correct me if I'm wrong, but the way I've always done it is to keep track of how many sig figs I have while I'm solving equations and whatnot BUT I don't round at all in my calculator until my final answer where I can see how many sig figs it is s...

Namie Fotion-1E

If you'd like to see professor Lavelle explain this exact concept I found 16:30 on his photoelectric effect video/module very helpful in clearing up what Planck's constant is

Namie Fotion-1E

I do my conversions using dimensional analysis, which I believe is the way most people were taught, so I find it most helpful to do all my conversions in a long line so I can continually cancel out my units until I end up with an answer in the units I wanted.

Namie Fotion-1E

For chemical formulas containing carbon:
1. Carbon
2. Hydrogen
3. Other elements in alphabetical order
example: C7H4Br2O2
For elements containing no carbon:
Elements in alphabetical order
example: H2O4S

Namie Fotion-1E

Yes! So 750 only has two sig figs because of that 0 at the end. It would be 3 if it was 751 because it is ambiguous whether that 0 is there due to rounding or if it is exactly 750, so it can be said that only two numbers are significant figures. In 750.01 and even 750.00, there would be 5 significan...

Namie Fotion-1E

start with the 702 grams of octane, multiply that by the molar mass of octane (in moles/grams so the units cancel out), then multiply by 25 moles of oxygen gas/ 2 moles of octane (this is directly from the balanced chemical equation), then multiply by the molar mass of oxygen in grams/moles so the m...

Namie Fotion-1E

I also did it the same way the previous answer mentioned. Since there is 1 mole of Na+ in 1 mole of NaCl, you would use that information as a conversion factor if you want to solve for something else or you'd know that there is .2 M of Na+.

Namie Fotion-1E

Just a little confused about the units for the constant in the equation v(lamda) = C
if v is frequency in units of cycles/sec
and lamda is wavelength in units of m
then how is speed of time in m/sec?
Maybe I wrote my notes wrong, please correct me if that is the case and thank you!

Namie Fotion-1E

I believe it's the questions in outline 2 on the 14A website, titled "The Quantum World". We haven't covered much of that section yet so our homework this week can come from the homework problems from last week as well, outline 1.

CHEMISTRY COMMUNITY

Search found 31 matches

Re: H+ and H3O+

Re: pH calculations on Final

4.95

Re: 4.5 Confusion

Re: VSEPR

Re: HW question 4.1

Dipole vs. london forces

problem 3.57 part b

Re: Boron and the octet rule [ENDORSED]

Re: test 3 [ENDORSED]

Re: Question 3 on midterm [ENDORSED]

Re: Question 3 on midterm [ENDORSED]

Re: Delta X

Re: Uncertainty in Kinetic Energy

Re: Module #18

Re: 2.19 part d

Re: Question 2.13

Re: Hydrogen Levels and Energy [ENDORSED]

Re: orbital values [ENDORSED]

Re: frequency and wavelength [ENDORSED]

Re: constants [ENDORSED]

Re: Photoelectric effect pre-assessment module [ENDORSED]

Re: Sig Fig Accuracy [ENDORSED]

Re: Planck's Constant

Re: writing out conversions in one long line vs. steps

Re: Order of elements in molecule

Re: Sig fifs in 750 [ENDORSED]

Re: Review worksheet from week 1, question 8 [ENDORSED]

Re: Finding the molarity concentration of one type of atom from a molecule

Units of speed of light [ENDORSED]

Re: Homework? [ENDORSED]