Search found 31 matches

by Xiangkun Shi 3E
Wed Dec 05, 2018 11:35 am
Forum: Lewis Acids & Bases
Topic: Inductiveness vs. atomic radii
Replies: 1
Views: 53

Re: Inductiveness vs. atomic radii

There is not one that you should look at first. Which one is having an effect depends on the molecules your are comparing. For molecules like HF, HCl whose protonation site is directly bonded to the atoms that are being compared, you should look at atomic radius. For molecules like CCl3COOH, CH3COOH...
by Xiangkun Shi 3E
Wed Dec 05, 2018 12:29 am
Forum: Bronsted Acids & Bases
Topic: 7th Edition 6C.21.b
Replies: 1
Views: 58

Re: 7th Edition 6C.21.b

Because the CH3 in acetic acid is electron donating. The CH3 contributes electron density towards the O-H bond, which makes it harder to remove the H, thus making acetic acid a weaker acid than formic acid.
by Xiangkun Shi 3E
Wed Dec 05, 2018 12:20 am
Forum: Bronsted Acids & Bases
Topic: Acids
Replies: 3
Views: 91

Re: Acids

Bronsted acid is a proton donor. Lewis acid is an electron acceptor. All Brønsted-Lowry acids are Lewis acids, but the reverse is not true.
by Xiangkun Shi 3E
Thu Nov 29, 2018 1:26 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw shape
Replies: 3
Views: 99

Re: Seesaw shape

There are three bond angles in seesaw shape: 90, 180, and between 90 and 120.
by Xiangkun Shi 3E
Thu Nov 29, 2018 1:16 am
Forum: Dipole Moments
Topic: Dipole Dipole Interactions
Replies: 1
Views: 54

Re: Dipole Dipole Interactions

Generally, polar molecules have dipole dipole interactions as there are nonzero charges on the atoms.
by Xiangkun Shi 3E
Tue Nov 27, 2018 11:56 am
Forum: Quantum Numbers and The H-Atom
Topic: H atom and degeneracy
Replies: 1
Views: 118

Re: H atom and degeneracy

When an atom only contains a single electron, its orbital energies depend only on the principle quantum numbers: a 2s orbital would be degenerate with a 2p orbital. The energy of 1s and 2p will be different.
by Xiangkun Shi 3E
Wed Nov 21, 2018 10:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 3
Views: 101

Re: VSEPR

VSEPR theory applies to gases just as it applies to other molecules. For example, CH4 is a gas that has a tetrahedral shape and NH3 is also a gas that has trigonal pyramidal shape.
by Xiangkun Shi 3E
Wed Nov 21, 2018 10:28 pm
Forum: Dipole Moments
Topic: London forces and dipole moments
Replies: 4
Views: 106

Re: London forces and dipole moments

I'm not sure what you mean by greater rate of dipole dipole moment, but from what I understand, London forces increase when size or mass of atoms increase.
by Xiangkun Shi 3E
Tue Nov 20, 2018 12:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles
Replies: 4
Views: 59

Re: Bond angles

Knowing the bond angles helps you better understand the shape and structure of the molecule. This will be useful in terms of explaining some physical properties like boiling point as well.
by Xiangkun Shi 3E
Wed Nov 14, 2018 10:10 am
Forum: Determining Molecular Shape (VSEPR)
Topic: MgO vs BaO
Replies: 5
Views: 268

Re: MgO vs BaO

Since water is polar, the more polar molecule will have higher solubility. Polarity is determined by the difference in electronegativity between two atoms. Since Mg and Ba's electronegativity is 1.2 and 0.9 respectively, and O's electronegativity is 3.5, the difference between O and Ba is larger tha...
by Xiangkun Shi 3E
Wed Nov 14, 2018 8:25 am
Forum: Administrative Questions and Class Announcements
Topic: Week 8 Discussion
Replies: 2
Views: 108

Re: Week 8 Discussion

I think if your discussion is on Wednesday and after then you don't. If it's before Wednesday then this depends on you TA.
by Xiangkun Shi 3E
Tue Nov 13, 2018 11:24 pm
Forum: Lewis Structures
Topic: Homework 2.25
Replies: 2
Views: 84

Re: Homework 2.25

Yes, the reasoning from the electronegativity and strength of attraction perspective is the best way to explain this problem.
by Xiangkun Shi 3E
Sat Nov 10, 2018 10:54 pm
Forum: Bond Lengths & Energies
Topic: Molecular Shapes
Replies: 2
Views: 91

Re: Molecular Shapes

I think the professor will discuss more about other shapes next week.
by Xiangkun Shi 3E
Sat Nov 10, 2018 10:48 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent vs Hydrogen bond in H20
Replies: 4
Views: 81

Re: Covalent vs Hydrogen bond in H20

That is just a covalent bond. The hydrogen bonding in water is intermolecular.
by Xiangkun Shi 3E
Sat Nov 10, 2018 10:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hydrogen Bonding
Replies: 2
Views: 38

Re: Hydrogen Bonding

Usually hydrogen bonds form between molecules, but they can also form within a molecule. In biology, intramolecular hydrogen bonding help proteins and nucleic acids maintain specific shapes.
by Xiangkun Shi 3E
Wed Oct 31, 2018 9:25 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Degenerate Orbitals
Replies: 1
Views: 123

Re: Degenerate Orbitals

There exist 3 degenerate 3p orbitals. No matter for 2p, 3p, or 4p, the answer is always 3 because there only exist 3 p-orbitals at each energy level. And each of the p orbital has the same energy, which means they are degenerate. The degeneracy of d orbitals would be 5 and degeneracy of f orbitals w...
by Xiangkun Shi 3E
Wed Oct 31, 2018 9:20 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3.5 c&d
Replies: 2
Views: 63

Re: 3.5 c&d

When electrons start filling in the orbitals, they fill 4s first and then fill 3d because 4s has lower energy state than 3d at first. But once 4s is filled, its energy became higher than 3d. When losing electrons, electrons in higher energy levels are given out first since they are less stable.So el...
by Xiangkun Shi 3E
Wed Oct 31, 2018 9:14 pm
Forum: Properties of Electrons
Topic: Electron Orbitals
Replies: 1
Views: 170

Re: Electron Orbitals

According to my TA, degeneracy simply means 'same energy'. For example, the degeneracy of p orbitals is 3.
by Xiangkun Shi 3E
Tue Oct 23, 2018 11:10 pm
Forum: Photoelectric Effect
Topic: Module: Photoelectric Effect #25
Replies: 1
Views: 127

Re: Module: Photoelectric Effect #25

The answer is E=hv. This equation is actually one main experiment result of the photoelectric experiment.
by Xiangkun Shi 3E
Tue Oct 23, 2018 11:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: m with subscript l
Replies: 4
Views: 86

Re: m with subscript l

It is the magnetic quantum number which tells you the orientation of the orbital. It can take the value from -l to l.
by Xiangkun Shi 3E
Tue Oct 23, 2018 10:41 am
Forum: Sigma & Pi Bonds
Topic: determining which bonds are in a molecule
Replies: 4
Views: 160

Re: determining which bonds are in a molecule

Yes, by writing out the electron configuration you will be able to know the number of valence electrons, which is the key in determining what bonds are present.
by Xiangkun Shi 3E
Tue Oct 16, 2018 9:44 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D.13
Replies: 2
Views: 48

Re: 1D.13

The 7 values from 0-6 are all possible L values. Quantum numbers can be larger than 4.
by Xiangkun Shi 3E
Tue Oct 16, 2018 9:38 pm
Forum: Einstein Equation
Topic: 1B 9 7th edition
Replies: 2
Views: 72

Re: 1B 9 7th edition

You can think of it this way. The energy of each photon is 4.7 x 10^-19J. If we multiply this energy by number of photons, we will get the total energy. Since now we want to get the number of photons, we do it backwards by dividing the total energy with energy per photon.
by Xiangkun Shi 3E
Tue Oct 16, 2018 9:32 pm
Forum: Properties of Light
Topic: Finding energy
Replies: 1
Views: 49

Re: Finding energy

The energy produced by each photon is given by the equation E=hv, and we also know v=c/λ, so we get E=hc/λ. Then you just multiply E by the number of photons to get the total energy produced by the radiation in one second.
by Xiangkun Shi 3E
Wed Oct 10, 2018 10:55 am
Forum: Empirical & Molecular Formulas
Topic: Writing formulas from mass compositions
Replies: 1
Views: 116

Re: Writing formulas from mass compositions

There is something called the Hill system, which states carbon atoms are listed first, hydrogen atoms next. All the other elements then follow hydrogen and are listed in alphabetical order. I think this rule only applies to molecular compounds. In your example, Cl should be before N because C is bef...
by Xiangkun Shi 3E
Tue Oct 09, 2018 1:36 pm
Forum: Photoelectric Effect
Topic: Problem 1B 15(c)
Replies: 2
Views: 85

Re: Problem 1B 15(c)

Your answer could just be an issue of not using enough sig figs throughout the problem, but I'll walk you through the steps I did to get 8.8 nm regardless. I used the equation: KE(of electron) = energy(of photon) - threshold energy. I first solved for the KE of the electron by converting the veloci...
by Xiangkun Shi 3E
Mon Oct 08, 2018 9:06 pm
Forum: Photoelectric Effect
Topic: Problem 1B 15(c)
Replies: 2
Views: 85

Problem 1B 15(c)

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6*10^3 km/s. (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50*10^16 Hz. How much energy is required to ...
by Xiangkun Shi 3E
Tue Oct 02, 2018 1:31 pm
Forum: Balancing Chemical Reactions
Topic: Audio Visual Focus Topics Balancing Chemical Equations Pre Assessment
Replies: 2
Views: 79

Re: Audio Visual Focus Topics Balancing Chemical Equations Pre Assessment

I agree that the net moles of gas produced should be moles of gaseous products minus moles of gaseous reactants
by Xiangkun Shi 3E
Sun Sep 30, 2018 11:18 pm
Forum: Empirical & Molecular Formulas
Topic: Problem E5
Replies: 6
Views: 765

Re: Problem E5

I got the same answers as you :)
by Xiangkun Shi 3E
Sat Sep 29, 2018 11:37 pm
Forum: Molarity, Solutions, Dilutions
Topic: Question G21 [ENDORSED]
Replies: 5
Views: 195

Re: Question G21 [ENDORSED]

Can you tell me the molar mass of each of the three compound you get? I have tried two periodic tables for now and I kept getting 4.57*10^-2 :(
by Xiangkun Shi 3E
Fri Sep 28, 2018 11:12 pm
Forum: Molarity, Solutions, Dilutions
Topic: Question G21 [ENDORSED]
Replies: 5
Views: 195

Question G21 [ENDORSED]

On the textbook the answer to G21 part (a) is 4.58*10^-2 M. I did it multiple times and no matter how many significant figures I kept during calculation, I could only get 4.57*10^-2 M. I know the difference is very little, but this bothers me a lot... Can anyone try to do this question and see if yo...

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