CHEMISTRY COMMUNITY

Vivian Tan 3F

Just remember the suffix to the functional groups: ie alcohol is -ol, carboxylic acid is -ic acid... etc., from the name you can identify the structure.

Vivian Tan 3F

Can anyone help walk me through this problem?

Vivian Tan 3F

For part A of question 4 on the 2013 final, can we also use E_cell = E_cell^o - 0.05916/n * logQ instead of E_cell = E_cell^o - RT/nF * lnQ ?

I get a slightly bigger answer when I use the Nernst equation with log in it than the one with ln.

Vivian Tan 3F

"E" is used in regards to a "trans" molecule where the priority molecule is on opposite sides. See my attachment for clarification!

Vivian Tan 3F

Whichever element has the highest atomic # gets priority. These are the elements on the right and left sides, not horizontal and vertical. For example, in the photo I've attached below... - The first molecule is "Z" because the chlorine gets priority on the left, and the bromine gets prior...

Vivian Tan 3F

The substituent isopropyl has distinct "Y" shape, and the propyl substituent is just a jagged line of CH₂CH₂CH₃.

In the attached picture, the first is the propyl substituent and the second is the isopropyl substituent.

Vivian Tan 3F

I like to think of the nucleophile as the area with the most e- density -- of course, this can be an element or a double/triple/etc bond.

Vivian Tan 3F

Try waiting until Lecture 3's Bruin Cast comes out!

Vivian Tan 3F

The H + protons are to balance the H atoms in the equation and the electrons are used to balance the charge. For example, to balance this equation: 2e - + SeO 4 2- --> SeO 3 2- + H 2 O You will need to add 2 H + ions to the left to balance out the 2 H molecules in H 2 O. This will form: 2 H + + 2e -...

Vivian Tan 3F

Vivian Tan 3F

Work is not a state function.

Do I only use the volume values because it's an isothermal reaction?

Vivian Tan 3F

Hello everyone, For the 3rd question for the prep quiz #1, "If 2.00 mol of an ideal gas at 300. K and 3.00 atm expands isothermally and reversibly from 6.00L to 18.00L and has a final pressure of 1.20atm, what is w, q and delta U?" Why do we use the equation w = -nRTln(V2/V1) and not w = -...

Vivian Tan 3F

In the formula, w= -P(deltaV), why do we use the one with the negative sign and not the one without the negative sign?

Vivian Tan 3F

The practice quizzes in the back of the course reader also give great insight to how Dr. Lavelle will phrase his questions (units included).

Vivian Tan 3F

Remember that hybridizations involve all areas of electron density , so that includes both bonds and lone pairs. The carbon in the ring structure of proline has 2 bonds between them, so it means that the carbon must have 2 pairs of lone pairs (to add up to 8 electrons total, to fulfill the octet rul...

Vivian Tan 3F

Your first step would be to find the molarity of BrCl by dividing moles over liters. (Also remember to balance the equation!)Then, multiply this value by 0.0812 to find how much BrCl was produced at equilibrium. Set up your ICE table and solve for x!

Vivian Tan 3F

I think most of the time we will be dealing with a central atom, hence the AXE notation (where A = central atom, X = number of bonds and E = number of lone pairs). For your molecule of C 2 H 2 , I think you are missing a bond: it should be H-C≡C-H. Upon a quick google search, this molecule's shape i...

Vivian Tan 3F

Also keep in mind that the lone pairs do affect the overall shape of the compound: for example, the Lewis structure for H2O seems to be "linear," but because oxygen has 2 lone pairs, they push the hydrogens down, therefore creating the shape "bent." I think most of the time it'll...

Vivian Tan 3F

When we write the electron configuration for elements Z=20, the d-subshells are in front of the s-subshells because they are lower in energy.

Vivian Tan 3F

I don't believe so. In the midterm review session with Yekan on Saturday, he mentioned that we should know the energy and wavelength differences of different types of radiation (ie: which type of radiation has the highest energy, etc).

Vivian Tan 3F

Remember to use parentheses!

Instead of typing in "1.53*10^(24) / 6.0221*10^(23)," you should enter it into your calculator as (1.53 * 10^(24)) / (6.0221*10^(23)) and you should get 2.54. Better yet, use the fraction function on your calculator if you don't want to type the parentheses.

Vivian Tan 3F

It's calculated on our syllabus:

Quizzes (2 x 40 mins) 80 pts
Weekly Online Discussion (2 pt per week) 10 pts
Two 2hr Exams (2x 120 mins) 240 pts
Total 330 pts

Vivian Tan 3F

Hi all,

I am using an old coursereader for our chem class, so I don't have the workbook with the preparatory quizzes that are due before our in-class quizzes. Can anyone post pictures of both quizzes for me?

Thanks!!!

Vivian Tan 3F

Well, when an electron transitions from a higher energy level to a lower energy level, it emits electromagnetic radiation.

Not sure if it is positive or negative energy... but you plug in positive energy into Bohr's Frequency equation (En= -(hR)/n^2).

Vivian Tan 3F

You can find the conversions on the back of the textbook. "pm," I believe, are picometers.

Vivian Tan 3F

I got a solution! I used the photoelectric effect equation: E(kinetic) = E(photon) - E(threshold) And using E = (hc)/λ (combining E=hv and c=λv), plugging in 194 nm into λ (remember to convert!), and finally plugging in the threshold energy (7.22 * 10^(-19) J), you'll get the answer! E(kinetic) = E(...

Vivian Tan 3F

Okay -- 7.22 * 10^(-19) J is correct for the above question!

But there is a part two...

"If molybdenum is irradiated with light of wavelength of 194 nm, what is the maximum possible kinetic energy of the emitted electrons?"

How would I proceed with this problem?

Vivian Tan 3F

Here is the problem I am stuck on: "Molybdenum metal must absorb radiation with a minimum frequency of 1.09 * 10^(15) s^(-1) before it can emit an electron from its surface. What is the minimum energy needed to produce this effect?" Would it be correct to use E=hv? I got an answer of E = 7...

Vivian Tan 3F

How about HBr? And HI?

Vivian Tan 3F

This is question 3B on the 2014 Final exam:

Which of the following molecules has the largest dipole moment?
CO
NO
HI
HBr
HF

How do I find the dipole moments of these molecules, and how do I know which one is the "largest"?

Thanks!

Vivian Tan 3F

Molecular Orbital video which Jasmine Paraiso, Swan Ng, and I worked on off Drake's "Hotline Bling". Enjoy & ask questions!

Here the Youtube link for anyone having difficulty watching the video: https://youtu.be/w8hSnSN2cVA.

Vivian Tan 3F

A single bond: 1 sigma bond
A double bond: 1 sigma bond and 1 pi bond
A triple bond: 1 sigma bond and 2 pi bonds

Vivian Tan 3F

How would you find the hybridization of a benzene (C6H6)? I don't understand how to map out the energy levels, 2s, 2p, etc.

Vivian Tan 3F

Hi everyone, Our first quiz for Chem 14A is next week, week 3, and I remember my TA saying something about completing a practice quiz before our actual quiz and turning it in the day. Does anyone know which practice quiz it is in our green workbook? There are a total of 3 quizzes in the workbook. Th...

CHEMISTRY COMMUNITY

Search found 34 matches

Re: 2013 final Q6B

Final 2013 Question 4b

Final 2013 Question 4

Re: Cis & Trans

Re: Priority in Alkenes

Re: Isopropyl vs Propyl [ENDORSED]

Re: Course reader p. 82

Re: Bruincast Friday 2/24

Re: H+ and e-

Re: Post All Chemistry Jokes Here

Re: Prep quiz 1 #3

Prep quiz 1 #3

Question about work

Re: Unit conversions

Re: Hybridization [ENDORSED]

Re: Workbook Problem #9 in Quiz 2 Prep 1

Re: Molecular Shape of molecules without a singular central

Re: Molecular Vs. electron [ENDORSED]

Re: Electronic configuration after Z=20

Re: Homework Question/ Midterm Question

Re: Math Question [ENDORSED]

Re: When must the Preparatory Self-quizzes be turned-in?

Summer 2016 Chem Workbook

Re: Atomic Spectra Question [ENDORSED]

Re: Fundamentals E Homework [ENDORSED]

Re: Photoelectric Effect Question [ENDORSED]

Re: Photoelectric Effect Question [ENDORSED]

Photoelectric Effect Question [ENDORSED]

Re: How do you find the "largest dipole moment"?

How do you find the "largest dipole moment"?

Video: Molecular Orbital

Re: pi and sigma bonds

How do you find hybridization?

Practice Quiz for Quiz 1