## Search found 34 matches

Sat Mar 18, 2017 5:46 pm
Forum: *Alcohols
Topic: 2013 final Q6B
Replies: 2
Views: 816

### Re: 2013 final Q6B

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.
Tue Mar 14, 2017 11:27 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Final 2013 Question 4b
Replies: 1
Views: 292

### Final 2013 Question 4b

Can anyone help walk me through this problem?
Tue Mar 14, 2017 11:25 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Final 2013 Question 4
Replies: 2
Views: 516

### Final 2013 Question 4

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

I get a slightly bigger answer when I use the Nernst equation with log in it than the one with ln.
Sun Mar 12, 2017 8:36 pm
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: Cis & Trans
Replies: 3
Views: 476

### Re: Cis & Trans

"E" is used in regards to a "trans" molecule where the priority molecule is on opposite sides. See my attachment for clarification!
Thu Mar 09, 2017 5:40 pm
Forum: *Alkenes
Topic: Priority in Alkenes
Replies: 2
Views: 394

### Re: Priority in Alkenes

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...
Sun Mar 05, 2017 11:56 pm
Forum: *Alkanes
Topic: Isopropyl vs Propyl [ENDORSED]
Replies: 4
Views: 10047

### Re: Isopropyl vs Propyl[ENDORSED]

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.
Sat Feb 25, 2017 12:02 am
Forum: *Nucleophiles
Replies: 2
Views: 507

### Re: Course reader p. 82

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.
Fri Feb 24, 2017 11:57 pm
Forum: *Electrophiles
Topic: Bruincast Friday 2/24
Replies: 5
Views: 873

### Re: Bruincast Friday 2/24

Try waiting until Lecture 3's Bruin Cast comes out!
Sun Feb 19, 2017 2:42 am
Forum: Balancing Redox Reactions
Topic: H+ and e-
Replies: 4
Views: 2393

### Re: H+ and e-

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 -...
Sun Feb 12, 2017 11:51 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8200
Views: 1430742

### Re: Post All Chemistry Jokes Here

Tue Jan 31, 2017 11:07 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Prep quiz 1 #3
Replies: 3
Views: 470

### Re: Prep quiz 1 #3

Work is not a state function.

Do I only use the volume values because it's an isothermal reaction?
Tue Jan 31, 2017 10:42 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Prep quiz 1 #3
Replies: 3
Views: 470

### Prep quiz 1 #3

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 = -...
Sun Jan 29, 2017 11:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Replies: 1
Views: 261

In the formula, w= -P(deltaV), why do we use the one with the negative sign and not the one without the negative sign?
Sun Jan 22, 2017 11:42 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Unit conversions
Replies: 2
Views: 466

### Re: Unit conversions

The practice quizzes in the back of the course reader also give great insight to how Dr. Lavelle will phrase his questions (units included).
Mon Jul 25, 2016 4:39 pm
Forum: Hybridization
Topic: Hybridization [ENDORSED]
Replies: 4
Views: 745

### Re: Hybridization[ENDORSED]

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...
Wed Jul 20, 2016 12:02 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Workbook Problem #9 in Quiz 2 Prep 1
Replies: 2
Views: 344

### Re: Workbook Problem #9 in Quiz 2 Prep 1

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!
Tue Jul 12, 2016 7:42 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape of molecules without a singular central atom
Replies: 2
Views: 771

### Re: Molecular Shape of molecules without a singular central

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...
Sat Jul 09, 2016 10:45 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Vs. electron [ENDORSED]
Replies: 3
Views: 669

### Re: Molecular Vs. electron[ENDORSED]

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...
Mon Jul 04, 2016 11:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electronic configuration after Z=20
Replies: 3
Views: 688

### Re: Electronic configuration after Z=20

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.
Sun Jul 03, 2016 3:02 pm
Forum: Properties of Light
Topic: Homework Question/ Midterm Question
Replies: 2
Views: 329

### Re: Homework Question/ Midterm Question

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).
Wed Jun 29, 2016 7:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Math Question [ENDORSED]
Replies: 1
Views: 504

### Re: Math Question[ENDORSED]

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.
Fri Jun 24, 2016 6:31 pm
Forum: Administrative Questions and Class Announcements
Topic: When must the Preparatory Self-quizzes be turned-in?
Replies: 3
Views: 504

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

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
Fri Jun 24, 2016 11:56 am
Forum: General Science Questions
Topic: Summer 2016 Chem Workbook
Replies: 1
Views: 363

### Summer 2016 Chem Workbook

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!!!
Fri Jun 24, 2016 11:54 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Question [ENDORSED]
Replies: 3
Views: 514

### Re: Atomic Spectra Question[ENDORSED]

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).
Thu Jun 23, 2016 5:43 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Fundamentals E Homework [ENDORSED]
Replies: 2
Views: 509

### Re: Fundamentals E Homework[ENDORSED]

You can find the conversions on the back of the textbook. "pm," I believe, are picometers.
Thu Jun 23, 2016 4:13 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Question [ENDORSED]
Replies: 3
Views: 568

### Re: Photoelectric Effect Question[ENDORSED]

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(...
Wed Jun 22, 2016 10:39 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Question [ENDORSED]
Replies: 3
Views: 568

### Re: Photoelectric Effect Question[ENDORSED]

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?
Wed Jun 22, 2016 10:30 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Question [ENDORSED]
Replies: 3
Views: 568

### Photoelectric Effect Question[ENDORSED]

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...
Fri Dec 04, 2015 12:08 pm
Forum: Dipole Moments
Topic: How do you find the "largest dipole moment"?
Replies: 6
Views: 69081

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

Thu Dec 03, 2015 9:05 pm
Forum: Dipole Moments
Topic: How do you find the "largest dipole moment"?
Replies: 6
Views: 69081

### How do you find the "largest dipole moment"?

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!
Wed Nov 25, 2015 11:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Video: Molecular Orbital
Replies: 4
Views: 13285

### Video: Molecular Orbital

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.
Sun Nov 01, 2015 9:47 am
Forum: Hybridization
Topic: pi and sigma bonds
Replies: 2
Views: 319

### Re: pi and sigma bonds

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
Sat Oct 31, 2015 11:59 pm
Forum: Hybridization
Topic: How do you find hybridization?
Replies: 3
Views: 838

### How do you find hybridization?

How would you find the hybridization of a benzene (C6H6)? I don't understand how to map out the energy levels, 2s, 2p, etc.
Sat Oct 10, 2015 11:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Practice Quiz for Quiz 1
Replies: 3
Views: 504

### Practice Quiz for Quiz 1

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...