Search found 36 matches

by Alexander Chen 3N
Tue Mar 14, 2017 12:13 am
Forum: Calculating Work of Expansion
Topic: Reversible vs irreversible equations
Replies: 3
Views: 352

Re: Reversible vs irreversible equations

I'm confused about your equation for adiabatic processes. I thought for adiabatic processes.

Thanks for the help Dr. Lavelle!
by Alexander Chen 3N
Fri Mar 10, 2017 3:58 pm
Forum: *Cycloalkenes
Topic: Numbering carbon atoms
Replies: 1
Views: 524

Re: Numbering carbon atoms

I'm not sure if I am understanding your question, but we do look for the longest chain even if there is a cycloalkane. For example, if there is a decane with a cyclopropane attached to the 2nd carbon, it would be called 2-cyclopropyl-decane. Let me know if you have more questions or if I misundersto...
by Alexander Chen 3N
Sun Mar 05, 2017 9:16 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Functional Groups
Replies: 1
Views: 216

Re: Functional Groups

This is because by definition, aldehydes only have 1 R group to connect to, so it must be at the end. On the other hand, ketones, by definition, must connect to 2 R groups, so it cannot be at the end of a carbon chain.
by Alexander Chen 3N
Sun Mar 05, 2017 7:48 pm
Forum: *Cycloalkanes
Topic: Prefix in Naming
Replies: 1
Views: 293

Re: Prefix in Naming

Tert describes the structure of the substituent. Here it shows that the butyl group has a tertiary carbon.
by Alexander Chen 3N
Sun Feb 19, 2017 8:45 pm
Forum: General Rate Laws
Topic: Derivation for the Differential Rate Law
Replies: 3
Views: 308

Re: Derivation for the Differential Rate Law

Actually I think I understand it now.

is just the general term for the instantaneous rate and is just the experimentally determined rate at which the reaction occurs.
by Alexander Chen 3N
Sun Feb 19, 2017 8:03 pm
Forum: General Rate Laws
Topic: Derivation for the Differential Rate Law
Replies: 3
Views: 308

Re: Derivation for the Differential Rate Law

20170219_200202.jpg


This is page 60.

Thanks for the help!
by Alexander Chen 3N
Sun Feb 19, 2017 1:43 am
Forum: General Rate Laws
Topic: Derivation for the Differential Rate Law
Replies: 3
Views: 308

Derivation for the Differential Rate Law

The course reader was very clear on how the integrated rate law is derived. However, I am confused about how the differential rate law is derived and neither the course reader nor the textbook explicitly show this. The course reader states RATE = -\frac{1}{a}\frac{d[R]}{dt} = k[R]^{n} , but I am uns...
by Alexander Chen 3N
Sat Feb 18, 2017 1:39 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1012124

Re: Post All Chemistry Jokes Here

Did you hear about the man who got cooled to absolute zero?

He's 0K now.
by Alexander Chen 3N
Wed Feb 15, 2017 4:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Winter Midterm 2014 QB
Replies: 3
Views: 421

Re: Winter Midterm 2014 QB

I assumed it was hexane because it has more isomers, but I am also unsure.
by Alexander Chen 3N
Fri Feb 03, 2017 9:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: The Salt Bridge
Replies: 1
Views: 248

Re: The Salt Bridge

If Cl- stays in the cathode, the cathode would be negatively charged, so electrons would be repelled from the cathode. The salt bridge allows these ions to move to the anode and make the 2 solutions neutral in charge. About electronegativty: Chlorine itself is electronegative so it takes an electron...
by Alexander Chen 3N
Sun Jan 22, 2017 8:12 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Different ways to calculate reaction enthalpies
Replies: 1
Views: 247

Re: Different ways to calculate reaction enthalpies

My TA told me that for the other methods, we should assume that the information given is at the temperature of the reaction enthalpy. For example, if you need to find the reaction enthalpy at 30ºC using Hess's law, the other reactions must also be at 30ºC. I do not believe temperature change can be ...
by Alexander Chen 3N
Fri Jan 20, 2017 9:15 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: General questions [ENDORSED]
Replies: 4
Views: 673

Re: General questions [ENDORSED]

I know number 1.

1. NA () is Avogradro's number, but it does represent the number of particles.

Following for the others.
by Alexander Chen 3N
Mon Jan 16, 2017 11:52 pm
Forum: Phase Changes & Related Calculations
Topic: Boiling Points at Altitude [ENDORSED]
Replies: 2
Views: 338

Re: Boiling Points at Altitude [ENDORSED]

Water boils at a lower temperature at lower pressures. This is because the atmospheric pressure is lower, so less vapor pressure (created by increasing temperature) is needed for the gas to escape.
by Alexander Chen 3N
Thu Dec 01, 2016 3:01 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Question 12.23 (Kw not at STP) [ENDORSED]
Replies: 1
Views: 300

Question 12.23 (Kw not at STP) [ENDORSED]

Question 12.23 asks to find the pH of neutral water at 37C and gives the Kw=2.1X10^-14. The answer is pH=6.80. What I'm confused about is the hydronium ion concentration is equal to the hydroxide ion concentration, so if we take the -log of [OH-], pOH = 6.8. Does pH+pOH=14 not apply to systems not a...
by Alexander Chen 3N
Thu Dec 01, 2016 11:12 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier
Replies: 3
Views: 384

Re: Le Chatelier

That would be the equilibrium constant. For example, if and you add more B, then A would increase and B would decrease until you reach the equilibrium constant.
by Alexander Chen 3N
Fri Nov 25, 2016 5:18 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Indicators of strong or weak acid/base
Replies: 3
Views: 396

Re: Indicators of strong or weak acid/base

A simple indicator is if the question gives you the Ka or Kb, you should assume that it is a weak acid/base. This is because a strong acid/base has a very large Ka/Kb, so we just say that the reaction goes to completion and the acid is fully dissociated (HCl fully becomes H+ and Cl-).
by Alexander Chen 3N
Thu Nov 17, 2016 1:20 am
Forum: Naming
Topic: Quizlet for the names of Common Ligands
Replies: 10
Views: 1127

Re: Quizlet for the names of Common Ligands

I'm sure we need to know them for Quiz 3. I'm pretty sure we need to know them for the final too.
by Alexander Chen 3N
Thu Nov 17, 2016 1:01 am
Forum: Naming
Topic: Homework 17.31 (d): Naming Alphabetically
Replies: 2
Views: 398

Re: Homework 17.31 (d): Naming Alphabetically

You should alphabetize according to the actual ligand name, not the prefixes. Aqua is before oxalato in alphabetic order, so diaqua comes first.
by Alexander Chen 3N
Fri Nov 11, 2016 4:28 pm
Forum: Naming
Topic: Asterisks on the Table of Ligands [ENDORSED]
Replies: 4
Views: 517

Re: Asterisks on the Table of Ligands [ENDORSED]

I don't think the asterisks mean that it is a polydentate because neither nitrito nor sulfato are polydentates, but they have asterisks.

I don't know what the asterisks mean either, so I'm following this thread.
by Alexander Chen 3N
Thu Nov 10, 2016 11:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chapter 17 Question #33
Replies: 1
Views: 228

Re: Chapter 17 Question #33

What you can do to figure this out is draw the lewis structures for each of the ligands and find how many areas of high electron density there are to determine the number of binding sites. If the number of binding sites is greater than 1, it is a polydentate. Additionally, you can use the informatio...
by Alexander Chen 3N
Thu Nov 10, 2016 11:18 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular orbitals
Replies: 1
Views: 204

Re: Molecular orbitals

MO orbitals describe the electrons in an entire molecule while hybrid orbitals describe the electrons around a single atom. They can and often do appear together, but the MO diagram only shows the energies of the electrons while we can determine the shape of the areas of electron density from what w...
by Alexander Chen 3N
Sun Nov 06, 2016 11:54 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1012124

Re: Post All Chemistry Jokes Here

If H20 is water, what is H204?

Drinking, bathing, washing, swimming, etc.
by Alexander Chen 3N
Fri Oct 28, 2016 3:00 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1012124

Re: Post All Chemistry Jokes Here

I hate it when I make a chemistry joke, but there's no reaction.
by Alexander Chen 3N
Sun Oct 23, 2016 5:01 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1012124

Re: Post All Chemistry Jokes Here

Chemistry version of Pen Pineapple Apple Pen. So dumb, yet so funny!

https://www.youtube.com/watch?v=nqL75fASb6U
by Alexander Chen 3N
Sat Oct 15, 2016 2:49 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 2.21
Replies: 5
Views: 388

Re: 2.21

l=0 is the s orbital
l=1 is the p orbital
l=2 is the d orbital
l=3 is the f orbital

If you have any more questions let me know!
by Alexander Chen 3N
Sun Oct 09, 2016 11:34 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Homework 1.13 [ENDORSED]
Replies: 3
Views: 376

Re: Homework 1.13 [ENDORSED]

Sorry for the late reply, but R is Rhydberg's constant and
by Alexander Chen 3N
Sun Oct 09, 2016 10:53 pm
Forum: SI Units, Unit Conversions
Topic: Sig Figs [ENDORSED]
Replies: 16
Views: 1883

Re: Sig Figs [ENDORSED]

3

This can be seen more easily if you convert this to scientific notation.
by Alexander Chen 3N
Sun Oct 09, 2016 10:52 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Quiz 1 Preparation: Fall 2014 Question #10 [ENDORSED]
Replies: 6
Views: 752

Re: Quiz 1 Preparation: Fall 2014 Question #10 [ENDORSED]

I didn't get rid of the negative, the number that is being square rooted is positive. I first used the equation E = h\nu to find the energy. Then I used \Delta E = E_{final} - E_{initial} where E_{n}=\frac{-hr}{n^{2}} . You just equations that have variables you know and variables you need to find, ...
by Alexander Chen 3N
Sun Oct 09, 2016 8:57 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Quiz 1 Preparation: Fall 2014 Question #10 [ENDORSED]
Replies: 6
Views: 752

Re: Quiz 1 Preparation: Fall 2014 Question #10 [ENDORSED]

Here's my work, but I didn't include every step, so if you have any questions about it, please let me know.

Hope this helps! :)

-Alexander Chen
by Alexander Chen 3N
Thu Oct 06, 2016 12:02 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Homework 1.13 [ENDORSED]
Replies: 3
Views: 376

Re: Homework 1.13 [ENDORSED]

Hey Grace!

I worked out the problem for you in the picture below.

Let me know if you have any questions!
by Alexander Chen 3N
Thu Oct 06, 2016 11:47 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Video Module Question
Replies: 2
Views: 282

Re: Atomic Spectra Video Module Question

Hi Raj!

I just went through this question and got that the principle quantum level is 6.

Attached is a picture of my work.

Let me know if you have any more questions!
by Alexander Chen 3N
Wed Sep 28, 2016 7:31 pm
Forum: General Science Questions
Topic: Memorizing Constants
Replies: 2
Views: 571

Re: Memorizing Constants

I believe Dr. Lavelle said we would have a formula sheet during exams that will give us the formulas and constants that we would need. The only thing you would have to know is when to use what, because each question will not tell you the constant or formula you need to solve the question.

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