Search found 33 matches

by Ilana Golub 1A
Tue Mar 08, 2016 1:29 am
Forum: *Cyclohexanes (Chair, Boat, Geometric Isomers)
Topic: Hw 3.15
Replies: 1
Views: 311

Hw 3.15

I'm having some trouble with this problem! It states the following: 1,1-Bromochlorocyclohexane has preference for one conformation. Draw this conformation and draw it undergoing a ring flip. Looking at the answer key, I understand that the preference is technically trans-1,1-Bromochlorocyclohexane. ...
by Ilana Golub 1A
Tue Mar 01, 2016 7:28 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Activation Energy
Replies: 1
Views: 319

Re: Activation Energy

The orange organic textbook states the following:
a reaction with an activation energy above 80kJ will not occur at room temperature while one below 80kJ can occur at room temperature.
by Ilana Golub 1A
Sun Feb 28, 2016 10:47 am
Forum: *Alkanes
Topic: Quiz 3 preparation: practice quiz 1.2--possible error?
Replies: 1
Views: 308

Quiz 3 preparation: practice quiz 1.2--possible error?

This question asks you to name the following compound: ch3ch(ch3)ch(ch2ch3)c(ch3)3.
The answer key names it 2,2,4-trimethyl-3-ethylpentane.

Shouldn't it be named 3-ethyl-2,2,4-trimethylpentane instead? Shouldn't ethyl come before methyl in terms of alphabetical order?
by Ilana Golub 1A
Mon Feb 22, 2016 7:44 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: 4.30
Replies: 4
Views: 650

Re: 4.30

Hi there! I took this to be a rather intuitive question rather than one that is calculation based. The problem tells us that we have an activation energy of 125kJ/mol. Comparing this value to the others given thus far in our experience with activation energy....woah...this one is pretty huge! We kno...
by Ilana Golub 1A
Mon Feb 15, 2016 4:34 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Course Reader pg75 Pre-Equilibrium example
Replies: 1
Views: 305

Course Reader pg75 Pre-Equilibrium example

I have a quick question regarding the pre-equilibrium example on pg75 of the course reader. When predicting the rate law assuming the reaction mechanism's slow step is correct, we write 1/2d[NO2]/dt=k2[N2O2][O2]. I understand that here, before we substitute for the N2O2 intermediate, we must write 1...
by Ilana Golub 1A
Sun Feb 14, 2016 8:46 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: HW 15.101
Replies: 2
Views: 477

Re: HW 15.101

Wow, can't believe I missed that!
Thanks for the help!
by Ilana Golub 1A
Sat Feb 13, 2016 8:53 pm
Forum: Administrative Questions and Class Announcements
Topic: The Orange Book & Additional Organic Chem Problems
Replies: 1
Views: 390

The Orange Book & Additional Organic Chem Problems

I have two questions that I believe relate to one another...here they go! 1) I understand that the orange booklet that came with our course reader is specifically for reviewing principles that will pertain to Organic chem. When will this material appear on quizzes/exams? When should we start to revi...
by Ilana Golub 1A
Sat Feb 13, 2016 8:48 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: HW 15.101
Replies: 2
Views: 477

HW 15.101

I'm rather confused by part b in this problem. 1) I understand that, when writing the rate law based on the mechanism, intermediates cannot appear in the rate law. Thus, we must substitute [HClO] out, etc. The book comes up with the overall rate law to be rate=(k2k1[ClO-][I-])/(k1'[OH-]) However, ho...
by Ilana Golub 1A
Sat Feb 13, 2016 8:38 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8242
Views: 1437651

Re: Chemistry Jokes

In honor of Valentine's day coming up....
Here are some chemistry pick up lines!

http://chemistry.about.com/od/valentinesdaychemistry/a/Chemistry-Pick-Up-Lines.htm
by Ilana Golub 1A
Mon Feb 08, 2016 9:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt/Galvanic Cell
Replies: 1
Views: 544

Re: Pt/Galvanic Cell

Platinum is used as the electrode when no other solid is present in the given reduction or oxidation half reaction. However, the element does not actually participate in the reaction--it simply serves as the anode or cathode electrode. Graphite [C(s)] is another relatively common example of an elect...
by Ilana Golub 1A
Mon Feb 08, 2016 9:30 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: nernst equation
Replies: 2
Views: 427

Re: nernst equation

You may use either. However, they aren't "interchangeable" per say. For instance, log(10) does not equal ln(10).

Note that the inverse of log (base 10) and ln are different. While the inverse of log is 10^-x, the inverse of ln is e^-x.
by Ilana Golub 1A
Mon Feb 08, 2016 9:22 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Midterm 2014 Question 8
Replies: 2
Views: 404

Re: Midterm 2014 Question 8

If not stated otherwise, I would assume that the reaction occurs at standard room temperature; 25degrees Celsius and 298K.
by Ilana Golub 1A
Tue Feb 02, 2016 12:25 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrode composition
Replies: 1
Views: 270

Re: Electrode composition

I am slightly confused by your question, but I will try to answer it accordingly. The electrode is by definition "a conductor through which electricity enters or leaves an object, substance, or region." Essentially, it represents the solid metal present in both the anode and cathode side o...
by Ilana Golub 1A
Tue Feb 02, 2016 12:19 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Drawing Cell Diagrams
Replies: 1
Views: 331

Drawing Cell Diagrams

I understand that, to the left of the double vertical lines, is the anode reaction and that, to the right, is the cathode reaction. Within these two categories, however, does the order of each molecule/ion listed matter? For instance, might we be able to write either Cl2(g) first and then Cl-(aq) or...
by Ilana Golub 1A
Tue Jan 26, 2016 9:26 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy in regards to Temperature
Replies: 2
Views: 419

Re: Entropy in regards to Temperature

Entropy is by definition "a thermodynamic quantity representing the unavailability of a system's thermal energy for conversion into mechanical work, often interpreted as the degree of disorder or randomness in the system." Basically, what you should take away from that is the following: en...
by Ilana Golub 1A
Tue Jan 26, 2016 9:18 pm
Forum: Calculating Work of Expansion
Topic: Isothermal and Reversible
Replies: 2
Views: 370

Re: Isothermal and Reversible

Specifically, isothermal signifies constant temperature. Also, isothermal systems have a deltaU=0 and so the change in internal energy is zero. Because q+w=deltaU and q+w=0, q=-w. As for whether an isothermal system is reversible or irreversible...we're used to associating a reversible example to an...
by Ilana Golub 1A
Tue Jan 19, 2016 9:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Work of expansion question?
Replies: 3
Views: 627

Re: Work of expansion question?

Jumping off what people have already said...here's what I have:) Imagine you have a red balloon. The balloon and the air particles within it constitute the system while the surroundings are everything outside of the balloon. Think of this example conceptually; ignore any equations you've learned for...
by Ilana Golub 1A
Tue Jan 19, 2016 9:08 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Review
Replies: 2
Views: 402

Re: Review

The course reader is definitely very helpful. I'd also recommend skimming the textbook and doing the practice quizzes. In addition to those things, make sure to go through the "syllabus" for the given chapter...in the beginning of each section, there is a bullet list of all the concepts we...
by Ilana Golub 1A
Tue Jan 12, 2016 5:16 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy of Physical Change self-test
Replies: 1
Views: 358

Re: Enthalpy of Physical Change self-test

This problem illustrates the process in actually calculating benzene's heat of vaporization. So that scientists don't have to conduct a separate experiment each time to calculate this value, it is recorded...hence, the chart :) The enthalpy of vaporization is essentially one way to define benzene; i...
by Ilana Golub 1A
Tue Jan 05, 2016 10:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Defining the system
Replies: 1
Views: 551

Re: Defining the system

I believe that (at least in all the cases I've seen) determining which is "system" and which is "surroundings" is fairly straightforward. Essentially, the system is the source of the chemical reaction or physical change--the location in which these changes occur. The surroundings...
by Ilana Golub 1A
Tue Dec 01, 2015 12:31 am
Forum: Calculating the pH of Salt Solutions
Topic: pH of H2O
Replies: 1
Views: 427

Re: pH of H2O

The equation is as follows: HCl + NaOH <-> Na+ + Cl- + H2O It's important to look at the ions formed: Na+ and Cl-. Na+ is the conjugate acid of the strong base, NaOH & Cl- is the conjugate base of the strong acid, HCl. Because both of these dissociated ions come from "strong" compounds...
by Ilana Golub 1A
Mon Nov 23, 2015 11:40 pm
Forum: Lewis Acids & Bases
Topic: Acids and Bases
Replies: 1
Views: 358

Re: Acids and Bases

IMG_6133.JPG


Here is a basic response to your question. I think it's a good start to understanding acids and bases.
by Ilana Golub 1A
Wed Nov 18, 2015 10:50 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.39 Combination of Reactions
Replies: 2
Views: 412

Re: 11.39 Combination of Reactions

Part 2:

IMG_6091.MOV [ 13.44 MiB | Viewed 406 times ]



Hope this helps:)
by Ilana Golub 1A
Wed Nov 18, 2015 10:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.39 Combination of Reactions
Replies: 2
Views: 412

Re: 11.39 Combination of Reactions

I am attaching two videos, but here is a short summary. We know that our final equilibrium equation must be 2BrCl(g) + H2(g) <---> Br2(g) + 2HCl(g) From Table 11.2, we can pull out the two equations 2BrCl(g) <---> Br2(g) + Cl2(g), K1=377 and H2(g) + Cl2(g) <---> 2HCl(g), K2=4.0x10^31 If we "add...
by Ilana Golub 1A
Wed Nov 18, 2015 10:13 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: name to formula (order of ligands)
Replies: 1
Views: 508

Re: name to formula (order of ligands)

You are absolutely correct in stating that, when writing the actual name of a coordination compound, the ligands must be listed in alphabetical order. This is then followed by the name of the metal and it's charge. (Remember that, if the coordination ion has a negative charge, you must add "ate...
by Ilana Golub 1A
Tue Nov 10, 2015 12:08 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: heterogenous/homogenous equilibrium
Replies: 1
Views: 2068

Re: heterogenous/homogenous equilibrium

IMG_6053.MOV Here's a short summary of what I'm saying in the video... Homogeneous Equilibria is chemical equilibrium with all reactants and products in the same state--i.e. all are aqueous or gas and are hence all included in the Kc constant Heterogeneous Equilibria is chemical equilibrium with NO...
by Ilana Golub 1A
Thu Nov 05, 2015 11:37 pm
Forum: Octet Exceptions
Topic: How to tell if Xe will form double bonds?
Replies: 5
Views: 1305

Re: How to tell if Xe will form double bonds?

IMG_6034.MOV [ 10.6 MiB | Viewed 1265 times ]



Here is Part 2 of the video!!
by Ilana Golub 1A
Thu Nov 05, 2015 11:35 pm
Forum: Octet Exceptions
Topic: How to tell if Xe will form double bonds?
Replies: 5
Views: 1305

Re: How to tell if Xe will form double bonds?

IMG_6033.MOV This is Part 1 of the video! A basic summary: Many elements can violate their octet. In particular, they may have an "expanded" octet. This means that they actually have more than 8 electrons around them. However, only elements that are in Period 3 or below on the period tabl...
by Ilana Golub 1A
Mon Oct 26, 2015 11:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Correct Lewis Structure for CH2Cl2
Replies: 1
Views: 1625

Re: Hw 4.25

IMG_6008.MOV [ 12.26 MiB | Viewed 1621 times ]



Hopefully this helps!
by Ilana Golub 1A
Mon Oct 19, 2015 11:27 pm
Forum: Resonance Structures
Topic: Resonance and blending of structures
Replies: 2
Views: 438

Re: Resonance and blending of structures

I hope this helps!!

IMG_5989.MOV [ 9.32 MiB | Viewed 433 times ]

by Ilana Golub 1A
Mon Oct 12, 2015 7:50 pm
Forum: Resonance Structures
Topic: Bond Angle
Replies: 2
Views: 420

Re: Bond Angle

IMG_5953.MOV [ 14.67 MiB | Viewed 408 times ]

by Ilana Golub 1A
Mon Oct 05, 2015 10:52 pm
Forum: Administrative Questions and Class Announcements
Topic: How much do I need to know for this class from course reader
Replies: 2
Views: 626

Re: How much do I need to know for this class from course re

The course reader so far seems to be extremely helpful. Essentially, it is an outline for the notes Professor Lavelle gives in class--it's the key concepts from his lecture, that is. Of course, that shouldn't be all you depend on for notes...but it's a definite start. Taking a look at the lectures o...
by Ilana Golub 1A
Thu Oct 01, 2015 8:54 pm
Forum: Properties of Electrons
Topic: Electrons moving down energy levels
Replies: 2
Views: 458

Re: Electrons moving down energy levels

Hi there! That's a really good question! So for that electron to be elevated to an energy level of n=3, it needs to absorb a specific (quantized) amount of energy...otherwise nothing would happen. But we already know that--it makes sense. From that energy level of n=3 (or any excited state), the ele...

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