Search found 21 matches
- Wed Mar 15, 2017 10:49 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 504152
Re: Saying Thank You to Dr. Lavelle
Dr. Lavelle, Although I still can't say chemistry is my favorite subject, I really think having you as a teacher really challenged me to think analytically and problem solve. I appreciate the positive attitude you project in lectures and how you provide all these resources for your students. It has ...
- Tue Mar 07, 2017 9:44 pm
- Forum: *Alkanes
- Topic: Drawing/Labeling reaction profile
- Replies: 3
- Views: 733
Re: Drawing/Labeling reaction profile
My TA told me that the class would focus more on exergonic reactions. So when they tell us to draw the reaction profiles, they would also tell us if the reaction was exergonic or endergonic. If it's exergonic, the reactants start off higher than the products, and if endergonic vice versa.
- Tue Mar 07, 2017 9:33 pm
- Forum: *Alkanes
- Topic: Alkane name
- Replies: 3
- Views: 715
Re: Alkane name
I think if you're having trouble identifying the parent chain, you can just count all the C's outside the parentheses, then consider the one in parentheses the subsituent of the adjacent C atom.
- Wed Mar 01, 2017 11:03 pm
- Forum: *Electrophilic Addition
- Topic: Electrophilic addition reaction of HBr and Propene
- Replies: 2
- Views: 663
Re: Electrophilic addition reaction of HBr and Propene
I was also thinking the same thing: whether it can be written as CH3-CHBr-CH3 as opposed to CH3-CH2-CH2Br.
- Wed Feb 22, 2017 3:55 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Quiz 2 Practice Question 11
- Replies: 2
- Views: 543
Re: Quiz 2 Practice Question 11
I think we might have to use the first order equation: ln(k2/k1)=Ea/R * ((1/T1)-(1/T2)). Maybe first solving for Ea, then using the equation again to solve for k2 at 770 K.
- Tue Feb 14, 2017 4:24 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: .05916 In Nernst Equation
- Replies: 5
- Views: 1301
Re: .05916 In Nernst Equation
I think the answer should be the same even if you used the one with 'ln' instead of 'log'. But then instead, it would be 0.02568/n when you plug it into the Nernst equation: {Ecell= Escp - (0.02568/n)*lnQ}
- Tue Feb 07, 2017 5:34 pm
- Forum: Calculating Work of Expansion
- Topic: Entropy - Reversible vs Irreversible
- Replies: 3
- Views: 835
Re: Entropy - Reversible vs Irreversible
I think it may have something to do with entropy being a state function. So if the reaction returns to the same state it was in before, then there was no change.
- Wed Feb 01, 2017 9:08 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Bond Enthalpies
- Replies: 7
- Views: 1048
Re: Bond Enthalpies
Also, I think it would require more energy to break the double bond than it would be to break the single bond (if you want to say something in terms of energy).
- Wed Jan 25, 2017 7:41 pm
- Forum: Phase Changes & Related Calculations
- Topic: Derivations
- Replies: 21
- Views: 3338
Re: Derivations
I think most of what will be asked for is the manipulation of given equations to solve for problems.
For example, delta U= q+w; since w=-PV we can substitute it into the equation -> delta U= q - PV
For example, delta U= q+w; since w=-PV we can substitute it into the equation -> delta U= q - PV
- Wed Jan 18, 2017 2:43 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Enthalpy [ENDORSED]
- Replies: 3
- Views: 707
Re: Enthalpy [ENDORSED]
Since a bond is being formed, energy is being released from the system and the enthalpy of that part of the system would be negative.
In the case where a bond is being broken, energy is being taken up by the system to break a bond and the enthalpy of that part of the system would be positive.
In the case where a bond is being broken, energy is being taken up by the system to break a bond and the enthalpy of that part of the system would be positive.
- Fri Jan 13, 2017 4:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calculating the Heat Given Off By a Reaction
- Replies: 2
- Views: 484
Re: Calculating the Heat Given Off By a Reaction
I think you can use the equation [q= m* Csp *(delta T)], where m is mass in grams, to find the "specific heat capacity".
- Sat Dec 03, 2016 1:49 pm
- Forum: Dipole Moments
- Topic: Dipole and Polarity [ENDORSED]
- Replies: 3
- Views: 852
Re: Dipole and Polarity [ENDORSED]
If given a list of molecules, how would you determine which has the highest dipole moment? (Assuming they all have dipole moments)
- Tue Nov 22, 2016 6:53 pm
- Forum: Lewis Acids & Bases
- Topic: strong or weak acid
- Replies: 6
- Views: 1290
Re: strong or weak acid
The longer the bond, the stronger the acid; for example this order from weakest to strongest acids:
H-F < H-Cl < H-Br < H-I
H-F < H-Cl < H-Br < H-I
- Wed Nov 16, 2016 11:48 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Identifying Polydentates? [ENDORSED]
- Replies: 8
- Views: 2266
Re: Identifying Polydentates? [ENDORSED]
Is there a way to identify whether something is mono-, bi-, try-, etc. dentate just by looking at the compound given? Or do we always have to draw the structure?
- Sat Nov 12, 2016 4:08 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Shape of coordination compound
- Replies: 3
- Views: 1103
Re: Shape of coordination compound
I think we should know the structure of the coordination compound if we were asked about the dentisity of the compound (eg. the polydentate: EDTA)
- Tue Nov 01, 2016 9:27 am
- Forum: Ionic & Covalent Bonds
- Topic: Covalent and Ionic Character
- Replies: 3
- Views: 1337
Re: Covalent and Ionic Character
So is there a quick way to determine the order of ionic/covalent characteristics just by looking at the periodic table? The closer two elements are to each other in a molecule on the periodic table, the more covalent they are. The farther they are from each other on the periodic table, the more ioni...
- Wed Oct 26, 2016 11:06 pm
- Forum: Lewis Structures
- Topic: Noble Gas as central atom
- Replies: 1
- Views: 1179
Noble Gas as central atom
Since Xenon can be considered a central atom, does that mean Krypton and Radon can also act as the central atom?
- Mon Oct 17, 2016 6:27 pm
- Forum: Lewis Structures
- Topic: Chapter 3 #57 [ENDORSED]
- Replies: 2
- Views: 547
Re: Chapter 3 #57 [ENDORSED]
The central atom should be the one with the least electronegativity. From left to right on the periodic table, electronegativity increases. From top to bottom, electronegativity decreases. So for a) sulfite ion, the sulfur ion would be in the middle and connected to 3 oxygens. Even though they are i...
- Mon Oct 10, 2016 10:45 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Showing Work [ENDORSED]
- Replies: 3
- Views: 789
Re: Showing Work [ENDORSED]
Plus, in my opinion, showing work helps make sure you're on the right track, like having the correct units for your numbers and also having the right amount of sig figs in the end.
- Wed Oct 05, 2016 9:36 am
- Forum: DeBroglie Equation
- Topic: Worked Example on page 52 in the Course Reader
- Replies: 2
- Views: 585
Re: Worked Example on page 52 in the Course Reader
Yeah. I think Professor Lavelle just meant 10^15 was the general cutoff point to determine if a wavelength is measurable. Like if a question were to ask whether an object with a certain mass and velocity has a measurable wavelength, 10^15 would be the cutoff. >10^15 meaning it is, and <10^15 meaning...
- Mon Sep 26, 2016 4:47 pm
- Forum: Empirical & Molecular Formulas
- Topic: Calculating Molecular and Empirica Formulas
- Replies: 5
- Views: 2801
Re: Calculating Molecular and Empirica Formulas
This is an example we did in our discussion session, if you find it helpful. Ex. Caffeine is 49.48% C, 5.19% H, 16.4% O, and 28.61% N. Find the empirical formula. 1. First, we had to assume it was over 100 g so that we could get rid of the percentages and make them into grams. 2. Then we divide each...