Search found 19 matches

Fri Mar 10, 2017 10:43 am
Forum: *Free Energy of Activation vs Activation Energy
Topic: Delta G Double Dagger 2 vs Ea2
Replies: 2
Views: 1514

Re: Delta G Double Dagger 2 vs Ea2

So just to clarify, in the second transition step, Delta G double dagger 2 is the distance between TS2 and the original reactant, while Ea2 is the distance between TS2 and the intermediates? Please correct me if I'm wrong, or tell me this is right. Yes, delta G double dagger 2 is the distance betwe...
Fri Mar 03, 2017 12:49 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Reaction
Replies: 11
Views: 916

Re: Slow Reaction

Zulfiqar Lokhandwala 1H wrote:When it comes to the slow step reaction is the reaction that is reversible also the slow step reaction? So if it states that the reaction is reversible k and k(prime) would be included in the slow step reaction as well?

If the forward the reaction is slow, then its reverse reaction should be fast.
Wed Feb 22, 2017 3:21 pm
Forum: Second Order Reactions
Topic: Quiz 2 Practice Question 7
Replies: 3
Views: 538

Re: Quiz 2 Practice Question 7

couldnt we set Δt = 22.0 min, Δ[Α] = 0.622-0.773 M, n = 1 (it says it is first order) and [A] = 0.773 (initial concentration) in the differential rate law and solve for k? Differential rate law is used to compare different initial reaction rate when the initial [Reactants] changes, since there is o...
Mon Feb 20, 2017 7:24 pm
Forum: General Rate Laws
Topic: 15.5
Replies: 3
Views: 363

Re: 15.5

Madison_Moore_1I wrote:So all you do is multiply (0.44 mol/Ls) x 3 mol? Or is it not that straightforward?

Yes, just multiply 0.44 mol/L.s by the stoichiometric number.
Fri Feb 10, 2017 9:55 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.13
Replies: 5
Views: 658

Re: 9.13

During the test of an internal combustion engine, 3.00 L of nitrogen gas at 18.5 C was compressed suddenly (and irreversibly) to 0.500 L by driving in a piston. In the process, the temperature of the gas increased to 28.1 C. Assume ideal behavior. What is the change in entropy of the gas? Anybody h...
Sun Feb 05, 2017 12:15 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Why isn't q zero during isothermal reactions?
Replies: 3
Views: 1049

Re: Why isn't q zero during isothermal reactions?

Hello, thank you for your answer! I think I understand your answer, but I am still a little confused about this one point: I understand that under constant pressure, we can rewrite q as H. However, I still don't get why q=mCdeltaT won't work? In other words, while it is true that delta H =mCdeltaT,...
Fri Jan 27, 2017 10:28 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Integral
Replies: 1
Views: 327

Re: Integral

Fayt Sarreal 1G wrote:When taking the negative integral from the initial volume to the final volume, why is PEX the integrand instead of PINT? found on page 22 of the course reader

the equation is used for systems at equilibrium and for a system at equilibrium, Pexternal approximately equals to Pinternal.
Fri Jan 20, 2017 10:39 am
Forum: Phase Changes & Related Calculations
Topic: Constant P vs Constant V Calorimetry [ENDORSED]
Replies: 4
Views: 642

Re: Constant P vs Constant V Calorimetry[ENDORSED]

Constant V calorimeters are usually used when there are gases in the reaction.
Fri Jan 13, 2017 12:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 7
Views: 524

Re: Bond Enthalpies

To calculate what delta H is for a particular reaction using bond enthalpies (method 2), we have to know the structure with which the bonds break in the reactants and the new bonds are formed in the products. But, how do we know which bonds require energy and are broken, and which bonds release ene...
Wed Nov 30, 2016 2:02 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Video: Buffer Solution, Henderson-Hasselbalch Equation
Replies: 4
Views: 757

Re: Video: Buffer Solution, Henderson-Hasselbalch Equation

in the video, pKa was looked up in a chart in the book... will this be given to us during the final or is this something we have to memorize? What chart exactly also?? I don't think we need to memorize the chart. Ka or Kb will be given in the exam. There are two charts in the chapter 12 of the text...
Tue Nov 22, 2016 1:03 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: 12.49 Stronger Base
Replies: 6
Views: 1213

Re: 12.49 Stronger Base

How do we know that BrOH is a weak acid? HBrO is a weaker acid compared to HClO. This is because Cl is more electronegative than Br. Thus, Cl will draw more electron density towards itself and away from the O-H bond which makes the O-H bond in HClO easier to break. Therefore, HBrO is a weak acid (w...
Fri Nov 18, 2016 6:37 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Le Chatelier's Principle Conditions
Replies: 3
Views: 771

Re: Le Chatelier's Principle Conditions

So when a balanced chemical equation involves both solids and gases, and pressure is changed (volume is changed), do we just use the quick method in the course reader? (V decreases and more moles of gas on left, then reaction shifts to the right. And vice versa) We would then just count the moles o...
Fri Nov 18, 2016 6:30 pm
Forum: Ideal Gases
Topic: Ideal Gas Law and Equilibrium Constant
Replies: 7
Views: 891

Re: Chemical Equilibrium Part 3 Module

Wait how do you solve that second problem without knowing the equilibrium constant? For that question, we don't really need to know the equilibrium constant to solve it. If the pressure of the whole system is increased by decreasing the volume, the reaction will proceed to the side with less moles ...
Wed Nov 09, 2016 2:45 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K vs Kc
Replies: 6
Views: 5975

Re: K vs Kc

So what if in a chemical equation, there are both gas and aqueous solution? Should we use Kc or Kp?
Sun Oct 30, 2016 11:21 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Homework Problem 2.39 Issue
Replies: 4
Views: 697

Re: Homework Problem 2.39 Issue

About nitrogen in this problem, I'm curious if it's even possible for one of the unpaired electrons to have an opposite spin to the other two unpaired electrons. Is this a violation of Hund's Rule? Yes, It is possible and that's why this is not a ground state configuration. The opposite spin makes ...
Fri Oct 21, 2016 8:43 pm
Forum: Lewis Structures
Topic: Lewis Structure for CO
Replies: 1
Views: 276

Lewis Structure for CO

In the textbook, there's a question asking what is the lewis structure of CO. And the answer is :C = O: Then I calculated the formal charge for both C and O. The formal charge for C is -1 and for O, it's +1. However, the electron affinity of O is larger than that of C. Doesn't this mean that this le...
Thu Oct 13, 2016 9:16 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation [ENDORSED]
Replies: 4
Views: 648

Re: Rydberg Equation[ENDORSED]

In regards to the partial credit vs. no credit, I was doing a problem where I first wrote down E=-hR/n^2, then needed to find frequency v, so using Einstein's equation E=hv, I divided everything by h. I then put it into the form of Ef - Ei = change in Energy. Essentially, I derived the Rydberg's fo...
Fri Oct 07, 2016 12:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals [ENDORSED]
Replies: 9
Views: 1122

Re: Orbitals[ENDORSED]

I understand that the number corresponds to the energy level and the letter is the shape, but what does the shape actually mean? How do the orbitals have different shapes? Is it the path the electron takes? I think it is just conceptually hard to visualize but I am still very confused on this conce...
Fri Sep 30, 2016 12:23 pm
Forum: Properties of Light
Topic: Increasing Intensity in Photoelectric Effect [ENDORSED]
Replies: 9
Views: 1255

Re: Increasing Intensity in Photoelectric Effect[ENDORSED]

The main concept was that Dr. Lavelle said that increasing the intensity of white light (the light source) does not lead to electrons being removed. In order to remove electrons from the metal you must have a light source with a shorter wavelength. Then in your increase the intensity of this shorte...