Search found 37 matches
- Sat Mar 17, 2018 8:51 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation 15.61
- Replies: 3
- Views: 365
Re: Arrhenius Equation 15.61
why do they multiply by the LCF in the solutions manual to obtain t-t'/t times t"
- Sat Mar 17, 2018 6:30 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Organic Chem
- Replies: 2
- Views: 350
Re: Organic Chem
Troy Tavangar 1I wrote:Does anyone know if any organic chemistry will be covered on the final?
just identify the functional groups. ketones, carboxylic acid, alcohol, ether, amine, and aldehyde:)
- Sat Mar 17, 2018 6:25 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: True/False Catalyst
- Replies: 3
- Views: 453
Re: True/False Catalyst
"A catalyst is not consumed in the course of a reaction." I am confused as to why this is false. I understood that a catalyst is first found on the reactant side of the equation and then is later found as a product. Is it not consumed even though it goes from the reactants to the products...
- Sat Mar 17, 2018 6:11 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.67?
- Replies: 5
- Views: 666
Re: 15.67?
also, why do we set it up so that it is rate of the cat rxn/ rate of the uncat rxn?
- Sat Mar 17, 2018 5:47 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: True/False Catalyst
- Replies: 3
- Views: 453
Re: True/False Catalyst
"A catalyst is not consumed in the course of a reaction." I am confused as to why this is false. I understood that a catalyst is first found on the reactant side of the equation and then is later found as a product. Is it not consumed even though it goes from the reactants to the products...
- Sat Mar 17, 2018 5:44 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation
- Replies: 3
- Views: 406
Re: Arrhenius Equation
it is consistent with products/reactants or y/x or final/intial^^
- Sat Mar 17, 2018 5:42 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: catalyst
- Replies: 4
- Views: 414
Re: catalyst
think of "lowering the activation energy" as "it makes it easier for the reaction to occur" its like extra help for the products to undergo a reaction.
- Sat Mar 17, 2018 5:36 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.67?
- Replies: 5
- Views: 666
Re: 15.67?
in the solutions manual it tells you that the rate of the uncatalyzed reaction is .60. how did they know this??
- Sat Mar 17, 2018 12:22 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: catalysts and intermediates
- Replies: 2
- Views: 231
Re: catalysts and intermediates
I agree: I don't believe one step equations have intermediates, only products and reactants. don't forget that while catalysts lower activation energy the energy of the products and reactants is still the same between a reaction with a catalyst and without. the reaction without a catalyst is lower b...
- Sat Mar 17, 2018 12:07 pm
- Forum: Van't Hoff Equation
- Topic: Derivation
- Replies: 9
- Views: 652
Re: Derivation
I think its essential to know that the vant hoff equation relates temperature to the equillibrium constant and you get this by setting the two gibbs free energy equations equal to each other. always think critically about which information you are given and therefore which equation would be the best...
- Thu Mar 15, 2018 12:23 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Question 15.47
- Replies: 4
- Views: 284
Re: Question 15.47
intermediates get immediately used up, so in a sense its like they're not even there in the first place. their existence is temporary.
- Thu Mar 15, 2018 12:21 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow Step in Reaction Mechanisms
- Replies: 7
- Views: 2400
Re: Slow Step in Reaction Mechanisms
let's say that the first step of a 2 step mechanism is the forward and reverse reaction, where both are fast and at equilibrium. and the second step is the slow step. does the first step also not affect the rate law? if not, then why? if anyone is curious im referring to problem 15.53 (c).
- Thu Mar 15, 2018 12:04 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Question 15.51
- Replies: 8
- Views: 552
Re: Question 15.51
Another main point to add to this is that the slow step must occur before other elementary steps in order for the overall reaction rate to only depend upon this slowest step; in other words, if there is another elementary step occurring before the slow step, this must be included in the overall rxn...
- Mon Mar 12, 2018 11:46 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 15.47
- Replies: 4
- Views: 301
Re: 15.47
ya this could have very well easily been a typo, because it makes sense that in step 1 the Cl- reacts with OH+ just like in the second step. I too treated it as an intermediate.
- Mon Mar 12, 2018 11:44 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 15.47
- Replies: 3
- Views: 255
Re: 15.47
if the diagrams are exactly the same, they are the same molecule. for simplicity sake, i started out by naming the entire molecule x or y or z so I would see where the intermediates are easily, and then when it asked me for the overall reaction or the actual molecule i wrote out the full version fro...
- Mon Mar 12, 2018 11:39 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: HW 15.49
- Replies: 5
- Views: 651
Re: HW 15.49
since the question is still asking you for the rate law of each step, it is appropriate to include the intermediate molecule in the rate law since it is part of the reaction in step 2.
- Mon Mar 12, 2018 11:34 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Question 15.51
- Replies: 8
- Views: 552
Re: Question 15.51
can someone elaborate on what the solutions manual is talking about when we say that the second elementary reaction is fast and it does not affect the reaction order??
- Mon Mar 12, 2018 9:37 pm
- Forum: Second Order Reactions
- Topic: 15.35
- Replies: 6
- Views: 605
Re: 15.35
why is the fraction subtracted from 1 when we asking for the time for the concentration to reach that value of the initial? subtracting implies that it is the remainder after the said fraction gets used up in the reaction.
- Tue Mar 06, 2018 12:01 am
- Forum: First Order Reactions
- Topic: 15.23
- Replies: 6
- Views: 462
Re: 15.23
how do you get rid of the negative??
- Mon Mar 05, 2018 11:39 pm
- Forum: First Order Reactions
- Topic: k
- Replies: 16
- Views: 886
Re: k
a zero order reaction should have the same units as the rate, mol/L/s or mol x L-1 x s-1
- Mon Mar 05, 2018 11:35 pm
- Forum: First Order Reactions
- Topic: Book Problem 15.21
- Replies: 5
- Views: 658
Re: Book Problem 15.21
note that in solving for this the ln's DO NOT cancel, instead you use the inverse operation (e^) to get rid of the lns, and then divide both sides by A0 to get At=10% of A initial.
- Mon Mar 05, 2018 7:26 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2 Q6
- Replies: 4
- Views: 324
Re: Test 2 Q6
i remember hearing something like "the more positive the positive the potential the more likely it will be reduced" in biology. is this the same principle perhaps??
- Mon Mar 05, 2018 7:06 pm
- Forum: Second Order Reactions
- Topic: 15.17
- Replies: 4
- Views: 380
Re: 15.17
therefore, is it safe to say that you DO NOT calculate the order of C because it is independent of the rate?? in other words, only the orders of A and B matter because they affect the rate
- Mon Mar 05, 2018 6:35 pm
- Forum: Zero Order Reactions
- Topic: 15.15
- Replies: 3
- Views: 312
Re: 15.15
this reaction IS a first order reaction because the rates are directly proportional to each other
- Mon Mar 05, 2018 5:32 pm
- Forum: Zero Order Reactions
- Topic: Units of k
- Replies: 12
- Views: 1102
Re: Units of k
shouldn't it be mol/l/s for zero order reactions??
- Mon Mar 05, 2018 5:30 pm
- Forum: Zero Order Reactions
- Topic: K limiting rate
- Replies: 3
- Views: 257
Re: K limiting rate
how are the units for k the same as the rate for a zero order reaction? if rate =k[A]^0 then wouldn't you divide both sides by mol/L to get s^-1=k? i know this is the answer to the units for k for a first order reaction, but i'm assuming for a zero order reaction they are the same because of the 0 e...
- Mon Feb 12, 2018 4:52 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.43 HW
- Replies: 3
- Views: 373
Re: 9.43 HW
how does one know to use the molar heat capacity rather than the specific heat capacity of water when calculating delta S??
- Thu Feb 01, 2018 12:25 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.7 vs 9.13
- Replies: 4
- Views: 254
Re: 9.7 vs 9.13
how do we know to use 5/2R for heat capacity?? what words or phrases in the question hint at this??
- Mon Jan 22, 2018 10:49 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.67(a)- how do we know the phase?
- Replies: 2
- Views: 175
Re: 8.67(a)- how do we know the phase?
in part c of this problem, why is it not acceptable to do 6 mol of C-C bonds? in other words, what does 3 mol CRC bonds mean, and why is this seprate from 3 mol C-C?
- Mon Jan 22, 2018 6:09 pm
- Forum: Phase Changes & Related Calculations
- Topic: Problem 8.43
- Replies: 5
- Views: 248
Re: Problem 8.43
can someone therefore explain why a isn't the correct choice also??
- Mon Jan 22, 2018 6:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: Problem 8.71
- Replies: 1
- Views: 133
Problem 8.71
in the solutions manual, to solve this table, the value given for electron affinity is subtracted instead of added like all the other values (with the exception of the energy used to form the compound). Is this because affinity for electrons requires energy from the compound to take in electrons? or...
- Wed Jan 17, 2018 6:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Problem 8.57 [ENDORSED]
- Replies: 3
- Views: 288
Re: Problem 8.57 [ENDORSED]
I have looked over multiple discussion questions on this question and there are two things I am still very confused about. First, how does this question assume there is no enthalpy of formation? Secondly, if we do apply Hess's Law using combustion reactions, how do we eliminate the appearance of Oxy...
- Mon Oct 16, 2017 3:46 pm
- Forum: Properties of Light
- Topic: Photoelectric Effect Post-Assessment Question 31A
- Replies: 1
- Views: 183
Photoelectric Effect Post-Assessment Question 31A
31A. If 3.607 x 10^-19 J is required to remove an electron with zero kinetic energy from a metal surface, what would be the longest wavelength light that could do this? So in other words, we are being asked to find the maximum wavelength where the photons will still have sufficient energy to remove ...
- Sat Oct 14, 2017 9:12 pm
- Forum: Photoelectric Effect
- Topic: Difference between Photoelectric effect and Atomic Spectra [ENDORSED]
- Replies: 2
- Views: 203
Re: Difference between Photoelectric effect and Atomic Spectra [ENDORSED]
as professor notes, the photoelectric effect detects electrons while atomic spectra detects the wavelengths/frequencies of light emitted. the photoelectric effect also completely removes the electron from the metal surface while in the atomic spectra experiments electrons typically remain bound to t...
- Sat Oct 14, 2017 9:08 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Pre-assessment atomic spectra number 35 [ENDORSED]
- Replies: 2
- Views: 269
Re: Pre-assessment atomic spectra number 35 [ENDORSED]
You can use Rydeberg's equation (1 step) or E=hv and then subtract the differences of the two (multistep). I believe this example is worked in the video module towards the end.
- Fri Oct 06, 2017 3:30 pm
- Forum: Limiting Reactant Calculations
- Topic: Determining Limiting Reactant
- Replies: 6
- Views: 914
Re: Determining Limiting Reactant
sometimes, the limiting reactant is not always the one with the least value given. You should always use the ratios present in the chemical equation because although there may be less of one reactant you may need more than what's provided of the other. for example, if a ratio is 1:5 and you are give...
- Thu Oct 05, 2017 12:50 am
- Forum: Molarity, Solutions, Dilutions
- Topic: G25 homework problem
- Replies: 7
- Views: 599
Re: G25 homework problem
I actually approached this problem a bit more practically in terms of limits. I tested the doublings in the formula MinitialVinitial=MfinalVfinal sort of like this: (.1M)(.010L)=(xM)(.020L) where the final concentration is .05 M. This is just the FIRST doubling. as expected, the concentration became...