Search found 32 matches
- Thu Mar 15, 2018 1:27 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 2
- Views: 390
Re: Catalysts
Catalysts aren't really consumed in the reaction since they are usually formed in a later state so that they can be used again and again. And I think the equilibrium isn't affected because both the forward and reverse rates are affected by the catalyst equally, since creates a new pathway. Hope that...
- Thu Mar 15, 2018 1:18 am
- Forum: *Alkanes
- Topic: Chapter for O-Chem
- Replies: 2
- Views: 1277
Re: Chapter for O-Chem
Chapter 19 and 20 are on O chem, so you might want to check those chapters. I think chapter 20 would be your best bet. Hope that helps.
- Thu Mar 15, 2018 12:54 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13 d?
- Replies: 1
- Views: 353
Re: 14.13 d?
Hi,
I had a similar problem with this concept, but I think this has to do with the fact that the more positive cell potential (1.69>1.40)wants to be reduced more, so it becomes the cathode where the reduction occurs.. Hope this helps.
I had a similar problem with this concept, but I think this has to do with the fact that the more positive cell potential (1.69>1.40)wants to be reduced more, so it becomes the cathode where the reduction occurs.. Hope this helps.
- Thu Mar 15, 2018 12:18 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: endothermic reaction.
- Replies: 5
- Views: 736
Re: endothermic reaction.
Hi,
I'm a little confused on how the Ea corresponds to whether the reaction is endothermic or exothermic. Can someone please explain this to me?
Thanks.
I'm a little confused on how the Ea corresponds to whether the reaction is endothermic or exothermic. Can someone please explain this to me?
Thanks.
- Wed Mar 14, 2018 11:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lavelle: Professor by day, wizard by night
- Replies: 6
- Views: 1545
Re: Lavelle: Professor by day, wizard by night
Oh my haha. You don't see that everyday.
- Sun Mar 11, 2018 3:29 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Heat Required to Heat a Substance
- Replies: 5
- Views: 703
Re: Heat Required to Heat a Substance
Hi, One of the easiest ways to determine this is the complexity of the molecule. In this case, butane has much more complexity. Hope that helps
- Sun Mar 11, 2018 3:12 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Units
- Replies: 3
- Views: 665
Re: Units
Hi,
I think this is bc what youre finding is delta H rxn so per mole of product or whatever youre measuring, if I remember correctly. I think they said they wouldnt mark off points for using just kJ vs kJ/mol tho.. Hope that helps.
I think this is bc what youre finding is delta H rxn so per mole of product or whatever youre measuring, if I remember correctly. I think they said they wouldnt mark off points for using just kJ vs kJ/mol tho.. Hope that helps.
- Sun Mar 11, 2018 2:45 pm
- Forum: First Order Reactions
- Topic: Log vs ln
- Replies: 9
- Views: 1275
Re: Log vs ln
Yeah, I think you should just go with given equation. If you convert, you're adding an additional step where you could potentially introduce error.
- Tue Mar 06, 2018 1:02 am
- Forum: General Rate Laws
- Topic: 15.19a Order
- Replies: 6
- Views: 762
Re: 15.19a Order
Yes, exactly what Beza was saying. You compare the two rate laws and their initial rates. Although the solutions manual does say 2&3 for the order of B you would actually use 1 and 3. So to solve for B it would look something like rate3/rate 1= [A]^l[B]^m[C]^n/[A]^l[B]^m[C]^n where everything wo...
- Wed Feb 28, 2018 5:18 pm
- Forum: Second Order Reactions
- Topic: positive slope in second ordre graph
- Replies: 2
- Views: 1381
Re: positive slope in second ordre graph
Hi, So I think the difference in these has to do with the way it is integrated, using the second order differential rate law (-1/a* d[A]/dt = k[A]^2) as starting point then separating variables and integrating using the power rule (which is in his integration rules tab on the website) you get -[A]^-...
- Mon Feb 26, 2018 7:50 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4008591
Re: Post All Chemistry Jokes Here
If Avagadro calls, tell him to leave his number.
- Mon Feb 26, 2018 7:45 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4008591
Re: Post All Chemistry Jokes Here
What is the chemical formula for banana?
BaNa^2
BaNa^2
- Wed Feb 21, 2018 8:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Reduction Half-Reactions
- Replies: 2
- Views: 464
Re: Reduction Half-Reactions
Hi,
So I believe this is because the equation itself accounts for the sign change, but as Ava said you can change the sign and then simply add them (instead of subtracting them). Hope that helps.
So I believe this is because the equation itself accounts for the sign change, but as Ava said you can change the sign and then simply add them (instead of subtracting them). Hope that helps.
- Wed Feb 21, 2018 8:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Test 2
- Replies: 2
- Views: 430
Re: Test 2
Test 2 covers Chapter 14.1-14.11 so basically all of Electrochem. Hope that helps
- Sun Feb 18, 2018 8:56 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4008591
Re: Post All Chemistry Jokes Here
Why did the chemist coat his shoes with silicone?
-He wanted to reduce his carbon footprint.
-He wanted to reduce his carbon footprint.
- Sun Feb 18, 2018 8:42 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Q
- Replies: 7
- Views: 882
Re: Q
Yeah, Q is the concentrations of products over reactants just like K, except Q represents any point in the reaction while K is specifically at equilibrium.
- Tue Feb 13, 2018 8:04 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U for Isothermal Expansion of Ideal Gas
- Replies: 2
- Views: 701
Re: delta U for Isothermal Expansion of Ideal Gas
The equation for an ideal gas is U=3/2*nRT. When you're calculating the change in internal energy, the number of moles and the gas constant are constant values and that means the change in internal energy is dependent upon temperature change. But in an isothermal expansion temperature doesn't change...
- Sat Feb 10, 2018 8:53 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: ∆S=q/T and irreversible reactions
- Replies: 2
- Views: 409
Re: ∆S=q/T and irreversible reactions
Yeah, since it's a state function the 'path' it took to get from initial to final doesn't matter so you could use the reversible path and that equation to solve for the irreversible. I think the book goes over this idea in more depth in the first few pages of chapter 9 as well. Hope that helps.
- Sat Feb 10, 2018 8:45 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: deltaG=0, Phases Coexist ?
- Replies: 2
- Views: 454
Re: deltaG=0, Phases Coexist ?
Hi,
Yeah so since at boiling point the particles don't have a higher tendency to go to liquid over gas or vice versa, you could just imagine some particles as gas and others as a liquid at this point. Hope that helps.
Yeah so since at boiling point the particles don't have a higher tendency to go to liquid over gas or vice versa, you could just imagine some particles as gas and others as a liquid at this point. Hope that helps.
- Sat Feb 10, 2018 8:41 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Calculating Gibbs Free Energy [ENDORSED]
- Replies: 2
- Views: 488
Re: Calculating Gibbs Free Energy [ENDORSED]
Hi, So I think the first one is used for any constant temperature while the standard Gibbs free energy is used when both the products and reactants are in their standard states at one bar and the temp(which I think is) 298K. Other than that I'd say just using what you're given is main way to tell. H...
- Sun Feb 04, 2018 10:05 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4008591
Re: Post All Chemistry Jokes Here
What type of dog do chemists have?
Laboratory Retrievers
Laboratory Retrievers
- Sun Feb 04, 2018 9:58 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated
- Replies: 9
- Views: 1113
Re: Isolated
I think this would be because the heat is contained within the system.
- Sun Feb 04, 2018 9:50 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity
- Replies: 4
- Views: 479
Re: Spontaneity
Yes, bc delta G takes into account both enthalpy and entropy, the two factors Dr. Lavelle said were needed to determine spontaneity. If delta G is negative, then it's spontaneous. Hope that helps.
- Sat Jan 27, 2018 6:47 pm
- Forum: Calculating Work of Expansion
- Topic: equation
- Replies: 2
- Views: 365
Re: equation
Hi, So the difference of when to use those two equations is whether or not the pressure is constant. If the pressure is a constant than you would use the w=-p delta V. If the pressure isn't a constant you would use the w=-nRT ln(v2/v1). Dr. Lavelle showed us how to derive them on the 24th I think if...
- Sat Jan 27, 2018 6:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Out of Topic
- Replies: 3
- Views: 564
Re: Out of Topic
Yeah, definitely check the syllabus and the TA and UA hours as well because if you cant do Dr. Lavelle's hours there are a some that would work for your schedule.
- Sat Jan 27, 2018 6:19 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneous [ENDORSED]
- Replies: 6
- Views: 725
Re: Spontaneous [ENDORSED]
Yeah so with spontaneous processes the entropy does increase so I think you would probably be able to assume that a positive delta S means spontaneous. Although Gibbs free energy might be a more definite way...
- Sun Jan 21, 2018 2:49 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4008591
Re: Post All Chemistry Jokes Here
"Thermodynamics just gets me so q-ed"
-Frustrated chem students everywhere
-Frustrated chem students everywhere
- Sun Jan 21, 2018 2:27 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.51
- Replies: 5
- Views: 391
Re: 8.51
DamianW, Something being in its "most stable form" refers to it being in its 'most pure/most stable' state, which I like to think of as how you would normally find it; an example of this would be oxygen which we know is all around us in the form of O2. In this particular problem, we know t...
- Mon Jan 15, 2018 9:20 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Q 8.11
- Replies: 1
- Views: 196
Re: Q 8.11
Hi. So I think the difference between the R value of 0.08206 or (0.0821) and the R value the book used is the pressure unit. The R=8.314 is using kPa vs the R= 0.0821 is using atm Straight from my constant sheet from last quarter: R = 8.314 L ∙ kPa ∙ K−1∙ mol−1 R = 0.08206 L ∙ atm ∙ K−1∙ mol−1 Hope ...
- Sun Jan 14, 2018 9:08 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Most Staple Phases
- Replies: 3
- Views: 284
Re: Most Staple Phases
Yeah those are the only ones I have written down as well. Carbon as graphite, I2 as a solid,Br2 as liquid and the others diatomic ones(N2, F2,O2 Cl2) as gases.
- Sun Jan 14, 2018 8:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar Heat Capacity
- Replies: 4
- Views: 196
Re: Molar Heat Capacity
Yeah I think so because molar heat capacity is given by Q=nC Delta T so the higher number of moles, the greater the heat capacity you should get/expect.
- Wed Jan 10, 2018 6:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lecture?
- Replies: 3
- Views: 322
Re: What is bond enthalpy and can someone explain to me what Lavelle was doing with the Lewis Structures in today's lect
Yeah exactly what Daniisaacson2F was saying. Using the bond enthalpies was just an alternative to the first method w/ Hess's Law. The bonds that were broken were the C=C bond and the H-Br bond and the ones formed/ rearranged were the C-C, C-H, C-Br bonds. Then he used the bond enthalpy values(knowin...