Search found 52 matches
- Sun Mar 17, 2019 10:01 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: steady state approximation
- Replies: 1
- Views: 491
steady state approximation
does anyone know if we used the steady state approximation or was it just the pre-equilibrium approximation?
- Sun Mar 17, 2019 1:42 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: catalyst vs intermediate
- Replies: 3
- Views: 650
Re: catalyst vs intermediate
intermediates are produced and then used up in another reaction. a catalyst appears at the beginning and then again at the end. A catalyst can also be a part of the rate law while an intermediate can't.
- Sat Mar 16, 2019 11:42 pm
- Forum: First Order Reactions
- Topic: Finding Order of Reactions
- Replies: 4
- Views: 677
Finding Order of Reactions
When setting up our rate rations to find the order of reaction, does it matter which rates we take from the experimental data? and how do we decide which to put as our numerator?
- Sat Mar 16, 2019 10:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Shifting K with changes in volume
- Replies: 4
- Views: 653
Re: Shifting K with changes in volume
If the volume increases, the pressure with decrease and it will shift to the side with more moles. If the volume decreases, the pressure will increase and there will be a shift to the side with less moles.
- Thu Mar 14, 2019 5:06 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Ranking species
- Replies: 3
- Views: 545
Ranking species
On test 2, there were a few questions that asked us to rank the given species in order of increasing oxidation power going from second oxidation state to neutral. Can someone explain how I would go about this?
- Thu Mar 14, 2019 4:55 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cells
- Replies: 1
- Views: 280
Concentration Cells
what is a concentration cell and can you give an example please? I want to get a better understanding
- Thu Mar 14, 2019 12:14 am
- Forum: Phase Changes & Related Calculations
- Topic: steam at 100ºC burn worse
- Replies: 7
- Views: 961
steam at 100ºC burn worse
Why does steam at 100ºC cause a worse burn than boiling water at 100ºC?
- Wed Mar 13, 2019 11:56 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: cell diagrams
- Replies: 6
- Views: 696
Re: cell diagrams
Also for cell diagrams don't forget to include the H+ as well!
- Wed Mar 13, 2019 11:40 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb calorimeter
- Replies: 6
- Views: 910
Bomb calorimeter
can someone explain what the difference between a regular calorimeter and a bomb calorimeter is?
- Mon Mar 11, 2019 11:44 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: stability of reactants and products
- Replies: 3
- Views: 512
stability of reactants and products
How do we describe the stability of reactants and products when we look at which reaction is favored?
- Thu Mar 07, 2019 5:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Calculating Eºcell
- Replies: 2
- Views: 579
Calculating Eºcell
I am looking over my Test 2 and I realized I made a couple of mistakes when calculating for Eºcell. I just want to get clarification on whether we switch the sign of a reaction when we flip it in order to use Eºcell = Eºcathode - Eºanode?
- Thu Mar 07, 2019 5:02 pm
- Forum: General Rate Laws
- Topic: Ratios and Rate laws
- Replies: 2
- Views: 272
Ratios and Rate laws
I am still confused on how we can use ratios when working with rate laws. Can someone give me an example of how we would set this up?
- Thu Mar 07, 2019 12:08 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Ecell
- Replies: 13
- Views: 1507
Re: Ecell
Use Ecell= Eº(cathode) - Eº(anode) and you might have to flip one of the equations. I believe the professor will provide us with the sheet that has the E values for each half reaction so you would just plug in accordingly.
- Thu Mar 07, 2019 11:56 am
- Forum: General Rate Laws
- Topic: Deriving rate laws
- Replies: 2
- Views: 333
Re: Deriving rate laws
No, I just think you need to be able to understand the equations and how to use them
- Thu Mar 07, 2019 11:52 am
- Forum: First Order Reactions
- Topic: Using ln[A]
- Replies: 2
- Views: 332
Using ln[A]
Can someone explain to me why we would use ln[A] instead of [A] like we do for the rest of the orders?
- Tue Feb 26, 2019 9:50 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation Numbers
- Replies: 2
- Views: 303
oxidation Numbers
I am having trouble finding the oxidation numbers from elements. Can someone explain to me how we find them? I know there are a few rules, but I am still confused
- Mon Feb 25, 2019 11:29 am
- Forum: Balancing Redox Reactions
- Topic: determining charges
- Replies: 1
- Views: 237
determining charges
Can someone explain how we read the total charges on the reactions and when we would need to add electrons to either side?
- Mon Feb 25, 2019 10:55 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs Free Energy
- Replies: 1
- Views: 262
Gibbs Free Energy
How is the stability of a reaction related to its spontaneity?
- Sun Feb 24, 2019 1:38 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 1
- Views: 171
Platinum
Can someone explain to me what the purpose of platinum is? And how do we know when to use it?
- Sun Feb 24, 2019 1:37 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Oxidation and Reduction
- Replies: 3
- Views: 353
Oxidation and Reduction
When writing our half reactions, will our oxidized reaction always have the e- on the right side? and the reduction reaction will have the e- on the left?
- Wed Feb 20, 2019 4:02 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 5
- Views: 566
Salt Bridge
Can someone re-explain to me the purpose of a salt bridge?
- Tue Feb 12, 2019 11:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 4
- Views: 468
Bond Enthalpies
Will the structures be given to us on the midterm or are we expected to know how to draw them?
- Tue Feb 12, 2019 9:26 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: strong and weak acids
- Replies: 5
- Views: 767
strong and weak acids
Can someone explain why solutions of weak acids have a higher pH?
- Mon Feb 11, 2019 4:06 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Higher Molar Entropy
- Replies: 3
- Views: 423
Higher Molar Entropy
How do we determine which molecules will have a higher molar entropy? and what is residual entropy?
- Sun Feb 10, 2019 11:20 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Molecular Interlude
- Replies: 5
- Views: 839
Re: Molecular Interlude
Andre_Galenchik_2L wrote:Don't we need to know that the Cp for a single atom is 5R/2 and the Cv for a single atom is 3R/2?
Yeah, that is what I thought as well
- Sun Feb 10, 2019 11:00 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 5
- Views: 539
Hess's Law
There are a few homework problems where we have to make several chemical reactions to solve for Hess's Law. Will we be expected to know how to make them or will the test provide them for us?
- Sun Feb 10, 2019 10:31 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 11
- Views: 1466
Re: Phase Changes
whitneyhawthorne_2C wrote:Understanding it would definitely make problem solving easier so I would try to as much as you can. I took some notes in my discussion with the graph labeled, a picture of it is shown below. Hope it helps!
thank you so much!
- Sun Feb 10, 2019 10:30 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 8.41
- Replies: 1
- Views: 185
8.41
"A 50.0-g ice cube at 0.0 degree C is added to a glass containing 400.0 g of water at 45.0 degree C. What is the final temperature of the system (see Tables 8.2 and 8.3)? Assume that no heat is lost to the surroundings." Can someone tell me how to go about this problem? I know we will have...
- Sun Feb 10, 2019 8:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Molecular Interlude
- Replies: 5
- Views: 839
Molecular Interlude
Will we have to memorize the Cv,m and Cp,m for the rotational motions? e.g. 3R for for nonlinear molecules
- Sun Feb 10, 2019 1:12 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 11
- Views: 1466
Phase Changes
Would it be a good idea to understand 100% the phase changes graph that was shown in class?
- Sun Feb 10, 2019 1:10 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: methods
- Replies: 8
- Views: 977
Re: methods
Eruchi Okpara 2E wrote:How do you know which bonds need to be broken?
if you draw out the lewis structures you will be able to cross out any new bonds formed or any bonds that were broken. This method will make it easier to go about these problems involving bond enthalpies
- Sun Feb 10, 2019 1:07 pm
- Forum: Calculating Work of Expansion
- Topic: Degeneracy
- Replies: 3
- Views: 366
Degeneracy
Hello y'all, I am still a bit confused as to what degeneracy is and why it is important for thermodynamics? can someone re-explain? thanks!
- Sat Feb 02, 2019 6:33 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Reaction Constant P
- Replies: 3
- Views: 373
Reaction Constant P
Can someone briefly re-explain what would happen to our internal energy when our P is constant and the moles of a gas change versus when our P is constant and solids and liquids are involved? I more or less understand what the Professor said at Friday's lecture, but I just want clarification.
- Sat Feb 02, 2019 5:57 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Compression of Gas
- Replies: 4
- Views: 445
Compression of Gas
When we compress a gas, are we adding heat?
- Mon Jan 28, 2019 10:06 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv and Cp
- Replies: 3
- Views: 397
Cv and Cp
Would it be specified when to use Cv vs Cp or vice versa? Or how would we go about when to use one over the other?
- Sun Jan 27, 2019 4:11 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 3
- Views: 227
Bond Enthalpies
Hello, I was wondering if someone can explain to me why bond enthalpy is the least accurate?
- Sat Jan 26, 2019 9:25 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Sign changes
- Replies: 3
- Views: 268
Re: Sign changes
yes, the signs can definitely change when adding them up to get the total. As for the negative and positive signs, they let us know whether the reaction was endothermic, absorbing heat, or exothermic, releasing heat.
- Sat Jan 26, 2019 3:39 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 3
- Views: 348
Bond Enthalpies
Can someone re-explain how we would use bond enthalpies? Would we only account for the new formations?
- Wed Jan 23, 2019 4:53 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 5
- Views: 410
Re: Hess's Law
I think this is a topic we will be covering in 14B soon
- Mon Jan 21, 2019 12:14 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Buffer Solutions
- Replies: 2
- Views: 251
Buffer Solutions
Hey y'all I am still having trouble understanding what buffer solutions are. Why is it that when we create our ICE tables we disregard the salts? How would we go about these types of problems?
- Sun Jan 20, 2019 10:11 pm
- Forum: Polyprotic Acids & Bases
- Topic: Question 12.79 (Sixth Edition)
- Replies: 2
- Views: 387
Re: Question 12.79 (Sixth Edition)
Would this be due to H2SO4 being a strong acid? so H3O+ would be the same value since it was completely dissolved
- Sun Jan 20, 2019 8:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: PEER LEARNING SESSIONS
- Replies: 2
- Views: 129
PEER LEARNING SESSIONS
does anyone know if the peer learning sessions will still take place tomorrow due to the holiday?
- Sun Jan 20, 2019 4:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.57 6th edition
- Replies: 1
- Views: 56
11.57 6th edition
Can someone explain why we wouldn't convert to molarity before solving the ICE table? I am confused as to why the solution manual didn't convert to molarity
- Sat Jan 19, 2019 10:22 pm
- Forum: Ideal Gases
- Topic: kc vs kp
- Replies: 19
- Views: 3533
Re: kc vs kp
Kp is specific to the equilibrium constant for partial pressures of gases while Kc is used for molar concentrations such as when working with aqueous elements.
- Fri Jan 18, 2019 5:33 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: percentage protonation
- Replies: 2
- Views: 271
Re: percentage protonation
Percentage protonation is a way for us to check if it was okay to approximate our concentrations rather than use the quadratic formula. So, if the percentage was less than 5%, then we are good to go, but if it is higher than 5%, we are going to have to go back and use the quadratic formula.
- Thu Jan 17, 2019 11:20 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: problem 11.11 6th edition
- Replies: 1
- Views: 120
problem 11.11 6th edition
Hi y'all I am having trouble understanding this problem. Can someone break it down for me and explain how to go about each one?
- Wed Jan 16, 2019 9:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration less than 10^-7
- Replies: 4
- Views: 344
Concentration less than 10^-7
Towards the end of the lecture today, the professor was talking about what would happen if the concentration was less than 10^-7. Can someone re-explain what he meant by this especially when he brought up using 10^-9?
- Sat Jan 12, 2019 9:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.39 6th Ed Multiplying K constants
- Replies: 3
- Views: 336
Re: 11.39 6th Ed Multiplying K constants
Samantha Kwock 1D wrote:If two reactions are added together to form another reaction, then their K constants are multiplied to give the new reaction's K constant.
can you explain why we would multiply the K constants when we add the reactions? Or is this just a property?
- Fri Jan 11, 2019 4:20 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle [ENDORSED]
- Replies: 3
- Views: 321
Le Chatelier's Principle [ENDORSED]
In lecture today, Professor Lavelle gave us the reaction N2(g) + 3H2(g) --> 2NH3(g) and described what would happen if we increased N2, increased NH3, and decreased H2. Can someone please explain to me each scenario, I am a bit confused still.
- Thu Jan 10, 2019 11:08 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K=1
- Replies: 5
- Views: 387
Re: K=1
When K = 1, this means that the reaction has reached equilibrium. So, the amount of reactants and products would be the same.
- Wed Jan 09, 2019 5:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Bar vs. atm
- Replies: 4
- Views: 256
Re: Bar vs. atm
They are both a measure of pressure so you can use either one depending on what the question gives you. If they give you pressure in terms of atm then you would use atm or vice versa.
- Tue Jan 08, 2019 11:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constants for Gases
- Replies: 1
- Views: 234
Re: Equilibrium Constants for Gases
From my understanding, if we increase the pressure of gases, the equilibrium constant will not be affected. The only way the equilibrium constant would be affected is if we changed the temperature.