Search found 30 matches
- Fri Mar 16, 2018 12:47 pm
- Forum: Experimental Details
- Topic: Rate Unit Conversion
- Replies: 4
- Views: 705
Re: Rate Unit Conversion
I remember that on the test we took on kinetics, when asking for half time, the question specifically asked for the answer to be in seconds. So, probably, the best would be to use seconds unless the problem specifically asks for another measurement of time to be used.
- Thu Mar 15, 2018 9:39 pm
- Forum: *Ethers
- Topic: Nucleophile
- Replies: 3
- Views: 1047
Re: Nucleophile
A nucleophile is a chemical species attracted to positive charges. Therefore, they would be negatively charged.
- Thu Mar 15, 2018 9:37 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: The Effect of Temperature
- Replies: 3
- Views: 256
Re: The Effect of Temperature
Raising the temperature raises the rate constant as well.
- Thu Mar 15, 2018 9:36 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Gibbs and Activation Energy
- Replies: 4
- Views: 430
Re: Gibbs and Activation Energy
From my discussion section, on the reaction profile, our TA defined the difference in energy between the reactants and products as the ∆G (in reference to kinetics). Activation energy is the minimum energy required for the reaction to take place. I don't think we defined much of a relationship betwe...
- Mon Mar 05, 2018 4:58 pm
- Forum: Second Order Reactions
- Topic: Limiting Step
- Replies: 7
- Views: 673
Re: Limiting Step
Akash_Kapoor_1L wrote:Do we have to know how to calculate the limiting step for test 3? Which hw problems focus on the limiting step?
I don't think so. Dr. Lavelle said test three would go up to 15.6, and this topic isn't on there.
- Mon Mar 05, 2018 4:33 pm
- Forum: Experimental Details
- Topic: Rate Constant
- Replies: 4
- Views: 634
Re: Rate Constant
Any of the experiments should work for finding the rate constant.
- Mon Mar 05, 2018 4:30 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate Laws of Elementary Reactions
- Replies: 4
- Views: 240
Re: Rate Laws of Elementary Reactions
No, I don't think you would be able to do that for an overall reaction. The example you gave was for a bimolecular elementary step in which then I think your assumption may be correct.
- Mon Mar 05, 2018 4:18 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Molecularity
- Replies: 3
- Views: 218
Re: Molecularity
The textbook defines molecularity as the number of reactant molecules or species taking part in a specified elementary reaction, so I would think that it has to do with the elementary step and not the overall reaction.
- Mon Mar 05, 2018 4:16 pm
- Forum: Zero Order Reactions
- Topic: Pseudo Zero Order Reactions
- Replies: 3
- Views: 925
Re: Pseudo Zero Order Reactions
I don't think so since zero order reactions don't have to do with the concentration of the reactants.
- Thu Mar 01, 2018 7:29 pm
- Forum: Zero Order Reactions
- Topic: Catalysts
- Replies: 2
- Views: 232
Re: Catalysts
A zero order reaction is when the rate is independent of the reactant concentration. From what I remember, they occur most often when the reaction is catalyzed. So, zero order reactions usually/most often happen with a catalyst involved. For example, if a substrate attaches to the activation site of...
- Thu Mar 01, 2018 7:22 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate Law [ENDORSED]
- Replies: 2
- Views: 204
Re: Rate Law [ENDORSED]
I believe that the rate law is in reference to the reactants. For the coefficients, I think it has to do with the way the rate is defined. Like coefficients matter in the equation where rate=(1/a)d[A]/d[t]. Besides this equation, I'm not too sure about the coefficients.
- Fri Feb 23, 2018 12:59 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Reducing Agent/ Oxidizing Agent
- Replies: 6
- Views: 673
Re: Reducing Agent/ Oxidizing Agent
From what I remember from during my discussion section, the more positive potential means its a greater oxidizing agent and after the potential, the size would be the next determining factor.
- Fri Feb 23, 2018 12:50 pm
- Forum: First Order Reactions
- Topic: Reaction order
- Replies: 4
- Views: 343
Re: Reaction order
The method we learned today in class was the method of using initial rates. You set up a ratio of concentrations and rates of two of the experiments to the equation rate=k[A]^n and then solve for n which makes the ratio true.
- Fri Feb 23, 2018 12:24 pm
- Forum: General Rate Laws
- Topic: Doubling Concentration in Second-Order Reaction
- Replies: 2
- Views: 308
Re: Doubling Concentration in Second-Order Reaction
It means that doubling the concentration for a second order reaction should increase the reaction rate by four times the original reaction rate. So mathematically, since the concentration is being raised to the second power, doubling it would cause it to be 2^2 or times 4.
- Fri Feb 23, 2018 12:13 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagram [ENDORSED]
- Replies: 4
- Views: 323
Re: Cell diagram [ENDORSED]
You use single lines between different states and a comma for multiple species in the same state.
- Sun Feb 11, 2018 3:36 pm
- Forum: Van't Hoff Equation
- Topic: Free Energy, pressure, and equilibrium constant
- Replies: 2
- Views: 321
Re: Free Energy, pressure, and equilibrium constant
I don't have a direct conceptual answer, but there were two equations given which both have pressure and the equilibrium constant which solves for Free energy. ∆G=nRTln(P2/P1) (for pressure) and ∆Go=-RTlnK.
- Fri Feb 09, 2018 6:02 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy Concept
- Replies: 1
- Views: 168
Re: Entropy Concept
If you think about a spontaneous natural process of heat flowing from a hot region to a cold region, the entropy for the hot region would be S1=q/T. The entropy for the cold region would be S2=q/T. So if you calculate ∆S=S2-S1, ∆S is positive since T2<T1. There was an increase in the entropy of the ...
- Fri Feb 09, 2018 5:54 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Degeneracy
- Replies: 2
- Views: 208
Re: Degeneracy
Degeneracy is the number of ways a given energy state can be achieved. I think one way is you can raise the number of states possible to the number of atoms. So if there were 2 states possible and 3 atoms, it would be 2^3.
- Fri Feb 02, 2018 3:49 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: When to use Q versus K [ENDORSED]
- Replies: 6
- Views: 1518
Re: When to use Q versus K [ENDORSED]
I think you use Q when the system is not in equilibrium.
- Fri Feb 02, 2018 3:07 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Work and Reversible Process [ENDORSED]
- Replies: 2
- Views: 194
Work and Reversible Process [ENDORSED]
Can someone explain more concisely why a process produces maximum work in a reversible reaction? I don't fully understand why.
- Fri Feb 02, 2018 3:05 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Clausius Inequality [ENDORSED]
- Replies: 1
- Views: 149
Clausius Inequality [ENDORSED]
The textbook mentions a Clausius Inequality, ∆S≥q/t. Could someone explain the importance for it and what it is saying about the reaction? (Also do we need to know about it for the class?)
- Fri Jan 26, 2018 1:03 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: State properties of heat and enthalpy
- Replies: 2
- Views: 196
Re: State properties of heat and enthalpy
Heat is not an intrinsic property and depends on the path of the reaction. Tt occurs when there is a change in the system. Heat provides information on how the final state was attained not just the final and initial state. The energy transferred through heat does depend on how it is transferred, and...
- Fri Jan 26, 2018 1:00 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacities of monatomic gas and linear molecule
- Replies: 2
- Views: 212
Heat Capacities of monatomic gas and linear molecule
I don't fully understand the two equations of 3/2R and 5/2R, or why they are the equations for the heat capacities of a monatomic gas and linear molecule. Do we have to necessarily know this information?
- Fri Jan 26, 2018 12:53 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Reversible Vs Irreversible
- Replies: 3
- Views: 222
Reversible Vs Irreversible
Why is the temperature constant in reversible reactions whereas temperature changes along the path for irreversible reactions?
- Fri Jan 19, 2018 4:28 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: P delta V is significant?
- Replies: 2
- Views: 459
Re: P delta V is significant?
I'm not sure about all the details of it, but I do know that with solids and liquids, the volume can't really change and there's no expansion work being done. Since the pressure is constant, and liquids and solids aren't compressible, the volume isn't changing either.
- Fri Jan 19, 2018 4:05 pm
- Forum: Phase Changes & Related Calculations
- Topic: 8.39
- Replies: 2
- Views: 161
8.39
I didn't fully understand 8.39. The question asks for the amount of heat needed to convert 80.0g of ice at 0 °C into liquid water at 20°C. Would there be a calculation for phase change we need to take into consideration? I wasn't sure how to go about it.
- Thu Jan 18, 2018 4:05 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Adiabatic [ENDORSED]
- Replies: 8
- Views: 625
Re: Adiabatic [ENDORSED]
My TA mentioned it too. I'm not entirely sure, but my TA mentioned that it would be a closed system with no heat transfer.
- Sat Jan 13, 2018 12:59 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb Calorimeter
- Replies: 2
- Views: 169
Bomb Calorimeter
Can someone explain how bomb calorimeter works, and would we need to know technically how it works?
- Thu Jan 11, 2018 4:56 pm
- Forum: Phase Changes & Related Calculations
- Topic: Temperature during phase changes [ENDORSED]
- Replies: 4
- Views: 410
Re: Temperature during phase changes [ENDORSED]
The energy used to otherwise increase the temperature (specific heat) is instead used to change phases (heat of fusion). Once the temperature for the boiling point or melting point is reached, the energy that would have raised the temperature goes into changing the phase.
- Thu Jan 11, 2018 4:30 pm
- Forum: Phase Changes & Related Calculations
- Topic: ∆Hsub= ∆Hfus+ ∆Hvap
- Replies: 4
- Views: 1188
Re: ∆Hsub= ∆Hfus+ ∆Hvap
If you think of it from a mathematical standpoint, you can substitute ∆Hfus and ∆Hvap with their equations to get the original ∆Hsub equation. ∆Hfus=Hliquid-Hsolid and ∆Hvap=Hvapor-Hliquid. So if you substitute it, ∆Hsub= (Hliquid-Hsolid) + (Hvapor-Hliquid). The Hliquid cancels out leaving Hvapor-Hs...