## Search found 31 matches

Fri Mar 15, 2019 12:31 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 6th Edition 15.61
Replies: 2
Views: 94

### Re: 6th Edition 15.61

It all just clicked, thanks .
Fri Mar 15, 2019 12:26 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 6th Edition 15.61
Replies: 2
Views: 94

### 6th Edition 15.61

Can anybody explain where the equation Ln(k'/k) = Ea/R ((1/T)-(1/T')) came from? Thanks!
Thu Mar 14, 2019 11:53 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Solving for Arrhenius Equation
Replies: 2
Views: 111

### Re: Solving for Arrhenius Equation

I do not know exactly where you are going wrong, but I would make sure that you are using parentheses in the e expression: e^(-Ea/(RT)). I would also write out all of the units of what you are solving to make sure that they all cancel out to get you the desired units of k.
Thu Mar 14, 2019 11:48 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Question 15.9 Comparing Experiments
Replies: 3
Views: 387

### Re: Question 15.9 Comparing Experiments

yes, they are comparing experiments 1 and 3 if the problem you are talking about also corresponds to problem #15.17 in the 6th edition book.
Thu Mar 14, 2019 11:46 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Question 15.9 Comparing Experiments
Replies: 3
Views: 387

### Re: Question 15.9 Comparing Experiments

Generally when solving these types of problems, I try to compare two experiments where only one variable is changing. For example, when trying to figure out the order with respect to reactant B, I would compare two experiments with the concentrations of A and C held constant. Therefore, you can easi...
Thu Mar 14, 2019 11:43 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Endothermic vs. Exothermic Based on K
Replies: 1
Views: 95

### Re: Endothermic vs. Exothermic Based on K

Because exothermic reactions are spontaneous, they occur naturally. Therefore, generally exothermic reactions have a very low activation energy barrier when compared to endothermic reactions, as it takes very little input of energy for the reaction to occur.
Thu Mar 14, 2019 11:38 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: homework 6N7 a and b
Replies: 1
Views: 79

### Re: homework 6N7 a and b

I believe Dr. Lavelle sent out an email with a link that answers this exact question :)
Thu Mar 14, 2019 11:36 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts vs Intermediates
Replies: 4
Views: 149

### Re: Catalysts vs Intermediates

Simply put, catalysts are not consumed in a reaction whereas intermediates are. In other words, intermediates are formed and used up, where as catalysts are not consumed and are there from the beginning.
Thu Mar 14, 2019 11:34 pm
Forum: First Order Reactions
Topic: Integrated Rate Law
Replies: 1
Views: 112

### Re: Integrated Rate Law

I believe that the regular integrated rate law usually works with problems that have set concentrations and a set amount of time, where you are manipulating known variables to solve for an unknown in the problem. I believe the exponential decay formula you are referring to might be a derivation/mani...
Thu Mar 14, 2019 11:28 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reactions with multiple reactants
Replies: 2
Views: 163

### Re: Reactions with multiple reactants

I'm still a little confused on this concept on determining the rate. In lecture, we said if [A]0 >> [B]0 and [C]0 then rate = k'[A]^N. Why do we use k' instead of k? k' is generally used instead of k to symbolize the rate of the reverse reaction, as to your specific question, A is probably in the p...
Thu Mar 14, 2019 11:22 pm
Forum: Second Order Reactions
Topic: Question 13 6th Edition
Replies: 2
Views: 305

### Re: Question 13 6th Edition

Do you mean when finding the initial reaction rate instead of the initial order?
If this is the case, the initial rate would be the constant, k * concentration of H2 *concentration of I2, being as it is a second order process for the reaction, with first order in respect to both reactants.
Sun Mar 10, 2019 2:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6th Edition 14.15b
Replies: 1
Views: 113

### 6th Edition 14.15b

Can somebody explain how to do the problem: Write the half reactions and draw a galvanic cell diagram to study the following reaction:
H+ (aq) +OH- (aq) ---> H20 (l)
Thu Mar 07, 2019 6:21 am
Forum: Experimental Details
Topic: Final [ENDORSED]
Replies: 4
Views: 899

### Re: Final[ENDORSED]

Also knowing this topic helps to understand where some of the equations are derived from, kind of like what Dr. Lavelle does in lecture when he goes through the derivation of an equation.
Thu Mar 07, 2019 6:19 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: how is kinetics different?
Replies: 17
Views: 727

### Re: how is kinetics different?

Raj_Bains_2C wrote:Thermodynamics only cares about the initial and final states, while kinetics focuses on the pathway of the reaction.

Thermodynamics only cares about the initial and final states unless you are considering heat and work, both of which are not state functions
Thu Mar 07, 2019 6:17 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Replies: 73
Views: 3986

Is there any way to get access to the worksheets distributed at these sessions if we missed this week?
Sat Mar 02, 2019 2:05 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 4F.1
Replies: 2
Views: 341

### Re: 4F.1

Hello, I believe for part A it is positive because it is the entropy for the surroundings which are gaining the heat given off the body. Hope this helped! I agree with this statement because you want to focus on the surroundings gaining entropy instead of doing what I initially did by looking at th...
Mon Feb 25, 2019 11:03 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy equations
Replies: 8
Views: 560

### Re: Entropy equations

You can also use the equation
delta S= nR ln (P2/P1) to calculate the entropy change for an isothermal increase in pressure.
Mon Feb 25, 2019 10:11 pm
Forum: Calculating Work of Expansion
Topic: Equations for work
Replies: 7
Views: 476

### Re: Equations for work

Thank you that was really helpful and clarified so much.
Sat Feb 23, 2019 11:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Moles of Gas affecting shift in equilibrium
Replies: 1
Views: 100

### Moles of Gas affecting shift in equilibrium

Can anyone clarify how equilibrium can shift when pressure is increased in a reaction involving different amounts of moles of gas making up the products and reactants?
Sat Feb 23, 2019 11:06 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy at 0 K
Replies: 4
Views: 393

### Re: Entropy at 0 K

0K will additionally almost never appear in nature, therefore when referring to entropy at 0K, it is mostly used for conceptual limits.
Sat Feb 23, 2019 11:03 pm
Forum: Calculating Work of Expansion
Topic: Equations for work
Replies: 7
Views: 476

### Equations for work

I am still confused as to when each equation for work is supposed to be used.
w=-p* Δv
w= - v1∫v2 Pdv
w=-nRT ln (v2/v1)

Can anyone specify in which type of case each equation is used?
Sat Feb 23, 2019 11:03 pm
Forum: Calculating Work of Expansion
Topic: Equations for work
Replies: 1
Views: 244

### Equations for work

I am still confused as to when each equation for work is supposed to be used.
w=-p* Δv
w= - v1∫v2 Pdv
w=-nRT ln (v2/v1)

Can anyone specify in which type of case each equation is used?
Sat Feb 16, 2019 1:04 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Calorimeter - Type of System
Replies: 5
Views: 531

### Re: Calorimeter - Type of System

Also, a bomb calorimeter, an isolated system, will always have constant volume.
Sat Feb 16, 2019 12:56 pm
Forum: Calculating Work of Expansion
Topic: Expansion Against a Vacuum
Replies: 4
Views: 244

### Re: Expansion Against a Vacuum

would this be an example of an irreversible system?
Sat Feb 16, 2019 12:55 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 4
Views: 193

### Re: Reversible vs Irreversible

Is a reversible system always isothermal?
Thu Feb 07, 2019 9:09 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Open vs Closed System
Replies: 13
Views: 1195

### Re: Open vs Closed System

Is the only example of an isolated system a calorimeter?
Thu Feb 07, 2019 9:07 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpy vs Bond Enregy
Replies: 3
Views: 111

### Re: Bond enthalpy vs Bond Enregy

Are both bond enthalpy and bond energy always positive?
Thu Feb 07, 2019 8:58 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpy
Replies: 4
Views: 157

### Re: Bond Enthalpy

Bond enthalpy is always positive because it is the energy put into breaking a bond, which is an endothermic process (energy is being put in).
Sat Feb 02, 2019 4:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Registering/Creating Your Chemistry Community Account
Replies: 25
Views: 44601

### Re: Registering/Creating Your Chemistry Community Account

Does it matter what our alias is?
Sat Feb 02, 2019 4:10 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Reversible rxn
Replies: 5
Views: 164

### Re: Reversible rxn

Will the reverse reaction always be doing more work than the forward reaction?
Sat Feb 02, 2019 4:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 226
Views: 116234

### Re: Advice from a Medical Student[ENDORSED]

Thank you so much for this advice, it is super helpful to hear from someone who is actually going through the process.