Search found 31 matches

by Ardo 2K
Sun Mar 18, 2018 8:51 am
Forum: Second Order Reactions
Topic: Derivations
Replies: 4
Views: 503

Derivations

When deriving the integrated law for a second order reaction why isn't the kt negative, and also does a positive kt value mean that the slope of the line of 1 over the concentration of reactant plotted against time will be positive as well?
by Ardo 2K
Sat Mar 17, 2018 11:13 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pseudo Rate Laws
Replies: 5
Views: 496

Pseudo Rate Laws

Can someone please explain Pseudo Rate Laws and how they are obtained. Thank you
by Ardo 2K
Sat Mar 17, 2018 5:39 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Second Law application
Replies: 3
Views: 283

Second Law application

According to the second law of thermodynamics the natural progression of a system along with its surroundings is from lower entropy to higher entropy, so wouldn't that mean that a reaction with a positive change in entropy be a spontaneous one? But when we implement Gibbs free energy we see that und...
by Ardo 2K
Sat Mar 17, 2018 2:59 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-Equilibrium
Replies: 2
Views: 138

Pre-Equilibrium

When using the pre-equilibrium method when we get our final rate law and we have an equilibrium constant K in it, is it more correct to express that K as the forward rate constant over the reverse or just leave it as is?
by Ardo 2K
Sun Mar 11, 2018 10:03 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: SN2
Replies: 2
Views: 119

SN2

Can someone please explain what a nucleophile is and how exactly do they replace certain atoms within a molecule to produce a completely new molecule?
by Ardo 2K
Sun Mar 11, 2018 9:59 pm
Forum: *Enzyme Kinetics
Topic: 15.81
Replies: 1
Views: 194

15.81

Can someone please show me how to approach problem 15.81 from the book. How are we suppose to account for the loss of the unreacted substrate from the active site?
by Ardo 2K
Sun Mar 11, 2018 9:55 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy and heat
Replies: 2
Views: 122

Internal Energy and heat

When the temperature of a system doesn't change does the heat equal 0? Or is that just the change in the internal energy of the system?
by Ardo 2K
Sun Mar 04, 2018 5:39 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Homework Problem 15.45
Replies: 1
Views: 79

Homework Problem 15.45

To write the overall reaction for the mechanism that is proposed in the given problem all we need to do is add the reactions together? Also how can we tell which step is the longest one?
by Ardo 2K
Sun Mar 04, 2018 5:32 pm
Forum: Second Order Reactions
Topic: Half life constant and Rate reaction constant
Replies: 4
Views: 212

Half life constant and Rate reaction constant

When we find the constant K for a reaction from the half life equation can we apply that same constant to the second order reaction equation to find the concentration of a given reactant?
by Ardo 2K
Sun Mar 04, 2018 5:31 pm
Forum: Zero Order Reactions
Topic: Significance of Zero order reactions
Replies: 3
Views: 136

Significance of Zero order reactions

Can someone please explain the significance of zero order reactions as they relate to the rates of reactions and give an example of one? Thank you
by Ardo 2K
Sun Feb 25, 2018 8:20 pm
Forum: General Rate Laws
Topic: Rate Constants
Replies: 4
Views: 209

Rate Constants

Why do the rate constants of each molecule being composed or consumed correspond with a different temperature, why aren't they all under standard conditions of 298K?
by Ardo 2K
Sun Feb 25, 2018 8:15 pm
Forum: First Order Reactions
Topic: Reaction Order [ENDORSED]
Replies: 6
Views: 365

Reaction Order [ENDORSED]

So do the reaction orders of reactions depend upon the amount of moles decomposed in a standard decomposition reaction?
by Ardo 2K
Sun Feb 18, 2018 9:11 pm
Forum: Balancing Redox Reactions
Topic: Basic and Acidic conditions [ENDORSED]
Replies: 11
Views: 3373

Basic and Acidic conditions [ENDORSED]

So under basic conditions there is water that is balanced out on both sides by water itself and hydroxide? And under acidic solutions there are hydrogen molecules balanced out by water molecules?
by Ardo 2K
Sun Feb 18, 2018 9:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: The Nernst Equation
Replies: 2
Views: 199

The Nernst Equation

Can someone please derive the Nernst equation the way we did it in class one more time? Thank you
by Ardo 2K
Sun Feb 11, 2018 10:08 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.55, 9.57
Replies: 1
Views: 91

9.55, 9.57

Can someone please explain why in problem 9.55 we only use the delta H of formation of the products to find the Standard change in enthalpy of the reaction, but in 9.57 we subtract the the sum of the enthalpy of the formation of products by the sum of the enthalpy of formation of reactants. Don't we...
by Ardo 2K
Sun Feb 11, 2018 3:35 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Using q reversible
Replies: 1
Views: 84

Using q reversible

When calculating the change in entropy why do we need to take into account the heat transfer, q, of a reversible reaction instead of an irreversible reaction. Is this due to the fact that the work done by a reversible reaction is greater than the work done in an irreversible one therefore through th...
by Ardo 2K
Sun Feb 11, 2018 3:34 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: ∆S = n R ln (V2/V1 )
Replies: 1
Views: 220

∆S = n R ln (V2/V1 )

I don't have the derivation of this equation in my notes, so if we derived this one in class can someone please show me how we do it again. Thank you so much. ∆S = n R ln (V2/V1 )
by Ardo 2K
Sun Feb 04, 2018 9:23 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Homework Problem 9.69
Replies: 1
Views: 76

Homework Problem 9.69

I'm not sure how to approach this problem and the significance of the pH=7 for Gibbs Free Energy. If anyone can help me understand it I really appreciate it thank you.
by Ardo 2K
Sun Feb 04, 2018 5:52 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Max work related to Gibbs Free Energy
Replies: 2
Views: 103

Max work related to Gibbs Free Energy

Does the change in Gibbs Free Energy always represent the maximum work or is it when the Pressures and Temperatures are constant in a spontaneous reaction?
by Ardo 2K
Sun Feb 04, 2018 2:14 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Using Q
Replies: 2
Views: 117

Using Q

Can we use Q when calculating Gibbs free energy with the Equation deltaG= -RTlnQ? Or does the reaction need to be at equilibrium for us to use this equation, in which case we would use K.
by Ardo 2K
Sun Jan 28, 2018 1:24 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: Spontaneous Processes for Entropy
Replies: 2
Views: 194

Spontaneous Processes for Entropy

So in all cases when the change in entropy is positive the process is spontaneous? Or is it specifically when we use the equation when we take Delta S=nRln(V1/V2) because V2 is greater than V1?
by Ardo 2K
Sun Jan 28, 2018 1:15 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy Change of Phase Changes
Replies: 1
Views: 150

Entropy Change of Phase Changes

When calculating the entropy change of a specific phase change do we use the enthalpy change? Also for example in #9.15 when calculating the change in entropy of a liquid becoming a solid do we take the negative value of the enthalpy change of fusion in this case?
by Ardo 2K
Sun Jan 28, 2018 11:58 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Homework Problem 9.13
Replies: 1
Views: 73

Homework Problem 9.13

When given a problem like this one when a gas changes both volume and temperature how would we calculate the entropy change? Do we take each change individually, for example do we take the change from 3L to 0.500L first into account and calculate the entropy change and then the change of temperature...
by Ardo 2K
Sun Jan 21, 2018 6:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Homework Problem 8.99
Replies: 1
Views: 100

Homework Problem 8.99

Can someone please explain the solution to this problem. I understand that we find the standard reaction enthalpies and through that we calculate the enthalpy of the overall reaction, but from then on I'm a little confused as to how we find the heat released of the system.
by Ardo 2K
Sun Jan 21, 2018 4:01 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Homework Problem 8.41
Replies: 2
Views: 120

Homework Problem 8.41

So when given a problem of this type, when a colder solid substance such as ice is submerged into a warmer surrounding of water, when calculating the heat given off by the system which is the ice in this case, we always assume the ice will melt? Meaning that we should always take into account the en...
by Ardo 2K
Sun Jan 21, 2018 3:54 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Standard Enthalpies of Formation
Replies: 3
Views: 168

Standard Enthalpies of Formation

So when calculating the total enthalpy of a reaction and we are given standard enthalpies of formation of the individual products and reactants all we need to do from there is add up the bonds formed in the products and the bonds broken in the reactants and subtract the total enthalpy of the formed ...
by Ardo 2K
Mon Jan 15, 2018 12:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Homework Problem 8.31
Replies: 2
Views: 136

Homework Problem 8.31

When finding the heat capacity at constant volumes and constant pressures when do you know to multiply R by 3/2, 5/2,7/2, 3, or 4? Does it only have to do with whether the sample is an atom, linear molecule or nonlinear molecule?
by Ardo 2K
Sun Jan 14, 2018 1:27 pm
Forum: Calculating Work of Expansion
Topic: Homework Problem 8.9
Replies: 2
Views: 172

Re: Homework Problem 8.9

You would first calculate the work being done by the system by using the equation -Pex*Delta V. After making the proper conversions and finding the work being done by the system, you then subtract the work done on the system which is 5.50 kJ by the work done by the system.
by Ardo 2K
Sun Jan 14, 2018 1:08 pm
Forum: Calculating Work of Expansion
Topic: Homework Problem 8.3 Using Proper Units
Replies: 1
Views: 129

Homework Problem 8.3 Using Proper Units

For problem 8.3 when finding the change in the volume of the bicycle pump in order to find the work, the solutions manual found it in liters, but in the book it states that when finding work we should only work in Pascals for pressure and meters cubed for volume. It makes the conversion for Pascals ...

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