Search found 31 matches

by Ju-Wei Wang 1I
Tue Mar 13, 2018 6:09 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate-Determining Step
Replies: 4
Views: 211

Re: Rate-Determining Step

You're correct that the rate law for step 2 is rate = k[NO3][CO], but that is the rate law for that specific step, not for the overall reaction.
by Ju-Wei Wang 1I
Tue Mar 13, 2018 5:15 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Value of Q
Replies: 1
Views: 113

Re: Value of Q

Liquids and solids are not included when solving for equilibrium constants.
by Ju-Wei Wang 1I
Tue Mar 13, 2018 5:13 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate-Determining Step
Replies: 4
Views: 211

Re: Rate-Determining Step

The second step being the slow step makes finding the rate law for the overall reaction more difficult because it may contain an intermediate, which is never included in the overall rate law.
by Ju-Wei Wang 1I
Tue Mar 13, 2018 5:02 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst vs Intermedaite
Replies: 3
Views: 198

Re: Catalyst vs Intermedaite

A catalyst is present as a reactant in the first step of a given reaction mechanism and is not consumed in the reaction. An intermediate is a species that plays a role in a reaction but does not appear in the chemical equation for the overall reaction; it is produced in one step but is used up in a ...
by Ju-Wei Wang 1I
Sat Mar 10, 2018 3:03 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: SN2 Organic Reaction
Replies: 3
Views: 146

SN2 Organic Reaction

What exactly is a nucleophile? Is it just a molecule that carries a negative charge and is attracted to the partially positive region of another molecule?
by Ju-Wei Wang 1I
Sat Mar 10, 2018 2:53 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-Equilibrium
Replies: 4
Views: 174

Pre-Equilibrium

When using the pre-equilibrium approach, we are given the steps involved in the reaction right?
by Ju-Wei Wang 1I
Sat Mar 10, 2018 2:38 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Slow Reaction
Replies: 3
Views: 107

Slow Reaction

This is probably a dumb question, but how do you determine which step is the slow step?
by Ju-Wei Wang 1I
Sat Mar 03, 2018 3:03 pm
Forum: First Order Reactions
Topic: Directly Proportional [ENDORSED]
Replies: 1
Views: 113

Re: Directly Proportional [ENDORSED]

Direct proportionality can be depicted using the equation y=kx + c, where one variable depends on the other by a factor of "k". A first order rate law's two variables are ln[A] vs. time. The factor that relates the two is -k, which is also the slope of the equation. In a zero order reactio...
by Ju-Wei Wang 1I
Sat Mar 03, 2018 2:44 pm
Forum: Second Order Reactions
Topic: Non-integer orders [ENDORSED]
Replies: 3
Views: 179

Re: Non-integer orders [ENDORSED]

My TA said it's very unlikely that Dr. Lavelle would make us do problems like these, especially since we have not done any examples in class.
by Ju-Wei Wang 1I
Sat Mar 03, 2018 2:24 pm
Forum: General Rate Laws
Topic: Differential and Integrated Rate Laws
Replies: 3
Views: 170

Differential and Integrated Rate Laws

How do you know when to use a differential rate law versus an integrated rate law? Are there specific things you can look for in the question that direct you to use a certain equation over the other?
by Ju-Wei Wang 1I
Sat Feb 24, 2018 3:10 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Gas in Products [ENDORSED]
Replies: 2
Views: 153

Gas in Products [ENDORSED]

Can we assume that if a gas forms in the products, it will always leave the solution, causing the reverse reaction to become less likely to occur?
by Ju-Wei Wang 1I
Sat Feb 24, 2018 2:58 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate constant (k)
Replies: 4
Views: 190

Rate constant (k)

Why is the rate constant called the rate constant even though the value varies since it depends on temperature and activation energy?
by Ju-Wei Wang 1I
Sat Feb 24, 2018 2:26 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13 (b)
Replies: 3
Views: 126

Re: 14.13 (b)

Platinum is needed because I2(s) isn't a metallic conductor. Just because there is the presence of a solid does not necessarily mean that it is the electrode.
by Ju-Wei Wang 1I
Sat Feb 17, 2018 1:43 pm
Forum: Balancing Redox Reactions
Topic: Acidic vs. Basic Solutions
Replies: 3
Views: 191

Acidic vs. Basic Solutions

Is it correct that in acidic solutions, we balance H by adding H3O+ for each H needed, and in basic solutions, we use OH- instead?
by Ju-Wei Wang 1I
Sat Feb 17, 2018 1:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrodes in Cell Diagrams
Replies: 2
Views: 98

Electrodes in Cell Diagrams

I know that Dr. Lavelle explicitly stated that we should use platinum as the electrode when half reactions have no conducting solids, but are there exceptions to this rule?
by Ju-Wei Wang 1I
Sat Feb 17, 2018 1:27 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing/reducing agent given E˚
Replies: 1
Views: 87

Re: Oxidizing/reducing agent given E˚

Yes, that is correct. The reducing agent is itself oxidized; therefore, the most negative E˚is most likely to be oxidized because it is more willing to give up an electron.
by Ju-Wei Wang 1I
Sat Feb 10, 2018 3:30 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Clausius Inequality [ENDORSED]
Replies: 2
Views: 144

Clausius Inequality [ENDORSED]

Dr. Lavelle never mentioned the Clausius Inequality in class, so is it relevant for the midterm? If so, can someone explain how it relates to ΔS = qrev/T?
by Ju-Wei Wang 1I
Sat Feb 10, 2018 3:14 pm
Forum: Van't Hoff Equation
Topic: 11.116
Replies: 2
Views: 218

11.116

During discussion, we did this practice problem by using Van't Hoff's equation and the relationship between ∆G = -RTlnK = ∆H - T∆S. We didn't write out all the steps, so I'm a little confused on how to solve for the first K value that would be subsequently substituted into Van't Hoff's equation. Can...
by Ju-Wei Wang 1I
Sat Feb 10, 2018 2:20 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: ∆S total [ENDORSED]
Replies: 4
Views: 199

Re: ∆S total [ENDORSED]

∆Stot is the same as the entropy of the universe. According to the Second Law of Thermodynamics, the universe tends to shift towards disorder, so ∆S cannot be less than zero. Thus, a negative ∆Stot is not only nonspontaneous but also considered a forbidden process.
by Ju-Wei Wang 1I
Sat Feb 03, 2018 11:30 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy of Transition
Replies: 1
Views: 92

Entropy of Transition

How do you find the entropy of transition at a temperature other than the transition temperature?
by Ju-Wei Wang 1I
Sat Feb 03, 2018 11:19 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Change in Entropy of Universe
Replies: 3
Views: 202

Change in Entropy of Universe

When do you know that you can set delta Suniv equal to zero? Is it just for reversible processes?
by Ju-Wei Wang 1I
Sat Feb 03, 2018 11:05 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Isothermal pressure change
Replies: 3
Views: 117

Re: Isothermal pressure change

According to the ideal gas law, specifically Boyle's Law, pressure is inversely related to volume, so at constant temperature, V2/V1=P1/P2.
by Ju-Wei Wang 1I
Sat Jan 27, 2018 1:38 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: Perfect Crystal
Replies: 9
Views: 360

Perfect Crystal

During lecture, we talked about perfect crystals, which I don't really understand. Can someone explain what that is, i.e. what conditions make them a perfect crystal?
by Ju-Wei Wang 1I
Sat Jan 27, 2018 1:33 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Positional disorder
Replies: 1
Views: 97

Re: Positional disorder

Positional disorder is disorder related to the positions of molecules and causes a change in entropy; you would observe an increase in positional disorder when molecules are dispersed over a greater volume.
by Ju-Wei Wang 1I
Sat Jan 27, 2018 1:21 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontaneous [ENDORSED]
Replies: 6
Views: 211

Spontaneous [ENDORSED]

In a problem, how are we supposed to determine whether a reaction/process is spontaneous or not? I know you can figure it out when given Gibbs free energy, but what other way can be used to figure this out?
by Ju-Wei Wang 1I
Sat Jan 20, 2018 3:09 pm
Forum: Phase Changes & Related Calculations
Topic: Change in Internal Energy
Replies: 3
Views: 147

Re: Change in Internal Energy

Compression is work being done on the system. Remember the equation is delta U = q + w. Internal energy, U, will increase because work (w) is a positive value.
by Ju-Wei Wang 1I
Sat Jan 20, 2018 2:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: State Properties
Replies: 1
Views: 91

State Properties

What are the state properties that we should know?
by Ju-Wei Wang 1I
Sat Jan 20, 2018 1:52 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Quadratic Degrees of Freedom
Replies: 1
Views: 116

Quadratic Degrees of Freedom

During discussion, we talked about the three types of quadratic degrees of freedom (translational, rotational, and vibrational), but what exactly are quadratic d.o.f. and when would we need to use them?
by Ju-Wei Wang 1I
Sat Jan 13, 2018 5:17 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible vs irreversible
Replies: 2
Views: 141

Re: Reversible vs irreversible

I think in the textbook it said something about how during irreversible expansion, which is a type of irreversible process, some of the potential to do work is lost. One of the main differences between reversible and irreversible processes is that in irreversible processes, there is always a change ...
by Ju-Wei Wang 1I
Sat Jan 13, 2018 5:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeters
Replies: 1
Views: 80

Calorimeters

Do we need to know any other types of calorimeters besides the adiabatic and bomb calorimeters?
by Ju-Wei Wang 1I
Sat Jan 13, 2018 5:02 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy [ENDORSED]
Replies: 1
Views: 109

Enthalpy [ENDORSED]

The definition of enthalpy specifies that it is the amount of heat released or absorbed at constant pressure; how is it affected/what is it considered if pressure is variable?

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