Search found 38 matches

by Samira 2B
Sat Mar 17, 2018 5:31 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Doubling, quadrupling
Replies: 1
Views: 179

Re: Doubling, quadrupling

That would mean that the rate would quadruple or multiply by 6.

If you increase your reactant for a second order, that means that the rate would be increased by the square of however much you increased your reactant.
by Samira 2B
Sat Mar 17, 2018 5:26 pm
Forum: *Nucleophiles
Topic: Electrostatic Attraction
Replies: 1
Views: 400

Re: Electrostatic Attraction

Electrostatic Attraction has to do with nucleophilic substitution.

It is when a nucleophile attracts an electrophile to the point where a part of the molecule leaves thus, substituting it.
by Samira 2B
Sat Mar 17, 2018 5:23 pm
Forum: Zero Order Reactions
Topic: Shortcut
Replies: 1
Views: 165

Re: Shortcut

If it is 0th order, then it would just be M/s.
For 1st order, it would just be 1/s.
For 2nd order, it would just be M^-1/s.

So, the shortcut is to subtract the exponent of M (1) by the order that the reaction is.
by Samira 2B
Sat Mar 17, 2018 5:19 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Practice Final 2010
Replies: 1
Views: 227

Re: Practice Final 2010

To use Cp or Cv, you would have to have constant pressure or constant volume, respectively.
by Samira 2B
Thu Mar 08, 2018 5:29 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-Equilibrium Approach Methodology
Replies: 2
Views: 123

Pre-Equilibrium Approach Methodology

Why do we set the rate law equal to the formation of product in the pre-equilibrium approach?
by Samira 2B
Mon Mar 05, 2018 9:39 pm
Forum: Second Order Reactions
Topic: 2nd order rxn integration
Replies: 2
Views: 115

2nd order rxn integration

In the integration for the 2nd order rxn, where does the negative go?
by Samira 2B
Sun Mar 04, 2018 9:37 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Friday Lecture
Replies: 5
Views: 182

Friday Lecture

I understand the concept of intermediate species. I just do not get how just from the NO2 eqn and the rate eqn, we got that an intermediate species is needed. In the lecture notes, Lavelle states that "NO2 cannot form NO and CO2 so there must be an intermediate species" but in the eqn itse...
by Samira 2B
Sun Mar 04, 2018 11:54 am
Forum: Second Order Reactions
Topic: 15.35 homework
Replies: 2
Views: 114

Re: 15.35 homework

Also, I used a ratio instead of the actual values given and I got the wrong answer? Why is that?
by Samira 2B
Sun Mar 04, 2018 11:50 am
Forum: Second Order Reactions
Topic: 15.35 homework
Replies: 2
Views: 114

15.35 homework

Why can't we use the same trick that was used in 27 to determine the half-lives for the times that are multiples of 2?
by Samira 2B
Sun Mar 04, 2018 11:07 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 0 order
Replies: 6
Views: 2101

Re: 0 order

If you look at page 631 in the chemistry textbook it shows you in the table.

However, the graph itself has an x-axis of time and a y-axis of the concentration of A at time t with a slope that is equal to -k and a y-intercept of the initial concentration of A.
by Samira 2B
Sun Mar 04, 2018 11:04 am
Forum: First Order Reactions
Topic: 15.23
Replies: 4
Views: 166

Re: 15.23

It is because that accounts for the change in reactants going to products. Since, products is produce that means the reactants must be reduced. So, you would subtract the 0.068 from the initial reactant concentration.
by Samira 2B
Sat Feb 24, 2018 5:29 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.41b. Homework b
Replies: 2
Views: 159

14.41b. Homework b

In the solutions manual, it says that the n=1. However when I separate the rxn into two half-rxn, the n=2?
by Samira 2B
Sat Feb 24, 2018 4:38 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q of eqn [ENDORSED]
Replies: 2
Views: 138

Q of eqn [ENDORSED]

Why can you include concentration and partial pressure when calculating the Q of a rxn?
by Samira 2B
Mon Feb 19, 2018 4:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13
Replies: 5
Views: 299

Re: 14.13

In the problem I am referring to, there is an equation given where it can go either way. So it is not as easy as looking at which species is oxidized or reduced( or which species is losing or gaining electrons). What I have figured out is that the anode usually has the lower E of cell? Is that a goo...
by Samira 2B
Mon Feb 19, 2018 3:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13
Replies: 5
Views: 299

14.13

How do you tell which equation is the anode and which is the cathode ?
by Samira 2B
Sun Feb 18, 2018 6:21 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Notation
Replies: 1
Views: 102

Cell Notation

When do you add Pt(s) to the cell notation? Also, how do you recognize the species that you would put in that place rather than the Pt(s) in the equation?
by Samira 2B
Sun Feb 18, 2018 4:46 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential
Replies: 1
Views: 90

Cell Potential

What does the book mean when it takes about "pushing and pulling" regarding to the potential difference?

When it states that a rxn with a lot of pushing and pulling power generates high potential difference or a high voltage.
by Samira 2B
Mon Feb 12, 2018 7:00 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Calorimetry
Replies: 2
Views: 124

Calorimetry

In a calorimetry problem where ice with a temperature below 0 C is put into water and you are asked to find the final temperature, would you have to have 3 q's for ice: one for the change of heat for ice to 0, the H of fusion and then the change of heat from 0 to the final temperature? or would you ...
by Samira 2B
Sun Feb 11, 2018 11:26 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Homework Problem 9.69
Replies: 2
Views: 117

Homework Problem 9.69

I don't understand how the second and third equations relate to the first one. How does that help us find the answer?
by Samira 2B
Sun Feb 11, 2018 11:24 pm
Forum: Phase Changes & Related Calculations
Topic: Lyndons practice midterm
Replies: 3
Views: 225

Re: Lyndons practice midterm

As Lyndon said in the review, water can evaporate in a room that is room temperature without having to reach boiling point. If you think of the temperature change graphs, a phase change is one where the temperature does not have to change. Thus, the temperature does not have to change for there to b...
by Samira 2B
Sun Feb 11, 2018 10:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Homework Problem 9.65
Replies: 2
Views: 110

Homework Problem 9.65

How do we tell if something will become more or less stable as T increases? Don't we not have enough information to tell that?
by Samira 2B
Mon Feb 05, 2018 11:28 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Homework Problem 9.17
Replies: 1
Views: 122

Homework Problem 9.17

Why do we have to account for the entropy of the cooling process when finding the standard entropy of vaporization of water?
by Samira 2B
Sun Feb 04, 2018 11:58 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy in real life
Replies: 1
Views: 113

Re: Entropy in real life

The entropy of a room may decrease with the cooling of the system. However, that does not mean that the whole system would have the entropy decrease. The heat particles just flow to a different object. DeltaS means the change in total entropy as the energy of contents of the two components change so...
by Samira 2B
Sun Feb 04, 2018 11:47 pm
Forum: Calculating Work of Expansion
Topic: Midterm [ENDORSED]
Replies: 3
Views: 168

Midterm [ENDORSED]

For the midterm, we will not need to know any of the equations (just the connections between the variations), right? Or will not all of them be on the eqn sheet?
by Samira 2B
Sun Feb 04, 2018 11:44 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: maximum G
Replies: 3
Views: 144

Re: maximum G

"Energy is free to do all useful work" so the Gmax is just when the work stops being useful with the process.
by Samira 2B
Sun Feb 04, 2018 11:42 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: maximum G
Replies: 3
Views: 144

Re: maximum G

If you think about it on the graph that Dr. Lavelle showed us, there is a minimum to the parabolic curve meaning that the free energy of process cannot go below it. The process itself is at equilibrium so, it cannot spontaneously change and if work is put into it it will only be able to go up on the...
by Samira 2B
Sun Feb 04, 2018 11:38 pm
Forum: Calculating Work of Expansion
Topic: Lecture notes, free energy graph
Replies: 1
Views: 67

Re: Lecture notes, free energy graph

Nevermind I just answered this for myself.

On the graph, a process that leads towards equilibrium is spontaneous while one that leads away equilibrium is non-spontaneous.
by Samira 2B
Sun Feb 04, 2018 11:34 pm
Forum: Calculating Work of Expansion
Topic: Lecture notes, free energy graph
Replies: 1
Views: 67

Lecture notes, free energy graph

During lecture, there was a graph presented showing spontaneous processes as going down a parabolic curve. Does that non-spontaneous processes happen at equilibrium?
by Samira 2B
Mon Jan 29, 2018 8:00 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Clausius Inequality
Replies: 1
Views: 201

Clausius Inequality

I was reading the textbook and I am a bit confused on the Clausius Inequality and the logic of getting to it. I understand in what context we would use this equation in but not the concept itself.
by Samira 2B
Mon Jan 22, 2018 10:05 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Lecture notes, Boltzmann Eqn [ENDORSED]
Replies: 1
Views: 75

Lecture notes, Boltzmann Eqn [ENDORSED]

After the introduction of Boltzmann Equation, there were some notes about error in the thermodynamic property and in the statistical. I do not really understand this concept of small and large "error"
by Samira 2B
Mon Jan 22, 2018 7:59 pm
Forum: Calculating Work of Expansion
Topic: 8.117 Homework Problem
Replies: 1
Views: 78

8.117 Homework Problem

Why is the net production of gas 2/3?
by Samira 2B
Sun Jan 21, 2018 3:58 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.67
Replies: 3
Views: 155

8.67

For a. when calculating bond enthalpies one finds the enthalpy of formation for water in its gas state. However, the equation has water in its liquid state. So, how do we know that water is in its gas state versus knowing it is in its liquid state?
by Samira 2B
Sun Jan 21, 2018 2:47 pm
Forum: Calculating Work of Expansion
Topic: Lecture notes , work eqn
Replies: 3
Views: 141

Re: Lecture notes , work eqn

So, the system being at equilibrium means that it is a reversible process?
by Samira 2B
Sun Jan 21, 2018 12:21 am
Forum: Calculating Work of Expansion
Topic: Lecture notes , work eqn
Replies: 3
Views: 141

Lecture notes , work eqn

This is from the lecture notes on Friday. Do we only use the work equation when the system is at equilibrium? Because that is when we use the derivative for the small changes in V that leads to the integral of the work eqn.
by Samira 2B
Mon Jan 15, 2018 5:47 pm
Forum: Calculating Work of Expansion
Topic: 8.13
Replies: 2
Views: 78

8.13

For this problem, why is the heat added (947 kJ) negative? I thought when you add heat to a system it is supposed to be positive?
by Samira 2B
Sun Jan 14, 2018 3:40 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Irreversible vs. Reversible [ENDORSED]
Replies: 10
Views: 429

Irreversible vs. Reversible [ENDORSED]

I read about this in the textbook and I understand that you are supposed to use two different equations for each but what is the difference between these two processes?
by Samira 2B
Sun Jan 14, 2018 2:46 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 3
Views: 204

Re: Systems

An open system is one that can exchange matter and energy with its surroundings. A closed system is one that can only exchange energy and an isolated is one that can't exchange either matter or energy.
by Samira 2B
Sat Jan 13, 2018 3:36 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Work vs. Heat
Replies: 6
Views: 286

Work vs. Heat

Is this difference between work and heat the same difference between velocity and speed? Why I think of this is because in the textbook it describes the fundamental difference between these two is that when energy is transferred as work, the molecules in the surroundings move in directed directions ...

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