Search found 28 matches

Sun Mar 11, 2018 10:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 6
Views: 402

Re: Cell Diagrams

The anode is listed first.
Sun Mar 11, 2018 10:29 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Midterm Question
Replies: 4
Views: 366

Re: Midterm Question

For that specific problem it was ok to use Celsius because we were calculating the change in temperature, so it would be the same regardless of if it was in Celsius or Kelvin.
Sun Mar 11, 2018 10:26 pm
Forum: *Enzyme Kinetics
Topic: Kinetics and Enzymes
Replies: 7
Views: 787

Re: Kinetics and Enzymes

From what I have learned in biology, enzymes act as catalysts for biological reactions, which serve to lower the activation energy needed to drive a reaction forward and stabilize the transition state.
Sun Mar 04, 2018 10:58 pm
Forum: First Order Reactions
Topic: Tests
Replies: 1
Views: 163

Re: Tests

Yes, we will just need to memorize it. Zero order is [A], first order is ln[A], and second order is 1/[A].
Sun Mar 04, 2018 10:49 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: k units [ENDORSED]
Replies: 7
Views: 573

Re: k units[ENDORSED]

There is a different equation for each rate order, and thus a different k unit to cancel out to get the final units.
Sun Mar 04, 2018 10:44 pm
Forum: Zero Order Reactions
Topic: Half life and rate order
Replies: 4
Views: 314

Re: Half life and rate order

I believe that you need to know the order to know which rate law to use, and then you find the half life by using the initial concentration.
Sun Feb 25, 2018 11:55 pm
Forum: First Order Reactions
Topic: Order of a reaction
Replies: 3
Views: 264

Order of a reaction

I am still a little confused on what the order of the reaction represents, can someone explain that conceptually?
Sun Feb 25, 2018 11:52 pm
Forum: General Rate Laws
Topic: Reaction Rates [ENDORSED]
Replies: 2
Views: 195

Re: Reaction Rates[ENDORSED]

I believe we write the rate as positive because products are being formed meaning the reaction is proceeding forward.
Sun Feb 25, 2018 11:50 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: standard conditions [ENDORSED]
Replies: 4
Views: 291

Re: standard conditions[ENDORSED]

The equilibrium constant should be different depending on the conditions such as temperature and pressure, so it does have to do with it a little. In general, all of our calculations involving equilibrium will be at standard conditions unless stated otherwise.
Sun Feb 25, 2018 11:46 pm
Forum: General Rate Laws
Topic: Rate of Reaction
Replies: 4
Views: 289

Re: Rate of Reaction

In the chemical equation, the stoichiometric coefficients show that for every mol of O2 formed there are 2 mol of NO and NO2, so it O2 is forming half as fast. Thus, its rate would have to be doubled to equal the rate of NO being formed and NO2 being broken down.
Mon Feb 19, 2018 10:53 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.11
Replies: 1
Views: 129

Re: 14.11

After the reading the sol. manual I realized that the reaction equation was just reversed, so how are we supposed to know which element is the cathode and which is the anode without looking at the reduction potential?
Mon Feb 19, 2018 10:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.11
Replies: 1
Views: 129

14.11

I do not understand part e. If Sn is being reduced, why would it be the anode?
Tue Feb 13, 2018 7:22 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reaction enthalpy
Replies: 2
Views: 189

Reaction enthalpy

Why is the reaction enthalpy less negative than the reaction internal energy for reactions that generate gases?
Sun Feb 11, 2018 11:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: delta H
Replies: 4
Views: 253

Re: delta H

Energy is released when bonds form and energy is put into a bond in order to break it. As a result, if the energy released by forming the bonds of the products is greater than the energy it took to break the bonds of the reactants than the change in H is negative and it is a exothermic reaction
Sun Feb 11, 2018 11:29 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Stability and deltaG
Replies: 2
Views: 229

Re: Stability and deltaG

If delta G is negative the reaction has a tendency to occur and will proceed towards the compounds with the most negative delta G.
Sun Feb 11, 2018 11:22 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Revsersible vs. Irreversible reactions
Replies: 3
Views: 234

Revsersible vs. Irreversible reactions

Why does it matter whether a reaction is reversible or irreversible when calculating the entropy, and which equations are used for each scenario?
Sun Feb 04, 2018 10:02 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Equations
Replies: 4
Views: 280

Equations

Do we have to know how to derive any of the equations we learned in class using calculus for any tests?
Sun Feb 04, 2018 9:59 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Measuring delta G
Replies: 4
Views: 298

Re: Measuring delta G

In problems dealing with multiple reactions, there are values in the appendix giving the standard Gibbs free energy for various reactions, which will be used like with standard enthalpy calculations.
Sun Feb 04, 2018 9:57 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Favorability
Replies: 4
Views: 296

Re: Favorability

The reaction favorability really depends on Gibbs free energy which is given by the equation delta H - delta S times the temperature. As long as delta G is negative the reaction is favorable. So a reaction will always be favorable if delta H is negative and delta S is positive. A reaction is never f...
Mon Jan 29, 2018 12:00 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: ideal cooler [ENDORSED]
Replies: 5
Views: 367

Re: ideal cooler[ENDORSED]

I believe this means that energy transfers are efficient and there is no energy transfer in the form of heat.
Sun Jan 28, 2018 11:55 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropy vs. Standard Entropy
Replies: 4
Views: 315

Re: Entropy vs. Standard Entropy

I believe that the standard entropy of vaporization is something like the specific heat capacity where there is a standard amount of entropy always associated with a particular reaction. Also, this might indicate that all of the reactants and products are in their standard state.
Sun Jan 28, 2018 11:17 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.41
Replies: 3
Views: 212

8.41

Can someone explain how to do number 41 in chapter 8? I believe there was a problem like that on my test and I got stuck on it and I'm not sure if I did it right. I am confused about where to place the negatives and how to know if the final temperature is correct.
Sun Jan 21, 2018 9:11 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Open System
Replies: 7
Views: 757

Re: Open System

As far as increasing the internal energy, you could add matter to the system, compress it which would be doing work on the system, and heating the system.
Sun Jan 21, 2018 8:59 pm
Forum: Phase Changes & Related Calculations
Topic: Irreversible vs reversible
Replies: 3
Views: 228

Re: Irreversible vs reversible

A reversible reaction is one that can take place in either direction, meaning that it is a process that can be reversed by an infinitely small, or "infinitesimal" change in a variable. If the external or internal pressure increases infinitesimally, then the piston will move in or out respe...
Sun Jan 21, 2018 8:49 pm
Forum: Calculating Work of Expansion
Topic: Reversible and Irreversible Reactions
Replies: 2
Views: 212

Reversible and Irreversible Reactions

Can anyone explain further how the work done during a reversible expansion of a gas is the maximum expansion work possible?
Sun Jan 14, 2018 10:59 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed Versus Isolated System
Replies: 3
Views: 240

Re: Closed Versus Isolated System

Closed systems usually are more applicable to real life situations, because energy is constantly being transferred between the system and the surroundings without the transfer of matter. The textbook gave the example of using an ice pack for treating athletic injuries. The only time isolated systems...
Sun Jan 14, 2018 10:52 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard States
Replies: 4
Views: 393

Re: Standard States

It might be helpful to memorize the standard states for the more common elements. Gas is the standard state for fluorine, chlorine, hydrogen, nitrogen, oxygen, the halogens, and the noble gases. Mercury and bromine are liquid at standard state the rest are solids. However, there will probably be an ...
Sun Jan 14, 2018 10:41 pm
Forum: Phase Changes & Related Calculations
Topic: Problem 8.29
Replies: 4
Views: 265

Re: Problem 8.29

NO2 would have a higher molar heat capacity because there are a greater number of atoms within the molecule, and thus more possible outlets to absorb energy such as in vibrational and rotational energy. As a result, it would take more energy to increase the temperature of an entire molecule of NO2 a...