Search found 29 matches

by andrewr2H
Thu Mar 15, 2018 5:22 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.49
Replies: 4
Views: 133

Re: 15.49

The intermediate is substituted out in the total reaction rate law.
by andrewr2H
Thu Mar 15, 2018 5:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13 b
Replies: 4
Views: 131

Re: 14.13 b

Going back to the characteristics of each group on the periodic table we know that metals tend to be conductive whereas non metals such as the halogens are non conductive.
by andrewr2H
Thu Mar 15, 2018 5:08 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.49
Replies: 2
Views: 96

Re: 8.49

I believe we assume ideal gas behavior just because we wouldn’t be able to solve the question if we didn’t.
by andrewr2H
Fri Mar 09, 2018 9:28 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Equations
Replies: 4
Views: 284

Re: Equations

Generally if it isn't on the equations sheet, it tends to be a derivation of an equation that is already on the equation sheet. You could figure it out that way
by andrewr2H
Fri Mar 09, 2018 9:25 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction Intermediates
Replies: 4
Views: 110

Re: Reaction Intermediates

Irma, I doubt we would be asked such a question because the only method we've been introduced to so far to find an intermediate would be to look at the elementary reactions and look for a term that is created in one step and used up in another. So it would have to be listed for us to find it.
by andrewr2H
Fri Mar 09, 2018 9:22 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Activation Energy and Temperature
Replies: 3
Views: 170

Re: Activation Energy and Temperature

Yes, these conditions are possible. Having a high temperature just means you're more likely to reach the activation energy, though it may be higher. The effect these two conditions would have on the rate constant, in terms of increasing or decreasing it, would depend on the magnitude of each conditi...
by andrewr2H
Mon Feb 26, 2018 9:44 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 787700

Re: Post All Chemistry Jokes Here

What do you call a fish that is really salty?

Too Na
by andrewr2H
Mon Feb 26, 2018 9:31 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Cell Potential
Replies: 9
Views: 2149

Re: Cell Potential

These equations are equivalent to each other, it is just that one is simplified.
by andrewr2H
Mon Feb 26, 2018 9:28 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Slowest Elementary Step
Replies: 4
Views: 113

Re: Slowest Elementary Step

I believe this is because many of the reactions may be occurring at once, so regardless if one of these reactions finishes in a very short amount of time, it does not necessarily make the reactions slower than it occur faster or sooner.
by andrewr2H
Mon Feb 26, 2018 9:20 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: changing sign of of standard cell potentials
Replies: 4
Views: 114

Re: changing sign of of standard cell potentials

Yes you can flip the reaction and the sign of Eo, but if in the case you are determining cell potentials and you happen to be using the equation Ecell = Ecathode - Eanode, you would just keep the signs of the E cathode and E anode as given because the negative sign in the equation accounts for the s...
by andrewr2H
Mon Feb 26, 2018 9:16 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Value of k
Replies: 4
Views: 108

Re: Value of k

K cannot be negative because K is determined by dividing the concentration of the products by the reactants, and you cannot have negative concentration. And yes, temperature will affect K of a reaction.
by andrewr2H
Mon Feb 26, 2018 9:10 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Q and K
Replies: 7
Views: 185

Re: Q and K

The concepts remain true throughout chemistry, but it is true that there may be additional methods such as Gibbs Free Energy that we may learn to determine if a reaction is at equilibrium and in which direction it will occur if it is not.
by andrewr2H
Mon Feb 26, 2018 9:05 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Kinetics vs Thermodynamics
Replies: 7
Views: 211

Re: Kinetics vs Thermodynamics

My understanding is that if a reaction is thermodynamically unfavorable, it cannot be kinetically favorable. And if a reaction is kinetically favorable, it must be thermodynamically favorable. However, a reaction being thermodynamically favorable does not automatically make it kinetically favorable.
by andrewr2H
Wed Feb 21, 2018 3:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework Question 14.13 Part (d)
Replies: 1
Views: 77

Homework Question 14.13 Part (d)

The question states: Write the half-reactions, the balanced equation for the cell reaction, and the cell diagram for each of the following skeletal equations. (d) Au+(aq) --> Au(s) + Au3+(aq) ------------------------------------------------------------- The answer in the back of the book states that...
by andrewr2H
Fri Feb 16, 2018 4:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard cell reduction potential
Replies: 1
Views: 57

Re: Standard cell reduction potential

Yes. This is because Eo is an intensive property. As for flipping the sign of the Eo value, that depends on which of the two methods that Dr. Lavelle demonstrated to us that you are using. If in the case you are using the Eo cell = E cathode - E anode method, then you do not flip the sign because th...
by andrewr2H
Fri Feb 16, 2018 4:48 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: s vs. delta s
Replies: 7
Views: 209

Re: s vs. delta s

S is generally used in reference to to the statistical/residual entropy of a perfectly ordered crystal at 0 K. It’s equation is s = kb * lnW
by andrewr2H
Fri Feb 16, 2018 4:46 pm
Forum: General Science Questions
Topic: Battery voltage
Replies: 4
Views: 297

Re: Battery voltage

Batteries in real life tend to use lithium ion because it has a very high Eo value equal to -3.05 V.
by andrewr2H
Thu Feb 08, 2018 5:15 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Kelvin
Replies: 4
Views: 142

Re: Kelvin

Unless specified otherwise, it is generally safe to perform calculations with temperature in terms of Kelvin. Even in the case of a specific heat equation or of the like, most often the calculation involves using change(difference) in temperature. Because degrees K = degrees C + 273, the difference ...
by andrewr2H
Thu Feb 08, 2018 5:06 pm
Forum: Balancing Redox Reactions
Topic: Standard Reduction Potentials Concept
Replies: 4
Views: 147

Re: Standard Reduction Potentials Concept

Essentially, yes it is. If you flip the reaction the electrons will appear on the right side of the equation thus making it an oxidation reaction. However, I'm not sure if there is any thing "officially" as a standard oxidation potential.
by andrewr2H
Thu Feb 08, 2018 5:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Intensive Property of Standard Cell Potential
Replies: 3
Views: 110

Intensive Property of Standard Cell Potential

In the example with the redox reaction between Fe3+(aq) and Cu(s) that Dr. Lavelle gave during Wednesday's lecture, he stated that because of the fact that standard cell potential is an intensive property, we do not double the value of Eo for the Fe3+ half reaction despite the fact that twice the am...
by andrewr2H
Fri Feb 02, 2018 11:11 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Problem 9.19 about Standard Entropy
Replies: 6
Views: 141

Re: Problem 9.19 about Standard Entropy

The boiling point of water is 100 degrees C. So to find the entropy of the vaporization of water at 85 degrees you have to account for the cooling down of water. I'm not sure how it is that water is able to be vaporized at 85 degrees though.
by andrewr2H
Fri Feb 02, 2018 11:06 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Residual Molar Entropy?
Replies: 3
Views: 121

Re: Residual Molar Entropy?

Residual entropy refers to the entropy that exists at T = 0 K. Residual entropy results from the different micro states that exist because of the different orientations a molecule may have.
by andrewr2H
Fri Feb 02, 2018 10:44 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7337
Views: 787700

Re: Post All Chemistry Jokes Here

Credit my awesome (single) cousin (818)-963-3909

WHAT ELEMENT IS THE PROFESSOR MADE OUT OF?

BORON

LMAO
by andrewr2H
Fri Jan 26, 2018 12:32 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Homework 8.57
Replies: 2
Views: 117

Re: Homework 8.57

The order in which you add values does not change the final sum. And when you apply a double negative to a value it becomes a positive value. Thus the equation can also be written as (reactants - products) instead of (-products + reactants).
by andrewr2H
Fri Jan 26, 2018 12:28 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Superheating
Replies: 3
Views: 137

Re: Superheating

I second the above post. I happen to already have had discussion as well.
by andrewr2H
Fri Jan 26, 2018 12:21 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Question regarding ice in water?
Replies: 2
Views: 140

Re: Question regarding ice in water?

So I believe what you're asking is how you know if the ice melts completely? To find this out you would look at ∆Hfus = 6.01 kJ.mol-1. This means that for every one mole of ice you need 6.01 kJ of energy in order to melt it completely. So if you want to know if the ice in a problem melts completely ...
by andrewr2H
Wed Jan 10, 2018 10:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question about today's lecture problem?
Replies: 3
Views: 119

Re: Question about today's lecture problem?

Well in the first reaction nitrogen and oxygen combine to form nitrogen oxide. Then in the second reaction the nitrogen oxide that was formed combines again with another oxygen to produce nitrogen dioxide, the final product.
by andrewr2H
Wed Jan 10, 2018 9:04 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Notation
Replies: 4
Views: 163

Re: Notation

Yes, so long as the correct number of sig figs is used, either way should technically be correct. Scientific notation can just be useful in avoiding having to write out a large number of zeroes and, as already mentioned, in removing ambiguity surrounding the number of sig figs.
by andrewr2H
Wed Jan 10, 2018 8:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Conceptualizing enthalpy
Replies: 2
Views: 189

Conceptualizing enthalpy

I was a little confused about the equation q/p = enthalpy. During Monday's lecture Dr. Lavelle defined enthalpy as the heat released or absorbed during a chemical reaction or phase change (change in heat), but I'm confused over why the heat released or absorbed is equal to heat at constant pressure....

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