Search found 19 matches

by Kristienne Edrosolan
Fri Mar 11, 2016 11:30 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy's Relation to Reversible/Irreversible Processes
Replies: 1
Views: 2090

Entropy's Relation to Reversible/Irreversible Processes

Hello, As I was reviewing my notes I noticed that I'd written that for a reversible process, deltaS(universe) = 0, and therefore that deltaS(system) = - deltaS(surroundings. On the other hand, for an irreversible process, deltaS(Surroundings) = 0 and therefore that deltaS(universe) = deltaS(system)....
by Kristienne Edrosolan
Fri Mar 11, 2016 2:20 am
Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
Topic: 1-chloropropane Newman Projection
Replies: 1
Views: 2448

Re: 1-chloropropane Newman Projection

Because the name 1-chloropropane suggests that the substituent carbon is on the first Carbon, we know that carbon 1 is bonded to Carbon 2, Cl, H, and H. If carbon one had a methyl group attached to it, then it would not be the first carbon in the parent chain! Personally, the way that helps me under...
by Kristienne Edrosolan
Wed Mar 09, 2016 4:52 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Radioactive Decay
Replies: 1
Views: 312

Radioactive Decay

Hello! I was just wondering if there's a possibility that radioactive decay will be tested on the final, and if so, would we just have to apply the formula -dN/dt = kN(knot)exp(-kt), where N is given to us? We skipped the majority of it in the course reader but I just wanted to make sure. And if so,...
by Kristienne Edrosolan
Sun Feb 28, 2016 5:37 pm
Forum: *Alkanes
Topic: Difference
Replies: 1
Views: 239

Re: Difference

All of them classify as hydrocarbons, it's just that an alkane, alkene, or alkyne indicates they are in a chain formation. (In contrast, if cyclo is added in the name, this means the hydrocarbons are in a ring formation.) If the suffix is ANE, that means the hydrocarbon chain consists of only single...
by Kristienne Edrosolan
Sun Feb 28, 2016 5:22 pm
Forum: *Organic Reaction Mechanisms in General
Topic: Activated complex versus transition state
Replies: 1
Views: 250

Re: Activated complex versus transition state

In transition state one, the double bond between the two carbons is in the process of breaking while the hydrogen bond to the second carbon (from the H in HBr) is in the process of forming. The intermediate, Propan-2-ylium is formed once the double bond has completely broken and the hydrogen bond ha...
by Kristienne Edrosolan
Sun Feb 28, 2016 5:15 pm
Forum: *Alkanes
Topic: alkyl vs. aryl compounds
Replies: 1
Views: 1789

Re: alkyl vs. aryl compounds

"Alkyl" and "Aryl" refer to the shape of the compound or the shape of the molecule connected in the compound. An alkyl means the compound contains a hydrocarbon chain whereas an aryl means the molecule is connected to a hydrocarbon ring. For example, on page 146 of the orange tex...
by Kristienne Edrosolan
Thu Feb 18, 2016 7:19 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Steric requirement
Replies: 1
Views: 252

Re: Steric requirement

I believe the course reader says that it is included in "A", the frequency factor. So it is possible you will have to solve for A via the Arrhenius equation, or A can be given, but you won't have to find the steric requirement.
by Kristienne Edrosolan
Thu Feb 18, 2016 7:16 am
Forum: General Rate Laws
Topic: k' confusion
Replies: 2
Views: 424

Re: k' confusion

These two values are different. The first k' is the pseudo-constant, but the second k' is the reverse rate constant. I think usually the reverse rate constant is (k)^-1 but Dr. Lavelle used k' because that is the what the textbook does.
by Kristienne Edrosolan
Wed Feb 10, 2016 12:05 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Midterm 2013 question 5B
Replies: 1
Views: 424

Re: Midterm 2013 question 5B

Substances that have higher molecular mass have greater entropy. Because the number of atoms in each molecules is equal (5), one should look at the molecular mass. Because F is heavier than C and H, the molecule that has the most F atoms has the highest entropy.
by Kristienne Edrosolan
Tue Feb 09, 2016 10:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.11 part B
Replies: 1
Views: 278

Re: 14.11 part B

C and Pt are disregarded because they simply refer to the inert conductor which stands in as an electrode to transfer e-. Thus, they are included in the cell diagram when half reactions have no conducting solids, but they don't actually affect the reaction because they are inert, so they don't get i...
by Kristienne Edrosolan
Tue Feb 09, 2016 5:45 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Hogwarts Problem, 2015 Midterm
Replies: 2
Views: 353

Re: Hogwarts Problem, 2015 Midterm

To solve this problem, you have to know that because entropy is a state function, we can decide the path it takes (state functions are independent of path). As you can see in the solutions, the calculations for entropy are split up into two. This is because two things are changing (T, V). There are ...
by Kristienne Edrosolan
Tue Feb 09, 2016 5:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt (s)
Replies: 1
Views: 263

Re: Pt (s)

In class Professor Lavelle said that although one can use graphite, it is very rare and thus it is probably safer to just use Pt.
by Kristienne Edrosolan
Sun Feb 07, 2016 8:42 pm
Forum: Calculating Work of Expansion
Topic: P Vs V graph
Replies: 3
Views: 725

Re: P Vs V graph

It says on page 24 of the course reader that "P is the external pressure that the system must push against (Pex)". This applies for calculating work at constant pressure in an irreversible change and also in a reversible change, because if the process is reversible, P internal is about equ...
by Kristienne Edrosolan
Mon Feb 01, 2016 9:14 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Spontaneity
Replies: 1
Views: 946

Re: Spontaneity

Hi Shivam, G,H, and S aren't necessarily the ones that are spontaneous, but rather their signs (-G, -H, and +S) are indicators, when put into the equation delta G = delta H - T delta S, that a reaction could be spontaneous. I believe spontaneity basically means that a chemical reaction will occur by...
by Kristienne Edrosolan
Sun Jan 31, 2016 7:40 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Entropy vs Gibbs
Replies: 2
Views: 414

Re: Entropy vs Gibbs

Hi Brock, Entropy is a measure of the system's "disorder" and measures the number of possible states or position the substance considered can occupy. Delta S being positive is more favorable and spontaneous (but S still has to be considered in the Gibbs' free energy equation, delta G = del...
by Kristienne Edrosolan
Sun Jan 31, 2016 7:19 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Quiz Question
Replies: 1
Views: 361

Re: Quiz Question

Hi Daniela, S=KblnW is used for entropy on a molecular level. Kb stands for Boltzmann's constant and W stands for the number of ways of achieving a given energy state, microstates. Delta S = qrev/T is used for isothermal reversible reactions and for phase changes (when heat goes into a system but th...
by Kristienne Edrosolan
Sun Jan 17, 2016 11:34 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Internal energy and state property
Replies: 1
Views: 304

Re: Internal energy and state property

For a reaction occuring at constant pressure, we use the equation delta U = delta H - PdeltaV. Because of the ideal gas law equation, PV=nRT, we know pressure, volume, and number of moles are all related. If the number of moles of gas change in a reaction, but pressure is held constant, there must h...
by Kristienne Edrosolan
Sun Jan 17, 2016 11:14 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 1
Views: 302

Re: Systems

When looking at a problem, one should be able to identify the system, or the object of interest (such as a chemical reaction that is occurring), and the surroundings. This is important because the way that you answer a question can change depending on if you're considering the system or the surround...
by Kristienne Edrosolan
Sun Jan 10, 2016 3:16 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework Question 8.49 - Why can you not use a mole ratio?
Replies: 4
Views: 611

Homework Question 8.49 - Why can you not use a mole ratio?

Hi, I'm looking for some help with homework question 8.49, which asks, "Oxygen difluoride is a colorless, very poisonous gas that reacts rapidly with water vapor to produce O2, HF, and heat. It gives the formula OF2 (g) +H20 (g) --> O2 (g) + 2HF (g) with delta H being -318 kJ. What is the chang...

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