## Search found 10 matches

Sat Mar 12, 2016 10:23 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 2012 practice final#2A
Replies: 3
Views: 514

### 2012 practice final#2A

For this problem, why is the change in entropy calculated using only \Delta S = nR ln(\frac{V2}{V1}) and not \Delta S = nR ln\frac{P1}{P2} ? The problem states that "The He in the metal case is initially held at a pressure of 1.0 atm", so doesn't that mean that the pressure is goin...
Sat Mar 12, 2016 4:19 pm
Forum: General Rate Laws
Topic: Winter 2013 Final Q4C reaction rate
Replies: 2
Views: 424

### Re: Winter 2013 Final Q4C reaction rate

And can someone explain why the answer for this question is supposed to be positive even though we are using the reactant (O2) concentration to determine the average rate?
Fri Mar 11, 2016 3:03 pm
Forum: *Alkanes
Topic: Prioritizing substituents
Replies: 2
Views: 496

### Re: Prioritizing substituents

For substituents like ethyl and propyl, you would only prioritize alphabetically if there's a tie. Otherwise just number them to the lowest number. But for halogens like Cl or Br, you would prioritize by size but still list alphabetically in the name.
Fri Feb 26, 2016 2:32 pm
Forum: *Alkanes
Topic: Naming substituents
Replies: 2
Views: 364

### Re: Naming substituents

The prefix for the longest carbon chain/parent chain isn't minimized but the number in front of substituents is counted so that it is minimized.
Tue Feb 09, 2016 8:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 2015 Midterm #7
Replies: 2
Views: 406

### 2015 Midterm #7

Where could E° for the half reactions be found? The formula/data sheet in the front only gives the E° for Al2O3 -->2Al, not Al3+ -->Al. However, they happen to have the same E° of 1.66V?
Sun Feb 07, 2016 10:33 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Winter 2014 1C (Bond Enthalpies)
Replies: 2
Views: 398

### Re: Winter 2014 1C (Bond Enthalpies)

Because there are also 3 C-H bonds formed in the products, so they cancel out with each other and aren't taken into the calculation.
Mon Feb 01, 2016 12:54 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Cp^n and Cr^n
Replies: 2
Views: 355

### Re: Cp^n and Cr^n

The C means the concentration of the solution, n is the number of moles, p is products, and r is reactants. So Cp^n means the (concentration of the product)^(number of moles of product) and Cr^n means the (concentration of the reactant)^(number of moles of reactant). Hope this clears it up!
Sun Jan 24, 2016 8:08 pm
Forum: Phase Changes & Related Calculations
Topic: phase change
Replies: 2
Views: 442

### Re: phase change

Pressure and temp both play a role on how a substance would behave. CO2 can go through sublimation because it was given the conditions, like 1 atm and room temp. I think it would go through the "normal" solid, liquid, gas phase changes if the pressure were higher. It's like how water could...
Sun Jan 17, 2016 11:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated Systems
Replies: 2
Views: 504

### Re: Isolated Systems

I think maybe an example could be soup in a very high quality thermos because mass can't go into the surroundings and the thermos should also keep the energy (heat) inside too.
Sun Jan 10, 2016 10:10 pm
Forum: Phase Changes & Related Calculations
Topic: Standard State
Replies: 3
Views: 393

### Re: Standard State

The standard state of something is just the most stable state of matter of a substance at 25 degrees Celsius and 1atm :)