Search found 16 matches

by Chiao-Wei Cheng 3e
Sat Mar 18, 2017 2:11 pm
Forum: Balancing Redox Reactions
Topic: Writing Cell Diagrams
Replies: 5
Views: 916

Re: Writing Cell Diagrams

I took a look again and confirmed with someone that for the order, the element before it is reduced is placed first, then the reduced form of it comes afterwards. There is an example in the coursereader on page 48 where Fe3+(aq) is written before Fe2+(aq). And it also looks like this is the case fo...
by Chiao-Wei Cheng 3e
Sat Mar 18, 2017 1:51 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Course Reader Final Practice "2016 Final" Q4 part B
Replies: 5
Views: 873

Re: Course Reader Final Practice "2016 Final" Q4 part B

After reading this post, I'm even more confused. In my course reader it said that both Student B and Student C has the correct mechanism, both with the second step as the rate-limiting step, NOT student A and Student C.
by Chiao-Wei Cheng 3e
Sun Mar 05, 2017 11:33 pm
Forum: *Electrophiles
Topic: Is F a electrophile or nucleophile?
Replies: 3
Views: 832

Re: Is F a electrophile or nucleophile?

F is an electrophile because it is electron deficient. It has 7 valence electrons and wants to complete the full octet.
by Chiao-Wei Cheng 3e
Mon Feb 20, 2017 10:53 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Power issues
Replies: 2
Views: 395

Re: Power issues

I think there may be an error in the answer key. I also got 2.85 if I kept it in mmol. However, this was the answer in the answer key: k =2.85 x 10^12 L^4/mmol^4 * s ^1. The answer was not converted to mol, but answer is 2.85x10^12 in terms of mmol. Is the correct answer k =2.85 x 10^12 L^4/mol^4 * ...
by Chiao-Wei Cheng 3e
Tue Feb 14, 2017 9:56 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: Midterm Winter 2013 problem 5B
Replies: 10
Views: 1118

Re: Midterm Winter 2013 problem 5B

Correct if I'm wrong, I think molar mass is related to molecules quantity, related to the W in S=klnW. Therefore, entropy will increase with the increase of the molar mass.
by Chiao-Wei Cheng 3e
Tue Feb 14, 2017 9:52 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Midterm 2016 Q2
Replies: 4
Views: 509

Re: Midterm 2016 Q2

What about dry ice? Do we assume that it doesn't sublime?
by Chiao-Wei Cheng 3e
Tue Feb 14, 2017 3:39 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Midterm 2016 Q2
Replies: 4
Views: 509

Midterm 2016 Q2

My question is why is the change in state of dry ice not included in the calculations for q?
by Chiao-Wei Cheng 3e
Tue Feb 14, 2017 3:22 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: Midterm Winter 2013 problem 5B
Replies: 10
Views: 1118

Re: Midterm Winter 2013 problem 5B

Check out the molar mass. CF4 is the heaviest therefore it has the most entropy. Hope that helps!
by Chiao-Wei Cheng 3e
Sat Feb 11, 2017 11:01 am
Forum: Balancing Redox Reactions
Topic: Writing Cell Diagrams
Replies: 5
Views: 916

Writing Cell Diagrams

MnO^{-}_{4}(aq) + 5Fe^{2+}(aq) + 8 H^{+} (aq)\rightarrow Mn^{2+}(aq)+ 5Fe^{3+}(aq)+ 4H_{2}O (l) and the cell diagram looks like: Pt(s)|Fe^{3+} (aq), Fe^{2+} (aq) ||H^{+}(aq), MnO^{-}_{4}(aq), Mn^{2+}(aq)...
by Chiao-Wei Cheng 3e
Sat Feb 11, 2017 9:02 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Question on Inert Electrodes [ENDORSED]
Replies: 1
Views: 195

Question on Inert Electrodes [ENDORSED]

For question 14.13 (c)Write the half-reactions, the balanced equation for the cell reaction, and the cell diagram for each of the following skeletal equations:(b) Ce 4+ (aq) + I - (aq) -> I2 (s) + Ce 3+ (aq), the solutions manual says that "an inert electrode such as Pt is necessary when both o...
by Chiao-Wei Cheng 3e
Sun Feb 05, 2017 2:00 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Standard Hydrogen Electrode
Replies: 1
Views: 194

Standard Hydrogen Electrode

I'm kind of confused about the standard hydrogen electrode. What is it's purpose and will it always be reduced when it is used?
by Chiao-Wei Cheng 3e
Mon Jan 30, 2017 3:09 pm
Forum: Phase Changes & Related Calculations
Topic: Question in Section 9.9
Replies: 1
Views: 189

Question in Section 9.9

I was reading section 9.9 and came upon this statement that I don't really understand. "Because the surroundings taken to be large, their temperature is constant however much energy is transferred to or from them as heat so we can use deltaS=q(surr,rev)/T" I don't really understand the rea...
by Chiao-Wei Cheng 3e
Sat Jan 21, 2017 7:00 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Stuck on Question 8.67 [ENDORSED]
Replies: 1
Views: 283

Stuck on Question 8.67 [ENDORSED]

The question is Use the information in Tables 8.3, 8.6, and 8.7 to estimate the enthalpy of formation of each of the following compounds in the liquid state. The standard enthalpy of sublimation of carbon is -717 kJ/mol. (a) H 2 O; (b) methanol, CH 3 OH; (c) benzene,C 6 H 6 (without resonance); (d) ...
by Chiao-Wei Cheng 3e
Fri Jan 13, 2017 4:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Thinking Point 8.5
Replies: 1
Views: 281

Thinking Point 8.5

At the end of section 8.5, the thinking point was "Why does a hot pan inside a heated oven scald our hands when we touch it, but the air inside does not?" My answer is that the molecules in the pan is densely packed and holds more heat than the loosely packed molecules in the air, where th...
by Chiao-Wei Cheng 3e
Fri Jan 13, 2017 4:48 pm
Forum: Phase Changes & Related Calculations
Topic: Sublimiation
Replies: 6
Views: 817

Re: Sublimiation

I could be incorrect, but I remember that we have to calculate all of the phase changes for sublimation. (link: http://chem.libretexts.org/Core/Physical_and_Theoretical_Chemistry/Thermodynamics/State_Functions/Enthalpy/Heat_of_Sublimation) The heat of sublimation can be calculated by H(gas)-H(solid)...

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