## Search found 25 matches

Sun Mar 11, 2018 6:07 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-Equilibrium
Replies: 4
Views: 209

### Re: Pre-Equilibrium

Is the process the same for when you're looking for the rate of decomposition versus the rate of formation?
Sun Mar 11, 2018 3:24 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: 15.51
Replies: 6
Views: 356

### Re: 15.51

Since the exponents do not come from the coefficients, how are they determined?
Sun Mar 11, 2018 3:22 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction Mechanisms [ENDORSED]
Replies: 2
Views: 169

### Re: Reaction Mechanisms[ENDORSED]

I'm a little unclear on which example problems in the textbook use which method, does anyone know?
Mon Mar 05, 2018 3:29 pm
Forum: Second Order Reactions
Topic: 15.35
Replies: 2
Views: 189

### Re: 15.35

So for second order reactions, unlike first order, we have to use two equations not just the the one half life equation?
Sat Mar 03, 2018 3:33 pm
Forum: General Rate Laws
Topic: Test 3
Replies: 5
Views: 288

### Re: Test 3

which equations do we need to be able to derive?
Sat Mar 03, 2018 3:31 pm
Forum: Zero Order Reactions
Topic: Dependence on concentration
Replies: 2
Views: 205

### Dependence on concentration

Why is it said that 0th order reactions do not depend on concentration while first and second do. In the equations it looks like they all depend on concentrations.
Sat Mar 03, 2018 3:28 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: How to tell difference btwn thermo and kinetics [ENDORSED]
Replies: 7
Views: 527

### Re: How to tell difference btwn thermo and kinetics[ENDORSED]

All reactions are affected by both but some are more dependent on one or the other. Kinetics and thermodynamics are two ways or describing the same phenomenon; its like saying I have to drive for 100 miles or I have to drive for 2 hours. Both are measuring the same thing in different ways.
Sun Feb 18, 2018 4:12 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Explaining 14.4 (Cell potential and gibbs)
Replies: 2
Views: 173

### Re: Explaining 14.4 (Cell potential and gibbs)

I agree with the first response, the statement is saying first that to use a voltmeter it must have very high resistance (be very non-conductive) because otherwise some of the electricity that would normally be going from one end of the cell to the other would be drawn away. Second it says how becau...
Sun Feb 18, 2018 4:04 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: HW 14.107
Replies: 1
Views: 162

### Re: HW 14.107

They use [H]/[OH] because this is relating the concentrations of products and reactants but only considering the compounds (H30+ and OH-) that matter for PH. It is a way of simplifying the problem's calculations I think. You cannot use the equation you listed E=E°+(0.0592v) X pH? because the questio...
Sun Feb 18, 2018 3:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potentials
Replies: 5
Views: 218

### Re: Standard Cell Potentials

Is this because electrochemical reactions are intensive or is that incorrect?
Sat Feb 10, 2018 4:19 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 11.15
Replies: 12
Views: 1004

### Re: 11.15

I'm not sure what I am doing wrong but I keep getting an answer around 1.5kj. I am using in the Gnot part of the equation a T of 273 and a k of 6.8 and and in the G side a T of 1200 and ln(.13/.98). What am I doing wrong?
Sat Feb 10, 2018 3:56 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.63
Replies: 2
Views: 180

### Re: 9.63

Doesn't the sign of gibbs that makes the reaction more stable depend on which side of the reaction the compound is written? If it is on the reactants then a positive gibbs would imply stability and if it is on the products a negative.
Sat Feb 10, 2018 3:52 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Problem 9.63
Replies: 1
Views: 132

### Problem 9.63

In problem 9.63 the book asks which of a set of compounds are stable with respect to their decompositions into their elements. Is it asking if the Gibbs free energy of the reaction of the compund going to its parts is positive? Would a positive gibbs free energy of this reaction imply stability?
Sat Feb 10, 2018 3:47 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.67
Replies: 2
Views: 688

### Re: 9.67

So you have to combine the deltaH of products and reacants and deltaS of products and reactants before you put them into the Gibbs equation?
Sun Feb 04, 2018 12:19 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Problem 9.19 about Standard Entropy
Replies: 6
Views: 326

### Re: Problem 9.19 about Standard Entropy

How is it possible for the water vapor to cool back down to 85 degrees without undergoing another phase change back to a liquid?
Sun Feb 04, 2018 11:52 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: 9.13
Replies: 5
Views: 289

### Re: 9.13

So for future reference if they do not specify number of moles and say assume ideal gas conditions this automatically means 1mol of substance?
Thu Feb 01, 2018 9:57 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 9.7 and 9.11 formula differences
Replies: 4
Views: 310

### Re: 9.7 and 9.11 formula differences

For 9.7 I understand why you use deltas=nCpln(t2/t1) but what do you use for Cp? Is there a way to solve it without knowing Cp because I don't think its given.
Sun Jan 21, 2018 8:45 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: question on solution for 8.49
Replies: 2
Views: 179

### Re: question on solution for 8.49

Would another way to solve it be knowing that for a equation like this it is appropriate to assume it is at constant pressure which would mean change in internal nrg= q which is in turn equal to, and constant pressure, enthalpy change which is given? The answer would then be -318, the book gives -32...
Sun Jan 21, 2018 8:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 3 Test Topic is endorsed
Replies: 37
Views: 2938

### Re: Week 3 Test Topic is endorsed

Does anyone know if the born-haber cycle will be tested? There is a whole section on it in the chapter but we have not talked about it in class
Sun Jan 21, 2018 8:35 pm
Forum: Phase Changes & Related Calculations
Topic: Problem 8.43
Replies: 5
Views: 242

### Re: Problem 8.43

Oops my mistake this is in fact problem 8.43, I have corrected the title. Thank you Diane I thought heat capacity would be indicated by how long that phase of the graph was but I know understand that it is the slope.
Sat Jan 20, 2018 1:23 pm
Forum: Phase Changes & Related Calculations
Topic: Problem 8.43
Replies: 5
Views: 242

### Problem 8.43

I am not sure hwy the answer for this problem is C instead of either B or D which both seem like reasonable choices because they fulfill the requirements of having a "longer" line for the vaporization than fusion and same is true for the heat capacities. Can someone please enlighten me?
Sat Jan 13, 2018 10:39 pm
Forum: Phase Changes & Related Calculations
Topic: Why can state properties be added?
Replies: 11
Views: 684

### Re: Why can state properties be added?

Maybe the most basic example of the difference between a state property and one that is not is the difference between displacement and distance. Displacement is a state property because if you look at the beginning and ending point that tells you everything you need to know displacement however for ...
Sat Jan 13, 2018 10:23 pm
Forum: Phase Changes & Related Calculations
Topic: Extensive/Intensive
Replies: 5
Views: 719

### Re: Extensive/Intensive

The way I remember the difference is that extensive sounds like extension and the amount something extends into space is dependent on how much of something there is just like and extensive property is. Intensive I remember by it sounding liking inside, so all that matters is what is inside the objec...
Sat Jan 13, 2018 10:19 pm
Forum: Phase Changes & Related Calculations
Topic: Endo and Exothermic Ways to Remember
Replies: 28
Views: 5654

### Re: Endo and Exothermic Ways to Remember

For me remembering definitions through phonetic tricks/associations is pretty helpful. I remember exothermal by thinking how exo is like exo skeleton and how exoskeletons are on the outside, just like how in an exothermal reactions the heat moves to the outside of where it formerly was. Then I remem...
Sat Jan 13, 2018 10:19 pm
Forum: Phase Changes & Related Calculations
Topic: Endo and Exothermic Ways to Remember
Replies: 28
Views: 5654

### Re: Endo and Exothermic Ways to Remember

For me remembering definitions through phonetic tricks/associations is pretty helpful. I remember exothermal by thinking how exo is like exo skeleton and how exoskeletons are on the outside, just like how in an exothermal reactions the heat moves to the outside of where it formerly was. Then I remem...