## Search found 38 matches

Thu Mar 16, 2017 11:33 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Constant Volume and Constant Pressure
Replies: 3
Views: 470

### Constant Volume and Constant Pressure

Homework problem 9.7 that wants us to find the entropy change of 1 mol of ideal gas with a temperature change under constant pressure and constant volume. For the final, would we need to know that constant pressure is (5/2)R and that constant volume is (3/2)R? Also, for that same problem, how can so...
Sun Mar 12, 2017 9:04 pm
Forum: *Alcohols
Topic: C and functional groups
Replies: 2
Views: 449

### C and functional groups

Can functional groups share a carbon?
Wed Mar 01, 2017 2:57 pm
Forum: Administrative Questions and Class Announcements
Replies: 1
Views: 272

For the Homework from Ch 4, are we only suppose to do the odd-numbered problems? If we are also recommended to do the even-numbered problems, is there a way to access the solutions to those?
Thu Feb 23, 2017 8:33 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate Law and Intermediates
Replies: 1
Views: 257

### Rate Law and Intermediates

Is a rate law allowed to have an intermediate concentration? or do we always have to solve with K to find the substitute for the intermediate? (such an the pre-equilibrium example in the course reader)
Wed Feb 22, 2017 4:10 pm
Forum: General Rate Laws
Topic: Quiz Equations
Replies: 1
Views: 218

### Quiz Equations

For our quiz this week, will we be given the equations for zero, first, and second order reactions? Will we be given these equations, but with each just not identified as to which equation it is? or will we not be given any equations at all on our 'givens' note sheet?
Thu Feb 16, 2017 5:10 pm
Forum: General Rate Laws
Topic: General Rate Question
Replies: 2
Views: 367

### General Rate Question

When solving homework problems, are we only suppose to be finding rates in (mol)/(L*s) or are we allowed to also express it in (mmol)/(L*s) depending on the units given in the problem? More specifically, on a quiz or test, will we be marked off for using mmol instead of mol?
Mon Feb 13, 2017 4:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: H2O in Galvanic Cell Diagram
Replies: 1
Views: 495

### H2O in Galvanic Cell Diagram

When is water included in the Galvanic Cell Diagram? There have been a few problems in the homework in which water is involved in the reaction, but not included in the call diagram. (problem 14.11d, problem 14.15b, problem 14.23 a and c)
Sun Feb 12, 2017 11:22 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: homework 14.35
Replies: 2
Views: 330

### homework 14.35

Can anyone confirm that the solutions manual for 14.35 part b) is incorrect? The solutions wrote one of the half reactions as In^3+ (aq) + 2 e- ----> In^2+ (aq). The coefficient of the electron is obviously wrong as +3 - 2 does not equal +2. From my calculations considering n = 1, I obtained K = 1.0...
Thu Feb 09, 2017 9:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 3
Views: 412

### Re: Cell Diagrams

Thu Feb 09, 2017 10:01 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 3
Views: 412

### Cell Diagrams

I understand that the anode is on the right side of the cell diagram, and that the cathode is on the left side of the cell diagram, but does the order of the molecules within the anode or cathode matter for the diagram?
Wed Feb 08, 2017 11:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Homework 14.11
Replies: 1
Views: 293

### Homework 14.11

The solution states that Ni^2+ (aq) + 2e ---> Ni (s) has E(anode) = -0.23 V. The solution proceeds to flip the reaction so that the reaction is Ni (s) ----> Ni^2+ (aq) + 2e but does not switch the sign of the E(anode) to +0.23V. Aren't we always suppose to change the sign of the voltage when we reve...
Thu Feb 02, 2017 9:20 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Writing Balanced Equations
Replies: 1
Views: 314

### Writing Balanced Equations

When writing balanced equations in order to calculate Gibbs free energy from the Gibbs free energy of formation of the products and reactants, how do we know whether to use full integers to balance equations or fractions. For example, on problem 9.59, 2 Fe3O4 (s) + O2 (g) ---> 3 Fe2O3 was balanced t...
Sat Jan 28, 2017 2:59 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Homework 9.51
Replies: 1
Views: 261

### Homework 9.51

9.51 asks, why are so many exothermic reactions spontaneous? the answer gives the equation deltaG = deltaH - TdeltaS and says that exothermic reactions tend to be spontaneous because the result in an increase in the entropy of the surroundings. My question is, does the deltaS in the equation represe...
Fri Jan 27, 2017 11:47 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy from Mass
Replies: 1
Views: 306

### Entropy from Mass

Homework problem 9.27.
Which has great entropy, HBr(g) or HF(g). The answer is HBr, and the solutions says that it is because Br is more massive and contains more elementary particles than F. What elementary particles is it talking about?
Fri Jan 27, 2017 11:40 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Homework Problem 9.25
Replies: 1
Views: 260

### Homework Problem 9.25

My calculator will not compute ln(6^(6.02*10^23)) listed in the solution. It replies back with "overflow" anytime I enter this value. Will we have to worry about this for the quiz?
Fri Jan 27, 2017 10:20 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Homework Problem 9.13
Replies: 1
Views: 343

### Homework Problem 9.13

My questions pertains to Ch 9 Problem 13: During the test of an internal combustion engine, 3L or nitrogen gas at 18.5 degrees C was compressed suddenly (and irreversibly) to 0.5L by driving in a piston. In the process, the temperature of the gas increased to 28.1 degrees C. Assume ideal behavior. w...
Fri Jan 27, 2017 9:22 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Changing Pressure
Replies: 1
Views: 299

### Changing Pressure

What equation would we use when calculating entropy and enthalpy when pressure is changing?
Mon Jan 23, 2017 4:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Memorize Values for Quiz?
Replies: 2
Views: 531

### Memorize Values for Quiz?

Will we have to have the values of the enthalpy of vaporization or fusion or the specific heat capacities of different states of water memorized for the quiz or will they be given?
Sun Jan 22, 2017 7:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: The Value of R
Replies: 2
Views: 427

### The Value of R

what is a good rule of thumb for knowing which value of R we should use? (technically same value but just in different units)
Sun Jan 22, 2017 7:33 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Molar Heat Capacities
Replies: 1
Views: 303

### Molar Heat Capacities

For our quiz or midterm, will we need to have memorized the equations for molar heat capacity at constant volume and also at constant pressure? As in the 3/2R, 5/2R, 3R etc.?
Thu Jan 12, 2017 3:17 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Problem 8.49
Replies: 4
Views: 383

### Problem 8.49

I'm having some trouble understanding homework problem 8.49. It asks for the change in internal energy for the reaction of 1 mol of OF2 (g). Why wouldn't the change in internal energy just be the delta H given? Why do we have to take the work (-PdeltaV) into account? What work is being done? Wouldn'...
Wed Jan 11, 2017 3:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bonding Enthalpies
Replies: 2
Views: 345

### Bonding Enthalpies

For some clarification of the example in the course reader about enthalpies of bonds breaking (involving C-C, C-H, and C-Br bonds), is it correct that we have to account for the formation of the C-C single bond because the C=C breaks completely before it forms a single bond, rather than just jumping...
Tue Jan 10, 2017 3:04 pm
Forum: Administrative Questions and Class Announcements
Topic: Workbook
Replies: 2
Views: 393

### Workbook

Were we suppose to receive a workbook for 14B from the course reader store?
Sun Dec 04, 2016 8:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem Final [ENDORSED]
Replies: 6
Views: 1228

### Chem Final[ENDORSED]

When can we expect to receive our grades for the course? Thanks for a great quarter! :)
Thu Nov 17, 2016 4:49 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8037
Views: 1408938

### Re: Post All Chemistry Jokes Here

lovin all these chem jokes (click jump to post if you can't see the image)
Tue Nov 01, 2016 9:35 pm
Forum: Lewis Structures
Topic: Homework 3.95
Replies: 1
Views: 261

### Homework 3.95

How do we know that the formal charge of CH2 with one bond and one electron pair is -1?
Sun Oct 30, 2016 4:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Homework 4.25 [ENDORSED]
Replies: 1
Views: 387

### Homework 4.25[ENDORSED]

When drawing CH2Cl2, how does one know to place the H molecules next to each other and Cl molecules next to each other, rather than drawing them across from each other so that the molecule is non polar?
Sun Oct 30, 2016 4:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis structure and molecular shapes [ENDORSED]
Replies: 1
Views: 390

### Lewis structure and molecular shapes[ENDORSED]

How do you know when to write the Lewis structure like the one on the left versus the one on the right? (Attached picture)
Sun Oct 30, 2016 3:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw angles
Replies: 1
Views: 376

### Seesaw angles

For a molecule that has a seesaw shape because of one lone pair of electrons, wouldn't the bond angles be slightly less than 90 degrees and slightly less than 180 degrees because of the repulsion from the lone pair?
Sun Oct 30, 2016 2:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: ICL3 bond angles
Replies: 1
Views: 3188

### ICL3 bond angles

Homework question 4.9 asks for the shape of ICL3 and the ClICl bond angle.

ICL3 is T-shaped, and the solutions manual only lists the slightly less than 90 degree angle, but shouldn't we also note that there's a slightly less than 180 degree angle? Will we have to note both angles on the midterm?
Wed Oct 26, 2016 6:08 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations Exceptions?
Replies: 3
Views: 1232

### Electron Configurations Exceptions?

The solutions manual for electron configuration problems does not seem take into account the exceptions to electron configuration orbital patterns (unless I'm mistaken).

Should we not take into account the exceptions on the quiz when writing electron configurations on the quiz?
Tue Oct 25, 2016 7:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Quiz Info
Replies: 2
Views: 443

### Quiz Info

I missed the first 15 min of class on Monday. Were there any announcements regarding the quiz or other important info that I missed?
Thanks!
Fri Oct 21, 2016 12:11 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8037
Views: 1408938

### Re: Post All Chemistry Jokes Here

What is the chemical formula for coffee?

CoFe2
Tue Oct 11, 2016 10:32 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Pre Assessment Questions
Replies: 2
Views: 529

### Pre Assessment Questions

Pre assessment question from the Heisenberg Uncertainty module: The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertain...
Mon Oct 10, 2016 9:42 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8037
Views: 1408938

### Re: Post All Chemistry Jokes Here

What did iodine say while spying on copper?
I see you.
Thu Oct 06, 2016 4:32 pm
Forum: Balancing Chemical Reactions
Topic: Naming Compounds
Replies: 2
Views: 503

### Naming Compounds

anyone have a good resource for memorizing the names and charges of compounds?
Thu Sep 29, 2016 6:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Other Fundamentals
Replies: 1
Views: 231

### Other Fundamentals

Will we have quiz or test questions from the other fundamental sections not covered by Chem Refreshers or Audio Visual Topics (aka Fundamentals A B C D I J K), or should we just focus in on the fundamentals that Dr. Lavelle emphasizes (E F G H L M)?
Tue Sep 27, 2016 10:01 am
Forum: Administrative Questions and Class Announcements