Search found 34 matches
- Sun Mar 19, 2017 12:53 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Winter 2016 Final Question 4 [ENDORSED]
- Replies: 2
- Views: 824
Re: Winter 2016 Final Question 4 [ENDORSED]
How did you know that Step 2 was the slow/rate-limiting step? Why couldn't it be step 1?
- Fri Mar 17, 2017 5:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 513763
Re: Saying Thank You to Dr. Lavelle
To Dr. Lavelle, the TAs and UAs: Thank you all for your time and dedication to the class. The quality of the teaching was top-notch and all the resources outside of class from Chemistry Community, to Peer learning sessions, to office hours, has all been tremendously helpful. It has been an honor to ...
- Tue Mar 07, 2017 10:05 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Question 15.65 Part B
- Replies: 1
- Views: 504
Question 15.65 Part B
From Part A, I got the equilibrium constant to be .676.
Considering the Standard change in Gibbs Free Energy formula, with a positive K and positive T then the free energy would be negative and thus the reaction would be exothermic. However the answer is endothermic. Why?
Considering the Standard change in Gibbs Free Energy formula, with a positive K and positive T then the free energy would be negative and thus the reaction would be exothermic. However the answer is endothermic. Why?
- Tue Mar 07, 2017 9:25 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Question on Actual Quiz 2
- Replies: 2
- Views: 687
Question on Actual Quiz 2
I was wondering for number six on the actual quiz 2 we took in our discussion, why Step 1 was the slow step and not Step 2?
- Sun Mar 05, 2017 7:44 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006152
- Sun Feb 26, 2017 11:02 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 2/24/17 Bruincast
- Replies: 19
- Views: 3349
Re: 2/24/17 Bruincast
ntyshchenko wrote:What about Lecture 2s video?
Lecture 2 does not have a video because it is not filmed. Only lecture 3 is filmed
- Sun Feb 19, 2017 12:58 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006152
Re: Post All Chemistry Jokes Here
I want to post a joke, but all the good ones Ar (Argon)
- Sat Feb 11, 2017 8:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Winter 2017
- Replies: 87
- Views: 20767
Re: Midterm Winter 2017
As I am going over past midterms in the course reader I noticed that for certain problems points are deducted for not having the correct sig figs, while for other problems, sig figs were not taken into account for the total points. I was wondering for this midterm if sig figs will be a part of our t...
- Wed Feb 08, 2017 2:28 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Possible course reader error?
- Replies: 1
- Views: 494
Possible course reader error?
In class on Monday we went over page 59 in the course reader where Dr. Lavelle went over the reaction rates and derived a "formula" for us to follow when setting up the rates. In the process of the derivation, he multiply the d[O2]/dt by 2 but not for d[NO]/dt and -d[NO2]/dt. Shouldn't it ...
- Tue Feb 07, 2017 9:15 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Winter 2013 Midterm Q2A
- Replies: 10
- Views: 1499
Winter 2013 Midterm Q2A
Q: Your very particular friend Sheldon asks for a glass of exactly 400g of water at 16 C. You can get liquid water at room temperature from the faucet and ice at 0C from the freezer. How many grams of ice and how many grams of water must you combine to make Sheldon's very specific water? The only pa...
- Sun Feb 05, 2017 6:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy
- Replies: 8
- Views: 1585
Re: Enthalpy
How do you know when to use Kelvin or Celsius in a problem? Can you just always use and convert a question to Kelvin? How you know which unit to use is really dependent on the rest of the values in your problem and their units. Use the other values and units as a guide to help you determine whether...
- Fri Jan 27, 2017 9:17 am
- Forum: Student Social/Study Group
- Topic: Review?
- Replies: 4
- Views: 1005
Re: Review?
what do we use the green course reader for? I do not understand the difference between the torquoise and the green course readers we received from the course reader store. I believe that the green course reader starts covering organic chemistry, which I believe we will start to go over later in the...
- Fri Jan 20, 2017 2:36 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Ch 8.85
- Replies: 1
- Views: 1349
Ch 8.85
8.85 The oxidation of nitrogen in the hot exhaust of jet engines and automobiles occurs by the reaction N2 (g) + O2 (g) -> 2 NO(g) H°=180.6 kJ (a) How much heat is absorbed in the formation of 1.55 mol NO? (b) How much heat is absorbed in the oxidation of 5.45 L of nitrogen measured at 1.00 atm an...
- Fri Jan 20, 2017 1:05 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Kekulé structure?
- Replies: 1
- Views: 436
Kekulé structure?
What is the Kekulé structure that is referred to in problem 77 of chapter 8?
- Fri Jan 13, 2017 6:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Problem 8.65
- Replies: 3
- Views: 626
Problem 8.65
8.65 Calculate the standard enthalpy of formation of dinitrogen pentoxide from the following data, 2 NO(g) + O2 (g) -> 2NO2(g) H°= -114.1 kJ 4 NO2(g) + O2(g) -> 2 N2O5(g) H°= -110.2 kJ and from the standard enthalpy of formation of nitric oxide, NO (see Appendix 2A). At first I approached it using ...
- Fri Dec 02, 2016 11:24 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006152
Re: Post All Chemistry Jokes Here
Why do chemists learn about ammonia first?
...
Cause it's pretty basic stuff
...
Cause it's pretty basic stuff
- Sun Nov 27, 2016 6:16 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Sig figs in calculations for pH and pOH
- Replies: 2
- Views: 597
Sig figs in calculations for pH and pOH
This is a general question for when calculating. Do we still take into account sig figs when we give our final answer? As I do the textbook problems and compare the answers, I noticed that the answers in the textbook for pH and pOH are always rounded off to 2 decimal places regardless of the sig fig...
- Sun Nov 27, 2016 3:33 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Problem 11. 87
- Replies: 1
- Views: 496
Problem 11. 87
11.87 Dissociation of a diatomic molecule, X2(g) -> 2 X(g) occurs at 500 K. Picture 1 shows the equilibrium state of the dissociation and picture 2 shows the equilibrium state in the same container after a change has occurred. Which of the following changes will produce the change shown? (a) Increas...
- Tue Nov 22, 2016 3:37 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 11.73 b
- Replies: 1
- Views: 568
11.73 b
11.73 State whether reactants or products will be favored by an increase in the total pressure (resulting from compression) on each of the following equilibria. If there is no change, explain why that is so. (b) H2O(g) + C(s) ↔ H2(g) + CO(g) Since there are 2 moles on both sides, I thought that ther...
- Thu Nov 17, 2016 2:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming Question and Coord. # for Nitrito
- Replies: 3
- Views: 834
Re: Naming Question and Coord. # for Nitrito
Thank you for your reply! However in the course reader on page 117 there is an asterisk next to nitrito and the asterisk indicates which ligands are polydentates, as stated on the bottom of the diagram...So is that an error...?
- Thu Nov 17, 2016 1:21 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming Question and Coord. # for Nitrito
- Replies: 3
- Views: 834
Naming Question and Coord. # for Nitrito
I know that when you go from FORMULA to the NAME, the ligands must be in alphabetical order. However when you go from NAME to FORMULA, I noticed the metal comes first but is there a particular order for the ligands? Also I know that nitrito is a polydentate but specifically is it a bidentate? (Coord...
- Wed Nov 09, 2016 12:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14A Midterm Fall 2016 Rooms & Review Sessions
- Replies: 16
- Views: 9302
Re: Chem 14A Midterm Fall 2016 Rooms & Review Sessions
In class Professor Lavelle mentioned that the detailed solutions were posted online. However I couldn't hear what he said afterwards so I was wondering if he stated exactly where. I can't seem to find it on Chem Community or the Class website.
- Tue Nov 01, 2016 11:35 am
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14A Midterm Fall 2016 Rooms & Review Sessions
- Replies: 16
- Views: 9302
Re: Chem 14A Midterm Fall 2016 Rooms & Review Sessions
I noticed that sometimes the constant values given in our notes/course reader does not exactly match the laminated periodic table we received with the course reader. For example, h=6.626E-34 in our reader but is more specifically stated as h=6.62608E-34 on the periodic table Also c=3.00E8 vs c=2.997...
- Mon Oct 31, 2016 10:10 am
- Forum: Hybridization
- Topic: sp^2 Hybridization
- Replies: 1
- Views: 459
sp^2 Hybridization
I was wondering for the sp^2 hybridization if there is always an unhybridize p orbital that forms a pi bond or is that just the case for the Carbon atom because of its potential double bonds. How about for B? Would B have an unhybridize p orbital? How would you know or solve for the difference?
- Fri Oct 28, 2016 9:32 am
- Forum: Administrative Questions and Class Announcements
- Topic: Chem 14A Midterm Fall 2016 Rooms & Review Sessions
- Replies: 16
- Views: 9302
Re: Chem 14A Midterm Fall 2016 Rooms & Review Sessions
I have a lecture right before this midterm so I will not have time to go back to the hill to drop off my backpack, my phone, and all my books. May I bring my backpack into the testing room and leave it in the front and/or with the test proctor? If not, is there anywhere else I can store my stuff?
- Wed Oct 26, 2016 2:40 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3006152
Re: Post All Chemistry Jokes Here
CATions
An ion with a PAWS-itive charge
An ion with a PAWS-itive charge
- Wed Oct 19, 2016 2:01 pm
- Forum: Electronegativity
- Topic: Calculating EN Difference [ENDORSED]
- Replies: 1
- Views: 680
Calculating EN Difference [ENDORSED]
So let's say you want to calculate the Electronegativity Difference of CH4... ( C = 2.6 ; H = 2.2 )
Would the answer just be .4 or do you have to multiply 2.2 by 4 since there are 4 H atoms and then subtract by 2.6?
Would the answer just be .4 or do you have to multiply 2.2 by 4 since there are 4 H atoms and then subtract by 2.6?
- Tue Oct 11, 2016 10:17 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Quiz 1 Fall 2015 #3 [ENDORSED]
- Replies: 3
- Views: 944
Quiz 1 Fall 2015 #3 [ENDORSED]
Find the uncertainty in the position of a marble of bass 1.5 g given that its speed is known to within plus or minus .55 m/s
My question is whether the uncertainty in velocity is .55 or is it the difference...(.55 - -.55 = 1.10)?
My question is whether the uncertainty in velocity is .55 or is it the difference...(.55 - -.55 = 1.10)?
- Tue Oct 04, 2016 11:35 am
- Forum: Properties of Electrons
- Topic: 1.15....Where did I go wrong? [ENDORSED]
- Replies: 3
- Views: 1635
1.15....Where did I go wrong? [ENDORSED]
1.15 In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. [sol] Since it is a Lyman series, I know that nf (n final) is 1. I al...
- Mon Oct 03, 2016 12:01 am
- Forum: Properties of Electrons
- Topic: Atomic Spectra Post Assessment Question
- Replies: 3
- Views: 877
Re: Atomic Spectra Post Assessment Question
Where did you get 1 meter from?
- Tue Sep 27, 2016 9:27 pm
- Forum: Limiting Reactant Calculations
- Topic: Fundamentals M.5 Part B
- Replies: 4
- Views: 1490
Re: Fundamentals M.5 Part B
Thank you so much!
- Tue Sep 27, 2016 11:50 am
- Forum: Limiting Reactant Calculations
- Topic: Fundamentals M.5 Part B
- Replies: 4
- Views: 1490
Fundamentals M.5 Part B
M.5 Solve this exercise without using a calculator. The reaction 6 ClO2 + 2BrF3 -> 6ClO2F + Br2 is carried out with 12 mol ClO2 and 5 mol BrF3. (b) Estimate how many moles of each product will be produced and how many moles of the excess reactant will remain.
- Mon Sep 26, 2016 2:45 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Fundamentals G5
- Replies: 6
- Views: 1943
Re: Fundamentals G5
Okay make sense. So with that in mind then for part b, since for 1 mol of Na2CO3 there is only 1 mol CO32-, you would just divide the mol with .08 M, correct?
- Mon Sep 26, 2016 2:31 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Fundamentals G5
- Replies: 6
- Views: 1943
Fundamentals G5
G.5 A student prepared a solution of sodium carbonate by adding 2.111 g of the solid to a 250.0-mL volumetric fl ask and adding water to the mark. Some of this solution was transferred to a buret. What volume of solution should the student transfer into a fl ask to obtain (a) 2.15 mmol Na+; (b) 4.98...