Search found 21 matches
- Wed Mar 15, 2017 5:45 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Winter 2013 final Q4B
- Replies: 3
- Views: 718
Re: Winter 2013 final Q4B
Dr. Lavelle mentioned problem solving today in lecture and this is an example of what he is talking about. From what I know, I don't think we learned how to directly solve problems like these in the course reader before. But it makes sense that: [Current] = [Initial] + [Change in initial] So: [O2] =...
- Tue Mar 07, 2017 10:24 pm
- Forum: *Ethers
- Topic: Course reader pg 94
- Replies: 2
- Views: 1394
Re: Course reader pg 94
The ethane and methane molecules are substituents of the ether functional group. The reason why the ethane isn't the main "chain" is because the substituent O would have it's own substituent CH3. From what I know I don't think substituents can have their own substituents. Since an ether on...
- Tue Mar 07, 2017 10:13 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Why is K = kfor/krev?
- Replies: 3
- Views: 1529
Re: Why is K = kfor/krev?
Check out page 71 on the course reader.
- Wed Mar 01, 2017 9:57 am
- Forum: *Electrophilic Addition
- Topic: Question about Exercise 4.25
- Replies: 1
- Views: 500
Re: Question about Exercise 4.25
There is no negativity difference between the two atoms. However, ethene has an electron rich double bond. The pi bonds extend outwards from the molecule and effects Br2 upon collision. When the Br2 molecule approaches the electron rich area, it causes "induced polarization". The dispersio...
- Wed Feb 22, 2017 1:50 am
- Forum: First Order Reactions
- Topic: Calculating Half-life
- Replies: 2
- Views: 1636
Re: Calculating Half-life
t1/2 for first order reactions is .693/k or .693 / 6.7×10-4 s-1
t1/2 = 1034.32 seconds, or 1000 seconds for significant figures.
t1/2 = 1034.32 seconds, or 1000 seconds for significant figures.
- Tue Feb 14, 2017 12:29 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook Problem #14.27
- Replies: 2
- Views: 570
Re: Textbook Problem #14.27
In that problem, why does adding the two standard cell potentials and their respective half reactions using a Hess' Law approach not work? When added together, we still get U4^+(aq) + 4e- -> U(s) but E equals -2.4 instead of the correct answer.
- Mon Feb 13, 2017 10:15 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Pt in SHE
- Replies: 1
- Views: 450
Re: Pt in SHE
It's the metal used as a way to transfer electrons in the battery. Other than that, it doesn't actually react in the reaction itself.
- Tue Feb 07, 2017 12:53 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 1
- Views: 399
Re: Platinum
In terms of the reaction itself, Platinum doesn't "replace" anything, it just serves as a conduit for electron transfer. That's why it doesn't show up on the reaction equation. What happens to the Fe2+? It is the product of the reduction of Fe3+ and oxidation of Cu. The iron remains aqueou...
- Wed Feb 01, 2017 11:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Question about batteries
- Replies: 1
- Views: 365
Re: Question about batteries
It means the redox reaction has reached equilibrium.
- Mon Jan 23, 2017 1:27 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.19 part a
- Replies: 1
- Views: 558
Re: 8.19 part a
I'm assuming you need to heat both the copper and the water to the same temperature. Because if they weren't, they'd start doing some 2nd Law of Thermodynamics stuff and the water might transfer its heat out to the copper and vice versa. We wouldn't want that to happen on paper, although it is what ...
- Thu Jan 19, 2017 10:42 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Unit Confusion
- Replies: 1
- Views: 406
Re: Unit Confusion
For reaction enthalpy, we use kJ only without the /mol. That is because when a reaction proceeds, a certain amount of heat is released or absorbed by the system, which is directly related to the coefficients in the reactants and products anyway. And because the given enthalpy is tied to the coeffici...
- Thu Jan 12, 2017 6:00 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Problem 8.49
- Replies: 4
- Views: 743
Re: Problem 8.49
Internal energy = q + w
Not only is energy being put into the system externally, but work is being done WITHIN the system itself, which also adds to internal energy. This is why internal energy is not just delta h.
Not only is energy being put into the system externally, but work is being done WITHIN the system itself, which also adds to internal energy. This is why internal energy is not just delta h.
- Tue Nov 29, 2016 6:44 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Ions as Bases in CR
- Replies: 1
- Views: 515
Re: Ions as Bases in CR
A salt with a base will raise pH. Example: CH3COONa breaks up into CH3COO- and Na. Na does not affect pH. Adding in CH3COO- will automatically alter the equilibrium of the reaction: CH3COOH -> CH3COO- + H+ Because more base is added, the reaction favors the reactants and takes away H+ and CH3COO- to...
- Tue Nov 22, 2016 12:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chapter 11 problem 115
- Replies: 1
- Views: 479
Re: Chapter 11 problem 115
Imagine a seesaw. Reactants on left, products on right. Removing something from either side will cause the other side to be heavier and pull the seesaw down. To reach equilibrium, it needs more weight on the lighter side, which represents which side it favors. An imbalance forces the heavier side to...
- Thu Nov 17, 2016 7:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chemical Equilibrium 11.3
- Replies: 1
- Views: 473
Re: Chemical Equilibrium 11.3
Kp uses P instead of brackets by convention. Usually, brackets are used to represent concentration in a solution (Kc), whereas Kp uses P to show partial pressure - that is, the pressure exerted by its constituents. Concentration in solution is different than partial pressure exerted.
- Thu Nov 10, 2016 1:36 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3003824
Re: Post All Chemistry Jokes Here
Created by myself while shopping for shampoo.
- Mon Oct 24, 2016 10:37 pm
- Forum: Lewis Structures
- Topic: Lewis Structures Charges Always Balanced?
- Replies: 1
- Views: 432
Re: Lewis Structures Charges Always Balanced?
If your definition of "ideal" is stability, then yes. Molecules always try to have Lewis structures that are most stable in which the formal charges are as close to zero as possible. Take into account that the sum of formal charges should still add up to the charge of the ionic molecule it...
- Tue Oct 18, 2016 3:59 pm
- Forum: Trends in The Periodic Table
- Topic: Cation Vs. Anion [ENDORSED]
- Replies: 6
- Views: 2027
Re: Cation Vs. Anion [ENDORSED]
If an element has a positive or a negative superscript, it is an ion (Fe 2+, Ca2+, Cl- are some examples). Cations are positive. Anions are negative. These positive and negative characteristics are caused by less or extra electrons.
- Thu Oct 13, 2016 3:40 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: s and d orbitals
- Replies: 3
- Views: 809
Re: s and d orbitals
For Sc and other d orbitals, we write 3d before 4s because 4s is considered a higher energy level than 3d. Recall that n = 4 is a higher level than n = 3, naturally, but that 4s orbitals are easier to fill in at the beginning.
- Tue Oct 04, 2016 1:42 am
- Forum: Properties of Light
- Topic: Textbook Chapter 1, Question 9
- Replies: 1
- Views: 640
Re: Textbook Chapter 1, Question 9
Use table 1.9 as described on page 6 to determine what wavelength corresponds to what type of wave.
- Wed Sep 28, 2016 12:12 am
- Forum: SI Units, Unit Conversions
- Topic: SI Unit Kg
- Replies: 3
- Views: 916
Re: SI Unit Kg
It's conventional to report your answer in the units given to you by the question, unless it asks explicitly for you to provide an answer in a specific unit. I think the need to remain in Kg is stressed more in physics, however.