Search found 27 matches
- Thu Mar 16, 2017 5:54 pm
- Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
- Topic: How to tell whether a molecule is eclipsed or staggered by looking at the 2D repersentation?
- Replies: 4
- Views: 5522
Re: How to tell whether a molecule is eclipsed or staggered by looking at the 2D repersentation?
To add on to this, you can tell mostly because the Newman projection gives you the 2-D image looking along the C-C bond - think of it as facing C1 head-on so that C2 is perfectly behind it. Staggered and eclipsed just refer to the positions of the hydrogens in this radial image - staggered means tha...
- Fri Mar 10, 2017 12:28 am
- Forum: *Haloalkanes
- Topic: Introduction to Organic Chem ch. 4 #31
- Replies: 2
- Views: 1594
Re: Introduction to Organic Chem ch. 4 #31
The reaction is two steps because it creates intermediates. The slower step is determined by which one takes more energy, which in this case means breaking more bonds. Step one breaks one pi and one sigma bond, while step two only forms bonds, so step one takes more energy
- Fri Mar 10, 2017 12:24 am
- Forum: *Alkanes
- Topic: Tert vs. Neo?
- Replies: 4
- Views: 934
Re: Tert vs. Neo?
Not necessarily - tert is used for when the first Carbon, the Carbon attached to the R-group, we'll say, is attached to three other carbons. Neo is used specifically for a tail end Carbon that is connected to three other carbons.
- Tue Mar 07, 2017 11:11 pm
- Forum: *Cycloalkanes
- Topic: 3-Ethyl,1,1-dimethyl-2-propylcyclohexane
- Replies: 1
- Views: 571
3-Ethyl,1,1-dimethyl-2-propylcyclohexane
On page 21 of the OChem reader at the bottom, why is this structure not 1-ethyl-3,3-dimethyl-2-propylcyclohexane since ethyl comes first alphabetically
- Fri Feb 24, 2017 12:23 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation energy and its reliance on temperature
- Replies: 3
- Views: 714
Re: Activation energy and its reliance on temperature
If Ea is low, then the slope of the line made by the Arrhenius equation is also low, and closer to zero, leading to less variance with respect to temperature. Basically, if Ea is less, the plot of lnk versus temperature becomes more and more of a straight horizontal line.
- Fri Feb 24, 2017 12:22 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow Reaction
- Replies: 11
- Views: 1907
Re: Slow Reaction
Usually, if I'm not mistaken, this will be given to you
- Fri Feb 24, 2017 12:21 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Homework 15.19 c & d
- Replies: 3
- Views: 761
Re: Homework 15.19 c & d
Did you include the rate constant k in that equation?
- Fri Feb 24, 2017 12:20 am
- Forum: General Rate Laws
- Topic: Molecularity and Overall Rate Law Relationship [ENDORSED]
- Replies: 2
- Views: 732
Re: Molecularity and Overall Rate Law Relationship [ENDORSED]
The molecularity by itself does not determine the rate - what determines the rate is whether the step is a slow or fast step. The rate of the slow step = the rate of the overall rxn, since the fast steps will be forced to wait for the slow step to complete - think of the ferry analogy
- Fri Feb 24, 2017 12:19 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Activation Energy
- Replies: 4
- Views: 968
Re: Activation Energy
Yes. Essentially, because the activation energy is low already, not that much extra kinetic energy is needed to start the reaction, so increasing temperature (and therefore kinetic energy) does not do that much for the reaction
- Sat Feb 11, 2017 4:53 pm
- Forum: Calculating Work of Expansion
- Topic: Which process does more work?
- Replies: 5
- Views: 1729
Re: Which process does more work?
So when a question is asking you to consider the difference between reversible or irreversible processes, how can you tell the difference?
- Thu Feb 02, 2017 11:47 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy Integral
- Replies: 1
- Views: 514
Re: Entropy Integral
The integral of ds=nCv dT/T equates to Delta S= nCv ln (T1/T2) which gives you your equation for Entropy with temperature change
- Thu Feb 02, 2017 5:10 pm
- Forum: Balancing Redox Reactions
- Topic: reduction vs. oxidation
- Replies: 3
- Views: 800
Re: reduction vs. oxidation
Generally you can tell the oxidation number of an element by its group. Ones toward the right side, the non-metals, will generally have negative oxidation numbers. Ones on the left, the alkali metals, will generally have positive oxidation numbers. The ones that tend to change around are the metals ...
- Thu Jan 26, 2017 2:17 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Question 8.87
- Replies: 1
- Views: 492
Re: Question 8.87
So you'll need the specific heat for ice, and use it to calculate the amount of energy needed to raise the temperature of ice to 0 degrees Celsius. Then, the ice undergoes phase change, so you'll need to add the energy needed for that. Repeat the process for water and add all of it together to get y...
- Thu Jan 26, 2017 2:13 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Example of isolated System
- Replies: 4
- Views: 9009
Re: Example of isolated System
A bomb calorimeter is also particularly useful since it ensures that there is no volume change within the system and thus can most accurately measure the energy given by a reaction.
- Fri Jan 20, 2017 2:25 am
- Forum: Phase Changes & Related Calculations
- Topic: Derivations
- Replies: 21
- Views: 3358
Derivations
Will there be any questions on quizzes or midterms asking us to complete derivations of equations we learn in class?
- Mon Jan 09, 2017 2:34 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2968102
Re: Post All Chemistry Jokes Here
People who study organic chemistry can really get into alkynes of trouble
- Sat Dec 03, 2016 7:41 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Acid/Base Problem Estimation Method
- Replies: 1
- Views: 518
Re: Acid/Base Problem Estimation Method
If it's going to be anything like the 2015 final, yes, but you will be required to include a justification for why you are allowed to do so.
- Mon Nov 28, 2016 10:10 am
- Forum: Polyprotic Acids & Bases
- Topic: Polyprotic Acids and strength
- Replies: 2
- Views: 901
Re: Polyprotic Acids and strength
I don't think it's safe to assume that all polyprotic acids are weak, but most are because it's difficult to lose the second Hydrogen.
- Mon Nov 28, 2016 10:04 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When Should I use the ICE table?
- Replies: 5
- Views: 26681
Re: When Should I use the ICE table?
You should be using ICE when you're trying to track change in a reaction over time, esp from initial concentrations to equilibrium.
- Mon Nov 28, 2016 10:00 am
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: Weak Bases
- Replies: 4
- Views: 1134
Re: Weak Bases
Additionally, weak bases are weak bases because they are more stable and are less likely to take another H to form the conjugate acid, and therefore will result in less production of OH- when combined in an aqueous solution.
- Mon Nov 14, 2016 3:11 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Difference between Pressure and compression/expansion?
- Replies: 5
- Views: 4807
Re: Difference between Pressure and compression/expansion?
Compression/expansion is just a description of change in volume, which in turn has an impact on pressure given by P=nRT/V, where pressure and volume have an inverse relationship. Most of these problems also hold temperature constant, so you can just use P=n/V
- Wed Nov 09, 2016 1:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: [J] for solute in a dilute solution
- Replies: 1
- Views: 368
Re: [J] for solute in a dilute solution
the concentration of Zinc Chloride would go in the denominator, while the concentration of Zinc ion and Chloride ion would go in the numerator. EDIT: sorry, since Zinc Chloride actually appears as a solid, it is not included in the calculation of the equilibrium constant. Your end equation for chemi...
- Thu Oct 27, 2016 9:20 pm
- Forum: Hybridization
- Topic: sigma and pi bonds
- Replies: 3
- Views: 715
Re: sigma and pi bonds
A sigma bond is just a bond is just the first bond formed between two atoms. Any additional (double, triple, etc.) are considered pi bonds
- Thu Oct 27, 2016 9:15 pm
- Forum: Hybridization
- Topic: Defining Sigma and Pi Bonds [ENDORSED]
- Replies: 1
- Views: 556
Re: Defining Sigma and Pi Bonds [ENDORSED]
To sort of visualize them, Sigma bonds are basically a direct connection straight from one atom to another, whereas pi bonds form over and around those sigma bonds, if that makes any sense. This is why molecules with pi bonds cannot rotate.
- Wed Oct 19, 2016 12:35 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity and Bond Types
- Replies: 2
- Views: 665
Re: Electronegativity and Bond Types
For a couple it is straight memorization, but for others it should be fairly evident. For example, for any bond between a halide and a group I or II metal, it should be fairly apparent that this bond will be primarily ionic in character. On the other hand, for bonds between nonmetals, such as betwee...
- Wed Oct 12, 2016 10:24 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Negative frequency of light?
- Replies: 1
- Views: 640
Negative frequency of light?
when calculating the change in energy levels, say from n=4 to n=3, plugging this into \Delta E= E_{f} - E_{i} using E_{n}= -(hR)/n^2 gives a negative value for \Delta E . If you try to find frequency from this using E=h\nu , it will be negative, which isn't possible, since you can't have neg...
- Fri Oct 07, 2016 10:17 am
- Forum: Properties of Light
- Topic: Work Functions [ENDORSED]
- Replies: 1
- Views: 447
Work Functions [ENDORSED]
Will we have to know the work functions of different metals for the quiz? Or is that something that will be given with the questions?