CHEMISTRY COMMUNITY

edward_qiao_3I

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...

edward_qiao_3I

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

edward_qiao_3I

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.

edward_qiao_3I

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

edward_qiao_3I

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.

edward_qiao_3I

Usually, if I'm not mistaken, this will be given to you

edward_qiao_3I

Did you include the rate constant k in that equation?

edward_qiao_3I

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

edward_qiao_3I

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

edward_qiao_3I

So when a question is asking you to consider the difference between reversible or irreversible processes, how can you tell the difference?

edward_qiao_3I

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

edward_qiao_3I

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 ...

edward_qiao_3I

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...

edward_qiao_3I

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.

edward_qiao_3I

Will there be any questions on quizzes or midterms asking us to complete derivations of equations we learn in class?

edward_qiao_3I

People who study organic chemistry can really get into alkynes of trouble

edward_qiao_3I

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.

edward_qiao_3I

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.

edward_qiao_3I

You should be using ICE when you're trying to track change in a reaction over time, esp from initial concentrations to equilibrium.

edward_qiao_3I

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.

edward_qiao_3I

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

edward_qiao_3I

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...

edward_qiao_3I

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

edward_qiao_3I

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.

edward_qiao_3I

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...

edward_qiao_3I

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...

edward_qiao_3I

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?

CHEMISTRY COMMUNITY

Search found 27 matches

Re: How to tell whether a molecule is eclipsed or staggered by looking at the 2D repersentation?

Re: Introduction to Organic Chem ch. 4 #31

Re: Tert vs. Neo?

3-Ethyl,1,1-dimethyl-2-propylcyclohexane

Re: Activation energy and its reliance on temperature

Re: Slow Reaction

Re: Homework 15.19 c & d

Re: Molecularity and Overall Rate Law Relationship [ENDORSED]

Re: Activation Energy

Re: Which process does more work?

Re: Entropy Integral

Re: reduction vs. oxidation

Re: Question 8.87

Re: Example of isolated System

Derivations

Re: Post All Chemistry Jokes Here

Re: Acid/Base Problem Estimation Method

Re: Polyprotic Acids and strength

Re: When Should I use the ICE table?

Re: Weak Bases

Re: Difference between Pressure and compression/expansion?

Re: ［J］ for solute in a dilute solution

Re: sigma and pi bonds

Re: Defining Sigma and Pi Bonds [ENDORSED]

Re: Electronegativity and Bond Types

Negative frequency of light?

Work Functions [ENDORSED]