CHEMISTRY COMMUNITY

Vincent Tse 2B

You apply the pre-equilibrium approach when the mechanism has its first step as fast; this will create a "bottleneck" effect which results in a build-up of intermediates. You can then assume the first step reaction to be at an equilibrium, and use it to help you get rid of the intermediate...

Vincent Tse 2B

Using the reaction's name itself, the first step usually consists of the electrophile forming a bond to the electron source and the bond between the electrophile and its former group being broken; usually 2 bonds being broken in the first step, and, thus, why it is also the slow step.

Vincent Tse 2B

The E/Z naming system is used particularly for naming alkenes, determined by identifying the priority group bonded to the carbons: if the priority groups are on the same side, it is Z; if opposite, it is E. Cis and trans refer to conformations and the direction of substituents in either axial or equ...

Vincent Tse 2B

The chair conformation of cyclohexane is most stable when the substituents are equatorial as this will minimize steric interactions between the "bulkiness" of the substituents and the H-atoms.

Vincent Tse 2B

Typically you'll be given cell reduction potentials for redox reactions. With the values, you determine the oxidizing and reducing power of each reaction for the observed species. For example, the more positive the cell reduction potential is, the stronger the reduction power. The less positive, the...

Vincent Tse 2B

The values you listed correspond to molar heat capacities and are typically used for solving heat in terms of moles (q = nC(v/p)deltaT). The subscripts V and P stand for either constant volume or pressure: so, Cv reads as molar heat capacity at constant volume and Cp as molar heat capacity at consta...

Vincent Tse 2B

You might want to review setting up an ICE chart: since we're dealing with pressure, one would consider the initial partial pressures, the change in partial pressures, and the resulting partial pressures at equilibrium. In this problem, however, we are only given information at equilibrium, so we ca...

Vincent Tse 2B

You would want to choose elements that will give you the highest possible voltage by looking at their corresponding half-reactions.

I found this post to be very helpful: viewtopic.php?t=5476

Hope it clarifies things!

Vincent Tse 2B

Hello,

Does anyone with Lecture 2 for Chem 14BL with a Tuesday lab section (anytime)--preferably 2I--want to switch for a Wednesday lab section from 8am-10:50am (Lab 2N)?

Please let me know! Thanks.

Vincent Tse 2B

For reaction profiles, organic chemistry usually uses Gibbs free energy to describe energy changes. For a reaction that has a standard reaction Gibbs free energy < 0, it is the same as calling it an exergonic reaction in which the free energy of the reactants is greater than the products; therefore,...

Vincent Tse 2B

I believe so. You can think of a substituent as an atom (or group of atoms/molecule) that is bonded to one of the carbons of the longest carbon chain.

Vincent Tse 2B

At constant pressure, the change in enthalpy will be equivalent to heat (qp).

Vincent Tse 2B

Typically, balancing a redox reaction ensures that you are accounting for the correct amount of electrons being transferred from one species to another. It is this movement of electrons that generates the energy used for work in terms of voltage (in this case, emf or E). When calculating this availa...

Vincent Tse 2B

It usually depends on the context of the problem and the kind of system you're dealing with. For example, if you're calculating work for a reversible gas expansion, you'll need to know moles, temperature (most likely in kelvins), and the final/initial volumes. Disregarding the volume units--they are...

Vincent Tse 2B

Recall that Entropy (S) --an extensive property that relies on the number of particles--describes the likelihood or probability that the system will be in a particular state. Or, in more common terms, entropy describes how "disordered" a system is. In explaining how "disordered" ...

Vincent Tse 2B

For chemical reactions, they're best done in a chemical reactor-- typically vessels (e.g. a tank) and you can think of reactors as the system for reactions. Reactors are used because they help maximize the reaction's output by minimizing the extent of certain variables that could affect the efficien...

Vincent Tse 2B

Hello,

I am unsure about the concept(s) behind the following problem:

8.29
Which molecular substance do you expect to have the
higher molar heat capacity, NO or NO2? Why?

Can someone please explain how to approach and answer this problem?

Thanks!

Vincent Tse 2B

When you consider water, for example, you have to have an idea of what your desire equation should be.. Since we're working with standard reaction enthalpy and standard enthalpy of formation, we have to remember that the formation of a compound must be created from its elements in their most stable ...

Vincent Tse 2B

There exists diatomic molecules that naturally occur in the world because forming a bond with another of the same element could increase stability; e.g. H2, N2, F2, O2, I2, Cl2, Br2. For a substance that contains different elements, I think that you would have to draw lewis structures and consider f...

Vincent Tse 2B

Since heat is not a state property, it isn't continuous. Therefore, heat can't be differentiated or taken as a difference between an initial and final value of heat. (Refer to p. 14 in Course Reader). On the other hand, enthalpy is a state property and is denoted by ΔH; this means that you can add a...

Vincent Tse 2B

Referring to page 158 in the course reader, a neutral species (which is in relations to Ka1) would have a higher acidity constant since it's more readily to give up an H+ as opposed to a negatively charged species (say Ka2) since anions would hold onto the H+ more strongly. Therefore, Ka2 would be s...

Vincent Tse 2B

If you refer to page 148 in the course reader, there is a diagram that highlights all the amphoteric oxides; it's the diagonal band that closely matches the diagonal band of metalloids.

In case it is too hard to see, the following oxides are amphoteric: BeO, Al2O3, Ga2O3, SnO2, PbO2, Sb2O5.

Vincent Tse 2B

If you refer to page 118 in the course reader, it states that the ending -ate is added to complexes with a negative charge.

In other words, a transition metal complex should have -ate added to the metal ion's name only when the entire complex is negative.

Hopefully this helped!

Vincent Tse 2B

I'm not sure what you mean by "latin names" for the transition metals, but we are required to know how to name the ligands that bond with the central metal atom. You can review the table on page 117 for this. In a sense, it's similar to naming anions (e.g. chlorine --> chloride) but--since...

Vincent Tse 2B

A lewis base is any species that donates an e- pair whereas a lewis acid is any species that accepts an e- pair.

You might want to refer to the examples given on pages 85-86 in the course reader as they relate this concept to coordinate covalent bonds.

Hope this helped!

Vincent Tse 2B

Since you're trying to find the configuration for I^-2, it should just be [Xe] 6s^1

Vincent Tse 2B

I think the important thing to remember is that the electron configurations for ions require your attention on the addition or subtraction of electrons. For example, if you were to write the configuration for the anion Cl^-, it would be [Ar] and not its neutral config. [Ne] 3s^2 3p^5 since the ion a...

Vincent Tse 2B

A mnemonic that I often use to identify diatomic molecules is this: "Have No Fear of Ice Cold Beer."

Have = Hydrogen (H2)
No = Nitrogen (N2)
Fear = Fluorine (F2)
Of = Oxygen (O2)
Ice = Iodine (I2)
Cold = Chlorine (Cl2)
Beer = Bromine (Br2)

Hope this helps!

Vincent Tse 2B

Hey Kira! I think you should become familiarized with both formulas as they each have their own subtle characteristics. While both are used for atomic spectroscopy, Bohr's frequency condition is used to typically calculate the frequency associated with the energy difference between two energy levels...

Vincent Tse 2B

Hey Lexi! I found this site extremely helpful when I was learning how to write chemical formulas, including the various prefixes, suffixes, and rules for certain elements. It has different sections for different topics (e.g. naming polyatomic ions). Hopefully this is a good resource that will help y...

CHEMISTRY COMMUNITY

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Re: Pre- equilibrium approach [ENDORSED]

Re: Drawing the Transition State

Re: Determining cis, z, trans, or e [ENDORSED]

Re: Most stable confirmation? [ENDORSED]

Re: Determining reduction or oxidation

Re: Ideal gas

Re: Winter 2016 Final Question 2A

Re: Final Exam 2014 - Q3A

CHEM 14BL - LEC 2 Lab Switch

Re: Exergonic Reaction

Re: Substituent

Re: Entropy

Re: Balancing for E

Re: The Value of R

Re: Entropy and Degeneracy [ENDORSED]

Re: 8.111 part c [ENDORSED]

Homework 8.29: Need Clarification [ENDORSED]

Re: HW 8.67 [ENDORSED]

Re: Standard Reaction Enthalpy and Standard State

Re: delta H and delta Q

Re: Ka1 vs Ka2 vs Ka3

Re: Amphiprotic substances

Re: When naming metals...

Re: So lost on the naming

Re: Lewis Acids and Bases

Re: Electron Configuration for Ions

Re: Electron configuration for ions [ENDORSED]

Re: Diatomic Molecules

Re: Can Bohr be used as Rydberg?

Re: Writing Reactions