CHEMISTRY COMMUNITY

juchung7

In this post, viewtopic.php?t=27499, it says trans configured molecules have fewer packing positions compared to that of cis, so cis would have more entropy.

juchung7

because the elements in the further upper right corner of the periodic table will have a stronger pull for an electron to fill its shells, their oxidizing powers will be stronger.

juchung7

Yes, I'm pretty sure for this course we used the equation for irreversible expansion W=P(delta)V.

juchung7

In terms of rate, and considering a reaction A -> B + C, the rates will be (-1/a)d[A]/dt = (1/b)d[B]/dt = (1/c)d[C]/dt. In finding each rate of each species, you would multiply the unique rate of the reaction by its coefficient.

juchung7

What is the value of A exactly? What does it stand for/mean in terms of rates and the rate constant?

juchung7

What value do you use for N in this equation? Is it the electrons in the balanced redox reaction or the amount of moles?

juchung7

in this case, you would end up using the steady state approximation, since you can't have intermediates in your rate law.

juchung7

Q: What do chemists call a benzene ring with iron atoms replacing the carbon atoms?
A: A ferrous wheel:
Fe - Fe
/ \
Fe Fe
\ /
Fe - Fe

juchung7

Is the difference in cell potential just the E value calculated through the nernst equations, or is it the difference between E and E(standard)?

juchung7

How would you know when to use either approach to solving for rate law? Are there any factors that would make you assume one over the other?

juchung7

Also, the rate constant (K) is considered the slope of the graph showing rate of reaction. For first order reactions, the y axis is ln(molar concentration) versus the x axis of time, and the resulting line plotted has a slope of -K, and for second order reactions the y axis is 1/(molar concentration...

juchung7

I think the equations will be given to us (ex. slow and fast reaction equations), so from that we can determine the intermediates. They will appear in both the reactants and products, and can be cancelled out.

juchung7

Just a clarification, is the only way to determine rate law by experiment?

juchung7

How many atoms in guacamole? Avocado's number

juchung7

When are you supposed to convert gibbs free energy into cell potential (deltaG=-nFE) instead of just subtracting standard cell potentials?

juchung7

Why do chemistry teachers like to teach about ammonia? Because its basic material.

juchung7

It's easier to separate the half reactions, balance them, and then combine. It's less confusing so you want to do the oxidation and reduction reactions separately.

juchung7

What happens to nitrogen when the sun rises?
It becomes daytrogen :3

juchung7

the bonds broken are 1 C=C, and 1 CL-Cl, while bonds formed are 1 C-C as well as 2 C-Cl bonds. The C-H bonds are left intact throughout the reaction. If you see, in CH2 there are only C-H bonds and no H-H bonds

juchung7

Pressure does affect work, at least for gases (think our two equations for work that contain pressure). I think in terms of solids and liquids, pressure wouldn't affect because it's extremely hard to compress liquids and solids. Hopefully this answered your question!

juchung7

This is kind of random, but I was just wondering, how does entropy increase through air conditioning? Or any kind of cold-increasing system?

juchung7

I think the idea is that an ideal cooler will not let and heat or matter in or out (thus isolated) and in turn because the contents are inside, they will not be able to change from their original state either.

juchung7

I'm pretty sure you have to be told whether it is reversible or irreversible, just make sure to know which equations to know for what kind of reaction.

juchung7

Why is internal energy a state function?

juchung7

When heat is transferred out of a system, heat is lost so the q value is negative (exothermic). When heat is transferred into a system, heat is gained so the q will be positive (endothermic). I hope this answers your question.

juchung7

When would we use this equation -work=-nrt(ln(vf/vi))- versus w=-p(changeinv). I get that we use the first one when the system is in equilibrium, but would a problem explicitly say "this system is in equilibrium/ is reversible?"

juchung7

Q: What fruit contains Barium and double Sodium? A: BaNaNa!

juchung7

What is the difference between heat capacity and specific heat capacity and why is one an extensive property and the other an intensive property?

juchung7

What element derives from a Norse [censored]? Thorium.

juchung7

My TA also pointed out that for a molecule with COO attached, only one oxygen will be a dentate. Since one of the oxygens is double bonded and has 2 lone pairs, and the other is single bonded, only the singled bonded oxygen will be a point of attachment, so don't count every oxygen all the time.

juchung7

For question 63 in chapter 11 At 25 C, K =3.2 x 10^-34 for the reaction 2 HCl(g) <-> H2(g) + Cl2(g). If a 1.0-L reaction vessel is filled with HCl at 0.22 bar, what are the equilibrium partial pressures of HCl, H2, and Cl2? Do you have to solve this by first calculating number of moles of HCl using ...

juchung7

In the practice final, question number 32 asks if Kc is x at 400 K, what is Kc if the stoichiometric coefficients are halved? The answer says the root of x or x^1/2, and I know this makes sense mathematically, but doesn't the value of Kc for a reaction only change based on temperature?

juchung7

For example, with H2O, the Hydrogen has two single bonds to the two oxygens, and 2 lone pairs of electrons- so in conclusion it has 4 areas of electron density and sp3 hybridization. Remember that a double bond or triple bond will count only as one area of electron density.

juchung7

It's a weak base because it's only slightly soluble in water.

juchung7

Since there are 3 fluorides, Boron needs 3 lone electrons to bond with them. Since Boron has an electron config. of 1s2 2s2 2p1, an electron in the 2s orbital is excited into a 2p orbital (left with 1s2 2s1 2px1 2py1) which leaves us with 3 orbitals containing lone electrons thus 3 lone electrons. S...

juchung7

"That was sodium funny"
"I slapped my neon that one"

juchung7

An example: given Pt(NH3)2Cl4 find the oxidation number for Platinum So we know that NH3 is a neutral ligand, and Cl has a -1 oxidation number. Since there are two 0 charge NH3 and four -1 charge Cl, there is a -4 charge by the ligands. To make this compound have an overall charge of 0, Platinum mus...

juchung7

No, the Rydberg constant relates to atomic spectra and quantum levels of the hydrogen atom. These two constant correlate to different parts of chem.

juchung7

I'm pretty sure Lavelle said they would just call it K without specifying, but you should know by the values given in the problem as p has to do with pressure and c with molarity.

juchung7

They are interchangeable

juchung7

Why can't Carbon be double bonded to both oxygens and the radical electron go on one of the oxygens? Oxygen is more electronegative than Carbon, and if Carbon had 2 double bonds then its orbitals would be filled and formal charge in most places would be the lowest possible.

juchung7

Hybridization is basically when atomic orbitals combine to be more suitable for chemical bonds. For example, Carbon has a ground state configuration of 1s2 2s2 2p2, indicating it has two lone electrons. This would mean Carbon is inclined to only bond two electrons, however we know that is not the ca...

juchung7

Quantitatively, we can find ml by taking negative l to positive l. ml basically tells us how many orbitals there are present and their orientation within a subshell. Ie, we are given a 3p subshell- n would be 3, l would be 2 (n-1), and the possible solutions for ml would be -2,-1,0,1,2.

juchung7

So the way they give you cycline is kind of nice, because they group the location of the elements to help you draw lewis structure. Since carbon is the least electronegative element, we put one in the center, and then build off from there as said in the comment above. Because they give you H2C(NH2)C...

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