CHEMISTRY COMMUNITY

Prina Patel 1H

Nope no class tommorow! Dr.Lavelle is still going to have a review session from like 4:30- 6:00 in CS50!

Prina Patel 1H

the prefix just indicates 1,I think since decane is 10 meaning that undecane stands for an Alkane that has 11 carbons.

Prina Patel 1H

I think that ethers may not be given as much priority as the other functional groups simply because they are a part of the substituents name.

Prina Patel 1H

Yes the chair conformation is the most stable structure a cyclohexane can be no matter if it's a cis or trans structure.

Prina Patel 1H

I believe its asking for the molecules involved in the intermediate step.

Prina Patel 1H

I think because its bimolecular, and OH- is a nucleophile, so when the reaction occurs, the other nucleophile that is present, the bromine is kicked out and its there in its place hence SN2

http://static.wikidoc.org/f/f9/BromoethaneSN2reaction-small.png

Prina Patel 1H

An ambident nucleophile has an atom on it that has lone pairs which it means its a source of electrons. This atom lets the nucleophile act as the source of electrons through it. Thus it is called an ambident nucleophile.

Prina Patel 1H

They capitalized the B because its the first one in the name of the compound. Think of it like a sentence, you always capitalize the first letter. Likewise in the name you capitalize the first letter of the "sentence" (AKA compound). Notice you don't capitalize prefixes. IF the compound wa...

Prina Patel 1H

I think pentyl is the IUPAC name while amyl is like a common name that you can use whenever. "Alpha" order just stands for alphabetical order.

Prina Patel 1H

Do you mean kinetically favorable? if so yes there is a difference between thermodynamically favorable and kinetically favorable. Kinetically favorable means that the there is a large difference for activation energy so more products than reactants. Thermodynamically favorable means that there is a ...

Prina Patel 1H

I think those might be two different reactions.

Prina Patel 1H

The concentration is independent because if you write out the integral law of of a first order reaction and you figure out the half life equation. You can see that the [A] knot will cancel and your left with ln (1/2)= -kt. Then solving for t gives .693/k. Since the Concentrations canceled out we see...

Prina Patel 1H

I think it was, that all the the reactants and products have different reaction rates. What rate you get depends on what you chose. I found this formula that can that gets the average Unique rate:

rate of reaction = (−1/a)(Δ[A]/Δt)=(−1/b)(Δ[B]/Δt)=(1/c)(Δ[C]/Δt)=(1/d)(Δ[D]/Δt)

Prina Patel 1H

The reaction rate will depend on the only on the smallest reactant. The other two reactants will be in excess so they just remain constants in essence.

Prina Patel 1H

Is the cell potential effected by the size of the anode/cathode electrode? If so why?

Prina Patel 1H

Yes they do. The energy levels of atoms will give them the ability to vibrate and rotate. This disorder in movement is what gives it it's entropy.

Prina Patel 1H

The more negative the potential is the more electron donating power they have. That means those elements are strong reducing agents because they have the ability to reduce other compounds since they don't want the electrons themselves. They have potential to let the negative charge go. The elements ...

Prina Patel 1H

I think its just a convention to put the anode to the left and the cathode to the right since the electrons always from the anode to the cathode. It seems more logical.

Prina Patel 1H

In an isolated system nothing can exchange with the surroundings. If nothing can interact then nothing in the system will change. Therefore, the delta V in an isolated system=0 because volume doesn't go up or down its constant.

Prina Patel 1H

I think its supposed to represent changes but the infinitesimal (smaller) changes. On page 36 of the course reader, the equation for the isothermal process for changing temperature to determine entropy has ds , and professor Lavelle said in class that the d was supposed to represent small changes fo...

Prina Patel 1H

Enthalpy is the change in heat, the release and absorption. Entropy is the disorder in a system.
It's relationship can be seen in the equation delta G= delta H- T Delta S. This equation represents the change in free energy.

Prina Patel 1H

The value of q should be negative if the equation is delta S for a system because the system will be loosing energy since the heat will flow into the surroundings. Meaning the entropy for the system is negative. The surroundings should have a positive entropy. (For an exothermic process at a constan...

Prina Patel 1H

To calculate the integral you must take the antiderivative {For example, anti derivative of x is (x^2)/2} of the variables on the inside and pull out the constants if you can. Then plug in the values of the bounds you are given.
However, an easier form of the equation for expansion is w=-P delta V

Prina Patel 1H

According to the course reader, thermochemistry is "the study of heat released or absorbed in chemical reactions and physical changes"
While thermodynamics is more about the relationship of heat, work, etc.

Prina Patel 1H

There is a negative sign because whenever a system does work it loses energy because its pushing against the pressure. Having a positive sign means its gaining energy which doesn't make sense.

Prina Patel 1H

I think if it's not specified then we should just assume its 25C.

Prina Patel 1H

I think we also have to know that Irreversible processes are sudden and big changes.

Prina Patel 1H

Enthalpy is considered a state function because the value isn't determined by the path to the state. It's figured out by the state that it's in at the present.

Prina Patel 1H

q subscript p, p is for constant pressure. q subscript be is then heat being released and absorbed at constant pressure.

Prina Patel 1H

Those three values are supposed to indicate the 3 bonds that were formed to make that molecule from the reaction of CH2CH2 + HBR. The negative sign on those values is because bonds were formed and that releases heat.

Prina Patel 1H

http://crescentok.com/staff/jaskew/isr/chemistry/heatcurve.gif"onclick="window.open(this.href);return false; If you take a look at the picture you will be able to see that water has to have a lot of heat added and the temperature has to be high for a phase change to occur to steam. The line leading ...

Prina Patel 1H

One equation where you can see them acting together is that of the enthalpy of sublimation where
the delta H of Fusion and delta H vaporization added together can give you the delta H of sublimation.

Prina Patel 1H

The l value depends on which orbital gets filled last or the higher energy orbital the outer valence electrons occupy. Technically for Fe, the d orbital gets filled last even though it's placed before 4s^2 because its a higher energy orbital thus giving it the l number of 2 (s=0, l=1, d=2, f=3). m t...

Prina Patel 1H

Also wouldn't a strong acid and strong cause too big of a change resulting in a very high or low pH which is dangerous for the body?

Prina Patel 1H

I think both are valid. As long as you are getting the right answer and using correct reasoning it shouldn't matter. However, to be safe I would use the ICE box.

Prina Patel 1H

Fluorine is very electronegative so it won't easily give up its electrons which is what a strong acid would do easily. The disassociation energy trend is that that it decreases going to the left and up which can tell you if a certain acid is stronger than another. The lower the disassociation energy...

Prina Patel 1H

You can use the values that are given to you like the partial pressure of something or the number of mols of something to figure out how many sig figs you need in your answer along with keeping in mind like Jonathan said to use the least number of sig figs provided.

Prina Patel 1H

I believe it is a weak acid because HF bond is very strong because it has a short bond length. The short bond length is hard to break which makes it hard for it to give up the H+.

Prina Patel 1H

I think the sig figs are given by the initial concentration value of H20 which is has 3 sig figs because the zeroes are trailing the 1 in the decimal making them significant.

Prina Patel 1H

Most likely if it is not listed in the course reader then it you probably do not need to know it. The ones in the course reader are the most common ones and important ones that are seen. So don't worry about knowing other acids and bases.

Prina Patel 1H

I don't understand why the conjugate of a strong acid has to be a weak base and visa versa...Why is it like that?

Prina Patel 1H

If you only look at [CoF6] That has a negative charge hence the adding of at to the end of cobalt because that part is negative. The Potassium is on the outside which is why its not taken into account when deciding if the compound is to have an -ate ending or not.

Prina Patel 1H

If you have a ligand that has the same element denoted by itself and in a compound then the one that is denoted by itself comes first. I think the element by itself takes priority over the alphabetical rule.

Prina Patel 1H

Every Bronsted base will be a Lewis base however if you try to apply it the other way it is not always the case.

Prina Patel 1H

So if for all the compounds in a reaction it says (g). That means there is only one type of phase meaning its homogenous because the prefix homo- means the same. If in a reaction there is a compound that has the phase (l) and another that has phase (aq) that means that it is heterogenous because the...

Prina Patel 1H

Yes that is the way they are supposed to be. The rule is that you put them in alphabetical order. (NH3) is known by the name Amine and H2O is aqua so NH3 would go before H2O according to alphabetical order. Same with NH3 and SO4. NH3 is amine and SO4 is sulfate. A comes before S which means that NH3...

Prina Patel 1H

I think that we can use both on the quiz it doesn't seem to matter. However normally in class we seem to use the ones that are just under Name*. It doesn't mean that its wrong to use the new IUPAC Name Convention.

Prina Patel 1H

If you draw them out and place the lone electrons around the central atom you can easily see that AX2E3 , the lone electron pairs distort the shape so that it is linear. Whereas on AX2E2 You can see that the two lone electron pairs distort it so that it is a bent shape. The number of lone electron p...

Prina Patel 1H

I'm pretty sure you have to put it in whichever one comes first in order for it to be right. When you writing the configuration it will be right but on the diagram if you put it in the Pi*2py orbital it would be wrong. Since that isn't the one that would get filled first if you went in order.

Prina Patel 1H

It is based off of electronegativity. The more electro negative atom will be pulled "down" while the other atom that is less electronegative gets pushed up.

Prina Patel 1H

I am not sure what the specific equation is but it generally trends on the periodic table by increasing at you go up and to the right of the periodic table.

Prina Patel 1H

Yes we do have to know all of them.

Prina Patel 1H

Emma it would result in a linear shape. Polarity I think would depend on which atoms are attached to the molecule. If the other two attached are the same then it would be non polar. Most likely if it is linear the atom will be non polar.

Prina Patel 1H

An easy way to pick a central atom is to think how many open spaces it has. For example if you were to pick the central atom for CO2. C has four open spaces because there it needs 4 more electrons to fill its shell. O has 2 open spaces so it only needs two more electrons to fill its shell. Since C h...

Prina Patel 1H

Can you have more than one sigma bond?

Prina Patel 1H

How you determine whether a molecule has more than one sigma bond or pi bond? Or how many of each type to use? I don't understand this concept well...

Prina Patel 1H

Which page is this on?

Prina Patel 1H

Do hypervalent compounds have limitations? If so what are they? Is there a certain group of elements they can't form bonds with while having bonds with other elements?

Prina Patel 1H

I did not learn Hund's Rule in my chemistry class so I am still confused to as to what it is and how to use it effectively? Can someone give me an example of how to use it and what it is exactly?

Prina Patel 1H

I think it is quite legitimate. I think it is just a method to remember what order to go in. I know that it was useful for me when I used it. Maybe it's different for this class but I'm sure we can still use it if it helps us and we are getting the right results.

Prina Patel 1H

I don't understand how was the value of Planck's constant derived?

Prina Patel 1H

No, I should think not. I'm pretty sure we round up whatever answer we get. So if you got 40.07 it would be 40.1 which would be the same as the answer 40.13 if you didn't include the last number 3. I'm not sure but I think this is what we would do.

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