CHEMISTRY COMMUNITY

Kevin Antony 2B

We can see how reactions would proceed in a cell (spontaneous or not spontaneous) by comparing the ratio of products to reactants.

Kevin Antony 2B

The mass of a solid electrode would not impact the solid potential.

Kevin Antony 2B

In a concentration cell, we would want to find Q. To find Q we would use E = Enot - RT/nF lnQ . Enot will be equal to 0 so as long as you have an E value you can easily find Q.

Kevin Antony 2B

Thanks for all the review sessions that have helped us along the 14 series!

Kevin Antony 2B

As of this point its pretty much the only way to get in contact with them so I'd say yes.

Kevin Antony 2B

I believe we will submit the test electronically.

Kevin Antony 2B

Maya Beal Dis 1D wrote:Are all review sessions going to be cancelled?

I'm pretty sure they all will be cancelled.

Kevin Antony 2B

I believe Lyndon' s is the only one.

Kevin Antony 2B

I know the other 14b teacher made the final take home. Also with how things are going right now I don't think we'll have any review sessions.

Kevin Antony 2B

Cp and Cv are specifically meant to be used at a constant pressure or a constant volume. The values C=5/2R and C=3/2R correspond to values specifically for ideal gases.

Kevin Antony 2B

I feel that we just have to know what they are and when to use them although knowing how to derive them may end up being useful.

Kevin Antony 2B

To find the anode concentration you use the equation E = -RT/nF * lnQ where Q is the concentration of products over reactants. As long as you know the concentration of the cathode, E cell, and n you should be able to find the anode concentration.

Kevin Antony 2B

In a concentration cell your anode and cathode are the same so the Enot value is therefore 0. To create a charge, we use a concentration gradient instead. This gradient generates Volts as a result. We model this as E = -RTln(Q)/nF where Q is the concentration of the products over the concentration o...

Kevin Antony 2B

Im sure lyndon will hold a UA review session for the final. It will probably be announced in class sometime this week.

Kevin Antony 2B

It's still the same basic idea as balancing redox reactions in acidic solutions. In basic solutions, however, we use OH- instead of H+. Other than that it follows the same steps as balancing in acidic solutions.

Kevin Antony 2B

We use a solid if there are no solids in the cathode or anode.

Kevin Antony 2B

There is a different rate for both the forward and reverse reactions so we use k and k'.

Kevin Antony 2B

Honestly, your best options are just going slowly and practice. Going slow will help reduce the likelihood of errors and plenty of practice with that same calculator will help you get accustomed to the types of questions.

Kevin Antony 2B

If Ecell >0 then K >1. Similarly, if Ecell < 0, then K < 1.

Kevin Antony 2B

A cell can do work whenever Ecell > 0. This will always be the case if the Cathode is greater than the Anode.

Kevin Antony 2B

Cell diagrams can have any state of matter I believe.

Kevin Antony 2B

For K and Q we include gases and aq in the products/reactants

Kevin Antony 2B

Yes, all you have to do is flip the sign.

Kevin Antony 2B

The Cl- comes from the fact that the Hg2Cl2 is dissociating into both Cl- and Hg.

Kevin Antony 2B

The anode is where the oxidation reaction while the cathode is where the reduction reaction occurs. Convention dictates that the anode is on the right in a cell diagram and that the cathode is on the left.

Kevin Antony 2B

When we change the concentration of one of the reactants, zero, first and second reactions will all respond differently as to how much product is subsequently formed. The reaction order can tell us how impactful a certain reactant is.

Kevin Antony 2B

When you look at the individual half reactions, n represents the moles of electrons being transferred. This value must be the same for both half reactions.

Kevin Antony 2B

We don't need to make any assumptions as we know that delta G naught = -RTlnK. As a result, we can just substitute the delta G naught value.

Kevin Antony 2B

We need a solid to be the electrode. As there is no solid on the right hand side, we use Platinum.

Kevin Antony 2B

First you have to find what the two individual half rxns are. From there look in Appendix 2B to find the redox potential for the given half reaction. If your two half rxns are one oxidation and one reaction, make sure to multiply the oxidation reaction by a negative 1 and then add the two potentials.

Kevin Antony 2B

I believe its when there are no solids for the anode or cathode you would use Platinum.

Kevin Antony 2B

Its in the book at Appendix 2B. (After Chapter 11 but before the answer key)

Kevin Antony 2B

We know that neutralization reactions produce heat when they occur. We want the most heat released to generate the largest delta T possible. Therefore, we look to see which answer choice has the most moles reacting which ends up making the answer choice B.

Kevin Antony 2B

I believe the presence of the (OH) tells us that is in a basic solution.

Kevin Antony 2B

When using the Van't Hoff equation, we assume standard conditions which means that Pressure is 1 atm.

Kevin Antony 2B

I'm pretty sure he curved 14a at the end of last quarter, but I wouldn't expect him to do as much for 14b.

Kevin Antony 2B

Spontaneous reactions are characterized by having a deltaG. When a reaction gives off heat(exothermic) that means that H is negative. Now, unless S is positive, deltaG will be negative as deltaG = deltaH - T(deltaS).

Kevin Antony 2B

We know that deltaG = deltaH - T(deltaS), but we also have another equation, where deltaG = -RTlnK and K is the ratio of products to reactants. when K <1 lnK will be negative and thereby deltaG will be negative. If K > 1 then lnK is positive and then deltaG will be positive.

Kevin Antony 2B

Keep in mind if something is giving off heat and thereby lowering its temperature then something else has to take in that heat thereby increasing its temperature. As a result, we end up having two different entropies, one negative and one positive

Kevin Antony 2B

We can use both atm or Pa for pressure. Just keep in mind if you use atm you'll get L*atm which is NOT equal to J and you have to convert using the constant 101.325J/(L*atm)

Kevin Antony 2B

I can't remember the way he taught it in class, but the way I've always thought about it is the gas mixture is attempting to alleviate the increase in pressure as a result of the compression. Because fewer molecules of gas would mean less pressure, the reaction favors the side with fewer moles of gas.

Kevin Antony 2B

To see if something is endothermic r exothermic we look at delta G. If delta G is positive, the reaction is endothermic, but if it is negative the reaction is exothermic.

Kevin Antony 2B

I don't think he'll test on it since it wasn't on the outline. But with Dr. Lavelle the slides are fair game to be on the test so I'd know it just to be sure.

Kevin Antony 2B

Pure solids and liquids hold a value of 1 when calculating K. If you wanted you could add them in there but because their value is 1, it does not change the K value.

Kevin Antony 2B

Yes it does. If we are to infer that x is a minimal value that does impact the equation we need to know that it is less than 5% in both scenarios.

Kevin Antony 2B

In the end, Kp is unitless. For partial pressures however we use bar.

Kevin Antony 2B

R is equal to 8.3145 x 10^-2

Kevin Antony 2B

K is the reaction constant and remains the same at every point during the reaction, while Q is the ratio of products to reactants at a given point and can tell us which direction the reaction will proceed in next.

Kevin Antony 2B

Because K is such a small value, < 10^-3, we can assume x will be so small that it is inconsequential. As a result, we ignore the -x in the denominator and solve as if it were not there.

Kevin Antony 2B

At low temperatures, most gases are going to act ideally. In this course, we'll probably only deal with ideal gases because this allows for us to apply PV=nRT and infer molecular kinetic energy based on temperature.

Kevin Antony 2B

Look for relative anion stability. The more stable the anion, the stronger the base.

Kevin Antony 2B

If it was a polyprotic base then the conjugate acid of NH3NH3^+ would be NH3NH4^2+

Kevin Antony 2B

Look for which would have increased relative anion stability, that should be your stronger acid.

Kevin Antony 2B

I believe you can tell by looking at regions of electron density.

Kevin Antony 2B

Both anions would have resonance, but Chlorine's higher electronegativity makes the anion more stable. As a result HClO2 is the stronger acid.

Kevin Antony 2B

I think he'll just be picking up where he left off.

Kevin Antony 2B

I'm planning on just reading the textbook and doing any practice problems they give us/are on the outline.

Kevin Antony 2B

There might be something in the test bank if you want to check it out.

Kevin Antony 2B

I'm sure there will be some final review at some point where we'll be able to get practice problems, but until then you could always redo the problems from the outline.

Kevin Antony 2B

Has Lyndon posted a new final review yet?

Kevin Antony 2B

The Bronsted Acid is the proton donor and the Bronsted Base is the proton acceptor.

Kevin Antony 2B

The Roman Numeral (III) tells us that.

Kevin Antony 2B

Dr. Lavelle said he was working to organize rooms for the session in an email, we should probably hear about it in lecture soon.

Kevin Antony 2B

After looking it up, a coordination compound is a central atom or ion (typically a transition metal) surrounded by other molecules or ions known as ligands.

Kevin Antony 2B

A Bronsted acid is a substance that gives off protons, so the proton donor. A Lewis acid is a substance that can accept a lone pair of electrons. Just because something is a Lewis Acid, does not mean it has to be a Bronsted Acid.

Kevin Antony 2B

We're only looking for regions of electron density, so all bonds, lone pairs, or single electrons just count as a singular region.

Kevin Antony 2B

The only time it could be polar is if one of the X atoms was different so that the dipoles no longer canceled each other out

Kevin Antony 2B

I believe molecular geometry is the shape of a molecule when taking into consideration lone pairs of electrons while the molecular shape is the shape of the molecule when no taking into account the lone pairs.

Kevin Antony 2B

All of the molecules can have London Dispersion forces. A, C, and D will have dipole-dipole interactions, but only A and C will have Hydrogen bonding.

Kevin Antony 2B

Yes, all molecules do.

Kevin Antony 2B

The partial negative charge on the Oxygen is attracted to the partial positive of the Hydrogen. The short lines represent that attraction.

Kevin Antony 2B

I think it will end up being everything on Outline 4

Kevin Antony 2B

I believe that 14B has a lab that goes with it and I've heard all the organic chemistry courses are hard.

Kevin Antony 2B

I would probably ask you TA about it to see how they're grading you for chem community participation. Hope that helps!

Kevin Antony 2B

I believe that your TA will grade your midterm, and they do have partial credit.

Kevin Antony 2B

I hope he does because they're a great resource. If not we still have step ups and the workshops to help fill in any gaps of knowledge.

Kevin Antony 2B

From what I gather, you know have energy per electron. We know there are 6.022 x 10^23 electrons in a mol. If you divide by Avagadro's number you should get energy per mol.

Kevin Antony 2B

H, He, Li, Be, B, and Al I believe will never have a full octet. Additionally, some elements like Si, P, S, and Cl can have expanded octets. I'm pretty sure we just have to memorize what the exceptions are.

Kevin Antony 2B

As resonance structures show, electrons can group in different manners. Delocalized means it doesn't group in one specific manner/with a single atom but rather with multiple.

Kevin Antony 2B

102.6 nm would be part of the Lyman series which means n would equal 1.

Kevin Antony 2B

H, He, Li, Be, B, and Al I believe will never have a full octet. Additionally, some elements like Si, P, S, and Cl can have expanded octets.

Kevin Antony 2B

When choosing the central atom you look for which atom has the lowest ionization energy to be the central atom.

Kevin Antony 2B

delta x is the uncertainty in position as we do not know exactly where an electron is at a given time. Delta p is the uncertainty in momentum which is derived by mass x velocity because we are not sure about the velocity.

Kevin Antony 2B

To my knowledge, x, y, and z refer to the different electron pairs possible in orbital. There can be 2 electrons per orbital as long as they have opposite spin. In p, for example, there can be up to 6 electrons grouped in twos. To organize them we separate them by Px, Py, and Pz.

Kevin Antony 2B

For sodium, it would look like this: [Ne] 3s^1

If you look at a periodic table, the closest element before Na with a full octet is Neon, so we start with [Ne]. From there, the valence electrons of Na fill up to the 3s^1 so we write that after.

Kevin Antony 2B

From what I understand, we don't exactly know where an electron is at a given moment so the "x" is similar to probability in the sense that we think the electron should be somewhere in that vicinity. As far as momentum goes, we appear to be calculating linear momentum as it's just mass x v...

Kevin Antony 2B

Principal numbers are your n values while the angular values are your l values. For example for 6p, n = 6 and l = 1.

Kevin Antony 2B

For tests, are we expected to know all of the angular wave function equations for all values of l as seen in topic 1D.2?

Kevin Antony 2B

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6 x 10^3 km/s. (a) What is the wavelength of the ejected electron? I've been trying this for some time but I can't seem to get the same answer the book has. How do I tackle it? Edit: Ok I figured it out but why do y...

Kevin Antony 2B

After looking it up, the masses are as follows:

Neutron = 1.6749286*10^-27 kg
Proton = 1.6726231*10^-27 kg
Electron = 9.1093897*10^-31 kg

Kevin Antony 2B

I'm not sure if I heard this correctly, but I believe it was briefly mentioned that the De Broglie wave equation applies for any particle that has resonance with momentum. What exactly does it mean to have resonance?

Kevin Antony 2B

In the lecture it was mentioned that anything with a De Broglie wavelength of less than 10^-15 m does not have any detectible wave-like behavior.

Kevin Antony 2B

So if I understand this correctly, increasing the intensity of light means increasing the number of photons. How exactly are able to increase the number of photons in light?

Kevin Antony 2B

I believe that the posts are due each Sunday as that's how it was last week. To double-check I would suggest shooting your TA an email as they may have a special policy.
Hope this helps!

Kevin Antony 2B

First you'll have to divide the mass of UF6 by the molar mass. This gives you the moles of UF6 present. As there are 6 moles of F- in 1 mol of UF6, multiply the result by 6. This should give you the moles of F- ions.

Kevin Antony 2B

Some questions may be different, but there is a pdf version of the 7th edition textbook in many of the chem 14a facebook messenger groupchats. You can always take a look at that book and compare it to the one you have currently.

Kevin Antony 2B

In theory, I suppose it is possible. To not have any limiting reactants, all the reactants would have to be present in equal moles and be used up at an equivalent rate or as long as all the same moles of each reactant are used up and all of the reactants are used up. This would mean no side reaction...

Kevin Antony 2B

You forgot to balance the equation. When you do, the equation shows that 1 mole of C6H9Cl3 will yield 3 moles of AgCl. Thus, the .004 moles C6H9Cl3 should yield .012 moles AgCl. Just remember to convert to grams after!

Kevin Antony 2B

I believe the posts are due by next Sunday. As far as the order goes, after looking it up, the Hill System Order is one way to write it, but you may also write it in a manner where the notation indicates structure. For example, this is why you'll see the (OH) group together rather than being split a...

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