CHEMISTRY COMMUNITY

Sahaj Patel Lec3DisK

Dr. Lavelle, Thank you for making chemistry, a subject that is, personally, hard to grasp into a subject that I do truly enjoy learning about. I love how initially we see all these concepts and equations that we know nothing about, and by the end of the unit you somehow work your magic and it all ma...

Sahaj Patel Lec3DisK

I use hand written notes that really do help. I wrote everything down on his slides, in addition to anything he says that I think is important. Hope this helps!

Sahaj Patel Lec3DisK

When the battery is dead, or when a concentration cell is used, E naught will be zero. Also, when an oxidation and reduction reaction add up to 0, E naught also equals 0. Hope this helps!

Sahaj Patel Lec3DisK

Just by relaxing and doing what I like to do in my free time helps me deal with the anxiety. For me it’s playing video games and watching tv, but finding what makes you relax helps load.

Sahaj Patel Lec3DisK

I just relax by playing video games, watching tv shows/ anime, it reading. Just relaxing helps deal with burnout well.

Sahaj Patel Lec3DisK

The anode is usually on the left and it is where oxidation occurs. The cathode is on the right and it is where reduction occurs. Hope this helps!

Sahaj Patel Lec3DisK

I was surprised by my grade, and I am going to review it, but I am going to need to grind for this final if I want to end with the grade I want. Hope studying goes well for everybody else!

Sahaj Patel Lec3DisK

Taco Bell. I have not had a queserito in over a year. Feels bad man.

Sahaj Patel Lec3DisK

Anode is always on the left and the cathode is always on the right. With that being said, the cathode is positive and where reduction occurs, and the anode is negative and where oxidation occurs. Therefore, if you did encounter such a problem, that is how you would identify them. Hope this helps!

Sahaj Patel Lec3DisK

Drop in sessions are really helpful, and there is more discussion than problems from my experience. You can really flush out concepts in those sessions. Hope this helps!

Sahaj Patel Lec3DisK

Temperature affects K depending on the type of reaction. If the reaction is exothermic, the more temperature increases the lower K will get because the production of reactants are favored. If the reaction is endothermic, the more temperature increases the higher K will get because the formation of p...

Sahaj Patel Lec3DisK

Yeah, I didn't either but that pressure for H2 should be thought as the concentration of H2 since it is a gas, and then you just plug it into the equilibrium quotient. Hope this helps!

Sahaj Patel Lec3DisK

I'm actually stuck on that problem, do you have any tips to help?

Sahaj Patel Lec3DisK

UA sessions are really helpful, and they go over a lot of problems that probably show up on the midterm exams. If I am being honest, I am struggling too, but as long as you work hard everything falls into place. You got this, and hope this helps.

Sahaj Patel Lec3DisK

If delta G (not delta G naught) is negative, then the reaction is spontaneous in the forward direction. If delta G is positive, the reaction is spontaneous in the reverse direction. Hope this helps!

Sahaj Patel Lec3DisK

Khan academy (as boring as Sal Khan is), is an amazing resource that can help a lot. Other than that, you should email your professor just to get a head start on the content, and they can point you in the right direction. Hope this helps!

Sahaj Patel Lec3DisK

Redoing the textbook problems, looking at the sapling problems, and attending as many review sessions/ TA Office Hours during Finals Week will go a long way. Just try your best, and work hard. Everything else falls into place after that. Hope this helps!

Sahaj Patel Lec3DisK

Delta G is Gibbs free energy while Delta G naught is the standard Gibbs free energy. Its delta G that tells you if a system is at equilibrium (if it equals 0), not delta G naught.

Sahaj Patel Lec3DisK

While you can never create a 100% isolated systems that are 100% efficient (nothing is ever 100% efficient), an example I can think of is the universe. Theoretically speaking, this is the only isolated system that is 100% isolated. Hope this helps!

Sahaj Patel Lec3DisK

Hope everyone has a great valentine's day weekend! :)

Sahaj Patel Lec3DisK

In this equation, you would use R=8.314 J/K*m. Hope this helps!

Sahaj Patel Lec3DisK

I have seen it expressed as both, so look at your answer and convert it to the appropriate unites when the midterm comes around.

Sahaj Patel Lec3DisK

q in general denotes energy in the form of heat. qrev is specifically referring to the energy in the form of heat during reversible expansion. Hope this helps!

Sahaj Patel Lec3DisK

You raise it to e! just like to get rid of -log you raised it to 10, you raise the ln() to e. Hope this helps!

Sahaj Patel Lec3DisK

A Bomb calorimeter is considered an isolated system. Hope this helps!

Sahaj Patel Lec3DisK

It depends on the composition of the salt. If the salt has a strong acid and base its neutral. If it ha as weak acid and strong base, it’s basic. Lastly, when it has a strong acid and weak base, it will be acidic. Hope this helps!

Sahaj Patel Lec3DisK

Extensive properties depend on the amount of a certain substance presence. Since specific heat depends on the moles/ grams of a substance, heat overall is therefore extensive. Hope this helps!

Sahaj Patel Lec3DisK

When something goes to a solid to liquid, liquid to gas, or solid to gas, it is an endothermic reaction since the substance needs to absorb energy (heat) to reach that higher phase. When a gas goes to liquid, liquid to solid, it gas goes to solid, it is exothermic and the substance loses heat. Hope ...

Sahaj Patel Lec3DisK

It is the change in internal energy (which is a state function)!

Sahaj Patel Lec3DisK

I love watching anime/movies/shows, playing videogames, talking to people and working out.

Sahaj Patel Lec3DisK

"q" denoted heat, while H represents enthalpy. If I am not mistaken, heat (q) of a gas under constant pressure equals the change in Enthalpy (H). Hope this helps!

Sahaj Patel Lec3DisK

It would be the enthalpy of combustion of CH4 since that is the exact reaction that is happening, When an organic compound (usually made of Carbon, Hydrogen, and/or Oxygen) is burned with Oxygen (O2), and the products are Carbon Dioxide and Water, that is a combustion reaction. Hope this helps!

Sahaj Patel Lec3DisK

They are both the same thing! Vapor is more often sued to describe a liquid that has recently entered the gas phase. But, at the end of the day, they are the same thing!

Sahaj Patel Lec3DisK

An increase in temperature for an exothermic reaction means that the formation of reactants will be favored, while an increase in temperature for an endothermic reaction means that the formation of products will be favored. If you cool either reaction, then the opposite happens. Hope this helps!

Sahaj Patel Lec3DisK

"Carbon disulfide can be prepared from coke (an impure form of carbon) and elemental sulfur. 4C(s)+S8(s)⟶4CS2(l)ΔH∘=+358.8 kJ Calculate the amount of heat absorbed in the reaction of 169 g of carbon with excess sulfur. Calculate the amount of CS2 produced when 397 kJ of heat is absorbed."...

Sahaj Patel Lec3DisK

AV associated assignments are not graded, but are very very helpful for studying. I highly recommend them.

Sahaj Patel Lec3DisK

Once this midterm is over, I will be doing fantastic, how about you Sid?

Sahaj Patel Lec3DisK

I listen to everything (from country to hip hop), but if you want something else besides music to listen too, there are tons of podcasts out there (I can whole heartedly recommend GG over EZ, Because Videogames, the Jocko Podcast, and Views).

Sahaj Patel Lec3DisK

The units will vary for delta H, however whatever units they give it in will fundamentally be useful for the problem, so be sure to just use the units they give. Hope this helps!

Sahaj Patel Lec3DisK

If Ka/Kb is less than 10^-4, it is deemed as small enough, however, afterwards you calculate the percent ionization, and if it is more than 5%, the approximation is invalid and you have to do the calculation again without the approximation. Hope this helps!

Sahaj Patel Lec3DisK

pKa and -log Ka are the same thing! "p" is just short hand for -log.

Sahaj Patel Lec3DisK

No, pKa is just the -log(Ka)! Don't overthink it!

Sahaj Patel Lec3DisK

The textbook problems are a great way to study! Those, in addition to attending as many UA sessions, will help you a lot and take you a long way. Lastly, I would review your notes and lectures as often as possible, since he usually asks some conceptual questions on the midterms that pull content fro...

Sahaj Patel Lec3DisK

I believe they are synonymous, but ask your TA during discussion/ office hours to make sure.

Sahaj Patel Lec3DisK

For Salts, you have to look at its composition. Salts will be made of a cation and anion. If the cation belongs to a strong base, and the anion is part of a weak base, it is a basic salt. If the cation belongs to a weak base, and the anion is part of a strong acid, it is a acidic salt. If both the c...

Sahaj Patel Lec3DisK

As noted before, strong bases completely disassociate, there is no need for ice tables, all you need to use is the chemical equation to find the relative concentrations of H3)+ and OH-. For weak bases and acids, you have to use ice tables since they do not completely disassociate. Hope this helps!

Sahaj Patel Lec3DisK

Since h3O+ is being produced, you are dealing with acids and therefore need to use Ka. Hope this helps!

Sahaj Patel Lec3DisK

Definitely do the Textbook problems, and truly t attend the UA Sessions! They are super helpful and the UAs are a lot of fun!

Sahaj Patel Lec3DisK

You should either test them, or shift your equation around to maybe make it a bit easier to derive a x-value from. Hope this helps!

Sahaj Patel Lec3DisK

If you were given the pKA, you would find the anti log of that to find the KA. The anti log would be 10^pKA. Hope this helps!

Sahaj Patel Lec3DisK

Essentially, the stronger the acid, the weaker its conjugate base. The stronger the base, the weaker its conjugate acid.

Sahaj Patel Lec3DisK

Exams will be multiple choice again and during lecture. You will be allowed a calculator, and the formula sheet and periodic tables of elements found on the course website. You will be proctored on zoom, so join a few minutes early since it can get pretty crazy!

Sahaj Patel Lec3DisK

I would memorize it just for the sake of it and understand it conceptually.

Sahaj Patel Lec3DisK

I am sure he wil adress this in Friday's Lecture or on Chemistry Community. But do to the past and how he posted a lecture on Veterans Day, I am inclined to say he might post one this Monday as well.

Sahaj Patel Lec3DisK

Because Ba(OH)2 is a strong base, it completely disassociates, and therefore dissociates into Ba and OH. We were trying to find the pH of the solution, which is the [H3O]. For this, we can find the pOH, subtract that from 14, find the pH, then find the [H30] from that pH. Hope this helps!

Sahaj Patel Lec3DisK

The first midterm is Jan 29, the second midterm is Feb 19, and our final is March 14.

Sahaj Patel Lec3DisK

My go to movie is probablly, not gonna lie, The Dark Knight or The Dark Knight Rises. Just pure amazingness.

Sahaj Patel Lec3DisK

To try and recommend shows with scientific themes, Dr. Stone is a great show involving someone trying to rebuild society with science. There are numerous occasions in the show where the main character uses accurate chemistry in order to accomplish this. I highly recommend this show. Yoooo! Another ...

Sahaj Patel Lec3DisK

In general you do not include Solids and Pure liquids (such as water) when calculating equilibrium. Just keep this in mind!

Sahaj Patel Lec3DisK

Hi! SO the exception to the octet rule are the nonmetals from period 3 and onwards (they can have expanded octets, and example being P Cl5), as well as Hydrogen (satisfied with one bond), and the group three elements which can only form 3 bonds. Hope this helps!

Sahaj Patel Lec3DisK

Lewis bases will donate an electron pair to a compound while Bronsted bases will accept a proton (H+). On the other hand, Lewis acids will accept a donated electron pair while Bronsted Acids will donate a proton. When looking at specifically Bronsted Bases and Acids, Bronsted bases when added to wat...

Sahaj Patel Lec3DisK

Exactly what was said before. The stronger the acid, the weaker the conjugate base. The weaker the acid, the stronger the conjugate base. The same reasoning applies to strong and weak bases. Keep in mind the other rules that determines strength of an acid too (stability, bond length, etc.). Hope thi...

Sahaj Patel Lec3DisK

For naming acids we should know the strong acids (there are 7) and the strong bases. As for the molecules in the picture, just match up the atom with their respective color and write out the equation!

Sahaj Patel Lec3DisK

The sulfur will be double bonded to the oxygen and single bonded to the two oxygens. The molecular geometry should be trigonal pyramidal, and the central sulfur will have an sp3 hybridization. As for the name, I don't think from the naming rules we have learned you could have determined that :/ Hope...

Sahaj Patel Lec3DisK

That seems correct, but remember that the overall compound will have a +1 charge that is cancelled out by Bromine! Hey I'm just a little confused because there are two Bromines. So wouldn't the compound have a 2+ charge that the two bromines cancel out? Feel free to correct me if I'm wrong Yes you ...

Sahaj Patel Lec3DisK

If n=2, then l can equal 0 or 1. If l equals 0 that is the s orbital, and if l equals 1 that is the p orbital. Since, as stated before me, there is one s orbital and three p orbitals, the possible answer is 4 orbitals.

Sahaj Patel Lec3DisK

Exactly what Madilyn said, but keep in mind that we will only be tested on molecular geometry, and whenever the shape is asked we are talking about the position of the atoms. Hope this helps!

Sahaj Patel Lec3DisK

In addition to looking at the shape of the compound. look at the bonds present. When there are pi bonds, the molecules bonded with pi bonds cannot rotate, while those solely with sigma bonds can. Essentially, all double and triple bonded molecules cannot rotate, but single bonded molecules can. This...

Sahaj Patel Lec3DisK

That seems correct, but remember that the overall compound will have a +1 charge that is cancelled out by Bromine!

Sahaj Patel Lec3DisK

Hi! So for this problem, drawing them out would be best. When you draw out the first molecule, you will notice it has three nitrogens with lone pairs, and those three nitrogens can bond to a transition metal ion. So that would be a tridentate. The next three are a mix of bi and monodentate, but the ...

Sahaj Patel Lec3DisK

So the strong and weak bases/acids were given to us during lecture, along with a few examples of weak/strong bases and acids. Any base and acid besides the strong ones given to us can be assumed to be weak. The main point here is that strong acids and bases completely disassociate in water, and weak...

Sahaj Patel Lec3DisK

I would assume that you are not allowed to post the exam questions and discuss them on Chemistry Community, but you can ask your TA to review them with you.

Sahaj Patel Lec3DisK

Polar bonds are when there is a strong electronegative difference between the central atom and the other atom(s) in the bond. Nonpolar bonds result when there is a low to none electronegativity difference between the central atom and the other atom(s) in the bond. However, if there are polar interac...

Sahaj Patel Lec3DisK

Exactly what Isaac said. Whenever there are dipole vectors or polarity in play, then the molecule is likely polar. The way CH2Cl2 is actually structured is by having the Cls on one side and the Hs on the other. When drawn this way, the diploe moments do not cancel out. If it was nonpolar, no matter ...

Sahaj Patel Lec3DisK

While double and triple bonds may effect polarity, electronegativity is the main factor that affects polarity. Since Arsenic is surrounded by 4 oxygens, and the oxygens are more electronegative than As, there will be diploe vectors pointing towards those 4 oxygens. However, all of them cancel out me...

Sahaj Patel Lec3DisK

The lone pairs go on the equatorial axis since that is where the lone pairs will be most stable. Besides that, you won't need to know the details since that is out of the scope of this class. Just know if you have 4 atoms and two lone pairs on the central atom, it will be a seesaw molecular shape.

Sahaj Patel Lec3DisK

Try to go to as many step up, workshop, and review session possible. They will be reviewing a lot of stuff in those. If you have not already, do the textbook problems and if you have done them, I recommend to review them or redo them. Lastly, I would ask your TA for any tips/suggestions and if you m...

Sahaj Patel Lec3DisK

I usually workout in the morning and occasionally go on runs :) Also, bear-crawling, you should all try it is a very good full body exercise.

Sahaj Patel Lec3DisK

I am always worried about grades, and I bet most pre meds and college students in general can relate to this. Just take one day at a time, and always keep in mind there is a light at the end of the tunnel, as well as the fact that grades don't define. Your actions do.

Sahaj Patel Lec3DisK

As said before, the set up will be the same and there will be 16 questions on the midterm as well as an hour to complete it.

Sahaj Patel Lec3DisK

Always strive to have the most zeros throughout your molecule in terms of formal charges. You should always try to make your central atom have a formal charge of zero as well.

Sahaj Patel Lec3DisK

As stated, organic compounds are ones that contain carbon and are used throughout biology, like sugars (C6H12O6 for example). Inorganic compounds are all the other compounds you are used too seeing, like metals, salts, and different covalent compounds (like H2O).

Sahaj Patel Lec3DisK

Answering your second question, ions have a metal and a nonmetal (or more) bonded together, but covalent molecules have two (or more) nonmetals bonded together. I won't go into polarity of covalent molecules since that has already been discussed :/ Hope this helps!

Sahaj Patel Lec3DisK

Exactly what Kailani said! SO2 is an ion with a +2 charge, therefore since it can accept electrons it will be classified as a Lewis Acid. Alternatively, Lewis bases can donate electrons.

Sahaj Patel Lec3DisK

There are 16!

Sahaj Patel Lec3DisK

As said before, the general trend is that ionization energy increases from down to up and left to right on the periodic table. However, keep in mind that nitrogen has a higher ionization energy then oxygen and beryllium has a higher ionization energy then boron. Hope this helps!

Sahaj Patel Lec3DisK

The Schrodinger Equation shows the probability of finding an electron (which is what the "electron density" part of the equation refers to) in an the electron clouds of an orbital. Hope this helps!

Sahaj Patel Lec3DisK

I have heard the work load is somewhat the same, but the content is newer and not much of a review of highschool chem. Hope this helps!

Sahaj Patel Lec3DisK

When two molecules that contain ionic bonds interact with each other (such as salt with salt), that would be considered an "ion ion" moment.

Sahaj Patel Lec3DisK

Exactly what Darlene said, however the textbook questions and reading surrounding them are extremely helpful. Check those out!

Sahaj Patel Lec3DisK

Dr. Lavelle mentioned this when he went over the Schrodinger equation. The lecture which included this information is in Lecture 8 on October 19, 2020. Hope this helps!

Sahaj Patel Lec3DisK

You are confusing ionic bonds with H-Bonds. Ionic bonds are the bonds that form between a nonmetal and metal atom. Those are of course stronger than any intermolecular force. Any bond that forms between atoms will always be stronger than the bond formed between molecules in general. However, he said...

Sahaj Patel Lec3DisK

LDF are intermolecular forces that naturally occur between most polar (or induced molecules). They will always be present, however for certain polar molecules, in the moment they interact that moment of interaction is called a dipole dipole moment. Hope this helps!

Sahaj Patel Lec3DisK

Hi! We will not be needing to find those values, if anything they will be given to us. I believe that this equation will not be used for solving, but for conceptual use since the equation itself was never used in a problem during lecture.

Sahaj Patel Lec3DisK

Exactly what Evie said, just keep in mind the general trend and that will help you. However, remember that effective nuclear charge can play a role. For example, when comparing O+, O, and O-, the effective nuclear charge on O+ is higher then the rest, therefore it will have a higher ionization energ...

Sahaj Patel Lec3DisK

I am pretty sure the equation was for us to conceptually understand dipole moments and how it affects the polarity of a molecule. However, the units are in debyes, which is equivalent to coulombs*meters according to the equation (Dipole Moment = Charge * Distance between Atoms).

Sahaj Patel Lec3DisK

I assume you are talking about resonance in which there are multiple possible Lewis structures for the same molecule. In this case, the molecule will be a blend of these structures, in which the electrons that are part of changing double/triple bonds are delocalized, meaning they change their positi...

Sahaj Patel Lec3DisK

Yeah, unfortunately we cannot view our answers to the midterm, but he will be going over them during the final exam review sessions he'll be holding before finals week, and you can ask your TA if they can possibly go over it with you.

Sahaj Patel Lec3DisK

You want to get the structure to as close as possible to each atom having a Formal Charge equivalent to zero, therefore only having an O equivalent to -1 is the best possible option!

Sahaj Patel Lec3DisK

Yeah same, I recall him talking about higher subshells but they are way beyond the scope of this class.

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