CHEMISTRY COMMUNITY

Sreeram Kurada 3H

Temperature only affects k

Sreeram Kurada 3H

OH- would be used when the problem tells us the chemical rxn is basic, while H+ would be used if the problem told you that the chemical rxn was acidic.

Sreeram Kurada 3H

You wouldn't since water in this case acts as the solvent and wouldn't necessarily affect the concentrations of the reactants in the forward and reverse reactions.

Sreeram Kurada 3H

K would change to 1/K

Sreeram Kurada 3H

In the textbook problems and sapling, the units for Activation energy is in kJ/mol. So I would use an R constant of 8.314x10^-3.

Sreeram Kurada 3H

K represents the equilibrium constant while Q represents the reaction quotient.

Sreeram Kurada 3H

Typically if there is no solid electrode in the reaction, you would use Pt(s) as your electrode on both sides. I think the reason why they use Pt(s) is that it is non-reactive and won't influence the chemical reactions.

Sreeram Kurada 3H

mmol is mol x 10^-3. mmol and mole are pretty much the same thing but just different decimal points.

Sreeram Kurada 3H

You typically use the R-value in terms of joules so like 8.314. But like other people are saying, it really depends on what you are solving for.

Sreeram Kurada 3H

The higher the reducing potential, the stronger the oxidizing agent and vice versa.

Sreeram Kurada 3H

You could solve a reaction in a basic solution the same way as an acidic one, but once you get your balanced chemical equation make sure to cancel out the H+ by adding OH on both sides and rebalance the equation. I know this takes a little bit longer, but it is easier to learn one way rather than le...

Sreeram Kurada 3H

The Salt bridge's function is to equalize the charges (ions) on both the cathode and anode side of the reaction.

Sreeram Kurada 3H

Columb is nothing but a unit of measure. So a columb's si units would be joules/volts.

Sreeram Kurada 3H

Yeah they are since liquids and solids don't affect the chemical reaction. For example, H20(l) usually acts as the solvent, while a compound like C(graphite) usually remains as a solid. As a result, they are not included in the equilibrium constant or reaction quotient. However, it is important to k...

Sreeram Kurada 3H

Yes since this equation is under standard conditions. But there is another way to solve for E naught and that would be through Hess's approach.

Sreeram Kurada 3H

Yes since energy and matter can't be exchanged.

Sreeram Kurada 3H

Yeah only gases apply for Le Chatelier's principle.

Sreeram Kurada 3H

Cv and Cp are two different things. Cv is the ideal gas constant for constant volume, while Cp is the ideal gas constant for constant pressure.

Sreeram Kurada 3H

For this you look only at the gases. Since there is 1/2 moles of gas in the reactants side and 1 mole of gas in the products side, the molar entropy of CO is greater than the standard entropy of formation.

Sreeram Kurada 3H

The reason for this is because there are more monoatomic gas molecules than there are diatomic gases.

Sreeram Kurada 3H

Yeah, you would add 1 R if the problem stated it was a diatomic gas. Also, it is important to note that one the formula sheet, Cv and Cp are given for monoatomic gases, so when solving problems that ask for the entropy of a diatomic gas just make sure to add 1 R to your Cv or Cp.

Sreeram Kurada 3H

Entropy is not state-dependent, so the path taken (isothermal rxn or irreversible) doesn't matter. That's why you could use the same delta S for the b) as well.

Sreeram Kurada 3H

The standard entropy is just for the reaction at 49 C. You have to use the box method to find the standard enthalpy for the 25 C.

Sreeram Kurada 3H

Hi so my TA went over this problem in the discussion, and she told me that you have to look at the molecule from different viewpoints. For the cis-molecule, there are 2 viewpoints for each of the 6 molecules, therefore there is a total of 12 positions. For the trans-molecule, there are only 3 ways y...

Sreeram Kurada 3H

No, because this problem is looking more at the states of the molecules inside the containers than everything else. Container A has a monoatomic ideal gas and is subject to more disorder than a diatomic gas since there are more molecules to interact with the environment than a diatomic gas would. An...

Sreeram Kurada 3H

Here is what I got from the workshop.

Sreeram Kurada 3H

I think you might be able to get away like that, but I would just make sure to still make the ice table to confirm. Since there are different concentrations of these weak/strong acids and bases, the ph or poh would change.

Sreeram Kurada 3H

Yeah, the + means that the molecule is positively charged, and the - sign means that the molecule is negatively charged. This is useful when creating a reaction for acids and bases because you could easily see what the molecule would dissociate into when interacting with water.

Sreeram Kurada 3H

You wouldn't since they have different pkas.

Sreeram Kurada 3H

This means the enthalpy of the reaction through combustion. So you would need to put your molecule (x) in this format and balance it to get the reaction. X + O2 (equilibrium arrows) CO2 + H20.

Sreeram Kurada 3H

So for this problem you had to look at a table to see what alc3 would form. Al is kinda weird along with other metals in that it forms a polyatomic acid, so you would have to be given that information if on the test. The table you should look at is table 6d.1.

Sreeram Kurada 3H

I would just wait until he teaches them in lecture since you are more likely to confuse yourself while trying to learn by yourself.

Sreeram Kurada 3H

I listen to dubstep/gaming music when studying. It kinda helps make studying feel like a game for me, but I don't know whatever music motivates you to study, you should try that.

Sreeram Kurada 3H

I am pretty sure this question was wrong in the answer key. Your assumption is right, there are different # moles on each side. Since more moles of gas exist on the reactants side, an increase in pressure should shift the reaction to the right.

Sreeram Kurada 3H

Also the ka or kb must be given for you to set up the ice table. With that given you could solve for x and could get the concentrations of H+ ions, which you would -log to get the ph. Also, if you wanted to find the percent ionization, you would place (x/HA) * 100.

Sreeram Kurada 3H

The reaction quotient is basically the ratio of the products to reactants not at equilibrium (typically used when something new is added into the reaction). While the equilibrium constant is the ratio of products to reactions at equilibrium, or when the concentrations of products to reactants is con...

Sreeram Kurada 3H

You could also think of it this way. If there are a lot of people on one side of the room, and there are fewer people on the other side of the room, which side would you choose? More likely the less crowded side, right? This is the same way for gases. When volume decreases there is less space for th...

Sreeram Kurada 3H

The pressure is only important for gases. An increased pressure would favor the side with fewer moles of gases. Whereas temperature affects the equilibrium constant K. I don't know why yet, but he will teach us in the later weeks.

Sreeram Kurada 3H

The question would have to say the reaction is endothermic or exothermic, or (what is most probably going to happen) delta H is +, signifying an endothermic reaction, or delta H is negative, signifying an exothermic reaction.

Sreeram Kurada 3H

This difference is due to the place where heat is being added in the reaction. Because heat is in the reactants side for endo, when decreased reactants are favored. On the other hand, since heat is on the product's side for exo, when decreased products are favored.

Sreeram Kurada 3H

The reason for this is because the inert gas is not directly interacting with the reaction to form products or reactants. It is something that is just there.

Sreeram Kurada 3H

This means that you have to go to ccle to access sapling. If you go to ccle, you should see a link on the bottom of the site info that says sapling. If you click on that, it shall take you to the sapling page where you click on Lavelle, chem 14b, quarter 2, and use my credit. This then will register...

Sreeram Kurada 3H

Yeah, I think K is just a general term referring to the equilibrium constant, and Kp and Kc are specific into whether they are calculating for the equilibrium constant based on pressure or concentration.

Sreeram Kurada 3H

Yeah just play it on the safe side and write 50 comments for this quarter.

Sreeram Kurada 3H

If one of the positive numbers is greater than the initial conditions, then ignore it. You are basically trying to get positive equilibrium concentrations.

Sreeram Kurada 3H

Yeah, I think it is a typo. I ignored it and kept 0.494+x, and got the correct answer.

Sreeram Kurada 3H

Lesly, I did the same thing you did, and I got a different answer. When I kept your numbers into my calculator I got 0.0234. (0.12^2 x 0.06)/(.192^2)=0.0234.

Sreeram Kurada 3H

Oh, my bad my problem had different numbers, but yeah you are right. So kp would be (65^2)/(65^2*65).

Sreeram Kurada 3H

The reaction quotient would be 65\65^2 since the stoichiometric coefficient on the product's side is 1, while the stoichiometric coefficient on the reaction side is 2. So once u calculate that you would compare that to the equilibrium constant to see whether the reaction favors the products or the r...

Sreeram Kurada 3H

So basically Kp and Kc are both equilibrium constants and they don't have any units. The Kp is used when given the partial pressures of the gases, while the Kc is used when given the moles or concentrations of a molecule. The gas equation is not necessary for this concept, but simply put it explains...

Sreeram Kurada 3H

Yes, since the format of the final is exactly the same as the midterms. Plus, I think my TA said that there will not be partial credit on this exam, but I don't know for sure.

Sreeram Kurada 3H

To find the ph you would do -log[H+]=6.10. Then to find the poH, you would subtract the pH from 14=7.89. Lastly, to find the concentration of [OH], you would do 10^-poH=1.27x10^-8.

Sreeram Kurada 3H

KOH is a strong base since it has OH.

Sreeram Kurada 3H

For week 10 sapling questions #13 and #14, how do we determine whether the predominant species is neutral or charged. For both of the questions, the reactions were neutral, but both questions had different conditions such as when the ph was greater than the pka for #14 and where the pka was greater ...

Sreeram Kurada 3H

A general rule of thumb is to use m instead of nm for solving for photoelectric effect problems or de brogile problems. However, when you are solving for atomic spectra type of problems, you should be using nm.

Sreeram Kurada 3H

I have also been using the sapling chart to determine whether a particular compound was a strong acid/base or weak acid/base, but also another thing that I picked up from the sapling problems was that if the cation of the molecule is from a strong base and the anion is from a weak acid, the molecule...

Sreeram Kurada 3H

It's more of a preference than anything. Since O is the electronegative atom, people might write water that way to illustrate that the bonds are occurring from the oxygen rather than the hydrogens.

Sreeram Kurada 3H

pH is the concentration of H+, while pOH is the concentration of OH-. You could also see that pH is the opposite of poH. So if you are given the pH value and you want to find the pOH value, you subtract pH from 14 to get pOH.

Sreeram Kurada 3H

In this case, the electronegative atom pulls the delocalized electrons, which creates more stability in the anion, which then creates a stronger acid. So even though Br might be a more stable atom, it doesn't make the whole entire molecule stable, and that is what we are looking for in this problem.

Sreeram Kurada 3H

I would recommend doing the practice problems in the TB, UA worksheets, and going to the UA review sessions for the topics that you are still confused about.

Sreeram Kurada 3H

Yeah nonpolar molecules have dipole movements that are canceled out equally around the central atom.

Sreeram Kurada 3H

The lone pairs distort the shape, making what seems like a tetrahedral structure trigonal pyramidal.

Sreeram Kurada 3H

Hybridizations depends on the number of electron densities surrounding an atom. So in this case, since there are three electron densities surrounding the carbon (2 single bonds and one double bond), the hybridization would be sp2 (3-1=2: subtract the # of electron densities by 1 to get the hybridiza...

Sreeram Kurada 3H

Lewis acids accept electrons, while lewis bases donate electrons. Typically, you see cations to be lewis acids, while big molecules such as NH3 to be lewis bases.

Sreeram Kurada 3H

Since noble gases are already stable, they don't need more electrons to be added even if the noble gases have a d orbital.

Sreeram Kurada 3H

In the syllabus, the grade for an A+, A, and A- is not listed. Out of 500, what is an A+, A, and A-?

Sreeram Kurada 3H

The more lone pairs there in proximity to a bond, the smaller the bond angle would be.

Sreeram Kurada 3H

Polarity would be a characteristic of ionic bonds since there is a dipole movement, which ionic molecules such as NaCl has with the dipole movement from the Na going to Cl.

Sreeram Kurada 3H

Lone pairs typically have the highest repulsion since there are no electrons being shared, while bonded pairs typically have the lowest repulsion since the electrons are being shared. Therefore, two lone pairs have the highest repulsion, followed by one lone pair, and bond pairs have the least repul...

Sreeram Kurada 3H

Yeah, each column is +1 valence electron, that is until you go to the column that has carbon. Then after carbon, the columns after that go from -3 to 0 formal charge.

Sreeram Kurada 3H

No, I think that final will have content from midterm 1 and midterm 2 equally.

Sreeram Kurada 3H

The bigger the atoms the greater the chance the electrons of the atoms have in interacting with each other, which as a result leads to stronger LDF forces.

Sreeram Kurada 3H

Yes, you are correct, this is an inherent problem in lewis structures. Because of this problem, formal charges come into place.

Sreeram Kurada 3H

An effective nuclear charge is a total pull the nucleus has on electrons accounting for electron repulsions.

Sreeram Kurada 3H

The larger the atom the more chance individual electrons could interact with each other. As a result, the LDF forces between these electrons is greater.

Sreeram Kurada 3H

Pretty much they are the same thing, but the subtle difference between them is that electronegativity is the pulling power of individual atoms, while electron affinity deals with atoms in a molecule.

Sreeram Kurada 3H

The overall formal charge is the sum of all of the individual formal charges of the atoms in the molecule.

Sreeram Kurada 3H

Instead of taking bio and chem at the same time, I would recommend completing your GEs, as two science classes could be a lot of work.

Sreeram Kurada 3H

I have been practicing daily mindfulness every morning by running in a nearby park. This helped me release all my energy, so once I got home I could concentrate on my school work.

Sreeram Kurada 3H

Formal charge is used to accurately map the geometry of a compound, accounting for the bond length and extra electrons on the atoms.

Sreeram Kurada 3H

An easy way to remember this is to picture ionization energy, electron affinity, and electronegativity as the same thing, and how going across a period from left to right leads to an increase, while when you go from bottom to up a group leads to an increase in IE, EA, and E and vice versa.

Sreeram Kurada 3H

Yes since the formal charge is for lewis structures, and lewis structures are made to map the bonds of the atoms in a compound.

Sreeram Kurada 3H

The reason why atoms that have high electron affinity release energy is because they are so attracted to their electrons that if one of the electrons is taken away energy used to hold that atom is released.

Sreeram Kurada 3H

Basically use Avogadro's number whenever you are trying to convert to moles or from moles into individual particles of the substance.

Sreeram Kurada 3H

You have to know that they are different classification of atoms, meaning the electrons in these atoms are arranged in different ways giving them unique properties. The difference between the 3s and 2s orbital is that the 3s orbital has an extra shell of electrons.

Sreeram Kurada 3H

Yeah I would continue doing the same thing you are doing right now since it is much easier to balance the chemical equation.

Sreeram Kurada 3H

Depending on the equation I am using, I would try to make sense of how that equation was derived. This then would clarify whether v is frequency or velocity. For example, de Broglie's equation is based on the momentum of the electron so I would think of that v as velocity, while in the speed of ligh...

Sreeram Kurada 3H

Why is the 3d orbital lower in energy compared to 4s?

Sreeram Kurada 3H

Debrogile's equation is used to find the wavelength and momentum of small objects such as electrons, protons, and neutrons, while the speed of light equation is used to find the wavelength and frequency of light.

Sreeram Kurada 3H

Increasing amplitude increases the number of photons being released, which doesn't change the frequency of the photons since photons are individual particles. So no, increasing amplitude doesn't increase the frequency of the wave.

Sreeram Kurada 3H

I don't think the type of scratch paper you use matters. The scratch paper is for you.

Sreeram Kurada 3H

To be honest I would just use 41000 since you really can't do anything about it.

Sreeram Kurada 3H

My advice is to do as many practice problems as possible. Do the post-assessment modules, textbook problems, and UA worksheets. However, if you feel good in a topic already, then just move on to practice problems that you are not good at practice those instead. I think somewhere he said that the mid...

Sreeram Kurada 3H

Yes the answer is 150pm. You could check your answers on sapling btw. It's in the homepage of sapling titled Atkins_7e_SSM. Yeah, I would basically plug and chug into that equation.

Sreeram Kurada 3H

Like Sandra said, I'm sure we don't have to memorize any formula's or constants, and we could have a print out of the material. However, what I would recommend using is the periodic table and formulas he has on his class website.

Sreeram Kurada 3H

The way I'm studying for this class is by watching the lectures and doing the textbook problems. If I don't get any of the textbook problems I usually go over them with a study group I'm in. But if you don't have a study group, I would just go to the step up and UA sessions.

Sreeram Kurada 3H

The minus sign means energy is being released in the form of electromagnetic radiation.
The positive sign means energy is being absorbed in the form of electromagnetic radiation.

Sreeram Kurada 3H

Yes they are the same thing. The work function is used to mathematically model the threshold energy.

Sreeram Kurada 3H

A good rule of thumb is to use 4 sig figures unless the question states otherwise. Hope this helps :)

Sreeram Kurada 3H

Idk about the online software we are going to use yet, but I know that they are going to be taken with our TAs.

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