CHEMISTRY COMMUNITY

Albert_Luu3K

More positive E value means it will have a higher oxidizing power.
More negative E value means it will have a higher reducing power.

Albert_Luu3K

The transition state of a chemical reaction is a particular, short lived configuration of the reacting atoms along the reaction coordinate. It is defined as the state corresponding to the highest potential energy along this reaction coordinate.

Albert_Luu3K

I feel as if there probably is, but Pt(s) is what we've been taught and told to use. So I wouldn't worry about knowing other possible inert electrodes.

Albert_Luu3K

The unique rate of a reaction is not the same as the differential rate law. Check notes from last Friday because that's when we learned about the unique rate of a reaction. Also on page 613 of the sixth edition textbook, they introduce the unique rates. Hope this helps!

Albert_Luu3K

Hi Shirley! I can understand why this may seem confusing upon first glance because it may seem that the 2 in front of [O2] means that it's increasing two times as fast (or at least that is how it confuses me sometimes). I just think of it this way: since [O2] increases half as fast [NO2] and in orde...

Albert_Luu3K

Usually, one would have to flip the anode reaction! That is because the anode side is always an oxidation reaction where electrons are always on the products side being given off. The cathode/reduction reaction should have electrons on the reactants side. Then, you will have electrons on either side...

Albert_Luu3K

Yes, when writing out cell diagrams, the anode should be the left of the salt bridge and the cathode should be to the write of the salt bridge. This convention also works with porous discs/walls as well.

Albert_Luu3K

Yes, you do! An inert electrode such as Pt is necessary for gas/ion electrode reactions.

Albert_Luu3K

Delta G is the change of the overall free energy, whereas delta Gr is the change of free energy of a reaction. I guess both could mean the same thing depending on the context of the question. Do you have an example of where you are seeing both being used?

Albert_Luu3K

What I would is make sure all the half reaction reduction potential numbers are coming from similar set up equations, meaning that make sure all the equations start off with same neutral element and it goes to the same oxidation state. For example Fe^2+ + 2e- --> Fe and Cu^2+ + 2e- ---> Cu. That mak...

Albert_Luu3K

For that instance, my TA Jack Fuller said that they are both interchangeable, since they're the same state. If the one of them was a solid and the other aqueous, the solid would be closer to the electrode (outside) and the aqueous would be closest to the salt bridge. Hope this helps!

Albert_Luu3K

From looking at the cell diagram, you should be able to determine which is the anode and the cathode. Once you figure that out and you figure out the half reactions of those molecules, you can search up the E cell / reduction potential of each half reaction. With that information, you should be able...

Albert_Luu3K

For elements like O2 and Cl2, they will always have an oxidation state of zero because they are neutral diatomics. One oxygen atom can't be a negative 2 charge and the other atom be a positive 2 charge. If the elements are solids, liquids, or it is some sort of diatomic molecule, the oxidation state...

Albert_Luu3K

What Meachelle said above hits the spot perfectly. We will not be expected to know all of the oxidation states of elements, but know a few general rules for certain columns in the periodic table will help definitely.

Albert_Luu3K

I believe from what we learned in class so far, it should be. Knowing that a galvanic cell should have a positive potential difference can help you figure out which side is the cathode/anode and what species are being oxidized or reduced.

Albert_Luu3K

Remembering the difference between being oxidized and being the oxidizing agent AND being reduced and being the reducing agent can be confusing.You just got to remember that if a molecule is being oxidized, then it is the reducing agent because it is the one losing and transferring the electrons ove...

Albert_Luu3K

Oxygen is not being oxidized here. It remains (-2) on both sides. Carbon is being oxidized here.

Albert_Luu3K

I was stuck on this problem for a while as well! I believe that there's a typo in the problem. It should be Cl2 (g) ---> HClO (aq) + Cl- (aq).
Hope that helps! That would the answer looks like it came from in the solutions.

Albert_Luu3K

What Jonas said was spot on. The safest bet is to write out the half reactions, balance them, and combine them to see what the total number of electrons that cancel out each other is because that is your n. But you can also use your intuitition if you look at the equation they give you. See how much...

Albert_Luu3K

What Subhani said above is correct. I would just write the balanced half reactions and combine them to see what the number of electrons that cancel out each other is. That is your n. Hope that helps!

Albert_Luu3K

I was staring at this problem too, but I believe there's a typo in the problem. It should be Cl2(g) ---> HClO(aq) + Cl-(aq). Hope that helps you solve it!

Albert_Luu3K

For the reduction, you should end up with : 12e- +12H2O + P4 ---> 4PH3 + 12OH- You got the start correct but you just got to keep going and trying out different things to balance. First I saw that there were 12 H on the right side, so I needed to balance that. All I can add is H2O to add more H but ...

Albert_Luu3K

Not sure if I understand your question, but you should look at both! For example if 2Ce^4+(aq) --> 2Ce^3+(aq), then n should equal 2. Even though one electron was needed to lower the charge, there were two moles of the ions.

Albert_Luu3K

I believe you have to look at each couple's reduction potential. The couple that has the more positive reduction potential will be the one being reduced aka the oxidizing agent.

Albert_Luu3K

I wouldn't be surprised if it is included on the test. An example of this is the reaction of chlorine in water: Cl2 (g) -> HClO(aq) + Cl-
Cl2 acts as the oxidizing agent and reducing agent.

Albert_Luu3K

Here you go, this is what I got.

Albert_Luu3K

Why is deltaG at equilibrium equal to zero?

Albert_Luu3K

Usually if the charge is not given, that means the molecule is a neutral charge (0). Using that knowledge, you should be able to use the periodic table to find the oxidation state of one of the elements and deduct the oxidation state of the other.

Albert_Luu3K

What do you do if the solution is basic? Adding OH- would add more oxygen and hydrogen.

Albert_Luu3K

H+ is better because it's easier to write and you might get H3O+ confused with H2O.

Albert_Luu3K

Given the molarity and volume of the basic solution, you find the concentration of OH- ions. With that information, you can find the pOH and subtract that from 14, and you will have the pH. Hope this basic skeleton of how to solve it helps. Basically find out how many moles of the molecule there is ...

Albert_Luu3K

Salts are basically just ionic compounds such as NaCl. They raise or lower pH by ionizing in solution and either creating more hydronium or hydroxide ions. An example of an acidic salt would be NH4Cl. In solution, the NH4 would donate its H proton to H20 creating H30+. more acidic!

Albert_Luu3K

Yes it is asking for pi and sigma as well as the hydridization. There is an example given of what they are asking for: sigma(C2sp^2, C2sp^2).

Albert_Luu3K

It is a strong acid because it fully ionizes and dissociates in water. That means there are more hydronium ions in solution making it more acidic.

Albert_Luu3K

NaOH is a strong base because it fully dissociates in water. That means there are more OH- ions floating in solution making it more basic.

Albert_Luu3K

This is what Lyndon did to himself for one of the problems in his review session, but NO it is not needed to know how to do for the final.

Albert_Luu3K

I think it'll be useful to have memorized for when you encounter any problems with naming. Do enough practice problems and the names should be committed to memory.

Albert_Luu3K

I think for almost all the reactions we've worked with, NH3 acts a Bronsted base because it accepts the proton.

Albert_Luu3K

You can know what type of intermolecular forces a molecule goes through by know its shape and polarity. By knowing that there is a dipole in a molecule, you will know that opposite dipoles of molecules with attract.

Albert_Luu3K

Not sure if there are any exceptions to this trend, but it might be a good idea to take a quick look at the electronegativity periodic table. You'll be able to see for yourself the electronegativites of each element and be able to see the trends.

Albert_Luu3K

I believe including the angle would be enough since that would specify which bent shape it is.

Albert_Luu3K

I'm not sure about the textbook, but there's this sheet on Professor Lavelle's website:
https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf

Albert_Luu3K

Oh okay, I was just overthinking it. Thank you!

Albert_Luu3K

If you need help visualizing cis vs trans, take a look at the molecules cis-dichloroethene and trans-dichloroethene!

Albert_Luu3K

In 6th edition textbook, question 4.43, it talks about s-character in regards to hybridization. What is s character?

Albert_Luu3K

Hello, The way I imagine trans/cis molecules is that there are two different lewis structures that the molecule would be. To differentiate, which lewis structure is correct and what the molecule they are asking for is, trans or cis is added to the front. Cis molecules like cis-dichloroethene are pol...

Albert_Luu3K

Very interesting, Melissa. I googled this phenomenon, and it says that this is the electron configuration because experiment has shown. Our usual methods don't apply to this Pd because it's an exception due to what has been found in experiment. I doubt this we will need to know this. We'll only need...

Albert_Luu3K

First, use the 2.111g Na2CO3 and the 250.0mL and find the molarity. I got .07980mol/L. For part a, take the 2.15mmol Na+ ion and convert into moles. There are two Na+ ion per Na2CO3 molecule, so using dimensional analysis you find out how many moles of Na2CO3 you need. Using the molarity we found, w...

Albert_Luu3K

Thank you so much, Lyndon. These are going to help me a lot as I'm last minute cramming.

Albert_Luu3K

What Ana said above is correct. Adding another electron to the outer shell would increase the electron to electron repulsion, thus making the shell and atomic radius increase ever so slightly.

Albert_Luu3K

I'm not sure if they can just go anywhere. Just make sure the dots/electrons are paired up and the sides surrounding the atom (where there's not a bond).

Albert_Luu3K

The way I'd rationalize this is knowing that electron affinity, or the energy being released after an electron is added to a neutral atom, is opposite to ionization energy. It takes energy to be put in to break the bonds and release an electron from an atom, so it would only make sense that energy w...

Albert_Luu3K

I remember learning this somewhat in AP Chemistry. The way that I'd rationalize it is that Nitrogen's orbital is half filled. They are all spinning the same way. Orbitals that are completely filled as well as half filled are relatively stable. Of course the fully filled orbital is more stable than t...

Albert_Luu3K

We need to know the difference because the topic of electron configuration will be a large topic to be discussed later. We will probably be asked later to figure the different orbitals and shapes of different things.

Albert_Luu3K

I think there is a relationship between the two because for a bond length to be shorter, there needs to be more bonded electrons between the two. The energy is bond will be higher with more bonded electrons because it will take more energy to break the bond since the bond is shorter and stronger.

Albert_Luu3K

I can't seem to get the correct answer for part b. I converted 3.500x10^3 kg Al to g and then to moles by dividing by its molar mass. Then I used molar ratios to find out how many moles of Al2O3 is made, turned that to g and then to kg. My answer doesn't seem to match. Am I making any wrong steps?

Albert_Luu3K

Even though we'll be given molar masses from the periodic table, it doesn't hurt to memorize some of the more common elements! After doing a whole bunch of practice problems, molar masses of common elements used will just be ingrained in your memory. Oxygen, Carbon, Hydrogen, and Nitrogen are nice o...

Albert_Luu3K

The previous reply already explained what black body radiation is, but I believe during lecture that Professor Lavelle said that we don't need to worry ourselves with knowing and remembering about what black body radiation does because we will not be tested on it.

Albert_Luu3K

Dear friend, There is a beautiful computer website and even smartphone application called Quizlet! You are able to make flashcards for anything and test yourself anywhere at any time as long as you have your mobile device or computer. There are even games and tests that Quizlet can do for you. The b...

Albert_Luu3K

Dear Michelle Bui, I also had trouble with this question because my answer was always far off from the actual answer. Soon I came to realize my mistake. You start off by multiplying Avogadro's number to the amount of moles of Ag to the get the number of atoms you have in the fiber. Once you have tha...

Albert_Luu3K

Hello dear classmate, Your method of solving the problem would exactly what I would do. The beautiful thing about chemistry is that there are multiple ways about solving a problem. However, there is a mistake in one of your steps which is why your answer is off from the solutions manual. When you mu...

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