CHEMISTRY COMMUNITY

Bryce Barbee

It depends on if the give you pressures or concentrations. I am pretty sure that you can use both if its a gas though.

Bryce Barbee

Total includes surroundings and system.

Bryce Barbee

Anode is left, cathode on the right

Bryce Barbee

Maybe there is a range of values that they use that allow you to receive credit

Bryce Barbee

I believe that the main use of the equation is to tell how K is affected by a change in temperature. That's how I've seen it used.

Bryce Barbee

This will tell you if the reaction favors products or reactants at equilibrium. If K is greater than 1, then more products are formed. If it is less then more reactants.

Bryce Barbee

Does anyone know how the material is going to be distributed for the final exam? Is it going to be mainly kinetics since that is the only thing we haven't been tested on yet or is it going to be even with all of the material?

Bryce Barbee

n is the moles of electrons so you need to balance out the redox reaction in order to see how many electrons are being transferred.

Bryce Barbee

I was told that it is anode/cathode when using this equation.

Bryce Barbee

Can someone explain the concept behind reducing and oxidizing agents. How do you determine which is which?

Bryce Barbee

The left is losing electrons but they have no where to go so they build up. This is why the negative charge increases.

Bryce Barbee

I don't think that cell potential is affected or based on the spontaneity of the reaction but I might be wrong. The cell potential is based on the difference between potentials of the products and reactants.

Bryce Barbee

During discussion, my TA would tell us which one was the anode and which was the cathode. I think it is based off of left and right usually though.

Bryce Barbee

Can someone explain the differences between galvanic and voltaic cells?

Bryce Barbee

N is found by finding how many electrons are being transferred in the process.

Bryce Barbee

W is found by doing the number of positions to the power of how many molecules there are. This does have some relation to resonance,

Bryce Barbee

Yes. I am pretty sure that it means that the reverse is spontaneous. If positive, then the forward is spontaneous.

Bryce Barbee

I'm pretty sure that it is always anode to cathode.

Bryce Barbee

I believe that it relates to if the process is spontaneous. If negative, then it is not spontaneous. If positive, it is spontaneous.

Bryce Barbee

I think he meant half reactions by separating the red/ox into reduced and oxidized parts. This means that you show which reactants in the rxn become reduced or oxidized in 2 different pieces.

Bryce Barbee

This is because delta S naught is the standard entropy of that reaction, therefore making it constant. We then have to include the temperature to show how the observed entropy can change depending on how you change the different parameters such as temp.

Bryce Barbee

I'm pretty sure that we only need to know the really common ones that we also use as examples and in homework problems. Only the ones that are constantly repeated will have to be memorized most likely.

Bryce Barbee

Just like with entropy, the knot on the delta G means that it is the standard for that reaction at standard conditions.

Bryce Barbee

This is because energy has to be conserved. Therefore, if heat is loss by ice when turning to water, then that equal amount of energy must be transferred to the water.

Bryce Barbee

What is this telling us? Is it showing a relationship between them or just showing what each of the variables represents?

Bryce Barbee

I think we only use it with reversible reactions but I am not 100% sure.

Bryce Barbee

One of the TAs just posted the slides from the thermodynamics review. I tried to attach it.

Bryce Barbee

I think with entropy it matters because one of the formulas only uses heat (reversible) divided by temperature.

Bryce Barbee

Does anyone understand how to do 4H.9 on the homework outline? It talks about 3 different containers being filled with gases of different descriptions and asks you to tell which one will have a higher entropy change when temp is increased.

Bryce Barbee

In that equation, the Work is equal to Work(on the system). Therefore work would be positive because the system is being compressed by the piston.

Bryce Barbee

This is because we are only looking at the changes in each and because both have the same step size, it does not matter which is used.

Bryce Barbee

Constant pressure means that deltaP=0 and constant volume means that deltaV=0.

Bryce Barbee

I dont think that we will use the integral equation. I think it is more to show that the Wby is equation to the area under a graph of pressure vs volume.

Bryce Barbee

What is the difference between qc and qv? Do you use both of the as enthalpy in a system?

Bryce Barbee

I believe in a problem it has to give you some sort of information that leads towards either using partial pressure or concentration. If it doesnt exactly specify Kc or P of something, but then gives you the moles of one of the final products, then you know that Kc should probably be used.

Bryce Barbee

I saw a Khan Academy video that explained this pretty well. The main idea of it was that if having 4 moles on the reactant side can turn into 2 moles on the product side, then you have less on the products. If you increase pressure by decreasing volume, you are making the space that everything is in...

Bryce Barbee

Can someone explain the relationship between Entropy and Enthalpy if there is one?

Bryce Barbee

Vapors have a higher enthalpy than liquids because once the temperature of the system, in a water model, hits 100 degrees celsius there is more heat that is required to change the water from a liquid state to a gaseous state. This is compared to when water is at a solid ice state and needs less heat...

Bryce Barbee

Both mean the same thing so it does not matter which one that you use.

Bryce Barbee

Yes this is what that means. If Q is less than K, then the reaction still needs to form more products at a higher rate than it is going towards reactants.

Bryce Barbee

I think it is because it is a liquid and liquids aren't included when you are using concentrations that have to do with K.

Bryce Barbee

Can Kc be used when working with only gases or is Kp the only equilibrium constant used?

Bryce Barbee

I was told that Kp can be used for gases and Kc can be used for aqueous solutions. I believe that Kc can be used for gases as well if given concentrations but I am also unsure about that.

Bryce Barbee

I believe that the only factor that affects the equilibrium constant is temperature. Other things can affect the value of Q, but the constant remains the same. I am not 100% sure though.

Bryce Barbee

When looking at it in a pressure sense, I saw something that was explaining it by talking about how the pressure of a gas can be changed and measured better than the pressure of solids and liquids. Can someone please explain to me how to ask a question on Chem Community. I cannot figure it out. Thanks

Bryce Barbee

Last quarter our homework was graded for completion I am pretty sure.

Can someone please explain to me how to ask a question on Chem Community. I cannot figure it out. Thanks

Bryce Barbee

I also believe that they should be the same but I am not 100% sure. I think they should be tho since the equations only have to do with the relationship between the ratios of Products to Reactants. Can someone please explain to me how to ask a question on Chem Community. I cannot figure it out. Thanks

Bryce Barbee

Q and K are essentially the same when it comes to calculating them. The difference is that K is the value when the reaction is at equilibrium while Q can be found at anytime during the reaction to see if the action is at equilibrium or not. Can someone please explain to me how to ask a question on C...

Bryce Barbee

I believe only gases are included when finding equilibrium constants.
Also, can someone explain how to ask a question on Chem Community? I cannot figure out how to. Thanks

Bryce Barbee

Ka is the concentration of products over reactants and pka is the -log of that.

Bryce Barbee

I think we just should memorize the strong acids.

Bryce Barbee

It is because there are 2 double bonds on the Sulfur and the two single bonded oxygens have a negative 1 charge.

Bryce Barbee

This is because even though S can expand its octect and have 3 double bonds, it rather just have 4 bonds and the oxygen wants the negative charge because of its electronegativity.

Bryce Barbee

The coordination number is 6 because there are 6 ligands attached to the centralized atom.

Bryce Barbee

This means that it can be either a acid (which donates a proton) or a base (which excepts a proton).

Bryce Barbee

I believe this is correct because the H+ fully dissoctiates from HBr and bonds with the H20.

Bryce Barbee

conjugates have a central atom with ligands bonded to that central atom.

Bryce Barbee

A conjugate is a compound made up of two or more compounds.

Bryce Barbee

Weak acids means that the there is not a full dissociation of H+ in water.

Bryce Barbee

To expand on what max said, test 2 only forces you to know that sigma bonds are single bonds and pi bonds are in double bonds.

Bryce Barbee

Lone pairs have a bigger cloud around them versus a bound atom. This pushes the other surrounding atoms slightly farther than a bound atom would normally making the angles smaller.

Bryce Barbee

The orbitals of the bonds are arranged side by side which makes it so that they cannot rotate amongst themselves.

Bryce Barbee

I do not think that this is one of the main ones that we need to know. I am not 100% sure tho so dont go by my word completely just to be safe.

Bryce Barbee

I am pretty positive that the ligand has to be the surrounding bound atoms.

Bryce Barbee

I would not worry about dashes and wedges because he did say to not worry about them.

Bryce Barbee

I think it is because the extra bond makes the molecule more stable.

Bryce Barbee

My TA said that it should be outline 4. So I'm thinking that it's VESPR and intermolecular bonds like van der wals and hydrogen bonds.

Bryce Barbee

I think that we probably just have to know the ones that were said in lecture.

Bryce Barbee

This isn't exactly answering your question but I have the tetrahedral angles at 109.5. For the trigonal bipyramidal shape, the trigonal bond angles are 120 and the axial bond angles are 90 and 180.

Bryce Barbee

How do we tell if the structure is going to be bent versus linear?

Bryce Barbee

I talked to my TA and he told me that the test should be pretty much bust all of outline 4 i think.

Bryce Barbee

It's because the more bonds, the closer the molecules will be pulled together.

Bryce Barbee

For this instance, Ep does stand for potential energy.

Bryce Barbee

I think molecules have dipole moments when one atom is more electronegative than the other, such as water.

Bryce Barbee

I used the video modules that he has on the class site for the first test and those felt like they helped me a bunch.

Bryce Barbee

Do we have to memorize all constants and equations for the test or will there be some formula sheet?

Bryce Barbee

Ionic compounds are from metals and covalent are non metals.

Bryce Barbee

I also believe that the way to do it is to get the charge closest to zero so that it is stable.

Bryce Barbee

Yea I am pretty sure it is theoretically but in an actual experiment, there could be outside factors and side reactions that take place that could change the actual yield.

Bryce Barbee

The H is the Hamiltonian which is just an operator that acts on the ψ. The ψ describes the system mathematically and E is energy. In the review, the problem that was used as an example basically just gave you the H and you had to plug it into the equation and not solve. I think we just have to know ...

Bryce Barbee

I just came from the one at 2pm and it was formatted so that he went over different topics and what they meant and then did a couple examples. It was helpful.

Bryce Barbee

Isoelectronic is when different ions have the same number of electrons. For example, Na+ is isoelectronic with neon.

Bryce Barbee

I am not 100% sure but i thought that the triple and double bonds are shorter in theory but when they were actually tested they were the same as the single bonds.

Bryce Barbee

I am pretty sure that you can put them anywhere as long as the formal charges are correct.

Bryce Barbee

This is because the more electrons, the more shells there will be and the more shells, the bigger the difference between the nucleus and the electrons.

Bryce Barbee

The formal charge of the atom relates to how stable it is because if it is zero then it has less of a chance to gain or lose an electron.

Bryce Barbee

Ionization energy is always positive because it requires energy in the system to remove the electron. If it was negative, that means that it is loosing energy.

Bryce Barbee

H BAR is refering to plancks constant and manipulates it when doing problems.

Bryce Barbee

I am not 100% sure but I am pretty certain that it does not matter where the light strikes because it still just depends on the intensity of the light and the energy in a photon.

Bryce Barbee

The H bar is referring to plancks constant when using it in problems.

Bryce Barbee

It does not make the electron eject because each photon needs to have enough energy to make the electron eject. If the photons don't have enough of the energy, having more photons is not going to help.

Bryce Barbee

The valence electrons include both because valence electrons mean all electrons in the outer shell.

Bryce Barbee

I am not completely sure why carbon was chosen but I assumed that it had something to do with the importance of carbon and it's relevance in life in general.

Bryce Barbee

This is because they believed that the higher the intensity the higher the energy but the intensity of the light did not matter if there was not enough energy in the photons that were with the wave.

Bryce Barbee

I feel like the safest way to do it is to keep your sig figs long throughout the problem and then round at the end in order to get the most precise answer like you said. That's what I've been doing and I feel like you can't go wrong that way.

Bryce Barbee

From how I understand it, the photons deliver somewhat of a "package" of energy that allows the electrons to jump to different levels.

Bryce Barbee

Yes, the light is transferring energy through photons in the photon model of the experiment. I do not completely understand what is happening in the wave model of the experiment though.

Bryce Barbee

I always write M1V1 as MiVi to help me remember that those are the initial volumes and molarity for the problems.

Bryce Barbee

I find it easy to think of moles when I think of them in something other than a chemistry example. When I think about them as strictly just being a unit of measurement for anything, such as fruit, then the idea becomes simpler.

Bryce Barbee

I know that Lavelle offers chemistry review sessions led by TA's that are pretty useful, especially for the highschool material.

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