CHEMISTRY COMMUNITY

LorenzoDuvergne3I

What else was discussed today? I unfortunately couldn't make it because I was feeling ill.

LorenzoDuvergne3I

There is no "curve", but he does adjust what an A is. Last quarter, the requirement for an A was not a 93. I don't remember what it was exactly but hopefully that trend carries over to this quarter. Fingers crossed.

LorenzoDuvergne3I

From what I've seen, you cancel everything out that appears on both sides. Is B supposed to be the enzyme?

LorenzoDuvergne3I

I don't think they really carry any significance other than showing that your end units are always going to be mol/L/s, and k's units are going to be designed to cancel out any units for the other terms so that your end result is mol/L/s.

LorenzoDuvergne3I

Were any of the other terms mentioned in lecture today?

LorenzoDuvergne3I

In that particular case I think it is because one of the reactants does not affect the rate law and so you only have to worry about keeping the other two constant.

LorenzoDuvergne3I

E is a measure of how easily something is reduced. So if the value is very high (positive), it means that it is a good oxidizing agent because it is reduced with little effort and the electron it loses can be used to oxidize something else. If it is very negative, it is a good reducing agent because...

LorenzoDuvergne3I

I think it has something to do with the fact that you are going from Ti3+ to Ti (Since standard potential is written in the form of reduction), so instead of forming Ti3+ you are returning it to its standard form and have to change the sign. Not sure though.

LorenzoDuvergne3I

Yes, it is. The forward reaction would be an electrolytic cell while the reverse would be a galvanic cell.

LorenzoDuvergne3I

Gibbs is made up of enthalpy, entropy, and temperature values, all of which are state functions. If you have a combination of state functions, the result I guess is also a state function.

LorenzoDuvergne3I

Cell diagrams always write the left portion of the battery, the anode, first. So, our product has to have silver in a state with a higher charge (Anode has the oxidation reaction). If Ag is becoming AgI, its charge goes from neutral to +1. As a result, we know that AgI has to be our product. Hope th...

LorenzoDuvergne3I

Hi, I'm having issues with this problem as well. I think it has to do with the fact that if you add an electron to AgBr, Br is the one more likely to receive it since it's a halogen and thus more electronegative. If you flip that reaction, you have an oxidation reaction where Ag loses an electron. I...

LorenzoDuvergne3I

I feel like Gibbs is really just a couple of equations (deltaH-TdeltaS, standard Gibbs, Van't Hoff, etc.) while a lot can be asked about electrochemistry (Balancing redox equations, drawing a battery, explaining the use of inert metals/salt bridges, finding the voltage, etc.). That's just my opinion...

LorenzoDuvergne3I

Endothermic reactions cannot have a positive enthalpy because they need energy to occur, which bars them from being spontaneous.

With regards to the graphs I don't have any answers about that :(

LorenzoDuvergne3I

I have a feeling that it has to due with the fact that the universe is a constantly expanding isolated system. There's a limited amount of matter (Since it can't be created or destroyed) occupying an increasingly large volume, which would naturally offer more space for matter to occupy, thus increas...

LorenzoDuvergne3I

Where is this discussed in the textbook?

LorenzoDuvergne3I

It is important to remember that while diatomic molecules like O2 have a standard enthalpy of formation of 0, they nevertheless have bond enthalpies.

LorenzoDuvergne3I

Is H/T used for every state other than constant pressure? I'm confused about when to use one over the other.

LorenzoDuvergne3I

You would need the moles of the products and reactants to solve the problem, not the k value. The side with less moles is favored in the long run so long as the compression is really from a change in pressure and not the addition of an inert gas.

LorenzoDuvergne3I

I am guessing that yes it is since calorimeters are isolated systems (They are closed and insulated).

LorenzoDuvergne3I

The thermos is always a good example, but all an isolated system really is is an insulated closed system. So you could theoretically take any closed system (like a gas tank), insulate it, and create an isolated system

LorenzoDuvergne3I

Can you please explain how you know those values? Are they listed somewhere in the textbook?

LorenzoDuvergne3I

In both instances you use the q=n*c*delta t, but the constant for c varies whether you're keeping pressure or volume constant.

LorenzoDuvergne3I

If heat capacity is an extensive property, is there any point in using it? Why would we need to know/consider it when specific heat capacity is fare more useful?

LorenzoDuvergne3I

Why are both measured per mole?

LorenzoDuvergne3I

It should be noted that the other two methods also require some sort of given information, either the enthalpies of formation or the enthalpies of each reaction, so which method you use depends on what information the problem gives you.

LorenzoDuvergne3I

Seeing how it's the material we are covering this week, I think that would make the most sense.

LorenzoDuvergne3I

It seems like it is just the easiest to make uniform and work with for any non quantity dependent property of the gas/solution.

LorenzoDuvergne3I

Q is essentially the same thing as K, just not at equilibrium, so yes it should be the same formula. Does anybody know if it will be given to us?

LorenzoDuvergne3I

I also got about 5. I think it is because of a misplaced parentheses between the first and second reactants since your number is higher than what it should be. Make sure it is
(7.516E-5)^2/
(3.3672E-5)^2

LorenzoDuvergne3I

A ligand is anything that binds to a transition metal like Cobalt, copper. etc. Examples of ligands are water, ammonium, and cyanide
The way this happens is by forming a coordination covalent bond, where the 2 lone pairs of a ligand are shared between the metal and the ligand. Hope this helps

LorenzoDuvergne3I

Aqua is just the abbreviation for OH. I've looked at previous chemistry community posts and there seems to be some debate as to whether the oxalate (c2O4)2 or (OH)2 goes first, but I personally think it makes more sense to write the anion (OH) next to the ferrate since they're the two charged molecu...

LorenzoDuvergne3I

The list of homework questions for the acids and bases unit includes a question that asks you to name acids based on their structure. But like the previous answer states, the naming rules are unique to acids and bases. Since it hasn't been touched upon in lecture, I am going to assume it will not ap...

LorenzoDuvergne3I

That topic hasn't been covered in lecture and as a result shouldn't be a concern since it shouldn't appear on the final

LorenzoDuvergne3I

I also don't understand where that sqrt(2) comes into play

LorenzoDuvergne3I

Induced dipole-induced dipole is the weakest since the molecules aren't polar, the size of atoms creates some distortion and weak dipoles. Dipole-dipole is stronger because it is between molecules that are both polar and thus have stronger dipoles. The solid phase is stronger because a strong interm...

LorenzoDuvergne3I

As the cloud gets larger and easier to distort, it becomes more polarizable as polarizability is defined by how easily the valence electron cloud can be distorted. Dipoles and polarity are characteristics of covalent bonds, and so I'm guessing higher polarizability leads to the bond having some sort...

LorenzoDuvergne3I

It could be fair game since we covered the structures of sp3d and sp3d2 in class (trigonal bi-pyramidal and octahedtral), but I wouldn't know for sure

LorenzoDuvergne3I

BaBr2 is more ionic because of the electronegativity difference as well. Ba is way larger in than Be, and so it is less electronegative; as a result, the difference in Ba's electronegativity and Br's is larger.

LorenzoDuvergne3I

The structure with carbon being triple bonded to nitrogen allows for both carbon and nitrogen to have a formal charge of 0. N would have a FC of -2 if it was single bonded to C.

LorenzoDuvergne3I

I think it'd be safe to assume that we're gonna have to draw it as an Aufbau diagram, but I couldn't tell you whether we're gonna have to draw a molecule showing the sigma and pi bonds. Just remember that single bonds are always sigma and double/triple are pi.

LorenzoDuvergne3I

The 2p is not hybridized. The reason we use the 2p orbital is because the repulsion energy between two electrons is larger than the energy gap between the hybridized orbitals and the 2p orbital. That electron has to go somewhere because carbon has 4 valence electrons. That electron is also the one u...

LorenzoDuvergne3I

Can somebody explain why the energy for bonds is always negative? Does a negative energy always imply an attractive force?

LorenzoDuvergne3I

From what I understand we will only be given them, but if they are given we can determine bond lengths for molecules that have resonance. We saw this on the midterm with the length of a regular N-O bond and a double N-O bond. Given those two lengths we can find the length of the bonds in a structure...

LorenzoDuvergne3I

Where in the textbook did you find information about sigma and pi bonds? I don't think we've covered them in lecture yet

LorenzoDuvergne3I

When you remove electrons from an atom, the first ones that go are in the valence shell. In the case of Cadmium that would be the 5s electrons rather than the 4d electrons. Hope this helps!

LorenzoDuvergne3I

I don't think we've covered the shape of molecules in class so far, so maybe there's an optimal position for them but I don't know how to determine it. I'd love to know if there is one though

LorenzoDuvergne3I

Similar to how regular acids and bases are electron recipients and donors respectively, Lewis acids are molecules that do not have a full valence shell like H+ that when bonding receive a pair of electrons to fill it up whereas Lewis bases like NH3 have an extra pair of electrons to donate when form...

LorenzoDuvergne3I

Why is it that the equation for electron affinity is written E(x)-(E(x-) rather than the reverse? Pretty much every other form of measuring change takes the final product and subtracts it from the initial, not the other way around.

LorenzoDuvergne3I

Ionization energy is the amount of energy needed to remove an electron from an atom. Atoms that form cations have lower IE because they want to give away their electrons, which requires less energy. Electron affinity is the energy released when an electron is added to an atom. In simple terms, atom...

LorenzoDuvergne3I

Does the energy of an electron change if the value of n does not change? Eg if it goes from the 2s to the 2p orbital

LorenzoDuvergne3I

If I remember correctly I don't think this correlation was known when the periodic table was made, it just happened to be organized for it to have that property. I looked online and the study of orbitals happened in the 20th century while the periodic table had been around since 1869. Each group has...

LorenzoDuvergne3I

Atomic spectroscopy is the study of how e-m radiation interacts with atoms and molecules, while molecular spectroscopy is the same study but with properties unique to molecules. Atomic spectroscopy can only tell you the composition of the atom/molecule while molecular can be used to study molecule-s...

LorenzoDuvergne3I

Spin is the property of an electron so it doesn't indicate anything about the orbital. All it does is say whether whichever one of the orbital's two electrons is spinning up or down.

LorenzoDuvergne3I

Duby3L wrote:When talking about the incoming light that matches the energy difference are the words light and frequency used interchangeably?

The frequency of the wave determines the type of light the e-m energy is, so in that sense they can sort of be used interchangeably.

LorenzoDuvergne3I

Soyoung Park 1H wrote:What does a photon of energy mean?

A photon is the smallest measurable unit of electromagnetic energy (light)

LorenzoDuvergne3I

It might be short for excess energy, since the energy of the photon (e=hv) minus the energy threshold (work function) is the remaining energy that is converted into kinetic energy by the electron.

LorenzoDuvergne3I

In question M7, the problem requires for us to find the formula of boron oxide. Because boron has 1 valence electron and oxygen is missing 2 from its outermost shell, I assumed it was B2O. When checking the answer, however, the formula obtained by the book was B2O3. After googling why, I read that B...

LorenzoDuvergne3I

You may have the molar masses of both elements confused with one another. Gallium's is 70 g/mol and astatine's is 210. Because astatine is three times as heavy as gallium, we only need one astatine atom per gallium atom. The scale has 9 gallium atoms, so we need a third as many astatine atoms. 9*(1/...

LorenzoDuvergne3I

Is there any particular reason why in the textbook most units that are one unit over another (Eg molar mass being grams/mol) are written using exponents (Using the same example molar mass being grams*mol^-1)? It seems unnecessary and I'm wondering if there is a reason why the / sign is avoided or wh...

Search found 60 matches