CHEMISTRY COMMUNITY

Hammad Khan 2B

Chemistry Joke

Hammad Khan 2B

What is a physical chemists favorite show?
Law and Order

Hammad Khan 2B

From what I understand it’s just the number of reactants forming to a product. But I don’t think we went over moleuclarity as it applies to intermediate products. How would we calculate that?

Hammad Khan 2B

I’m guessing that half life of a zero order reaction would be itself?

Hammad Khan 2B

From what I understand, it’s because with a catalyst it increases reaction rate but after increasing reaction concentration we get to a point where and increase in concentration doesn’t change reaction rate. So it’s kind of like reaching the maximum reaction rate and not going any faster.

Hammad Khan 2B

We can also use the k constant to narrow it down to what order it might be. 0 and 1storder have negative k constant and 2nd order has positive k constant.

Hammad Khan 2B

When the reaction is balanced then E is usually the same.

Hammad Khan 2B

Anode is usually not the left side and cathode on the right. Anode is also usually being oxidized and cathode is being reduced.

Hammad Khan 2B

You should at least know how to derive the Van't Hoff equation and how to get work for an reversible process.

Hammad Khan 2B

How would you use the equation to solve for pressure?

Hammad Khan 2B

Cv with constant volume and Cp with constant pressure.

Hammad Khan 2B

I too would like to know if this is possible.

Hammad Khan 2B

I would assume it to be on Electrochemistry exclusively as we have just started it and it on 2/20/18

Hammad Khan 2B

I don’t really grasp the concept of what a faraday is and what it is used for. If anyone can help elaborate that would be great.

Hammad Khan 2B

With this, entropy approaches near zero and such that there is only the vibrational motion of molecules and no movements around. Meaning that we know exactly where molecules are.

Hammad Khan 2B

Meaning that the degeneracy of the process is also 1 meaning that we can calculate exactly where molecules are in a perfect crystal.

Hammad Khan 2B

The analogy that can be used to explain this is starting a fire during a snowstorm v starting a fire on a volcano. Although there is a higher temperature on a volcano entropy doesn't change much as the place already has high entropy. While a snowstorm would be affected more since there isn't much en...

Hammad Khan 2B

Moreover, it means that we can pinpoint exactly where the particles are within an object which we have never been able to do before.

Hammad Khan 2B

Same can also be said about pressure as a cell in the body doesn’t change pressure so w=0 in that case. Making $\epsil\bigtriangleup U=\bigtriangleup H$ .

Hammad Khan 2B

I would recommend to see outline 1 on his website to see what to focus on.

Hammad Khan 2B

The first equation is used to find the work done by a reversible process which will not be on the upcoming test. The second equation however, will be on the test as it is the work by expansion.

Hammad Khan 2B

My TA told me that reversible processes do the most work because instead of the work being performed instantly and staying constant, the work is gradually done which should look like this. Then if we take the integral of the graph we can adds that reversible processes do the most work. 2A5535FE-45B7...

Hammad Khan 2B

Internal energy is the energy of the whole system work + enthalpy. While enthaply is just heat released or absorbed, a part of internal energy.

Hammad Khan 2B

I would believe that if the piston would move then yes pressure would be the same since work would drive the piston back and forth trying to equalize pressure.

Hammad Khan 2B

In problem 5,the compression is a positive value because work is being DONE TO the system meaning that energy is being added to it in the form of work. In problem 7, when it says "absorbed heat" it's saying how heat is essentially being taken into a system as it's increasing in energy. The...

Hammad Khan 2B

From what I understand. when a system DOES work it loses energy, thus the work has to be negative as you lost it. While having work DONE to a system means that energy is being added to the system, thus the work is positive. Picture a car trying to move, it has a certain amount of gas (internal energ...

Hammad Khan 2B

This is because an isolated system is where there is no contact with surroundings. A bomb calorimeter is made such that whatever is happening outside it never affects the water that the bomb calorimeter is usually in. As such, it has no contact with its surroundings and it is an isolated system.

Hammad Khan 2B

I'll try a bit little more specific if it helps. So we use the equation q_{cal}=C\bigtriangleup T which is the equation for heat transfer for a calorimeter. So then we move around to equation to get \frac{q_{cal}}{\bigtriangleup T}=C which is the heat capacity of a calorimeter. Lastly, just plug in ...

Hammad Khan 2B

I believe Lavelle went over this in class but you can calculate negative pH of a superacid but I don't know if you can measure it since most litmus tests for pH go from 0-14.

Hammad Khan 2B

Think of the benzene that Lavelle talks so much about. It looks like a diamond structure with alternating double bonds. However, through resonance we can see that the bonding can be moved around but still be alternating. That is what I can think of as delocalized bonding.

Hammad Khan 2B

It should say if it has the long or short way but if not specified then do short-hand usually.

Hammad Khan 2B

Yes, I agree with you that PO4^-3 has no dipole moment has all the oxygens are pulling on the phosphorus thus making the dipoles cancel out. However, to truly understand whether there is a dipole moment, we need to draw the lewis structure of O3 where we get that the molecule in the middle has a lon...

Hammad Khan 2B

So the 18.3% is how much we have left of BrCl so we multiply that by the moles to get the grams and we get .183(1.84x10^-4)=3.36 x10^-5g BrCl. So now we use the ICE table 2BrCl(g) ⇌ Br2 (g) + Cl2(g) I 1.84x10^-4, 0, 0 C -2x, +x, +x E 3.36 x10^-5, x, x So now solve for x using 1.84x10^-4 - 2x= 3.36 x...

Hammad Khan 2B

When Q is greater than K it means that the reaction moves to the reactants or from right to left and vice-versa.

Hammad Khan 2B

It's because as the name implies, the molecule has six regions of electron density.

Hammad Khan 2B

From what I understand is that the first bond is always a Sigma bond as it can handle only one bond. The the next two bonds can only be Pi bonds as they can have upto two bonds. Hence 1 Sigma (Bonds it can have) + 2 Pi (Bonds it can have) = a triple bond.

Hammad Khan 2B

So this problem is a doozy. First, you wanna try and separate the element into groups such as H2C,NH2, and COOH so we get that C and H are bonded such that it is a single bond between C and H giving C four bonded electrons meaning that it connects to two other elements on its sides. So we can place ...

Hammad Khan 2B

So first find the element with lowest ionization energy which is N and then find the shape of the lewis structure which would be linear since you have 3 elements with one in the middle. Second, find the structure which makes each element have an octet. Lastly, find the formal charge of each element ...

Hammad Khan 2B

RenuChepuru1G wrote:what happens when there is a number in parentheses for example Bismuth(III)?

The number in the parentheses just means the charge of the element. Ex) Cu (II) would be Cu2+ and so on.

Hammad Khan 2B

I would assume that with CH the atom of H achieves the two electrons it needs to have a full valence shell compared to CN where neither element gets their valence shell full. So because H gets its shell full it would have a stronger bond with C to prevent it's electron being taken compared to CN whe...

Hammad Khan 2B

I would expect it to be a Lewis Acid since its going to try and become a full octet meaning it will accept electron which is a characteristic of Lewis Acids. It is also the element with lowest ionization energy so it has to be in the middle accepting electron from other elements. It also doesn't com...

Hammad Khan 2B

What I understand is that the central atom should try and achieve FC=0 and the other atoms should also try to approach this value if possible. But if there are multiple arrangements where the central atom has FC=0 and the other atoms just interchange charge, then we can show resonance between the st...

Hammad Khan 2B

So I know that Phosphorus (P) and Sulfur (S) both have extended octets meaning that they can have more than 8 electrons with them. Are all elements below them also extended octets for only certain ones like Xenon (Xe)?

Hammad Khan 2B

Leon, I think you messed up a bit on part b and d. As when l=2 then the orbital is of the d orbital so shouldn't it be 4d instead of 4p? The electron number is correct its just that and that part d should be 3d. Again, because when l=2 then it's a d orbital with the same number of electrons. Other t...

Hammad Khan 2B

In addition, ml ranges from -l to l so if the value of l is 2 then the ml numbers would be -2,-1,0,1,2.

Hammad Khan 2B

You would first go to Ar which is Argon and continue on from there. Then we use 3d10 which references to the d-orbital part of the periodic table and tells us to go to the 10th element on that row which is Zinc. Then it also as 4s2 which tells us to go to the 4th s-orbital row and the second element...

Hammad Khan 2B

Hello, I'm having some trouble finding out the when wavelength=velocity when the distance traveled is 1s. I looked online and the equation that I got was lamba=sqrt(h/m) but I have no idea where this equation came from and how to derive it. Does anyone know how to do it? h=planks constant m=mass of ...

Hammad Khan 2B

I would say to convert the problem to whatever the other variables are, so if you have meters in one and nm in another then convert both to meters to solve it and once solved, then put it back into what its asking or meters.

Hammad Khan 2B

Hello, I'm wondering if we should look to convert units when we finish the problem. So if I have an answer lets say, 290*10^-9m then should I convert it into nm or should I just leave it as is?

Hammad Khan 2B

Usually to balance the equation you would start from the chemical with the lowest stoichiometric coefficient so it is easier. Then you would work your way up from there. If there are two numbers with the same coefficient then you can just choose which one to do.

Hammad Khan 2B

I would recommend going to Dr. Lavelle's website as it has a helpful text on Sig Figs for more practice.

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