CHEMISTRY COMMUNITY

Jasmine Fendi 1D

What would be an applicable example of a 0 order reaction? When would that make sense?

Jasmine Fendi 1D

A catalyst is first a reactant and then a product while an intermediate is first a product and then a reactant

Jasmine Fendi 1D

I think we use it to describe how many things have to collide in a reaction.

Jasmine Fendi 1D

Different mechanisms have different slow steps and therefore different rate laws.

Jasmine Fendi 1D

I think if it is endothermic and enthalpy tells how much energy or heat input is necessary then that is analogous to activation energy.

Jasmine Fendi 1D

I think that the general rate law gives you the rate while the integrated rate laws gives the concentration of the reactants.

Jasmine Fendi 1D

I do not think that O2 is a catalyst, but rather just part of the reaction. The intermediates are NO2 and O, while the only catalyst is NO.

Jasmine Fendi 1D

I think that Lavelle makes the entire final, based off of what my TA has said in discussion.

Jasmine Fendi 1D

I do not think that this will be covered at all on the final. I think Lavelle said in class today that we will only use the pre-equilibrium approach.

Jasmine Fendi 1D

I think what was covered in the textbook was helpful!

Jasmine Fendi 1D

I think we have to know the axes and what axes would make a linear plot. And probably know the general shape of each graph too.

Jasmine Fendi 1D

Some collisions occur with wrong orientations, so this tells how many occur in the correct orientation for the reaction to occur.

Jasmine Fendi 1D

I think the exponent in the overall rate law is not the same as the coefficient in the equation.

Jasmine Fendi 1D

In this equation, n=the number of electrons transferred in the redox reaction.

Jasmine Fendi 1D

Yes! That is correct.

Jasmine Fendi 1D

Yes! I found the examples in class and discussion to be helpful about cell notation.

Jasmine Fendi 1D

I think that Lyndon's review sessions and office hours are good resources!

Jasmine Fendi 1D

Second half of outline 4 and all of outline 5! Does anyone know what the difficulty level is? Is it going to be similar to test 1?

Jasmine Fendi 1D

I don't think there is anything official, but I do know that some ta's are creating worksheets and helpful guidelines for students.

Jasmine Fendi 1D

For ex, in the chemical equation
-2Fe3+ + Cu -> Cu2+ + 2Fe2+
the cell notation is
Cu(s) / Cu2+(aq) ‖ Fe3+(aq) , Fe2+(aq) / Pt(s)
the comma indicates that Fe3+ is being reduced to Fe2+

Jasmine Fendi 1D

I think we can use most inert metals. To be safe, I think platinum is most commonly used.

Jasmine Fendi 1D

I also need help on this! I think it has something to do with the wording of the problem but I am not sure.

Jasmine Fendi 1D

Yes! The max potential of a cell is the maximum potential difference between two half reactions in a galvanic cell. I think you can calculate this by manipulating different equations.

Jasmine Fendi 1D

Test 2 will cover everything from "Understand why reaction free energy depends on pressure and the equilibrium constant" all the way through electrochemistry

Jasmine Fendi 1D

You need an inert conductor when there is no metal present to conduct the electrons from the anode to the cathode.

Jasmine Fendi 1D

The anode of a device is the terminal where current flows in from outside. The cathode of a device is the terminal where current flows out. I think you just use these terms when you are dealing with a Galvanic cell that converts chemical energy to electric energy.

Jasmine Fendi 1D

When the sign is negative, it means that the reaction is spontaneous. That is because the reaction would result in molecules being in their most stable state which would require less energy to maintain the bonds. As a result, the overall energy is negative because energy is being released. The same ...

Jasmine Fendi 1D

I think that the electrons have to be balanced because it is part of a redox reaction where two half-reactions are coupled. That means that the same amount of electrons are transferred from one reaction to another and the electrons cannot just be free floating.

Jasmine Fendi 1D

I agree with the comment above! In short, an increase in temp means that you are applying more energy, so the products/reactants with the higher energy level would be favored

Jasmine Fendi 1D

I agree with the previous comment! Reduction reactions are always paired with Oxidation reactions, thus giving the name redox reaction.

Jasmine Fendi 1D

I also felt the same way during the midterm. However, some things that somewhat helped me were listing everything that was given and some variables not given/needed to be solved for. Then, I wrote down multiple equations that involved those variables and used PV=nRT as a gateway to find other variab...

Jasmine Fendi 1D

I don't think you need to directly calculate the work with the integral. Just memorize the equations that are derived from the integral and know when to use each one!

Jasmine Fendi 1D

I am also not sure, but I do know that ATP hydrolysis is an exergonic reaction, which has a negative delta G. Also, Gibbs Free Energy is used in most biochemical reactions because they occur at constant temp and pressure

Jasmine Fendi 1D

I am also wondering this question! For now, I think I would just memorize it just in case.

Jasmine Fendi 1D

Multiply by 3 if all three bonds are being broken. It definitely will not be a big part of the test, but since we did go over it in lecture we are expected to know how to do it.

Jasmine Fendi 1D

A bomb calorimeter stays at constant volume! Because of this, there is no work being done to the system.

Jasmine Fendi 1D

I don't think we have to memorize it, but it would be convenient to memorize it! Also watch out for your units and use either K or C based on the units you want to cancel out.

Jasmine Fendi 1D

Delta H is the change in enthalpy while delta U is the change in internal energy in a system. Most of the time, I think you can use them interchangeably in this class.

Jasmine Fendi 1D

A closed system is a sealed system but energy can be exchanged with the surrounding. On the other hand, an isolated system is completely isolated from the environment and it cannot be affected by the surroundings. That being said, an insulated bottle is an isolated system if we assume that it is com...

Jasmine Fendi 1D

I think everything we have covered so far, including all of this week's lectures!

Jasmine Fendi 1D

I think so, but I am also wondering this question!!

Jasmine Fendi 1D

When filling out and ICE table, only include gases and aqueous molecules. In addition to the comments above, you want to leave our solids because you cannot really condense or expand solids since they are in a fixed state

Jasmine Fendi 1D

Enthalpy is just the measure of heat! Temperature and enthalpy are related but are different, as seen in heat curves. The x-axis is heat supplied and the y-axis is temperature

Jasmine Fendi 1D

In addition to doing the homework problems in the textbook, I found all of the workshop sessions very helpful :)

Jasmine Fendi 1D

After watching the videos that were mentioned in the previous comments, I would recommend trying to find some more practice problems to check your understanding :)

Jasmine Fendi 1D

Always balance the equation! When calculating K, the incorrect coefficients will change the exponents in the equation and you would not calculate the correct equilibrium constant

Jasmine Fendi 1D

Memorizing the quadratic equation would help! Also, it is good to know the shortcut with the 5% rule. if you are dealing with a weak acid and Ka is small, we can use approximation. The cut off is anything smaller than 10^-3

Jasmine Fendi 1D

K actually measures the activity of the reaction. For this class, I think we omit the units for simplicity

Jasmine Fendi 1D

They are the same thing, and Kw=Ka*Kb=10^-14

Jasmine Fendi 1D

To add onto the comments above, make sure you go back to the problem to see what you need to solve for. After you find x, you may need to multiply it by 2 if the concentration you are looking for is 2x

Jasmine Fendi 1D

I think that you can use either molarity or moles. It would definitely be easier to use molarity since that can be easily used in Kc. If you use moles, you would have to convert the values at the end to molarity by dividing by the volume(L)

Jasmine Fendi 1D

<-> means that the reaction is at equilibrium so there is a forward reaction and reverse reaction

Jasmine Fendi 1D

I think that is just part of the formula, but I was also wondering the same thing.

Jasmine Fendi 1D

I am also not sure. From looking at the outline, it looks like we just need to know how to use the equation.

Jasmine Fendi 1D

Unlike temperature, the change in pressure does not change the equilibrium constant.

Jasmine Fendi 1D

I don't think that there would be a hydrogen bond between water and oxygen gas because the two oxygen atoms are equally electronegative.

Jasmine Fendi 1D

I think we need to memorize it and also we should memorize the ligands list that Lavelle sent out in an email.

Jasmine Fendi 1D

Yes, I think that is all we need to know too. Also make sure that you know how to label each bond and know which hybrid/normal orbitals are used.

Jasmine Fendi 1D

I also do not think that we need to memorize the exact bond lengths. We should at least know the relative bond lengths between single, double and triple bonds and the 1.5 bonds in resonance structures

Jasmine Fendi 1D

I do not think there is a practice final, but there are a lot of past exam questions that will be helpful. Also, the 7:30 review session will be going over most things that were covered after the midterm so it would be helpful to go to other review sessions to go over the topics that were covered at...

Jasmine Fendi 1D

Adding to the comments above,
bronsted base: proton acceptor
bronsted acid: proton donor
lewis base: electron pair donor
lewis acid: electron pair acceptor
I would identify them by focusing on what is being transferred or changed in the reaction.

Jasmine Fendi 1D

The first step to solving this problem like this in general is finding the moles of hydrogen which is used through stoichiometry. After finding the moles of hydrogen, you can find the concentration of hydrogen, aka H30+, by using the formula molarity=moles/liter. [HNO3]=[H3O+] is just saying that th...

Jasmine Fendi 1D

You add a hydrogen to the formula and add a +1 to the overall charge of the acid

Jasmine Fendi 1D

One way is to look for the neutral ligands that are bonded to a central metal atom!

Jasmine Fendi 1D

I also think it would be calculations and concepts!

Jasmine Fendi 1D

Yes! I think we should memorize the chart that Lavelle sent out in an email a few days ago

Jasmine Fendi 1D

I don't think you would get marked down, but just make sure that you make it clear that you know that the O is the one being bonded to the central atom!

Jasmine Fendi 1D

I think it is only transition metals, but I am not sure as well :0

Jasmine Fendi 1D

Always make sure you have the right sig figs to be safe :)

Jasmine Fendi 1D

Adding on to the comment above, you use it so that it is not awkward saying didimethyl and it adds clarity

Jasmine Fendi 1D

I would say to look at all of the homework problems again! That for sure is a good start

Jasmine Fendi 1D

I don't think we need to memorize bond lengths! Maybe just know that the order of increasing bond lengths is triple<double<single bonds

Jasmine Fendi 1D

To add on to the previous comment, more electrons result in greater electron repulsion, which leads to greater polarizability and greater london dispersion forces

Jasmine Fendi 1D

To add on to the comment above, the name of the shape of the molecule only depends on the number of atoms attached to the central atoms and the number of lone pairs on the central atom. Single, double and triple bonds are considered the same as "one unit" and lone pairs on outside atoms do...

Jasmine Fendi 1D

I think this is because in order for the molecule to be in the most "stable" state, the lone pairs and attached atoms need to be as far apart as possible, and the lone pairs cause the angles to decrease.

Jasmine Fendi 1D

As I mentioned in another post, I think we can still do some homework problems from the chemical bonds unit because as of now we have not really learned anything new and it is still good to review material for the final! However it is good to look ahead to see what we will be covering next

Jasmine Fendi 1D

I think so! As of now we haven't really learned anything new and it is still good to review past material for the final

Jasmine Fendi 1D

I think this is because of electron repulsion!

Jasmine Fendi 1D

yes! I think that it is better to have the charge on the most electronegative atom, such as oxygen

Jasmine Fendi 1D

In addition to the comments above, the atomic radii decreases as you move towards the right of a period. This is because as you move right, the added electrons are added to the same n level but the number of protons in the nucleus increases. The protons have a much greater effect than the added elec...

Jasmine Fendi 1D

Hydrogen bonds are strong intermolecular forces created when a hydrogen atom bonded to an electronegative atom approaches a nearby electronegative atom, and greater electronegativity of the hydrogen bond acceptor will lead to an increase in hydrogen-bond strength. I think it is because the charge of...

Jasmine Fendi 1D

I think that everything in row 3+ can have an expanded octet, and elements such as Aluminum does not have to have an octet.

Jasmine Fendi 1D

I believe so! I do know that we will be going over more acids and bases towards the end of the quarter

Jasmine Fendi 1D

hello! the equation for formal charge may be confusing, so my TA told us that you do not have to memorize it. I think you can calculate it using the number of valence electrons from the periodic table and the number of shared electrons in the lewis structure

Jasmine Fendi 1D

I think that there would be one correct answers since some lewis structure could be drawn based on different orientations. However, there are some structures that are more stable than others due to formal charge so I think that there will be partial credit if you do not draw the most stable structure.

Jasmine Fendi 1D

I believe the replies count as posts!

Jasmine Fendi 1D

Do you think that the practice problems on the dino nuggets worksheet are about the same difficulty as the problems that would be on the midterm?

Jasmine Fendi 1D

I was wondering the same question. That is what I think also but I am not sure

Jasmine Fendi 1D

I think it would be helpful, but make sure to know where all of the common elements are so they are easier to find on the periodic table!

Jasmine Fendi 1D

Hi, can someone please further explain the exception for the electron configuration for 3d and 4s? especially for the elements Cr and Cu?

Thank you!

Jasmine Fendi 1D

Can someone please explain why ionization energy increases as you move from left to right on the periodic table?

Jasmine Fendi 1D

In addition to the other responds, nonmetals have high ionization energies. They are generally poor conductors of heat and electricity. Solid nonmetals are generally brittle, with little or no metallic luster, and most nonmetals have the ability to gain electrons easily

Jasmine Fendi 1D

Yes! Dr. Lavelle mentioned it and I believe sometime soon he will let us know when the review sessions are

Jasmine Fendi 1D

First, I like to go through practice problems and make a list of topics I am confused about. Sometimes I also rewrite my notes from lecture and try to explain it to others since it helps to talk through it out loud.

Jasmine Fendi 1D

Q: What do you do with a sick chemist?
A: If you can't helium, and you can't curium, then you might as well barium.

Jasmine Fendi 1D

I would use 2.998*10^8 m*s-1 because it would give you a more exact answer, but maybe ask your TA!

Jasmine Fendi 1D

I think that an orbital is the probability description of where an electron can be found, and the four basic types of orbitals are designated as s, p, d, and f. To my understanding, lobes are more specific areas within the orbitals in which there is a high probability of finding an electron.

Jasmine Fendi 1D

I think salt water is a mixture because it is made up of different compounds/elements (salt and water).

Jasmine Fendi 1D

There might be some points marked off, but I believe there is still partial credit! And as long as you are aware of it for the next test, you should be fine

Jasmine Fendi 1D

In addition to the sessions in covel, I recommend going over the lecture videos and trying to reexplain the lecture to someone else in your own words

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