CHEMISTRY COMMUNITY

mayapartha_1D

Raising the temperature will induce a larger k!

mayapartha_1D

I think we will be required to know how to differentiate between steps and show which one is the faster/slower one!

mayapartha_1D

I think normally we would assume that k is the forward reaction? But I am not positive! They should give it in the problem on the final, though.

mayapartha_1D

Does anyone know of any examples of naturally occurring, applications of zero order reactions that we should be able to recognize?

Thanks!

mayapartha_1D

Because there are 3 moles of B and only one of A it should be the same process just use the equation that would include 1/3!

mayapartha_1D

Yes, an order can be negative as well as a fraction! But we mainly just focus on zero, first, and second as those are the most common, naturally occurring orders for reactions.

mayapartha_1D

Because there are different charges in the cathode and anode, the electrons will naturally move through the conducive wire to the cathode side!

Hope this helped.

mayapartha_1D

Hi! Simply writing out the half reactions will make it a lot easier! I always make sure to write out the half-reactions that are given and make sure they cancel out electrons to become the final reaction. As Victoria stated, making sure that the electrons cancel is the easiest way to balance the rea...

mayapartha_1D

Does anyone know whether or not we will need to be able to define the electromotive force (emf) and its use for the final? If we do, could someone please give a definition?

Thanks!!

mayapartha_1D

I think you have to add H20 to one side and H+ to the other! So if you add hydrogen ions to one side it should be H20 on the other side. There are helpful worksheets on Lavelle's website under "Redox Reactions" if you want to look at that too.

mayapartha_1D

For Test 2, will we just need to know how to balance redox reactions and identify cathodes/anodes? Does anyone have a list of useful equations or concepts?

mayapartha_1D

Molar entropy is only for one mole of the substance, while standard entropy is just the general entropy for the formation of the product!

Hope that helps.

mayapartha_1D

The equation takes into account all the moles no matter the state! So just take what you are given with the equation and the enthalpies and then subtract the sum of the reactants from the sum of the products.

Hope that helps.

mayapartha_1D

The equations are opposite for the system vs the surroundings because heat is being transferred from one to the other, so the entropies must be opposite values to reflect this.

mayapartha_1D

If a system is isothermal, that means that q=0, so if the substance is reversible or irreversible, the internal energy change will still be 0-- this is because there is no change in heat!

mayapartha_1D

You use this equation for ideal gases! If in a problem, you are given a pressure and the other variables, and it is stated that the given substance is an ideal gas, you will use this equation.

Hope this helped,
Maya

mayapartha_1D

Hi!

Yes, make sure you add the enthalpy for melting the ice (the phase change) for the Q of the system. That should get you the right answer!

mayapartha_1D

Hi Chris!

We don't need to know the derivations of the formulas, but will be expected to show why we're using certain formulas on the test. For example, with Van't Hoff's equation, it would be useful to put both of the equations that we are using.

mayapartha_1D

Hi Tiffany!

Because q=0 as there is no transfer of heat or change in temp (isothermal) there will be no change in entropy of the molecules.

mayapartha_1D

Hi Bella!

Usually the book or test will tell you are using a constant pressure. Unless they give another pressure, I think it's safe to assume that the pressure is constant.

mayapartha_1D

Yes you use that equation! Also remember that reversible work does more work than irreversible work, as the area underneath the curve is greater.

mayapartha_1D

On the test where we were supposed to state the First Law of Thermodynamics, how specific were we supposed to get with the definition?

Thanks!

mayapartha_1D

A vacuum is a space that has no matter! For example, space is a vacuum because nothing can exist in that space. Because its pressure is lower, work will probably be done on that part of the system!

mayapartha_1D

Can anyone explain what exactly a DNA structural transition is? And its significance to thermodynamics?

mayapartha_1D

Does anyone know if there are heat capacities we must know/memorize? Such as the heat capacity of water, etc.

mayapartha_1D

Condensation is exothermic! It's easy to just think of where the heat is going (gas has more heat/energy than a liquid, so the heat must be leaving the gas).

mayapartha_1D

Can anyone explain why exactly the universe is an isolated system? How is it similar to a calorimeter?

mayapartha_1D

Why does delta H = q when there's constant pressure?

mayapartha_1D

Hi Warda!

Hess' Law is also especially helpful when you need to utilize the given reactions to come up with an unknown enthalpy. That way, you can use enthalpies that are known, rearrange the products and reactants, and solve for an unknown enthalpy.

Hope this helped!

Maya

mayapartha_1D

Hi Simrina!

I don't believe we need to know this! Dr. Lavelle didn't really go over using derivatives in lecture.

Hope this helped,
Maya

mayapartha_1D

Can anyone explain the order of the ligands in naming? When you are presented with a coordination compound, what is the normal order for naming the ligands and other atoms?

Thanks!

mayapartha_1D

Does anyone know if we will be tested on the final with biological examples? As in do we need to memorize a couple in case we are tested on them? In that case, does anyone have any logical/easy way of remembering them?

Thanks!!

mayapartha_1D

I don't think so either! Dr. Lavelle said we wouldn't have to use the molar concentrations that much.

mayapartha_1D

I agree with Emily! On the midterm, I thought about it as Silicon and Oxygen having two different electronegativities, so the Silicon and Oxygen would not bond ionically. They are also from the same "side" of the periodic table, and not from two different sides like all of the other ionic ...

mayapartha_1D

The variables A and X stand for different things in the VSEPR model! Lavelle went over it in his lecture I am pretty sure, but you might be talking about some sort of exception.

mayapartha_1D

Yes, it could be trigonal bipyramidal! The lone pair electrons may balance each other out to make it possible.

mayapartha_1D

Can anyone explain why exactly the HOCO compound has the Lewis structure that it does? Why is it not classified as a radical?

mayapartha_1D

Does anyone have any useful graphics for picturing hybridization? I am trying to come up with a more general picture of hybridization, and feel like watching some sort of a video would make it easier to understand.

Thanks!

mayapartha_1D

Is it possible to measure the power of a dipole moment? A.k.a. are there dipole moments that are stronger than others?

Thanks!
Maya

mayapartha_1D

I just checked also and it only says 2! Possibly the problem you are working on has the wrong answer? You might want to check the solutions manual online.

mayapartha_1D

I have a question regarding trends! Does anyone have any easy ways to be able to remember the trends? Let me know if you have any tricks to remember the increasing/decreasing trends.

Thanks,
Maya

mayapartha_1D

Hey!

I have a question regarding electron affinity trends. For problem 67 part B, the question is which has the higher electron affinity: nitrogen or chlorine. The answer should be nitrogen because it is to the right of chlorine, but in the book it says the answer is chlorine. Why is this??

Help!!

mayapartha_1D

Yes exactly!! You don't have to take into account the value of the velocity itself because it is only asking for the uncertainty.

Hope this helped.

mayapartha_1D

Hi!!

I have a question regarding the Uncertainty principle. If given a problem where the momentum uncertainty, for example, is + or - 2, does that mean the uncertainty amount is 4? Or do you have to take into account the value of the momentum?

Thanks!

mayapartha_1D

Hi!

You usually will not have to find a chemical formula without any given values. Metals, gases, etc. have different characteristics that make them easier to figure out; which is listed in the book.

Hope this helped.

mayapartha_1D

Hello!

The most electronegative atom would hold the electron as, by the definition of electronegativity, the atom holds a higher affinity for taking electrons.

Hope this makes sense, and good luck.

mayapartha_1D

Hey! The Lyman series corresponds to n=1 because it refers to wavelengths that start at a given energy level and end at 1 (2-1, 1-1, 3-1). The same goes for the Balmer series but with n=2. As for knowing which series to use, the problem will normally state which series is most appropriate! Hope this...

mayapartha_1D

I agree with the above as well! Sometimes it is easier to see the answer in meters (the SI unit), however in some cases it is more useful to see the answer in the closest unit. For example, if the closest thing is a nanometer, you would be able to see and compare the answer to other wavelengths.

mayapartha_1D

Hi Jelci! To calculate percent yield, all you have to do is divide the actual yield by theoretical yield. This will give you a decimal value, which you can then multiply by 100 to get the percent value. To think about this in an easier way just consider how much of your theoretical yield you have pr...

mayapartha_1D

Hello! One very easy way to go about sig figs is to simply look at the amount of sig figs in the value that is given. For example, if you are given a problem of combustion that begins with 7.00 g of butane gas, the amount of sig figs for the answer will most likely be 3-- as there are 3 sig figs in ...

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