CHEMISTRY COMMUNITY

Megan_Ervin_1F

Yes and in the event that you are dealing with a concentration cell the E^o becomes 0

Megan_Ervin_1F

do you think we have to know how to derive the nernst equation for our final?

Megan_Ervin_1F

You make the other concentrations so big that they are essentially viewed as constant so the rate law becomes "fake" first order

Megan_Ervin_1F

Do you think it is necessary to know how to derive the integrated forms of the rate laws for the final?

Megan_Ervin_1F

Also remember that it is acceptable for a catalyst to appear in the rate law

Megan_Ervin_1F

An endothermic reaction has a higher energy barrier in the forward direction so k forward is greater than k reverse which means that if you heated up a endothermic reaction the k forward would increase so the K overall would also increase and products would be favored For an exothermic reaction, the...

Megan_Ervin_1F

a catalyst is not consumed in a reaction whereas an intermediate is used up in a reaction and you can cancel it out in the elementary steps. This is why it is okay to have a catalyst in your rate law as well.

Megan_Ervin_1F

use the first one when you are trying to find out K at different temperatures

Megan_Ervin_1F

It is also important to note that K can be figured out by taking the ratio of the forward reaction K to the reverse reaction K

Megan_Ervin_1F

If ln(A) vs Time is a straight line, then the reaction is a first order reaction

Megan_Ervin_1F

I do not understand, what exactly is a psuedo reaction?

Megan_Ervin_1F

Also remember that you can always derive this equation it you have any doubts

Megan_Ervin_1F

How do you know when to add an inert metal to your cell diagram?

Megan_Ervin_1F

do you think we will get a list of redox equations like the appendix in our textbook?

Megan_Ervin_1F

What sections from electrochemistry will be tested on test 2?

Megan_Ervin_1F

What sections in the seventh edition will be on the test 2

Megan_Ervin_1F

Also it is just standard for the anode to appear on the left

Megan_Ervin_1F

you don't really have to flip the sign of the anode because in the equation you are subtracting the anode so the sign will become positive or favorable automatically just due to the equation we are supposed to use

Megan_Ervin_1F

Is the salt bridge the same thing as a porous disk?

Megan_Ervin_1F

Yes for example if the pressure is constant you know that delta h will equal q

Megan_Ervin_1F

when will you post the answers to hotdog?

Megan_Ervin_1F

Does anyone have a good summary of all the equations we should know? some of them aren't on the equation sheet...

Megan_Ervin_1F

irreversible can also be called "constant pressure"

Megan_Ervin_1F

Phase changes occur when the temperature is constant on the flat lines of the heating curve and you use: mass X enthalpy

Megan_Ervin_1F

If the work is negative that means the system DID the work so it lost the energy as work

if the work was positive that means that work was done ON the system so it gained energy as work

Megan_Ervin_1F

When the temperature is rising you need to use q=mcT (This is on the slanted lines of the heating curve)
When the temperature is constant and the substance is undergoing a phase change you use: mass X enthalpy

Megan_Ervin_1F

DO we have to know how to use every single method? Or, can we just always default to the method we feel most comfortable with?

Megan_Ervin_1F

So, we have not gone over 4A quite yet?

Megan_Ervin_1F

A good example of an isolated system would be a bomb calorimeter no energy is exchanged with the surroundings

Megan_Ervin_1F

Is there a certain order for approaching a Hess's Law problem that anyone finds useful? For example, is there a certain order in which you choose to balance and compute all the different equations?

Megan_Ervin_1F

Does this apply to all other variables as well?

Megan_Ervin_1F

Why is work not a state property?

Megan_Ervin_1F

Is the reason that N2 has enthalpy of 0 is because N2 goes to N2 so the change in enthalpy is 0? I am confused how you know it is zero

Megan_Ervin_1F

Why is the enthalpy for something in standard state 0?

Megan_Ervin_1F

I think Lavelle explained this concept well with the analogy of a mountain and hikers. If one group of hikers took a steep path to reach the top of the mountain and another group took a leisure path to the top of the mountain both groups have ended up at the same spot regardless of which path was ta...

Megan_Ervin_1F

Why does this section talk about delta U? I don't recall learning about delta U in lecture...

Megan_Ervin_1F

Why is it that the phase change for water from a liquid to a gas than from a solid to a liquid has more energy?

Megan_Ervin_1F

It is because there is more energy released for a gas than a liquid. The reason it burns so much is because the energy is released very quickly. For example, my TA explained it like if you were to punch someone slowly it would not hurt as much but if you punch someone quickly the pain is greater. Si...

Megan_Ervin_1F

Yes I had discussion today and received my test in section

Megan_Ervin_1F

Which variable represents heat capacity?

Megan_Ervin_1F

I don't understand the graph Lavelle drew for water's phase change. What is the difference between the straight lines and the slanted lines? Which line represents the phase change?

Megan_Ervin_1F

Is the reason that solids are not considered in the equilibrium constant because they do not have concentrations?

Megan_Ervin_1F

Why is it that if you start out with an initial larger value of reactants, the products will be favored at equilibrium?

Megan_Ervin_1F

Is water not counted in the chemical equilibrium constant? And if so, is this why liquids are not considered either since their concentrations are approximately water?

Megan_Ervin_1F

what makes F an exception?

Megan_Ervin_1F

I don't understand how to decide whether an aqueous solution of a salt has a pH equal to greater than or less than 7

Megan_Ervin_1F

I don't understand why when this problem says 200ml of a .025M HCL solution you don't have to divide .025 by 200 to find the Molarity of H

Megan_Ervin_1F

Bond order is the number of bonds. For example if there is a triple bond between two nitrogens, the bond order is 3

Megan_Ervin_1F

I feel like some of the homework problems can only be done when given the exact number for electronegativity. Will it be obvious on the test?

Megan_Ervin_1F

So, sigma bond is stronger than pi bond. However, in a double bond there is a pi and sigma bond. I thought double bonds were stronger than single bonds but a single bond would only have a sigma bond. Is the reason that double bonds are stronger than single bonds because double bond has both a sigma ...

Megan_Ervin_1F

What does s character even mean?

Megan_Ervin_1F

Why was doctor Lavelle talking about how sigma and pi bonds rotate and some cannot rotate because they snap? Could someone explain?

Megan_Ervin_1F

Will we have to know sigma and pi bonds and how in depth?

Megan_Ervin_1F

I was wondering, does every molecule have a dipole moment?

Megan_Ervin_1F

So, do hydrogen bonding just automatically have hydrogen, dipole dipole, and dispersion forces?
And then dipole dipole will have dipole dipole and dispersion?
And then ionic will just have ionic and dispersion?

Megan_Ervin_1F

Is this true for every single covalent and ionic bond comparison?

Megan_Ervin_1F

Also, will hydrogen, ionic, and dipole dipole bonds always have polarizability?

Megan_Ervin_1F

Also, on this topic, do ionic bonds also have dispersion forces?

Megan_Ervin_1F

*remember that there are exceptions for other trends like ionization! For example, Nitrogen is higher than Oxygen for first ionization energy!

Megan_Ervin_1F

I think these answers were made in relations to the graph in the book that lists specific electron affinities. Otherwise, you would not know the exact value for electron affinities. But, the general trend is to increase towards the right hand side of the table.

Megan_Ervin_1F

I also was wondering how do you find the valence electrons for elements in the d orbitals?

Megan_Ervin_1F

for Au, why is an electron more likely to be removed from the s orbital than the p orbital? I understand that the half full d orbital is more stable but why remove the electron from the s orbital?

Megan_Ervin_1F

What exactly is electron affinity and WHY does it increase towards the upper right diagonally?

Megan_Ervin_1F

Does the order of final and initial change if the problem is having to do absorption instead of emission?

Megan_Ervin_1F

Just to clarify, is the degeneracy related to the orbital in an atom?

Megan_Ervin_1F

I know we don't have to know the equations for Schrodinger, but I was wondering is this formula responsible for shapes in an atom?

Megan_Ervin_1F

For the upcoming test, do we have to read everything in the textbook? For example, the sections that were not discussed in class like the history of an electron?

Megan_Ervin_1F

I believe you do not need to know the extreme details of spin. Just know that there is a fifty fifty chance of positive one half or negative one half and pick one when asked on a test

Megan_Ervin_1F

In class we have established that black body radiation is useful in showing light to have particle light qualities, which is why it is part of the "quantum world". But what exactly is it and how much about this experiment do we need to know?

Megan_Ervin_1F

For the test, will we be given the Balmer series or Lyman series wavelengths? No memorization right...?

Megan_Ervin_1F

hey guys, I'm having trouble with the names of things. When is it Spectrum Absorption or Spectrum Emission and when does the term refer to the actual line that shows up. Please help me clear up the vernacular here. Thanks

Megan_Ervin_1F

In photoelectric experiments, typically what part of the EMR spectrum is the incoming light?

Megan_Ervin_1F

When the frequency of electromagnetic radiation decreases, the extent of the change in the electric field at a given point decreases. I don't understand this completely. I understand that the electrical field corresponds to the amplitude, but do not see how this would make a change at a point decrea...

Megan_Ervin_1F

For Mass percent composition questions, why doesn't it always add up to 100? What do you do when it doesn't add to 100?

Megan_Ervin_1F

So, in the problems so far we have only had 1 limiting reactant. I think it is unlikely to have more than 1 limiting reactant. However, if there is an equation with 3 reactants, then can there be 2 limiting reactants?

Megan_Ervin_1F

Also, if 5g of reactant A react with 7g of reactant B, can this produce 14 grams of product? No, correct?

Megan_Ervin_1F

On that same module, can the mass be greater than the total mass of reactants? No and the reason is conservation of mass right?

Megan_Ervin_1F

Are we doing any 7 problems we want that are listed? Or do the problems have to come from all sections?

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