CHEMISTRY COMMUNITY

ShastaB4C

You don’t usually need to find the tangent of the graph bc if you graphed they concentrations accordingly by their order, then the graph is linear so u just look in respect to its slope.

ShastaB4C

Is k’ and k prime have to be positive right? Like just because k’ is the reverse reaction doesn’t mean it has a negative sign

ShastaB4C

So derivations may come in handy based on the information given?

ShastaB4C

This is an old forum, but I just wanted to say a genuine thank you to Lavelle for your good spirit, willingness to help, and accommodation to you students in this transition period. It is truly appreciated.

ShastaB4C

Do we have to memorize the integrated rate law formulas for each order or how to derive them?

ShastaB4C

You are literally the only reason I made it through 14A/B lol. Thank you soooo much

ShastaB4C

Please post the question so we can better assist you, but in general, you will be given standard reduction potentials. The half reaction with the less positive standard reduction potential will tend to be oxidized rather than reduced, and that is the one that would be flipped to take place at the a...

ShastaB4C

Can someone explain each species on the cathode side of the reaction and why it’s written in this notation?

ShastaB4C

You would write the half-reaction without Pt(s), since it simply serves as a solid electrode for the cell diagram. Because a reduction reaction is occurring in the anode, there is a gain of electrons added to O2(g) as it also reacts with water, H2O(l) to produce hydroxide, OH-(aq). So the anode hal...

ShastaB4C

Maybe the solution manual just put it to explain it??

ShastaB4C

Where in the question specifies needing to find the E cell for the reaction?

ShastaB4C

You solve these how you normally would balance in a basic solution. Also, If you need help figuring out why each species in the product is which, look at how the oxidation number of the Br in them change.
I hope this helps!!

ShastaB4C

Hi!

The Br2 is acting as both an oxidizing and reducing agent. So the first half rxn is an oxidation from Br2–> BrO3 ^-2. The second half rxn is a reduction from Br2–> 2Br-

ShastaB4C

You pretty much follow the same process, but the basic solution has a few more steps.

I posted this video I found helpful in another forum but I’ll attach it here in case you may find it helpful!

https://youtu.be/v5sDNmYCaqo

ShastaB4C

ShastaB4C wrote:Also, these videos really helped me out. He goes step by step teaching how to balance redox in non-neutral solutions.https://youtu.be/IZ1tKxsqV74

https://youtu.be/v5sDNmYCaqo

ShastaB4C

Also, these videos really helped me out. He goes step by step teaching how to balance redox in non-neutral solutions.https://youtu.be/IZ1tKxsqV74

ShastaB4C

Abigail_Hagen2G wrote:It really depends if the solution is acidic, basic, or neutral

How would you balance in a neutral solution? Like what steps would not use?

ShastaB4C

Balance P4 → H2PO2- + PH3 in basic solution. I know that the half reactions are: 3 x (P4 + 8OH- → 4H2PO2- + 4e-) 12H2O + P4 + 12e- → 4PH3 + 12OH- and the answer is 3OH- + P4 → 3H2PO2- + PH3. But I don't know how the two half equations lead to that answer. Can somebody do it step by step, please? So...

ShastaB4C

How are we to assume that it is both the reduced and oxidized form?

ShastaB4C

Can someone explain where the reduction half reaction is for this prob?

ShastaB4C

For my reduction half run, Where am I going wrong, because I got that the charges were already equal on both sides but then no electrons are released?

ShastaB4C

Cooper Baddley 1F wrote:
ShastaB4C wrote:What did I do wrong? The answer is supposed to be 16 degrees Celsius

The ice goes through a phase change so you need to add that heat to the equation on the side of the ice.

Do I get that value from delta H fusion on the equation sheet?

ShastaB4C

What did I do wrong? The answer is supposed to be 16 degrees Celsius

ShastaB4C

I understand why we find the two delta S values using the heat capacities and find the sum. However, I don’t understand why we use the 3rd delta S value given at 100 degrees Celsius bc the answer key says we are heating the reaction to 100 degrees and then cooling to 85 degrees.

ShastaB4C

Can someone explain a step by step why we solve this problem the way it says in the solution manual?

ShastaB4C

The enthalpy of formation for diatomic molecules =0

ShastaB4C

And then add the standard enthalpy of formation for NO. Just don’t forget to multiply that value by the coefficient of NO in the desired equation.

ShastaB4C

It’s easier to keep the coefficients in whole numbers and multiply the first equation they have by 2

ShastaB4C

you can use the enthalpy as a conversion factor. I hope this helps.

ShastaB4C

Yes, I think when the volume is changing, its usually doing so to keep the pressure constant

ShastaB4C

Make sure that it’s Po and not P^o bc the second one just means standard state of pressure so usually 1 bar or 1atm

ShastaB4C

Anything w/ naught should mean “initial”

ShastaB4C

But J and kJ are pretty loosely interchanged for all of the above units so just make sure you notice which one they are giving you or use the conversion factor 10^3J=1kJ.

ShastaB4C

Can someone explain This problem and the reasoning behind it please?

ShastaB4C

Oh I didn’t know it was that simple lol. Okay thank you!

ShastaB4C

What is this constant (101.325 J/ L x atm)?? And what is it used for?

ShastaB4C

And what does effect does a common temperature have on the system doing work in a reversible process?

ShastaB4C

Why is the external pressure changing (slowly but still) in a reversible process?

ShastaB4C

Can someone give me an example of a property that is dependent on the path taken besides work?

ShastaB4C

And which one has the conversion factor of 4 joules?

ShastaB4C

Also which one is used on the nutrition facts on our food?

ShastaB4C

What is the difference between calories and Calories?

ShastaB4C

Solids don’t have concentrations or partial pressures, so it can’t be calculated in K.

ShastaB4C

Is the Kw for water always 10^-14 at any temperature or does it vary?

ShastaB4C

How does the temperature change of a neutralization reaction not have an effect on the K of the product solution? Or is it of the water?

ShastaB4C

Can someone clarify how taking out some of the product can increase the amount of product made without considering temperature or additional input?

ShastaB4C

Also, Is there a difference between saying the rxn “lies to the right” and “shifts to the right”?

ShastaB4C

What if K=0? Does that have an effect?

ShastaB4C

Would there be any solvent in which we would include it in K calculations?

ShastaB4C

So would it be incorrect to put brackets around a partial pressure?

ShastaB4C

Anne Tsai 1F wrote:Both oxygens and and the chlorine will be attached to sulfur. One of the oxygens will have a double bond, and the other one will have a formal charge of -1.

So the overall charge of the complex will be -1? The complex doesn’t end up being neutral?

ShastaB4C

When writing the 2 reaction equations for the amphoteric compound, HCO3-, is the equation where it acts as a base reacting with a hydronium ion or water?

ShastaB4C

Are there any other compounds that can be both amphiprotic and amphoteric besides water?

ShastaB4C

Test tip from one of the UAs: the number of minutes given for the exam=the number of points on the exam so pace yourself as best you can!!

ShastaB4C

How do I draw Lewis structure of the product between Cl- and SO2?

ShastaB4C

I think the best advice is to study all examples given in lecture and review the ones from the HW. From the tests so far, it seems as long as you nail down the concept and practice it in diff scenarios such as the HW you should be okay

ShastaB4C

Place one electron in each hybridized subshell first and and then one in your extra unhybridized subshell(s). You are trying to reduce electron repulsion so Hund’s rule still applies

ShastaB4C

The electron repulsion that would be caused if u tried putting all the electrons in the hybridized shells would increase the energy of the atom and not work for explaining how the atom can form so many bonds. Or which bonds. By leaving out a p subshell, the atom has the opportunity for forming pi po...

ShastaB4C

You would place the extra unpaired electron in the unhybridized orbitals in cases where each hybridized orbital subshell has one paired electron or just when it would make the atom of be more stable bc or lower energy.

ShastaB4C

If it had 3 hybrid orbitals it is sp2. The unhybridized orbital is left over because only 2 of the p sub shells were hybridized but one wasn’t

ShastaB4C

What does pKa stand for and its purpose?

ShastaB4C

What is the chemical formula for Chromium (III) picolinate? And will we need to know how to draw a Lewis structure of it?

ShastaB4C

Why does oxygen absorption and de-absorption in the heme complex depend on the local partial pressure of oxygen?

ShastaB4C

Does Carbon have to be present in an organometallic complex or just 1 or more Transition metals?

ShastaB4C

So does that mean that molecules with pi bonds are more reactive?

ShastaB4C

If the question asks for shape, would it be referring to molecular geometry or electron arrangement?

ShastaB4C

What does steric mean?

ShastaB4C

I get the purpose of a ligand is to attach to central atoms and forms a coordination compound but how is a coordination compound different from that of a regular covalently compound?

ShastaB4C

Is the heme complex present in another other bio molecules that can show up on the final?

ShastaB4C

Can someone explain how a sigma bond is stronger than a pi bond if double bonds are stronger than single?

ShastaB4C

Are there any other functional groups we need to know besides amine or carboxyl groups that indicate possible acids or bases?

ShastaB4C

ShastaB4C

Anna Wu 1H wrote:What is the chemical formula of coffee?

CoFe2

Isn’t this CoFeFe? LOL

ShastaB4C

Does anyone know approximately how many questions the final exam will be?

ShastaB4C

Or will will week 10 be more focused on review?

ShastaB4C

Will we be covering new topics in lecture all the way up to the Friday lecture before the final?

ShastaB4C

Will we be expected to know how to draw the Lewis structures of the biological examples we have covered in class? (Also meaning memorizing the chemical formula)

ShastaB4C

Which compound properties that we have covered have are affected by intramolecular forces rather than intermolecular forces?

ShastaB4C

Which properties have we covered are extensive? Having to do with intermolecular forces?

ShastaB4C

Week 9 has me like...

ShastaB4C

ShastaB4C

Can someone explain how coordinate covalent bonds work?

ShastaB4C

ShastaB4C

If the ion has a positive charge, electrons have been taken away. If it has a negative charge, electrons have been added

ShastaB4C

I would say just +/- 3 so 3 as an absolute value

ShastaB4C

We didn’t need to know this equation for the purpose of this class right?

ShastaB4C

Did u mean Percent yield?

ShastaB4C

I would say that each energy level, n, has different subshells/states (s,p,d,f). These subshells have a specific numbers of orbitals
S(1), p(3), d(5), f(7) and each orbital can hold two electrons given that the two electrons have opposite spin

ShastaB4C

I’m not sure how much it is confusing rather than we just don’t need to know it for 14A :/

ShastaB4C

Yes you’ve got it! Frequency and wavelength have an inverse relationship since their product equals a constant. So when one increases, the other decreases.

ShastaB4C

Does “v” represent velocity or frequency? We used to use it for frequency for E=hv but for de Broglie’s it’s velocity?

ShastaB4C

Will we have to know the names of the series to answer certain problems?

ShastaB4C

Also can someone please clarify what the lecture meant by waves being “in phase” (constructive) or “out of phase” (destructive)?

ShastaB4C

Can someone explain what diffraction has to do with electrons having wave-like properties?

ShastaB4C

This chart may help simplify it a bit.

ShastaB4C

https://youtu.be/nijb6UMvZuE

This video is a good little review for it. I hope this helps!

ShastaB4C

So is it correct to conclude that the equation c = wavelength x frequency is just relating to their inverse relationship and the light’s identity (e.g. red visible light, UV light, etc) while the amplitude just means that light’s intensity; therefore amplitude isn’t involved in the equation?

ShastaB4C

https://youtu.be/jjy-eqWM38g

I hope this video helps clarify how light interacts with electrons!

ShastaB4C

Is there a difference between quanta and photons?

ShastaB4C

Can someone please clarify what are quanta?

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