CHEMISTRY COMMUNITY

Ghadir Seder 1G

When we're given experimental data to determine rate laws, how do you know which rate goes in which order of the fraction? For example, how do I know if its rate2/rate1 or rate1/rate2?

Ghadir Seder 1G

How do you know which equation to flip so that the electrons cancel out? Is it the reduction or oxidation equation that you flip?

Ghadir Seder 1G

How do you know which equation to flip when the electrons are on the same side?

Ghadir Seder 1G

You've all been a great help this past quarter! Thank you for all that you do!

Ghadir Seder 1G

Is there a negative in a unique rate law for the reactants because that is what is being used up? Or is the negative there for a different reason?

Ghadir Seder 1G

When comparing initial reaction rates rates for different reactions, why does the reaction rate depend only on the concentration of a reactant?

Ghadir Seder 1G

What does it mean for a catalyst to "not be consumed during a reaction"?

Ghadir Seder 1G

Hi all! Does anyone know when the final will be posted and how we will turn it in?

Ghadir Seder 1G

Can there please be a livestream for this review session that can be posted for reference after as well? This is absolutely the most helpful thing :(

Ghadir Seder 1G

How do I determine the order of the reaction using experimental data such as those in problem 7a.17?

Ghadir Seder 1G

How do we decide which experiments to use to determine the rates with respect to A and B?

thank you!

Ghadir Seder 1G

apologies, I meant 7A.15, not 7B.15 :)

Ghadir Seder 1G

Why is it that when writing the rate law for the reaction (=k[A][B]^2) that the b is squared and the a isn't?

Ghadir Seder 1G

Part a of this question asks what the order of each reactant is and the overall order of the reaction. How does one calculate this using the data provided?

Ghadir Seder 1G

Why do we reverse the the anode half reaction for part a of 6l.3?

Ghadir Seder 1G

Can someone explain to me how to determine the n value in the standard gibbs free energy equation for 6l.1 B?

Ghadir Seder 1G

I know that oxidation is the loss of electrons and reduction is the gain of electrons, but how can I tell which one is which by looking at the chemical reaction? Do I use their oxidation states?

Ghadir Seder 1G

so something is neither oxidized or reduced when its in the same oxidation state in both the reactants and products?

Ghadir Seder 1G

How do I balance a reduction half reaction step by step? I am fairly confused :( the reaction is Cr2072----->Cr3+

Thank you!

Ghadir Seder 1G

In the reaction for problem 6k.1, what happens to the oxidation number of the h+ when being converted to h20? Can hydrogen alone even be oxidized or reduced?

Ghadir Seder 1G

What sections of the homework correspond to the "second page" of thermodynamics thats going to be on the test?

Ghadir Seder 1G

In cell diagrams, is the solid the one that is acting as a the thing that pulls the electrons and transfers them? Why don't we include liquids when drawing cells? Why must the solids be metals ?

Ghadir Seder 1G

When we're trying to calculate the E value of the cell when its not under standard conditions, what equation do we use? I'm a bit confused as to which one of the equations applies to which scenario.

Ghadir Seder 1G

is a cell galvanic if it has a positive E naught value? Or is it electrolytic?

Ghadir Seder 1G

when delta g naught is equal to the enthalpy - t(entropy), is there any other way to calculate enthalpy and entropy without use the formation and products - reactants?
Sorry if my question is a bit confusing!

Ghadir Seder 1G

Can someone explain why delta g equals 0 when the reaction is at equilibrium?

Ghadir Seder 1G

In class we learned that a positive E value is favored. Can someone explain why? Is that the energy that is available to do work ?

Ghadir Seder 1G

What does the salt bridge do? Why is it in the center of the cell diagram?

Ghadir Seder 1G

What is the purpose of platinum in cell diagrams? Why is it on one side sometimes and not the other ? Does it represent the solid aspect of the diagram ?

Ghadir Seder 1G

How do acidic reactions differ from alkaline reactions when balancing the equation?

Ghadir Seder 1G

How do you balance the oxygens in acidic reactions?

Ghadir Seder 1G

What does faraday's constant do in the equation delta G=-nFE?

Ghadir Seder 1G

I'm having trouble figuring out how to identify which is oxidized and which is reduced. Whats the method to this?

Ghadir Seder 1G

Dr. Lavelle said that for redox reactions, its easier to split them into two half reactions? How do we do this using the example he gave in class?

Ghadir Seder 1G

Why do we assume delta s naught is constant in the van't hoff equation?

Ghadir Seder 1G

Can someone explain to me what the difference between delta g and delta g naught is? How does this difference change the values in the equation?

Ghadir Seder 1G

Can you calculate the maximum work without a system being under constant temperature and pressure?

Ghadir Seder 1G

where does 23.4 kj per mole come from for the value of delta H in the gibbs free energy equation?

Ghadir Seder 1G

what are the fractions 5/2 and 3/2 and how do I use them?

Ghadir Seder 1G

Can someone explain to me why the graph of an irreversible reaction has a slope of zero, and why the graph of a reversible reaction has a decreasing slope?
Does it have to do with one being under constant pressure?

Ghadir Seder 1G

when I haveL. atm and I need to convert to joules for work, which gas constant should i use?

Ghadir Seder 1G

How do I know which equation to use for work without the question stating whether the reaction is reversible or irreversible? Alluding to problem 4B.5 :)

Ghadir Seder 1G

How can you determine if work was done on the system or by the system given heat values ?

Thank you!

Ghadir Seder 1G

In order to see which bonds were broken and which were formed, do you always have to draw the lewis structures? Or is there an easier way to calculate the bond enthalpies ?

Ghadir Seder 1G

why is the delta H of n2 not included in the reaction delta H?

Ghadir Seder 1G

hello,
I'm struggling with problem number 15 in section D of our homework, can anyone give me an explanation?

Ghadir Seder 1G

4A,B, and C talk about work functions, we haven't covered that in lecture have we?

Ghadir Seder 1G

Which sections in the homework correspond to what we've learned in lecture so far?

Ghadir Seder 1G

In problem 4C. 3 there is a fraction 5/2 being multiplied by 8.314 J mol K. Can anyone tell my where these values are coming from?

Ghadir Seder 1G

What are all the phase changes? Are they exothermic?

Ghadir Seder 1G

Can someone give me brief explanation of how to calculate enthalpy using the third method?

Ghadir Seder 1G

when a reaction is exothermic, how does increasing or decreasing the temperature affect the reaction?

Ghadir Seder 1G

is the cutoff 10^-3? or 10^3?

Ghadir Seder 1G

can someone explain to me the rules of when we can approximate when K is smaller than 10^-3?

Ghadir Seder 1G

I was doing the quadratic formula for the following equation (4.92)+/- sqr rt ((-4.92)^2-4(0.56)(0.36)) / 2(0.56) and did not get the same values that are in the solutions manual. Can anyone help?

Ghadir Seder 1G

For the ratio (PO2)^3/(PO3)^2 why is it that with either the concentrations of 0.10M and 0.5M of O3 is the K the same?

Ghadir Seder 1G

Are we always calculating Q when we don't know whether or not the reaction has reached equilibrium?

Ghadir Seder 1G

I am a little unsure of how these are calculated and how they share a relationship. Can anyone give me a brief explanation?

Ghadir Seder 1G

Can heat act just as a reactant or can heat act as a product as well going back to reactant formation?

Ghadir Seder 1G

How can you take a given molarity and use it to determine the initial mass of that substance?

Ghadir Seder 1G

For homework problem number 5.39, how do they go from the quadratic that is (4x^2) + (-0.08x)- (4.0 x 10^-4 )to x= (0.064)-(13x)+(6.4x10^2x^2) when calculating Kc?

thank you for the help !

Ghadir Seder 1G

How can you tell if a reaction is endothermic or exothermic without knowing its delta H value? For example, for problem 5.33 in the homework, is there a way to tell whether or not the reaction is endothermic or exothermic?

Thank you in advance!

Ghadir Seder 1G

When solving for pressure using the ideal gas equation, why don't we divide r and t by volume as well but only divide moles by volume?

Ghadir Seder 1G

Why are solids and liquids not included in the equilibrium constant? Is it because solids don't dissolve in the solution?

Ghadir Seder 1G

Professor Lavelle mentioned that when calculating K, you omit the units. What does this mean and why do we do it?

Ghadir Seder 1G

When calculating partial pressure, why is it called "partial pressure" and not just pressure? What does this value represent?

Ghadir Seder 1G

Why and how are Kc and Kp calculated the same way but represent different values?

Ghadir Seder 1G

Can you tell if a ligand is chelating just by looking at its molecular formula?

Ghadir Seder 1G

Why is it that cisplatin binds to guanine bases pairs but not the other A,T, or C base pairs?

Ghadir Seder 1G

I understand that you add -ate to the end of the metal if the compound is charged, so is there anything you do if it is a positive charge rather than a negative?

Ghadir Seder 1G

For fundamentals problem number J.9 are we supposed to know the chemical formula for something just by knowing its name for the final? For example, bromous acid and phosphoric acid off the top of our heads?

Ghadir Seder 1G

Why is ozone's lewis structure drawn as one double bond and one single bond? Why is it not two double bonds with the formal charges on the oxygens all equal 0?

Ghadir Seder 1G

Where can I find the learning objectives so I can make sure that I know each concept?

Ghadir Seder 1G

The solutions manual has [H30+] as 0.18 and [OH-] as 5.6x10^-14... how did they calculate this using that relationship?

Ghadir Seder 1G

-log (0.12x(HCL))/(HCL)
-log ((0.12x100)/(100))

Ghadir Seder 1G

what is pKa and pKb and what is their relationship? Can someone explain to me how to determine these values when just given the compound such as BrO-? What section of the book is this covered in?

Ghadir Seder 1G

for parts iii and iv in the table, I calculated the pH and pOH using the given information, but how do I use my calculations to derive H3O+ and OH-? So how do I use ph and pOH to get the moles value ?

Thanks in advance !

Ghadir Seder 1G

So, I'm working on the pH homework problems and I'm using a TI-30Xa calculator. I can't figure out how to input the information for question 6B.1 into my calculator to get 0.92. However, when I do this on a graphing calculator it works just fine. Any idea as to how to input the equation in the solut...

Ghadir Seder 1G

Can someone explain to me how when an photon is absorbed how the change will be positive and not negative?

Ghadir Seder 1G

Ohhhh i see it now, thanks for the help!

Ghadir Seder 1G

I get that you can get E=h.c/lambda but lavelle used v=E/H ... How can i get to the equation he used ?

Ghadir Seder 1G

what are the five electrons that are being referenced in the answer key for question 6a ?

Ghadir Seder 1G

Can anyone explain how for question 2a frequency is equal to E/H? Im referencing E=hc and c=lambda(v) and I couldn't find a way to manipulate them to get v=e/h. Thank you!

Ghadir Seder 1G

Hi all! I hope you had a great thanksgiving with your families! I had a question regarding how to prepare for the final. So to prepare for the midterm, I went back and redid all the homework that Lavelle assigned, starting from week 1. However, when I took the midterm, I did not do well at all. I th...

Ghadir Seder 1G

Can help clarify when dipole moments cancel out? I'm confused as to how they cancel :(

Ghadir Seder 1G

how is there 2 ens that bind to the pt?

Ghadir Seder 1G

I am working on section J question 9 part b... it asks us to write the neutralization reaction of zinc nitrate. Can anyone help me in the process of doing so?

Thank you !

Ghadir Seder 1G

How would the calculations differ if the ligand was neutral?

Ghadir Seder 1G

Can someone explain how this has 6 as a coordination compound ?

Ghadir Seder 1G

What must I do to determine whether or not a ligand is polydentate?

Ghadir Seder 1G

How do you determine the oxidation number of a metal in a complex ion?

Thank you!

Ghadir Seder 1G

I know that lone pairs can make the size of a bond angle less than its "control" size... is there anything that can make it greater?

Ghadir Seder 1G

What is the difference between atomic geometry and molecular geometry? Does molecular geometry come into play when lone pairs are introduced?

Ghadir Seder 1G

How do you identify the hybridization of each lone pair in a molecule ?

Ghadir Seder 1G

What exactly mean to hybridize and how does it happen? Why do molecules do this?

Ghadir Seder 1G

From my understanding, you derive a molecule's hybridization by looking at its molecular shape and its hybridization scheme. Is there another way to do this? Without associating each shape to a specific scheme?

Ghadir Seder 1G

How can you write the VSEPR formula for a molecule that has more than one central atom? i.e C2H4

Ghadir Seder 1G

Can you relatively know if a molecule is polar or nonpolar simply by looking at the molecular formula? Or do you have to draw the lewis structure of the molecule to do so?

Ghadir Seder 1G

When doing dipole moments, do you change one of the bond lines to an arrow? Or do you keep the bond lines the same and add an arrow?

Thank you!

Ghadir Seder 1G

When referring to structures, are bent and angular the same thing?

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