CHEMISTRY COMMUNITY

Mya Majewski 1L

but when? Is it when an irreversible expansion is occurring that DeltaSTotal=0?

Mya Majewski 1L

When is Stotal=0 and Ssurr=-Ssys?

Mya Majewski 1L

When does DeltaS Total=0, so Ssurr=-Ssys?

Mya Majewski 1L

okay, thank you! is there a homework problem like this?

Mya Majewski 1L

In solving for k in the Arrhenius equation k=Ae^-Ea/RT, my value always equals less than one when the answer key says it should be 6 x 10^8 for 6th edition 15.67? How does one solve this on the calculator?

Mya Majewski 1L

What is a pseudo first order reaction and what homework problem is it used in?

Mya Majewski 1L

Is the equation ln(k2/K1)= Ea/R(1-T1-(1-T2) a variation of the Arrhenius equation?

Mya Majewski 1L

Also in 15.89 for the 6th edition book.

Mya Majewski 1L

Can someone explain how mechanisms can be distinguished using kinetic data/energy?

Mya Majewski 1L

if your k is in min^-1 and your t is in seconds then what do you do?

Mya Majewski 1L

For [A]=[A]oe^-kt, there seems to always be conversions associated with the -kt and time, do you convert the k or the t to equal the same units (minutes, seconds, hours) as one another?

Mya Majewski 1L

How do you know whether to use the exponential decay 1st rate law or the regular integrated rate law? For example, in the 6th edition 15.25.

Mya Majewski 1L

How do you know whether to use the exponential decay 1st rate law or the regular integrated rate law? For example, in the 6th edition 15.25.

Mya Majewski 1L

When is the flow of electrons NOT from anode to cathode? In 6th edition 14.91 it flows from cathode to anode?

Mya Majewski 1L

look at what the x-axis and y-axis are and if its linear, its likely that order. For example, ln[A] vs. t if thats linear, its likely 1st order. If you search on Google there are super helpful charts that break down 1st, 2nd, and zero order in terms of linear plot to determine the rate order and the...

Mya Majewski 1L

You look at when one reactant changes and the other doesn't or stays the same (lets say the one reactant doubles). Then, you compare this to the corresponding reaction rate and if that changes (lets say it doubles for instance). So, you will be left with 2^x (2 raised to the X equals the rate)=2 (ra...

Mya Majewski 1L

Can someone explain why enzymatic/catalytic reactions are considered zero order?

Mya Majewski 1L

What do the definitions conceptually of the order of the reactions mean? Does the reaction rate increase from 0-->2nd order?

Mya Majewski 1L

G=-nFE
G=H-TS
G=-RTlnK
G=-RTlnK + RTlnQ
etc.
You can combine these and switch out variables but it depends what you are given.

Mya Majewski 1L

A lot of times Ag(s) and Ni(s) will be used as electrodes too.

Mya Majewski 1L

H+ and OH- both being aqueous are used in the cell diagram!
Water is NOT used

Mya Majewski 1L

Yes, you must make sure the coefficients and amount of R and P is balances as well as the charge

Mya Majewski 1L

In the 6th edition, what is the last problem that will be on the exam (before Nernst questions)?

Mya Majewski 1L

How do we know which elements have an oxidation number of 0 like O2 and Cl2? Is there a trick to knowing which elements have an oxidation state of 0?

Mya Majewski 1L

do electrons also flow from anode to cathode in electrolytic cells?

Mya Majewski 1L

In the textbook they give examples how to balance acidic and basic solutions within the electrochemistry chapter

Mya Majewski 1L

MCAT covers 14A-->D as well as biochemistry

Mya Majewski 1L

When writing cell diagrams, how do you know which goes closest to the electrode and which is closest to the salt bridge? For instance, when you have two things separated by a comma like Fe3+ and Fe2+, which one is closest to electrode when drawing cell diagrams?

Mya Majewski 1L

Whats the difference between the two?

Mya Majewski 1L

Do electrons always flow from anode to cathode?

Mya Majewski 1L

They are synonymous, however, once we get to it there is a difference between galvanic and electrolytic

Mya Majewski 1L

As stated in Lecture, Mn has a +7 charge- is their a table we should memorize in order to determine oxidation states?

Mya Majewski 1L

When do you use specific heat capacity of ice (2.03)? I have seen with problems in terms of ice melting in water we use the specific heat of water (4.184). Therefore, when do we use the ice specific heat?

Mya Majewski 1L

for question 8, isn't the answer going to be Kb x 3^8?

Mya Majewski 1L

For #6, how did we get w=9.119 x 10^3 J?

Mya Majewski 1L

Could someone please post the worked out answers to questions 3A and B please from the Lyndon review, thank you!

Mya Majewski 1L

In isothermal reactions, internal energy is always equal to 0 so -q=w?

Mya Majewski 1L

For 6th edition 8.85 or a phase change in general, do you use q=nDeltaH or deltaH=nDeltaH because for this phase change it uses deltaH=n x deltaHfus?

Mya Majewski 1L

Using the equation q=nCdelta T where n is in g, C is in J/Cg and Temperature is in Celsius, isn't the heat unit supposed to be J and NOT kj?

Mya Majewski 1L

For 8.23, why do we ignore the number of moles in q=nCdeltaT?

Mya Majewski 1L

Can someone explain exactly what degeneracy means? And how to calculate it?

Mya Majewski 1L

Most Likely not but knowing how to derive it is important in understanding the concepts and how the variables connect to one another

Mya Majewski 1L

How do you know determine if internal energy equals 0?

Mya Majewski 1L

Have we even went over internal energy in class yet (Delta U)?

Mya Majewski 1L

To add, I think of Work being the ability to do something. For example, if the piston is moving out, that means the gas (system) is doing work because it is physically pushing the piston out of place.

Mya Majewski 1L

Wait you said enthalpy of reaction for both, which one is which again?

Mya Majewski 1L

Do we get our Test #1 back in discussion section this week?

Mya Majewski 1L

I am enrolled in the 11am lecture, but on Monday I had to go to the 1pm and we didn't finish covering Method #3 on Friday in the 11am, could explain explain this one to me and maybe send a picture of the notes from lecture? Thanks!

Mya Majewski 1L

How do you know which one to use and what is the difference between them?

Mya Majewski 1L

What is the difference between the Enthalpy of Reaction and the Enthalpy of Formation?

Mya Majewski 1L

to correct the equation above pOH +pH=14 NOT pkw

Mya Majewski 1L

So basically the "x" you calculate needs to be within 5% of the initial concentration so do x/initial x 100%

Mya Majewski 1L

No, pka=-log Ka and pH=-log(H30+) so the equations both involve a negative log (the "p" signals a negative log) Basically they are related but the pH tells you the amount of H atoms in a solution and the pka is more specific in letting us know how acidic something is (the lower the pka the...

Mya Majewski 1L

Within the 6th edition, which problems start with using salts?

Mya Majewski 1L

Since strong acids and bases completely dissociate in a reaction, we do NOT need to do an ICE table and therefore we just need to look at the moles of OH or H30 on the product side and multiple that by the initial conc of the acid or base?

Mya Majewski 1L

pay attention if the problem gives you Kc or Kp, then you know which to use!

Mya Majewski 1L

How do you know when something is a salt? To add, how does a salt affect the ICE Tables because in lecture the product sides were NOT at 0??

Mya Majewski 1L

Lavelle mentioned if you are rusty on ideal gases to read up on them in the book! The textbook explains ideal gases well in the concepts of chemical equilibrium.

Mya Majewski 1L

I was wondering what the best way was to prepare for the quiz this week? To add, what is the format of the quiz and the quiz will be during discussion sections correct?

Mya Majewski 1L

How do you know when to use an ICE Table? Is it ALWAYS the case that the products start at 0?

Mya Majewski 1L

According to 11.69, an increase in pressure of the product causes the partial pressure of a reactant to decrease. How is this? Is there a general rule in predicting how pressure influences the changes in equilibria

Mya Majewski 1L

^as mentioned above, pure solids and liquids are not involved in any K expression. HOWEVER, H20 in aqueous or gas form is used in equilibrium expressions (refer to the first 10 problems in Homework in chapter 11)

Mya Majewski 1L

Even though gases use STP at 273K it will primarily depend on the question? Or you just have to know if you're given gases to use 273K?

Mya Majewski 1L

R is the universal gas constant that can be in many different variations in terms of units. However, for this class, I believe we will be primarily focusing on R= 8.3145 J/mol·K since T in PV=nRT will be in Kelvin as Dr. Lavelle stated in class. Hope this helps!

Mya Majewski 1L

How do you know whether to use K=273 K (STP) or K=298 K when calculating PV=nRT?

Mya Majewski 1L

Can someone give the definition of partial pressures and why its important to use partial pressures for gases and concentration for everything else?

Mya Majewski 1L

For organic naming with functional groups. Ether is the one one that is named in the beginning of the molecule?

Mya Majewski 1L

Whats the relationship between Temperature and Activation Energy? If one decreases what happens to the other? If one increases what happens to the other?

Mya Majewski 1L

Can someone explain the main differences between a cis and trans isomer? How could you tell looking at a molecule whether it is one or the other?

Mya Majewski 1L

When given the K of the reverse reaction and concentrations of the forward. How do you find the overall K? Also, how do you know whether the reaction is favoring the products or the reactants?

Mya Majewski 1L

What makes a molecule a more ambident nucleophile?

Mya Majewski 1L

I believe you would use formal charge to find out if it becomes positive or negatively charged.

Mya Majewski 1L

If given concentrations of a reaction, and the balanced reaction. How do you find K and if the reaction is going forward or reverse?

Mya Majewski 1L

When do you know when to use q=-q, mcdeltaT=-mcdeltaT, or q=ndeltaH + mcdeltaT????

Mya Majewski 1L

How do you determine if a redox reaction is favorable?

Mya Majewski 1L

What equations do we need to know for the quiz this week that aren't on the equations sheet given? In other words, what concepts do we fully need to understand that will not be given on the sheet?

Mya Majewski 1L

Can someone go over the difference between the two calorimeters that Lavelle explained in class?

Mya Majewski 1L

For calculating the work of expansion how do you properly solve an integral? I haven't had CALC in awhile and I forgot how to mathematically solve it.

Mya Majewski 1L

I know we went over these two topics in lecture today, but how exactly do these to correlate with enthalpy? In other words, what does specific heat and heat capacity tell us?

Mya Majewski 1L

How can you decipher what salts are involved in a certain reaction? Like how can you determine the outcomes or products within a buffer?

Mya Majewski 1L

Is there a proper way to finding the C part in the ICE box. I always get confused when trying to find this part.

Mya Majewski 1L

Can somebody give a list of steps in naming coordination compounds? How do you know the oxidation numbers for each metal ion?

Mya Majewski 1L

If you are given CO and you are told to do the molecular orbital theory for it, do you do the one where Z>8 or Z<8???

Mya Majewski 1L

How do you calculate the number of electron density regions?

Mya Majewski 1L

When doing a Lewis Structure, how do you know if an element has a lone pair or more than one lone pair?

Mya Majewski 1L

When making a Lewis Structure, how do you know whether to put a single, double, or triple bond? I know you look at the valence electrons but I get confused when deciding how many dots are around the element

Mya Majewski 1L

How do you know what the m(l) quantum number for an element is?

Mya Majewski 1L

In the review problems for E:23,

How do you calculate the amount (in moles) Cu^2+ ions in 3.00 g of CuBr2?

Mya Majewski 1L

I believe that the photon model of light showed that light has both wave and particle properties. Thus, this model shows that because it is specifically about the photon of light hitting the medal which emits an electron. I hope this helps!

Search found 89 matches