CHEMISTRY COMMUNITY

Micah3J

Charlyn Ghoubrial 2I wrote:
Angela Patel 2J wrote:Also, how would we know the sign of the internal energy?

If energy enters the system: +
If energy leaves the system: -
If work is done on the system: +
If work is done by the system: -

Thank you for this quick check for the internal energy

Micah3J

Just because we are increasing the number of collisions, how does this correlate to a decrease in activation energy? I thought that is something a catalyst does.

Micah3J

What are you guys referring to as "flipping"? Does this mean making one side negative or like looking at the reverse reaction instead?

Micah3J

Also, do catalysts affect the reverse reaction in the same way that it affects the forward reaction?

Micah3J

How exactly does a catalyst lower the activation energy of a reaction?

Micah3J

unimolecular would correspond with 1 molecule that initiates the reaction bimolecular would correspond with 2 molecules colliding to start a reaction termolecular would correspond with 3 molecules colliding and higher molecularity is very rare Termolecular can also be 2 of the same molecules collid...

Micah3J

Can someone help explain the gas phase example of Nitric Oxide that Lavelle gave for Homogeneous Catalyst? I don't quite get how we get to 3/2 O2?

Micah3J

How can we easily identify adsorption or absorption? What kind of information is need to be certain?

Micah3J

Can someone explain what makes a molecule a reducing agent or an oxidizing agent?

Micah3J

Yes please^
I was looking over my notes again and couldn't quite remember

Micah3J

Sorry this question is about 6M.3... Can someone briefly explain the process for 6M.3? I just want to make sure I have the right concepts down

Micah3J

kim 2I wrote:
Micah3J wrote:Test 2 is on all of outline 5 right and the second half of outline 4 right?

Yep! The second half of outline 4 being 5G or page 2 of the outline.

Sweet, thank you so much!

Micah3J

Test 2 is on all of outline 5 right and the second half of outline 4 right?

Micah3J

Does anyone have any good youtube videos that are short but helpful for the electro chemistry material? I highly recommend the Organic Chemistry Tutor. Search him up on YouTube and the topic you are looking for, and there is a very high chance there will be a video for the topic you need. Thank you...

Micah3J

Is it possible to have more than one reducing or oxidizing agent in a reaction?

Micah3J

Does anyone have any good youtube videos that are short but helpful for the electro chemistry material?

Micah3J

With a reversible pathway, the temperature is constant, volume increases, and pressure decreases. With a reversible process, you can use delta S= rev/T. There is more work done, which can be calculated using w= -nRTln(V2/V1). With an irreversible pathway, temperature will change (decrease then incr...

Micah3J

Yes can someone please go over when we use the 5/2R and the 3/2R? I still don't quite get when to use them and why to use them

Micah3J

By flipping the equation it would mean that you are just taking the reverse reaction instead right? So then basically the reactants are on the products side in order to cancel things out?

Micah3J

In Outline 3 it says, "Distinguish the three different types of thermodynamic systems." This is referring to open, closed, and isolated right?

Micah3J

Do you think he will go over any example problems tomorrow regarding the Gibbs Free Energy stuff that he discussed on Friday? Or does anyone have some good practice problems to share?

Micah3J

Majority of the points will be solving for values but dispersed throughout are conceptual questions that require you to understand why you might be doing what you are doing in the problem. Possible conceptual questions could be which why the reaction shifts with equilibrium or what is an intensive p...

Micah3J

Intensive properties do not depend on the amount of substance and is usually constant units. Like specific heat capacity is an intensive property

Micah3J

Yes, ICE tables are just for Concentrations of molarity or for the pressures of gas. Conversions to mass can be done later by knowing the molarities at equilibrium

Micah3J

Vinita Saxena 2I wrote:
Micah3J wrote:Does anyone have a list of the formulas we should be familiar with for this midterm?

The formula sheet is the same one we got for Test 1

Okay thanks

Micah3J

And so just because there is constant external pressure, the internal pressure can still be changing because of the reaction going on?

Micah3J

Is there a difference between a regular calorimeter and a bomb calorimeter? Yes, if you're talking about the simple calorimeters that are used in high school labs, which basically consist of thermometers suspended in a container filled with water. The difference between these calorimeters and bomb ...

Micah3J

Is there a difference between a regular calorimeter and a bomb calorimeter?

Micah3J

If on a test we were asked to use Hess's law, we would be given a table that shows the bond enthalpies right? If anything I just need to remember which ones are 0.

Micah3J

Does anyone have a list of the formulas we should be familiar with for this midterm?

Micah3J

So for Hess's Law, the sign of the resulting net enthalpy will tell if the sum of the reactions is endothermic or exothermic right? That is correct. If delta H of the sum of the enthalpies of the multiple reactions is negative, the overall reaction is exothermic. If delta H of the sum of the enthal...

Micah3J

Shivam Rana 1L wrote:A closed system cannot exchange mass with its surroundings but it can exchange energy, while an isolated system cannot exchange either.

So what would be an example of a closed system and an example of an isolated system?

Micah3J

Sorry this is for 4A.1 but I didn't know where else to ask. How can we tell if a system is open, closed, or isolated? Mainly, what is the difference between closed and isolated? I got those two mixed up

Micah3J

Just make sure that the R constant and your given units will cancel out and match accordingly

Micah3J

I think it is a constant volume because it was named the "bomb" calorimeter because it would explode when the pressure got too high.

Micah3J

I think that has to do with being at the ideal pressure and temperature of like 1atm and then 25C. I could be wrong though

Micah3J

Does anyone know when we will be getting Test #1 back?

Micah3J

Sodium Hydroxide

Micah3J

Why in the notes are they referred to as equal then?
qp = delta H = n(Cp)(delta T)

Micah3J

Will we be given whether the calorimeter is of constant pressure or of constant volume in the problem? Or how would we be able to tell?

Micah3J

So for Hess's Law, the sign of the resulting net enthalpy will tell if the sum of the reactions is endothermic or exothermic right?

Micah3J

I think that it can be either, its just a matter of making sure that your units are all compatible all the way throughout. I think Kelvin would be the more standard though

Micah3J

Also, what is the difference between intensive properties and state properties?

Micah3J

What are some other examples of extensive properties?

Micah3J

zfinn wrote:
Micah3J wrote:Pressure doesn't affect the equilibrium constant though right? It will only shift it one way or the other?

yep! heat is the only measure that affects the equilibrium constant

Wait, you mean heat as well as concentration of either the products or the reactants right?

Micah3J

Pressure doesn't affect the equilibrium constant though right? It will only shift it one way or the other?

Micah3J

there is also pkw = pka + pkb

Micah3J

When steam condenses onto the skin there is a large transfer of energy in the form of heat which causes the skin to burn.

Micah3J

Steam burns are severe since all of H20 is changing states and thus transfers a lot of energy in the form of heat onto the skin

Micah3J

When writing the formula for K, does it matter if you put the gases in brackets as well or how do you differentiate that it is a gas and not aqueous?

Micah3J

Is there a difference between bent and angular? Or is it just another way of saying the same thing?

Micah3J

AronCainBayot1L wrote:HI is more stronger because chlorine is more electronegative and will have a stronger bond. The weaker the bond the stronger the acid.

And this also means that the stronger the bond the stronger the base right?

Micah3J

This is only in regard to resulting molecules and Ka calculations right?

Micah3J

Does anyone know if Lavelle will be going over the same exam example problems during his lectures? Or would it be beneficial to attend more than one?

Micah3J

Can you use the de broglie equation to calculate the wavelength of something other than an electron? And when do we know to use the de broglie equation over KE?

Micah3J

I think that a good night's sleep is pretty important too. I'd suggest to not stay up super late cramming because that can limit your ability to perform on the test due to lack of sleep.

Micah3J

I find youtube videos to be helpful too. Sometimes they just explain it in a different way which can help increase understanding

Micah3J

What amphoteric compounds will we need to know for the final? Or is it just understanding the characteristics of the compounds?

Micah3J

What exactly will we need to know for titrations on the final?

Micah3J

What is the difference between melting point and boiling point?

Micah3J

So just to be clear, the prefixes cis and trans can be in front of any molecule that can be either symmetrical or asymmetrical?

Micah3J

I think it just affects the bond angles between the atoms but I could be wrong.

Micah3J

For the sigma and pi bonds, will we just have to identify where they occur and what their function is?

Micah3J

How can we tell if the bond angle should be equal to a certain degree or less than the certain degree. An example of this can be ClO2+... The shape is bent, but I don't know how to tell that it is less than 120 degrees instead of just exactly 120 degrees. Generally a bond is equal to a certain degr...

Micah3J

So that means that the stronger the bond strength, the higher the boiling point?

Micah3J

How can we tell if the bond angle should be equal to a certain degree or less than the certain degree. An example of this can be ClO2+... The shape is bent, but I don't know how to tell that it is less than 120 degrees instead of just exactly 120 degrees.

Micah3J

Is the AXE formula another name for the VSEPR formula? Are the two terms interchangeable?

Micah3J

Did Lavelle cover all of the different structures that we will need to know or will there be more on Friday's lecture?

Micah3J

What are the units of the formula for Interaction Potential Energy?

Micah3J

I was wondering about the example of the VSEPR Model of CO3 that we went over in lecture today. Does the double bond cause it to have any polarity?

Micah3J

For Dino Nuggets 6a, what equation do we need to use ? ive been trying to use different one (because theres a lot for E) and that molar mass is messing me up. I used de Broglie's since light isn't involved. Also, make sure you convert the molar mass to mass using Avogadro's... that also might be me...

Micah3J

Can someone explain the exceptions to electron configuration again? Thanks

Micah3J

What is the limiting reagent for #3? Thanks, i just want to be sure I'm doing it right

Micah3J

Do we use the De Broglie equation for the midterm review question 13a? Yes we do. We know this because we are using the wavelength of a potassium ion, which has mass. The speed of light equation (\textup{c}=\lambda \upsilon ) on the other hand would be used for situations involving electrom...

Micah3J

In broad terms, you need to figure out the total energy of one photon from the incident light to then discover the light's frequency. In more detail: 1. You're given the ejected electron's wavelength, and this tells you that there is excess energy (i.e. kinetic energy). Use this wavelength to calcu...

Micah3J

What exactly do we use the Heisenberg's equation for and what does it tell us? Thanks

Micah3J

Do we use the De Broglie equation for the midterm review question 13a?

Micah3J

Could someone please explain 8b please? I used the photoelectric effect equation relating kinetic energy, energy of the photon, and the work function, but for some reason I'm not getting the correct answer. What answer did you get? I'm having the same trouble and wondering if maybe we made the same...

Micah3J

Can someone explain to me the concepts behind 10a? I am confused on why it is Aluminum. Thanks

Micah3J

Do you think we will need to be able to draw the different atomic orbital patterns for the different types?

Micah3J

KayleyW_3L wrote:I would also highly recommend Khan Academy to study for material, because it explains concepts and reinforces ideas in your mind.

Which chemistry course has majority of the topics we are covering? Or do you just search around for the topics we are discussing?

Micah3J

Will we need to know the f block for the midterm?

Micah3J

PranaviKolla3G wrote:How do you calculate formal charge again?

The formal is...
FC = V - (L + S/2)

Micah3J

Is there a quick way of determining the formal charge of an atom without going through the equation each time? Thanks

Micah3J

Does anyone have any good review videos that they recommend for the midterm?

Micah3J

If I am unable to make the review session tomorrow night but still work out the problems on my own, will the answers be posted on here so I can check my work?

Micah3J

When calculating the formal charge, we want the outer elements to carry the negative charge as opposed to the middle element right? If so, can someone explain why?

Micah3J

How can you tell when there is resonance and if the middle element should just be left without a full octet?

Micah3J

What kind of questions might there be regarding the Aufbau Principle on a test? Questions regarding the electron configurations of elements. So you must be able to know the principles in order to determine the correct electron configurations or to figure out whether or not the electron is in a grou...

Micah3J

Is the electron affinity a number that we will have to calculate or something we memorize?

Micah3J

What kind of questions might there be regarding the Aufbau Principle on a test?

Micah3J

So will we be expected to use the alternative way or the Rydberg equation? Will both get us full credit?

Micah3J

I converted KeV directly to Joules so I also don't understand the ned to multiply KeV by 10^3. However, I am also very confused as to how these units cancel and my final answer was lambda=8.831pm. I multiplied plancks constant by c and got 1.9878x10^-25. I then divided the product by energy in joul...

Micah3J

Can someone confirm that a keV is really 10^3 eV which is equal to 1.602x10^-19 J?

Micah3J

And so just be clear on density, that is just referring to the central location of majority of the electrons? Is there a mathematical number associated with this density?

Micah3J

When are we able to tell when to use the wavelength model versus the photon model? It is still unclear the relationship between photons and frequency and how that applies to the photoelectric effect

Micah3J

Would there ever be a question in which the chemical equations cannot be balanced? How would we be able to tell without trying dozens of different combinations?

Micah3J

Do the significant figures of a constant such as Avogadro's number or Planck's constant matter in our final answer?

Micah3J

Why is Avogradro's number based on Carbon 12?

Micah3J

When would there ever be a situation in which there is zero Kelvin?

Search found 100 matches