CHEMISTRY COMMUNITY

Sean1F

Fried chicken

Sean1F

volume, whether or not the volume is changing, concentration, and the equations for all of these factors.

Sean1F

volume, whether or not the volume is changing, concentration, and the equations for all of these factors.

Sean1F

They represent different rate constants. The prime note is there to signify which you are referring to.

Sean1F

t(1/2) = 1/k[A]0

Sean1F

Frying an egg <— endothermic
Burning a stove <—- exothermic

Sean1F

tristenleem3B wrote:Most of the base equations are on the sheet, and everything we need to use is able to be derived from the sheet.

Yeah you can basically rearrange some of these equations and make use of the new ones

Sean1F

Freaks and Geeks

Sean1F

Remember LEO (loss of electron = oxidation) apply this to whatever compound you are looking at.

Sean1F

It should remain the same if I remember correctly.

Sean1F

k is the rate constant.

Sean1F

moles, as in number of moles

Sean1F

Just remember that the chloride molecule have to be in the middle!

Sean1F

Left is anode, right is cathode.

Sean1F

The aqueous chloride should be in the middle. Everything else is the same.

Sean1F

How would I go about balancing this equation? I understand finding the number of electrons for the iron half reaction, but I'm confused on balancing the NO2- to NO3- part. Anything helps. Thanks!

Sean1F

Had the same question thanks for posting

Sean1F

Kelvin is usually the standard for thermodynamics

Sean1F

Milli Zunich 3I wrote:When would we use this? Just curious.

I also have this question! Let me know if you find the answer.

Sean1F

it represents heat!

Sean1F

How exactly does EXTERNAL pressure affect an isothermal system with expanding volume? I understand how pressure is related to acquire the work done, but what about external pressure? Is there a relationship between the two?

Sean1F

Loss and gain of heat!

Sean1F

Also, exo relates to exterior which means the outside absorbs energy!

Sean1F

10 -7 comes from the autoprotolysis equation for water! When water undergoes such a process, it separates into H 3 O + and OH - . Since these ions are in equal concentrations, they both are equal to 10 -7 M, and when you multiply them together, you get K w , which is 10 -14 Hope this clears some co...

Sean1F

Jeffrey Yang 3I wrote:I would say just look at the other units in the problem, and make sure to calculate both the numbers you use and the units to have the correct unit that the question asks for as your solution.

I agree. It's good to loom at the units before using any constants!

Sean1F

Specific heat is how much energy is needed to raise the temperature by 1 degree, while the molar heat capacity is the energy required to heat a mole by 1 degree.

Sean1F

Think about a tea kettle. It can be heated up and cooled without transferring matter through it. Energy moves through the medium but matter cannot.

Sean1F

I think I saw that K usually refers to Kc, while Kp is usually just Kp. Not entirely sure but it makes sense, and that's what Organic Chemistry Tutor said.

Sean1F

There is by definition no way to change the energy.

Sean1F

Diya Kar wrote:At chemical equilibrium, the concentration or reactants to products does not necessarily have to be equivalent, however the rates at which the forward and reverse reactions are proceeding at must remain the same.

THANKS

Sean1F

PV = nRT is an exclusively kelvin equation!

Sean1F

I've seen delta u used more but I'm sure they are interchangeable. The last website I looked at, as well as the homework, had them as the same thing.

Sean1F

Organic chem tutor!!! He was a lot of help!

Sean1F

Ok I just went back to the lecture and found out that BECAUSE the rates of the forward and reverse equations are EQUAL, the concentrations do not change. I was just confused on the more accepted definition. Thanks guys

Sean1F

Just doing some review and I came across slightly different definitions of chemical equilibrium. So, I must ask: is chemical equilibrium more so that the rates are equal in both directions or that the concentrations are the same?

Sean1F

I doubt we'll have to use it on an actual test. Lavelle's thing is showing us concrete versions of what we're working with.

Sean1F

Adele Nguyen 2G wrote:Enthalpy is the amount of heat released or absorbed at a constant pressure.

What does it mean for the pressure to not be constant?

Sean1F

Paloma Sanchez 3L wrote:How do I calculate state property? What do I need to look at?

Yeah it really just depends what information is given to you. Just remember that enthalpy is always a state property!

Sean1F

I like to think of distance vs. displacement, where distance takes into account the changes that go on, while the displacement is simply a measure of beginning to end.

Sean1F

Also take into consideration what is happening to the surrounding objects. The heat doesn't just disappear. It is transferred to different system. So if its surroundings are getting warmer, it is exothermic.

Sean1F

Thank you for the replies!!!

Sean1F

1. Find the pOH from the pH which is given to you. (14-9.710) 2. Use pOH value to find [OH-]. Use formula pOH = -log[OH]. You'll need to do inverse log, or basically 10 -pOH 3. Substitute your [OH-] value in the K b formula. 3.297×10−5 = [OH-] 2 /[B] 4. Once you solve for [B] subtract [OH] from you...

Sean1F

Are we supposed to know the general chemical equation for acids? I did NOT know what the setup actually looked like when I was doing the first 2 problems on this week's homework. So, are we expected to know the formula for monoprotic weak acids in exams? If so, got any tips for learning the basics?

Sean1F

So when we're calculating equilibrium constants, how do we know when to not include water? I know that under some circumstances, H2O will end up being in the numerator and denominator of the equation, but is with any equation that involves H2O, any equation with aqueous solutions on both sides, or w...

Sean1F

Anthony Tam wrote:This is because strong acids dissociate completely in water. So the [H3O+] is essentially the same thing as the initial strong acid concentration.

Anthony u a real one

Sean1F

Anybody else a fan of the ICE box method? This is by no means an effort to get a point for the week, but I just wanted to see if others appreciate this strategy as much as I do. I couldn't imagine a chemistry class like this without it : )

Sean1F

Hi Hi Hi. On one of the lecture problems, a very strong acid or base is added to the water equation and from that, we somehow know or can easily estimate the resulting pH or equilibrium constant. Why is that? I understand that equilibrium constant for H3O and OH always adds up to 10^-14, but how can...

Sean1F

I had trouble with this one too! I made sure to find the x, convert to concentrations using the volume given, and solve!

Sean1F

Remember to convert mols to concentrations before solving the equations! I always forget

Sean1F

I had a similar question and apparently the difference is important. Based on what my peers are saying, it is very important to convert before going through with the calculation.

Sean1F

Are mol/L^-1 and M synonymous in this class? I noticed that both M and mol/L were used in the HW, so I'm wondering if there is a big difference.

Sean1F

Not sure if this is the right place to post this, but where is the 10^7 number derived from? I understand that it comes from one of the molecules in the water reaction, and that it has to do with 10^-14, which is the chemical equilibrium constant for the water reaction, but how did we get it?

Sean1F

It seems a little counter-intuitive to me that we write down two of something as an exponent rather than a coefficient on the equilibrium constant equation. Why is that?

Sean1F

Equilibrium: No net change in concentration of reactant and product. forward rate = reverse rate *The rate of a reaction depends on the rate constant and the concentration. The forward and reverse rate constants are not equal, and the [R] and [P] are not equal at equilibrium. *I will discuss this i...

Sean1F

Just remember that you are working with different units when it comes to Kp over Kc! My mistake at the beginning was confusing the two. Although the equation is similar, kp is for partial pressure, meaning gases, and Kc is for concentrations, usually meaning liquids!

Sean1F

I'm almost certain there are units within the components of the ratio, but otherwise, no. There are no units to the K constant.

Sean1F

Yes, whenever I think of catalysts, I think of enzymes. Especially because they do not affect much else but the reaction activation energy. So the difference in rate of equilibrium between the two is the same.

Sean1F

how do I know where to put the terms for the products and reactants? since the equation is K=P/R (so product is the numerator), does that mean when we look at a chemical equation the products are going to be on the right side of the equation symbol? Usually questions tell you what you start with an...

Sean1F

If the net rate of change is equal for both the reaction and its reverse, why is the K constant not always 1? I'm a little confused on that part because I thought their concentration values would be around the same.

Sean1F

No worries!In this case, the SI unit is meters, so multiplying the top by 10^3 is probably the easiest option to get there. For arithmetic decisions like this, I just do whatever I feel more comfortable with, as there're many paths that you can take where you end up with the right option. Hey Mingd...

Sean1F

Hello, I am currently working on a textbook word problem, 1b. 15, that requires the used of de Broglie's Equation. I ended up with Planck's constant (in meters) over the the momentum (in kilometers). Would it be more efficient to just multiply the top by 10^3 or should I convert one quantity to matc...

Sean1F

While I think it's not totally necessary to memorize and know the derivation, it might prove to be helpful since the equations used to derive it are equations that we should know and memorize anyways! This way we can have a greater knowledge of how these concepts work together which could hopefully...

Sean1F

Kimme Chun 1I wrote:The frequency is referring to how much energy a photon has and the intensity is referring to how many photons are present.

I don't think they have a direct relationship since both can vary.

Sean1F

Petrina Kan 3C wrote:I have not seen this before. The DeBroglie equation cannot be used for light, so I'm not sure if it can be applied or combined with the equation for the energy of a photon?

It is a general rule that some equations cannot be used for light, and I think this may be one of the cases.

Sean1F

How often would you have to rearrange this equation to find other quantities? Should this be practiced?

Sean1F

Gabriel Ordonez 1E wrote:Can someone please explain to a greater depth the following: Hund’s Rule, Pauli Exclusion Principle, and Aufbau Principle? Thank you in advance.

What exactly would you be looking for? The general meaning and use of these equations? I would love to help if you specified! :D

Sean1F

I think it would just be less likely. The bigger it is, the less wavelike, right?

Sean1F

Speed in a vacuum is defined as c= 3.00*10^8 m/s, which is a constant while measuring other speeds/variables in the electromagnetic spectrum topic. A formula given from the lecture is c=\lambda \times v , which is (the speed of light) = (wavelength) x (frequency). You can use the speed of light, a ...

Sean1F

Megan_1F wrote:What is the relationship between amplitude and intensity of light?

According to the school Physics website, "The intensity of a wave depends on its energy and the energy varies in a different way from the amplitude.". Hope this helped.

Sean1F

Hey Alice,

I had the same question! I just assumed it was some typeof divergence, but the definition seems to be exclusive to this topic.

Sean1F

Ethan Lam 4A wrote:Does the charge conservation work for ions too?

I, too, had this question. Can anybody elaborate? I saw an example with an ion and I was confused.

Sean1F

When is the speed in a vacuum used? Does anybody have any broad examples of when it is used?

Sean1F

As I've said in a previous reply to another post, I would say that you should round if the decimal is .1 or .2. Anything larger would lead to inaccurate results because a false ratio. Thanks for posting this! :D

Sean1F

I would recommend it as it is still correct; however, if you don't have much time, it is probably best that you imply them instead of explicitly adding them to your work.

Sean1F

I'm guessing it's always best to make the fraction into an integer. I've heard that that is the way it's done in the scientific field and that it is preferred by many since it is more user friendly for future calculations.

Sean1F

Remember to not be tricked! Sometimes many of my classmates forget to add the molar masses to compare it to the molar mass of the initial compound. It is always worth checking!!

Sean1F

My TA told us that rounding when the decimal was .1 or .2 was acceptable, while bigger numbers such as .3 are better multiplied. :D

Sean1F

Hey DTingey_1C!

I'd recommend using flashcards associate these unit prefixes to the actual values of each one. :D. It helped me so much in high school.

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