CHEMISTRY COMMUNITY

katherinemurk 2B

I thought so because the pressure and volume is constant!

katherinemurk 2B

K is the equilibrium constant so yes!

katherinemurk 2B

When the reaction is at equilibrium, are the rate constants of the forward and reverse equal? In my discussion notes I have
K=1 so k=k' ?

katherinemurk 2B

So the question asks to determine the time required for each reaction to take place. For part 1 it gives the reaction 2A ---> B + C. It also says these reactions are second order. If it is second order isn't the equation supposed to be 1/[A]t = 2kt + 1/[A]initial since there is a coefficient of 2 in...

katherinemurk 2B

How does stoichiometry come into kinetics? There are some questions in the book that ask about finding k constants when they give you the initial concentration of A but then give you a concentration of B at the some point in time?

katherinemurk 2B

I dont understand what happens to the negative in front of k for integrated 2nd order rate laws??

katherinemurk 2B

can someone please explain integrals to me? I never took calculus or ap calculus and I am super confused? Why does ln come in?

katherinemurk 2B

I think you use the rate law to find m and n which represent the order of the reactant.

katherinemurk 2B

I think so since the initial concentrations are the reactant concentrations

katherinemurk 2B

What is the difference between capital K and lowercase k??

katherinemurk 2B

You add an inert metal when the ions of the same element are in the same solution or when you have a gas and ion in the same solution

katherinemurk 2B

In the solutions manual for part d it says NO3- is the oxidizing agent and it is in the cathode, but how is this possible if it goes from NO3- to No2. Is it not losing an electron, therefore it is oxidizing so it is part of the anode??

katherinemurk 2B

how come for some of the homework problems in the solutions manual they reverse the reaction. What is the significance of this?

katherinemurk 2B

O2 is a naturally occurring compound.

katherinemurk 2B

under what conditions does delta S = 0

katherinemurk 2B

If you start at 100 L and end at 100 L then volume for the entire process is unchanging so if delta V is equal to 0 doesnt work = 0??

katherinemurk 2B

One of the TA's in the review session said it is possible to have a irreversible isothermal expansion but we do not need to worry about in this class.

katherinemurk 2B

To clarify, when the reaction is reversible delta S is 0?

katherinemurk 2B

Can someone explain how to do #1. I found the heat gained by the water but without the final temperature of the metal how would I find the specific heat??

katherinemurk 2B

Mya Majewski 1L wrote:For #6, how did we get w=9.119 x 10^3 J?

For the first part it says you preform an isobaric compression to 10L. Isobaric is constant pressure so work is equal to -PdV. So pressure is 1.00 atm and the change of V is 10-100 so -90. This comes to -90 L.atm you then convert this to Joules

katherinemurk 2B

Yes it just depends what units you are working with!

katherinemurk 2B

In a solid the molecules are not as free to move around as in a liquid, because in a solid molecules are more tightly packed so they occupy less positions

katherinemurk 2B

In the solutions manual they add the reaction enthalpy of fusion to the equation q=mCdeltaT when calculating heat of the ice cube. Can someone please explain why this is done?

katherinemurk 2B

I think you can still do hw on thermochemistry since we recently started to cover thermodynamics.

katherinemurk 2B

delta H is change in enthalpy and q is heat added to the system

katherinemurk 2B

Hi! I never took calculus in high school let alone AP calculus. Can someone explain to me why we need integrals? I know Professor Lavelle answered this question in class but I didn't get the answer. Thank you!

katherinemurk 2B

Ka is the constant relating to acids and its dissociation while Kb is the concentration related to bases and their ionization

katherinemurk 2B

pKa is a the -log of the acid dissociation constant, it is a measure of acid strength. pH is a measure of the concentration of H+ ions.

katherinemurk 2B

Will next weeks homework be on textbook questions from outline 3?

katherinemurk 2B

I have the 6th edition and for 12.35, it says list the acids in order of increasing strength, and it says the larger the Ka value, the stronger the acid, yet the list of acids is in the wrong order and it should be the other way around. Is this an error or am I thinking about this wrong?

katherinemurk 2B

How does the affect of temperature and pressure differ when it comes to changing the equilibrium?

katherinemurk 2B

There is a question in this post assessment asking about finding the equilibrium constant of reaction 2BrCI <-> Br2 + Cl2. The question says something about 18.3% of the BrCI gas remains at equilibrium. However, no matter how many times I attempt the question I cant get the answer. Can someone expla...

katherinemurk 2B

The flasks are in order of time. So to get the answer you just count the amount of diatomic molecules present in each flask. And if you do this you will notice both flask 3 and 4 both have 5 diatomic molecules. So the reaction reached equilibrium at flask 3 because that is where the reactants stay c...

katherinemurk 2B

Today in lecture, professor Lavelle gave an example with the reaction PCI5, PCI3, and CI2. When he made the ICE table he made the change in concentration +x. How do we know to put +x? Can someone please explain, thank you!

katherinemurk 2B

In some questions they ask to find the K value from reactions where the coefficients were either divided or multiplied by a certain number, such a 2. How come when you multiply by 2, you have to square the given K value, and when you divide by 2, you square root the given K value?

katherinemurk 2B

I am still confused on how to tell if an acid is strong or not. Does electronegativity play a role in acid strength??

katherinemurk 2B

How can you tell a substance is amphoteric by just looking at it? or is there a way you can figure it out?

katherinemurk 2B

I dont think there will be a chart provided since Dr Lavelle said you are expected to memorize the bond angles and shape names. Try memorizing the formulas for molecular shape (e.g AX3E, which correpsonds to trigonal pyramid)

katherinemurk 2B

Resonancy is not totally important when it comes to molecular shape because it does not matter which lewis structure you consider. Since all of the resonance structures will have the same shape it doesnt matter which one you focus on since single and multiple bonds are counted as one bond

katherinemurk 2B

So within a coordination compound, are the ligands always going to be lewis bases, and the central atom or ion is the lewis acid or can it be switched around??

katherinemurk 2B

Is it safe to say that polarizing power is indirectly proportional to atomic radius and directly proportional to electronegativity? and is polarizability indirectly proportional to electronegativity and directly proportional to atomic radius??

katherinemurk 2B

can someone please explain this question to me I don't get it at all

katherinemurk 2B

Can someone please clarify what the difference is when asked for arrangement vs when asked for molecular shape? I know it has something to do with the lone pairs but im not entirely sure

katherinemurk 2B

Higher polarizing power refers to "atoms and ions that CAN cause large distortions." I capitalized "can" because that word made me understand what is meant by polarizing power. So basically the higher poloarizing power an atom has, the more it can pull electrons toward it. Small,...

katherinemurk 2B

As you go down a group, atomic radius increases, so there is less pulling power on the electrons. CO2 is more ionic because oxygen is in the second period so its atomic radius is small which means there is more pulling on the elctrons by the nucleus. Therefore, Oxygen is very high in electronegtivit...

katherinemurk 2B

Potassium and Phosphorus have a high difference in electronegativity so they have more ionic so they are not covalently bonded so the Potassium atoms are separate.

katherinemurk 2B

Okay so there are many questions that give you the mass composition of each element in a compound and ask to find the empirical or molecular formula. The percentage of each element adds up to a 100%. What if they did not add up to 100%, how we would go about solving the problem??

katherinemurk 2B

For example when n=3 and l=2 we know this corresponds to 3d. Since l is equal 2 we know the values for ml can be: -2,-1,0,1,2. This tells us how many orbitals there are. In this case it is 5 orbitals. Since there are 2 electrons in each orbital, there are 10 electrons

katherinemurk 2B

Can someone please explain the answers to these two questions. I do not understand them at all. Thank you in advance!

katherinemurk 2B

For this question you just take the number of orbitals and multiply by 2 to get the number of electrons that can occupy that specific orbital. So for example the 4p orbital corresponds to the angular momentum quantum number 1. This number can have 3 values of the magnetic quantum number -1,0,1. Thsi...

katherinemurk 2B

Intensity is what effects the amount of electrons. So as intensity increases, quantity of electrons being removed increases

katherinemurk 2B

For part b, convert 5.00 mg to g. Then using the equation m=nM, find n, which is amount in moles. Then use the equation N=nNa to find N, which is number of sodium atoms. Use the answer from part a and multiple that number by the number of sodium atoms. For part c, just divide the answer from part a ...

katherinemurk 2B

First convert 420 nm to m. Then solve for the energy per photon by using the equation E=hc/(wavelength). Once you have that answer, you can divide the total energy which is 64J (1 W= 1 J.s, so 32 x 2=64 J) and divide that by the energy per photon. This will get you the amount in photons. To solve fo...

katherinemurk 2B

When the electron in a hydrogen atom makes a transition from the 1s orbital to a 2p orbital the atom's radius is increasing because the number of enegry levels is increasing, and so is the number of electrons. Each energy level is getting farther from the nucleus. So when a electron moves from 1s, w...

katherinemurk 2B

This was probably already asked, but will electron configurations be on test 2? For example, will we need to know the ground state electron configuration of an element??

katherinemurk 2B

The last time I took chemistry was 10th grade, so I am a little lost on the whole orbital concept and the wave function. Can someone give me a simple explanation? If you can me it as simple as possible that would be great.

katherinemurk 2B

When an electron jumps from a lower energy level to a higher energy level (ex. n=1 to n=3) then energy is absorbed. Therefore, the electron gains energy since it is moving away from the nucleus. When an electron goes down to a lower energy level (returning to ground state) it emits energy. Therefore...

katherinemurk 2B

When the size of the wavelength increases (more far apart) then frequency decreases and I believe this causes energy to decrease. If the wavelength decreases(less space in between), then frequency increases therefore energy increases, specifically electromagnetic radiation. I found this on wikipedia...

katherinemurk 2B

Does anyone know if test 2 will cover both chapter 1 and 2 of the textbook or just chapter 1?

katherinemurk 2B

Hi Katherine! First tests are always scary because it's hard to know what to expect, but just be confident and don't worry too much! My UA session is Tuesday 6-8pm and I go over practice test questions that are based off of previous exam questions, so that could be helpful. Doing problems is always...

katherinemurk 2B

Okay first balance the equation given if it is not already. Then if given the mass of the two reactants convert both to moles. Then divide each of those amounts by the number of moles in the equation. For example 2Al+6HCI --> 2AlCI3 + 3H2 If given the grams of Al and HCI you convert to moles. In thi...

katherinemurk 2B

I am really nervous about Test 1, and I have done all the homework problems about 4 times. Is there anything else I can study? Or what is the most difficult topic for students to comprehend or a topic students have the most questions on?

katherinemurk 2B

For me personally, it is much easier to convert all units to the correct units in the beginning instead of at the end. I don't know if that is the best way but it has worked for me!

katherinemurk 2B

Is the limiting reactant always going to be the one with the least moles? or do you have to take into account the molar ratio? and if you do take into account the molar ratio how would you work that into finding the limiting reactant??

katherinemurk 2B

Can someone please explain the difference between classical mechanics vs quantum mechanics because I was totally lost in lecture about the whole pouring water from a flowering can example??

katherinemurk 2B

When you subtract the molar mass of the metal of the two hydroxide atoms from the molar mass of the metal hydroxide, you get a molar mass of 40.084. And the metal matching this molar mass is calcium (40.078) so now you take find the molar mass of calcium sulfide!

katherinemurk 2B

Problem F13 in the textbook asks "In an experiment, 4.14g of phosphorus combined with chlorine to produce 27.8g of a white solid compound. What is the empirical formula of the compound? In the solutions manual it skips the step of finding mass percentage of each element. So instead of dividing ...

katherinemurk 2B

Can someone explain addition and subtraction with significant figures? We went over it in discussion today but I was still confused about how many significant figures should be in the final answer?

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