CHEMISTRY COMMUNITY

Riya Pathare 2E

Both delta G and delta Stotal can tell you the spontaneity of a reaction

Riya Pathare 2E

Kinetic control occurs when there is a lower activation energy barrier to overcome and because of that you will get a faster reaction with a higher k value, making it more kinetically stable. Thermal control means there is a larger energy barrier to overcome but the product will be at a lower delta ...

Riya Pathare 2E

I think we have to do it from complex molecules like we did in class when he showed us examples

Riya Pathare 2E

We use the coefficients in mechanisms/elementary steps but this is not valid for the overall reaction.

Riya Pathare 2E

work is equal to -P*deltaV so when there is no volume change delta V will be 0 making work also equal to 0

Riya Pathare 2E

We leave the catalysts out of the rate laws because they only change the activation energy and have no other role in creating the products.

Riya Pathare 2E

The frequency factor is how many times the molecules will collide with the correct orientation. If the frequency factor is high there will be more collisions resulting in a faster reaction and a higher k value. Additionally if you take into account something like a spherical molecule colliding there...

Riya Pathare 2E

I would just like to add that catalysts are "consumed" and "reproduced" but they are not intermediates. I think we have to be able to determine what are intermediates and what are catalysts.

Riya Pathare 2E

A galvanic cell will produce a current generally so the voltage must be positive. Thus if we are given reduction potentials we want to flip the half reaction that will produce a positive voltage when added. The anode will be the oxidation, the one you flip and the cathode will be the reduction which...

Riya Pathare 2E

I believe unique reactions are always positive because even when the concentration of the product decreases there is a negative sign implemented to make the rate positive. The rates for the reactants and products have to be proportional

Riya Pathare 2E

Test 3 only covers material from 15.1 to 15.6 I believe which is first, second, and zero order reactions and their laws and half lives. The rest of the material I don't think is on the test but will be on the final.

Riya Pathare 2E

Differential rate laws can only be committed from experimental data like a linear graph or table of reactions but mechanisms can be computed from their elementary equations.

Riya Pathare 2E

Im not sure if we have to assume but we might have to infer if we were given the graph vs tome or something like that. Or a set of experimental data.

Riya Pathare 2E

Generally if you plot the ln[A] vs time or 1/[A] vs time and its not first or second order then it should form an evidently curved line in stead of straight like an exponential decay function.

Riya Pathare 2E

Why do chemists like nitrates so much?
They're cheaper than day rates.

Riya Pathare 2E

The order of a reaction is just the exponents of all the reactant concentrations in the rate equation added up. So if a rate equation looked like this: rate = k[A]^2[B]^2[C] we would add 2+2+1 to get 5. So it would be a fifth order reaction.

Riya Pathare 2E

When you are using E(naut)=E(cathode)-E(anode) they are talking about the reduction potentials so we don't flip anything. But when we are adding the half reactions we flip the most negative half reaction so we get a positive cell potential with the entire balanced equation.

Riya Pathare 2E

Generally the format that the book takes is anode electrode|anode solution||cathode solution|cathode electrode.

Riya Pathare 2E

Using E(naut) = E(cathode)-E(anode) we take the reduction potentials and plug them in so no flipping. But when we are calculating the cell potential by adding the half reactions we add the half reaction cell potentials by flipping the more negative one.

Riya Pathare 2E

You can use either of the equations cause they are the same. The second equation essentially combines the R, T, and F to get 0.05916 and then takes into account the change from ln to log. Generally log is more efficient to use for biochemistry purposes rather than ln but both are valid.

Riya Pathare 2E

the deltaStot would also be able to tell you whether the reaction would be spontaneous or not while the deltaS would not be able to tell you that. With just delta S you would need to calculate delta G in order to find spontaneity.

Riya Pathare 2E

A clever way to remember it is "Red Cat" or "red"uction at the "cat"hode.

Riya Pathare 2E

intensive property would mean that the value calculated would not not be dependent on the amount of substance. A good example of this is an electrical cell. When we calculate cell potential it is always the same because it is an intensive property

Riya Pathare 2E

For this problem you had to calculate the Gibbs Free energy at two temperatures for two reaction and I tried using the deltaGtot = deltaGf products - deltaGf reactants but instead it said to calculate it with deltaG = deltaH - T*deltaS for each reaction. How do you know when to use which equation to...

Riya Pathare 2E

The two common forms of R used are 8.314 J/mol K and 0.08206 L atm/mol K. Which one you use depends on what units the rest of the parts of your equation has.

Riya Pathare 2E

The last lecture that will be on the midterm would be friday of last week. The midterm will not cover electrochemistry which we are learning this week.

Riya Pathare 2E

We can use either of those equations because with PV=nRT pressure is inversely proportional to volume so we can switch the v2/v1 to p1/p2

Riya Pathare 2E

This gives us the heat capacity for an ideal gas at constant pressure so we use it so we can plug it into our entropy equation to solve.

Riya Pathare 2E

Generally when the molecule tends to be more complex like the COF2 molecule it will have a higher entropy because of the different micro states there are.

Riya Pathare 2E

Since HBr is a larger compound than HF it will have more electrons that will be able to occupy more states thus giving it a higher entropy.

Riya Pathare 2E

Isothermal equations means that the system does not lose or gain heat. Think of it being in an isolated container

Riya Pathare 2E

deltaH = deltaU only when there is a constant volume. Because we know that deltaU = deltaH - PdeltaV when there is constant volume there is no volume change so the deltaV would be zero giving the PdeltaV a value of 0. Because of this we are left with deltaU = deltaH

Riya Pathare 2E

The main formula for internal energy is deltaU = deltaH - PdeltaV however when pressure is constant we can say that deltaH = q and when volume is constant that means deltaV will equal 0 since there was no change so deltaU = deltaH.

Riya Pathare 2E

degress K = 273 + degrees C

Riya Pathare 2E

You can use bond enthalpies in both cases but for the enthalpy of formation you are calculating the enthalpy of the formation of a product from its pure elements while in reaction enthalpies its just the reaction (that does not have to involve pure substances). But using bond enthalpies we can say t...

Riya Pathare 2E

If you look at table 8.3 you can see that 40.7 kJ/mol is the heat of vaporization of h2O needed to convert a liquid to a gas. In that step we have to account for how much heat is needed to convert the liquid water into a gas so we multiply the heat of vaporization by the number of moles there are of...

Riya Pathare 2E

The standard enthalpy of formation is the enthalpy of forming a compound from its purest elements. So for example the standard enthalpy of formation of H2O would be the enthalpy of the reaction of O2 + 2H2 --> 2H2O because H2O is being formed by the purest form of oxygen and hydrogen. heres some exa...

Riya Pathare 2E

Well I'm assuming that with a greater energy density you can store more energy in a smaller unit of space or concentrate the energy more to a smaller volume based on how large the energy density is. So the greater the density the further a car could drive because it has more energy in the same amoun...

Riya Pathare 2E

You need to first make the balanced equation of how the products form from their elemental forms because we are trying to find standard enthalpy of formation which means the products must be elemental forms. Then use the bond enthalpies and subtract the energy released when creating the new product ...

Riya Pathare 2E

The standard enthalpy of formation is when one mol of a product is formed from its pure element reactants while the standard reaction enthalpy is just when all the products and reactants are all in the same state at 1 atm. Essentially one is the elemental formation of a product while the other can d...

Riya Pathare 2E

I think lavelle said we are doing the second half of the section first and then going to the first half. The problems are all in the syllabus but since we didn't have problems due this week I believe we have 14 problems due in the week 2 discussion section.

Riya Pathare 2E

Also the kJ/mol represent the amount of energy for one mole of that compound so if you had to calculate the enthalpy of of a compound that had more than one mole of it in the chemical equation we would have to multiply the number of moles with the kJ/mol value to get the total enthalpy for that comp...

Riya Pathare 2E

Additionally for gases in their pure from (like Cl2, O2, N2 etc.) we know that the enthalpy of formation of them is equal to 0 kJ/mol. This is not true for other gases not in pure form (CO2, NO etc.).

Riya Pathare 2E

The Ka values are given in the tables 12.1 and 12.2

Riya Pathare 2E

When you set up your ICE table you should get that for the equilibrium concentration of HClO2 the equilibrium should be 0.1-x since its initial concentration is 0.1M. Then when you calculate the concentration of H3O+ from the pH value given you will get that it is 0.06 and that equals x in the ICE t...

Riya Pathare 2E

The number of ionizable H+ ions in the compound makes it polypro tic if there is more than one ionizable H+ ion but it does not necessarily change the strength of the acid compound

Riya Pathare 2E

In the context of problem 115, acetic acid is the acid when the solvent is a weaker acid than acetic acid. Since the nitrite ion is a weaker base than the acetate ion it implies that the nitrous acid is a stronger acid that acetic acid so it will act like the acid in the reaction. So I think it has ...

Riya Pathare 2E

Bronsted acids give off protons or H+ ions while bronsted bases give off OH- ions. Conversely, Lewis acids are electron pair acceptors and Lewis bases are electron pair donors. They are not necessarily exclusive. for example in coordination compounds NH3 has an extra electron pair to donate so it ca...

Riya Pathare 2E

it could be that (CH3)3N is a weak base while HNO3 is a strong acid so since they are not both strong they will not produce a water and a salt. Although it still should be somewhat neutralizing since it is an acid-base reaction

Riya Pathare 2E

The end anion is not named with a prefix so it would just end with chloride

Riya Pathare 2E

Use an ICE Box and plug in the values and you should get that K equals x^2/(0.1-x)^2 when you set it equal to K, 23.2 you can solve for x which will give you the concentration of the products at equilibrium and then if you subtract x from 0.1 in the table you will get the concentrations for the reac...

Riya Pathare 2E

You find the oxidation number of the metal ion by adding up the ligand charges and seeing what other charge is needed to create the overall charge of the coordination compound. For example if you had 6 CN and Co and the overall coordination compound charge is 4- then you know Co has a 2+ charge beca...

Riya Pathare 2E

a chelate is a compound containing a ligand bound to the central metal atom at two or more points. The ligands will usually form a ring with the metal ion so thats how you tell whether it is a chelating ligand

Riya Pathare 2E

I don't think a triple bond can rotate since it also contains two pi bonds.

Riya Pathare 2E

This is because its electron shape, taking into account the lone pairs, would be trigonal bipyramidal and i you keep removing the bonded pairs from that original shape we are down to the two opposite ends of the pyramid base giving us a final geometry of linear instead of bent. It has to do with the...

Riya Pathare 2E

If they represent the same shape they should be interchangeable. They are both resulting from a trigonal pyramidal losing a bonding pair or a trigonal planar losing a bonding pair where the bonding pairs become lone pairs.

Riya Pathare 2E

lone pairs cause the bond angles to change in some cases because they can pull the electrons in slightly different directions. A good example is a trigonal pyramidal structure where the bond angles are 109.5 degrees. Generally when an atom has three bonded pairs it will form a trigonal planar struct...

Riya Pathare 2E

Im bad at telling chemistry jokes because all the good ones Argon

Riya Pathare 2E

Hybridization of the central atom means that the orbitals of that atom have combined with another orbital to create a hybrid of the two orbitals with different energies and shapes.

Riya Pathare 2E

a) alkali metals all have an electron in the s orbital so their configuration will be ns^1 because the n can be any energy level as we go down the group b) Group 15 will have their s orbitals filled and three electrons in the p orbital so theirs would be np^3 ns^2 with n being any of the different e...

Riya Pathare 2E

The p orbital has more energy than the s orbital because the electron is absorbing more energy to jump to the n=2 energy level (p) instead of the n=1 (s) energy level which it is already at.

Riya Pathare 2E

From Scandium forward we always write the 3d shells before the 4s shells because they will have lower energy since their principal quantum number is 3 not 4.

Riya Pathare 2E

Test 3 includes the last two sections of chapter one (Heisenberg and Schrodingers (only conceptual for Shrodingers)) and all of chapter two which is the orbitals etc.

Riya Pathare 2E

The homework is posted on the syllabus under the Quantum World section and it contains problems Ch 2 1, 13, 17, 19, 21, 23, 25, 27, 29, 31, 33, 37, 39, 41, 43, 45(omit part d), 47, 51, 53, 55, 57, 59, 61, 63, 67, 71, 75, 77, 81, 85, 93. The testing is found under the link Test and Exam schedule and ...

Riya Pathare 2E

Q: What kind of dogs do chemists have?
A: Laboratory Retrievers

HARHARHAR

Riya Pathare 2E

The photon that causes the electron to be ejected off does not have the same wavelength. So if you are calculating using E = hv you are calculating the wavelength for the incoming photon not the ejected electron, whereas when you use De Broglie's equation you are calculating the wavelength of the ej...

Riya Pathare 2E

To the best of my knowledge I think work function and threshold energy are the same because they both represent the minimum energy needed to remove the electron form the metal surface.

Riya Pathare 2E

If you read in the textbook pg 7 of chapter one you can find that the second formula was written to solve for frequency while the first is written to solve for energy. They are same formula written in different ways however the second one you can use once to find the frequency and then the energy di...

Riya Pathare 2E

To the best of my knowledge the light generating the waves is like water if you think about it. Like when we skip stones on a pond or something how waves are generated on the waters surface. Like that, when the light passes through the slits it is restricted to the slit space (small) for a second an...

Riya Pathare 2E

The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle. I tried doing this problem but I kept getting none...

Riya Pathare 2E

For part be you would take the number of moles you have for copper chloride tetra hydrate and multiply it by its proportionality factor to chlorine. Since every mole of copper chloride tetra hydrate has 2 moles chlorine you would multiply it by (2 mol Cl/1 mol CuCl2 4H2O). For part d calculate the m...

Riya Pathare 2E

No I don't think its necessary as long as you have the correct number of significant figures in your answers

Riya Pathare 2E

Not sure if this is a limiting reactant calculation but for question G.25 can anyone explain the logic behind that? Why do we multiply by (1/2)^n and take logs etc?

Riya Pathare 2E

The M in the M(OH)2 represents a metal, not a particular element, so the problem wants you to find the metal that M represents, given the molar mass. If you subtract out the weight of (oh)2 from the molar mass you will get the mass of Ca which is what the M represents in the problem. Then you just f...

Search found 74 matches