CHEMISTRY COMMUNITY

Swetha Ampabathina1I

Yes when the cell potential is negative it means the reaction is nonspontaneous

Swetha Ampabathina1I

I believe you only do it for solids or at least that's what Lavelle implied in lecture today.

Swetha Ampabathina1I

In a concentration cell both the electrodes are of the same metal which is why E naught is equal to 0

Swetha Ampabathina1I

The homework problems are the best way to prepare for the final!

Swetha Ampabathina1I

You don't put H2O but you include H+ in the cell diagrams

Swetha Ampabathina1I

I don't think there is a unique rate law. I think you mean the unique average rate which is when you take the rate of product or reactants and divide it by the coefficients of the species monitored.

Swetha Ampabathina1I

No there is no curve for the class.

Swetha Ampabathina1I

Yes chemical equilibrium will be on the final

Swetha Ampabathina1I

I don't think there is a curve.

Swetha Ampabathina1I

Since they both serve the same purpose, I don't think either one is more efficient than the other.

Swetha Ampabathina1I

I think so since everyone has taken their test by now

Swetha Ampabathina1I

I don't think we need to know why it's called oxidation besides that it means the losing of electrons

Swetha Ampabathina1I

I'm pretty sure everything up until last Friday will be on the test and only the electrochemistry part of the textbook will be included on the test.

Swetha Ampabathina1I

Electrode potential is an intensive property because voltage difference is the same and does not depend on how many times the reaction will occur. Even if the half reactions are multiplied by an integer, it won't affect the value of the electrode potential for the reaction.

Swetha Ampabathina1I

Cell potential has to be positive in order for the reaction to be spontaneous because in the equation deltaG = -nFEcell, in order for delta G to be spontaneous (negative), Ecell must be positive.

Swetha Ampabathina1I

Oxygen has an oxidation state of -2 which means overall just counting the oxygens, there is an oxidation state of -8 (4 oxygens times -2), but since Mn has an oxidation state of -1 we want to find what value added to -8 would equal -1, which in this case is +7.

Swetha Ampabathina1I

I believe that the half reactions can be multiplied in order to achieve the balanced equation but that won't change the value of e°since that is an intensive property, so only sign changes for standard reduction potentials.

Swetha Ampabathina1I

heat capacity of the system

Swetha Ampabathina1I

n would equal 1

Swetha Ampabathina1I

I think it could be because the N2 molecule is in a more ordered form than the CO molecule is in so CO would have a higher entropy than N2

Swetha Ampabathina1I

The symbol U represents internal energy which is just the total store of energy in a system. Change in internal energy is equal to the work of a system.

Swetha Ampabathina1I

According to the textbook, a reversible process "is one that can be reversed by an infinitely small change in a variable." Whereas, a irreversible process is when it expands against an external pressure that differs by a finite amount from the pressure of the system.

Swetha Ampabathina1I

Yeah writing down all the given information always helps.

Swetha Ampabathina1I

I would still work on Thermochemistry homework.

Swetha Ampabathina1I

I'm pretty sure we will be given the heat curve.

Swetha Ampabathina1I

An example for an open system would be like an automobile engine or the human body. An example for a closed system would be putting an ice pack on an injury and for an isolated system would be a hot liquid inside a thermos bottle or a sealed vacuum flask.

Swetha Ampabathina1I

I agree you should just check for Q just to be on the safe side.

Swetha Ampabathina1I

Most likely yes you will be dealing with weak acids and bases.

Swetha Ampabathina1I

No there aren't any units for equilibrium constants.

Swetha Ampabathina1I

Lavelle's email is lavelle@chem.ucla.edu

Swetha Ampabathina1I

For part B, since you are technically working with the exponents, you'd have to square root the K to get the answer. Whereas, for part c the coefficients (which become exponents) are doubled so you would have to square the K.

Swetha Ampabathina1I

My TA said chemical the equilibrium outline and the acids/bases outlines will be on test 1.

Swetha Ampabathina1I

Yes, hydrogen bonding only occurs between N,O, and F. If not, yes it would be dipole-dipole interactions since hydrogen bonding is a type of dipole-dipole interaction.

Swetha Ampabathina1I

Nitrogen is more electronegative than carbon

Swetha Ampabathina1I

If a molecule is amphoteric, then it has to amphiprotic as well since amphoteric molecules can act as an acid or a base (example: water). Amphiprotic means that the atom can donate or accept H+ protons.

Swetha Ampabathina1I

An oxoacid is normally an acid containing an oxygen with a hydrogen atom bonded to the oxygen and another element bonded to the oxygen.

Swetha Ampabathina1I

If the molecule is symmetrical, it is normally nonpolar. If it is asymmetrical its probably polar. Normally, lone pairs on the central atom can make the molecule polar.

Swetha Ampabathina1I

Yes, pi bonds are always in the p subshell since it is not a part of hybridization.

Swetha Ampabathina1I

Normally, if the structure is symmetrical, it is safe to assume it's nonpolar. However, if there are lone pairs on the central atom or the Lewis structure is unsymmetrical, it is most likely polar.

Swetha Ampabathina1I

Hybrid orbitals are simply orbitals created by combining atomic orbitals of the same atom and atomic orbitals depended on the electron density surrounding an atom. As a result, the total number of orbitals for forming bonds don't change, only a new set of orbitals are formed.

Swetha Ampabathina1I

AX2E2 is bent because any VSEPR notation that has an E and a numerical value after it means there are lone pair electrons and in this case there are 2 lone pairs of electrons. Lone pair electrons (even if not on the same plane) have a high electron density and have a component that will push the bon...

Swetha Ampabathina1I

I honestly don't think it matters so whatever you feel like doing!

Swetha Ampabathina1I

I think it would be best to memorize the VSEPR chart, but I also think as you do more homework problems, it becomes intuitive and easier to figure out which shape each molecule is.

Swetha Ampabathina1I

If the charge distribution of the VSEPR model is symmetric then it is nonpolar, but if it is not symmetric then it would be polar

Swetha Ampabathina1I

Fluorine is a halogen which means it is a group 17 element and all group 17 elements have 7 valence electrons so they only need 1 more valence electron to completely fill their outer valence shell and get their noble gas configuration so they're stable. This pattern follows for all elements in group...

Swetha Ampabathina1I

Symmetric molecules have dipole moments, but since the molecules are symmetric the dipole moments cancel out and the molecule is nonpolar. If a molecule is polar then it's Lewis structure is not symmetric so the dipole moment vectors don't cancel out.

Swetha Ampabathina1I

Electronegativity is the tendency of an atom to attract another atom's electrons (kind of like stealing another atom's electrons). The electronegativity trend increases from left to right on the periodic table as well as when you move up a group on the periodic table.

Swetha Ampabathina1I

The presence of lone pairs causes the repulsion between lone pairs and bond pairs to be greater than just the plain bond pairs which causes the deflection angle to be lower than the a bond pair.

Swetha Ampabathina1I

The periodic table that Dr. Lavelle has given us for all our tests so far has had the elements' names, so I'm pretty sure we don't have to memorize any elemental names.

Swetha Ampabathina1I

Isoelectronicity is when elements/molecules have the same number of valence electrons and electron configurations. For example, Li+ and He are isoelectronic. Most isoelectronic elements also have similar chemical properties.

Swetha Ampabathina1I

the degeneracy of a 4p orbital would be 3

Swetha Ampabathina1I

It typically means that all the electron energy levels/ shells have the same energy. For example in the p orbitals, if the 2px, 2py, and 2pz orbitals all have the same energy level then the degeneracy is 3 for the 2p orbitals.

Swetha Ampabathina1I

Most nonmetals have a higher electron affinity since they have more valence electrons than metals and can easily attract more electrons and fulfill their octet. Also, nonmetals' valence electron shell is closer to the nucleus thus making it harder to remove electrons and easier for those elements to...

Swetha Ampabathina1I

No I believe it is not necessary. Most likely if you need it to solve a problem on your test the TA will have provided it to you on your formula/equation sheet.

Swetha Ampabathina1I

There is an absolute value around (q1)(q2) hence any large number whether positive or negative will end up producing a higher energy. When he says a larger negative charge would increase energy, he means a larger negative charge for the atom would end up increasing the overall energy produced.

Swetha Ampabathina1I

Yes the 2p orbital does experience shielding from the 2s orbital since the 2s orbital is closer to the nucleus and can block out the charge from the electrons from the 2p orbital since they are farther away

Swetha Ampabathina1I

I believe the midterm will cover topics from Fundamentals, The Quantum World, and the Chemical Bonds.

Swetha Ampabathina1I

Yes! Dr. Lavelle said that the homework is meant to be flexible and meet your needs, so it's okay to do review chemistry questions because that's most likely what you'll be using to review for the test this week.

Swetha Ampabathina1I

Black body radiation is a material that can absorb and emit all wavelengths of light.

Swetha Ampabathina1I

It's basically saying that one photon must have enough energy to remove one electron and if it doesn't than it cannot remove that electron. However, if it does have enough energy or more energy then it can remove the electron and the rest of the energy will become kinetic energy.

Swetha Ampabathina1I

The volume is measured after you add the solute in the solvent and I think when they said molarity the want to know the concentration of the solute that you have within your solution. For example, it would ask you what is the concentration of NaCl is in a solution, they want to know how heavily conc...

Swetha Ampabathina1I

I don't think it is necessary for all problems. I think you only have to do scientific notation in order to round your answer to the proper amount of sig figs to meet the requirements for sig figs for certain problems. Also, if its a really large number then you might have to do scientific notation,...

Swetha Ampabathina1I

The correct answer for that question was CoF6

Swetha Ampabathina1I

The pre/post assessment only grades your work. It only tells you if you got it correct or not

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