CHEMISTRY COMMUNITY

Anand Narayan 1G

It is a second order reaction, Im pretty sure that's a typo for that problem as in 15.39 they mention the same equation (2A --> B + C) and call it a second-order reaction

Anand Narayan 1G

You would use the Van't Hoff equation when there is a temperature change and you are looking to find an equilibrium constant.

Anand Narayan 1G

I wouldn't always convert the time units to seconds, because often times the units depend on the context of the problem. If the problem operates in hours or minutes, then you should use those units.

Anand Narayan 1G

I think you should have a general understanding of the derivation, but you shouldn't stress yourself out over studying that, as the formulas will be on the formula sheet.

Anand Narayan 1G

It does not matter which one you use, however I would use the ln one, since that is the one that is included on the equation sheet that we are given on tests and the final

Anand Narayan 1G

We focus a lot on initial reactants, as that tells us about the initial rate.

Anand Narayan 1G

Yes, that is precisely what happens.

Anand Narayan 1G

In this case, you would not need to include it since any number to the power of zero is one.

Anand Narayan 1G

You would choose the largest reducing agent as well as the largest oxidizing agent

Anand Narayan 1G

When a reaction is exergonic, energy is released from the system to the surroundings, and when a reaction is endergonic, energy is taken in (absorbed) from the surroundings

Anand Narayan 1G

When the question gives you a chemical reaction or units with moles, I would use kJ/mol

Anand Narayan 1G

Since Gibbs Free Energy is a combination of multiple state functions, the resulting function is also a state function.

Anand Narayan 1G

When we are given a temperature in degrees Celsius and we are required to convert to Kelvin, are we supposed to add 273 or 273.15?

Anand Narayan 1G

It will be the same equation sheet that we've been given for previous tests. It's also on his website under "Constants and Equations"

Anand Narayan 1G

It would be J/C*mol

Anand Narayan 1G

No, because they are two distinct types of systems. An isolated system does not allow energy or matter transfer, whereas a closed system allows energy transfer.

Anand Narayan 1G

I would say definitely doing the homework problems and reading the textbook as well as class notes are the best way to prepare.

Anand Narayan 1G

Heat Capacity is extensive

Anand Narayan 1G

This is because pKa is a the -log of Ka, the acid dissociation constant, it is a measure of acid strength. pH, on the other hand is a measure of the concentration of H+ ions.

Anand Narayan 1G

Thanks for the advice

Anand Narayan 1G

I believe it is 25 degrees celsius, unless the problem says differently

Anand Narayan 1G

When Delta H is positive, it's endothermic and when it's negative, it's exothermic

Anand Narayan 1G

Yes, salts are going to be on the test, since they were on the lecture, meaning they are fair game for the test.

Anand Narayan 1G

You should ignore it when k is equal to or less than 10^-3

Anand Narayan 1G

The reaction does not change if an inert gas is added

Anand Narayan 1G

Yes, it will continue until it reaches dynamic equilibrium.

Anand Narayan 1G

This is because the system would react in order to favor the production of NH3. Since you're removing NH3, it would allow the reactants to form more product

Anand Narayan 1G

If the reaction was only made up of solids and liquids, then K would be equal to 1.

Anand Narayan 1G

When going from the name to formula, if there are multiple ligands, how do we know which order to put them in for the formula?

Anand Narayan 1G

It is spelled ammine.

Anand Narayan 1G

When do we use cyanido vs cyano in naming?

For 9C.1 in the book, I thought the name of [Fe(CN)6]4- was hexacyanidoferrate(II), but the answer key has it as hexacyanoferrate(II).

Anand Narayan 1G

both ways of writing it are correct

Anand Narayan 1G

There is one sigma bond and two pi bonds in a triple bond.

Anand Narayan 1G

Yes, however we don't really use s hybridization since we focus on more complex molecules that typically involve p orbitals as well.

Anand Narayan 1G

Since there are 3 hybrid orbitals and 3 regions of electron density, the hybridization is sp2.

Anand Narayan 1G

Yes, Lone pairs do indeed count as an area of electron density, so yes, they count for hybridization.

Anand Narayan 1G

I don't think it matters which order it is written, but I prefer to do sp3d

Anand Narayan 1G

I believe the arrow should always point to the negative, and thats the way Lavelle did it in class, so I would probably do it that way

Anand Narayan 1G

The one I find the most helpful is # of valence electrons - (Lone electrons + Bonds)

Anand Narayan 1G

No, an octahedral cannot be polar, because the shape is symmetric

Anand Narayan 1G

Delta negative is the one that accepts electrons, while Delta positive is the one that gives electrons

Anand Narayan 1G

Double bonds don't have nearly the same effect on bond angles that lone pairs do. Double bonds and single bonds both are the same electron density thus it doesn't affect the bond angle

Anand Narayan 1G

Sigma bonds have their electron density along the bond axis, while pi bonds have their electron density above and below the bond axis. Therefore, pi bonds cannot rotate the same way as sigma bonds since rotation would break the pi bond interaction.

Anand Narayan 1G

Is there a set degree amount a lone pair causes bond angles to change? I know it lessens the angles, but is there a specific amount?

Anand Narayan 1G

As long as each dipole moment is equal in charge and opposite in direction, then they will cancel each other out.

Anand Narayan 1G

This is because Phosphorous is in the 3rd energy level, which means it can access the d-orbitals in order to have an expanded octet and form more than 4 bonds.

Anand Narayan 1G

That information wasn't covered in the sections we are required to know for the midterm, nor have we gone over the material in class, so they will not be on the midterm.

Anand Narayan 1G

Yes, your formula work, but I prefer to use FC = Valence Electrons - (Lone Electrons + Shared Electrons/2)

Anand Narayan 1G

All of the equations use SI units in order for them to all follow the same units. That's why its in meters, because meters is the SI unit for measurement of length.

Anand Narayan 1G

Make sure to use wavelength = h/p in order to find the velocity of the electron. Once you find the velocity, you then plug the values into KE = E - work function in order to solve for E. Once you find E, you use E = hV, in order to solve for frequency.

Anand Narayan 1G

When there are double bonds in a structure, for example the Nitrate ion, NO3 2-, and chemists observe the actual N-O bond length, is every bond length the same length, despite the fact that we draw it with one double bond and two single bonds indicating that they are different lengths?

Anand Narayan 1G

For number 11, part b why would delta E be a negative value? If the problem is asking for the change in energy from n = 6 to n = 4, and the formula is
E = -hR(1/n1^2 - 1/n2^2), the energy released from n = 6 to n = 4 equals 7.5689 x 10^-20 J. So, why is the answer negative?

Anand Narayan 1G

Is there a difference between using a line to represent bonds rather than 2 dots? Is there a chemical difference?

Anand Narayan 1G

px, py, and pz are helpful also to remember to follow Hund's Rule where every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied. Thus 1px, 1py, 1pz instead of 2px, 1py.

Anand Narayan 1G

An electron must have a full octet before It goes to the next energy level. Hydrogen and Helium are satisfied with only two electrons in their outermost valence shell.

Anand Narayan 1G

The test will only cover material that we went over in class until last Friday's lecture. The lecture on Monday will not be on the upcoming test.

Anand Narayan 1G

I believe we will be given the same first sheet with many equations and constants as we were given during the first test.

Anand Narayan 1G

I believe we will be given the same first sheet as we were during the first test where it provides us with many equations and constants.

Anand Narayan 1G

What does it mean that energy is quantized?

Anand Narayan 1G

Why can an electron only exist on specific energy levels?

Anand Narayan 1G

How does the wavelength of an electron change as it jumps to a new energy level?

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