CHEMISTRY COMMUNITY

Sarah Zhao 4C

Julia Cheng 4C wrote:What’s the funniest chemistry joke?

My final grade - don’t you C?

It just wasn't meant to B.

Sarah Zhao 4C

In raising the temperature, the reaction will tend to form the side that has more energy. In endothermic reactions, that will be the products and in exothermic reactions, the reactants. In lowering the temperature, the reaction will tend to form the side that has less energy. In endothermic reaction...

Sarah Zhao 4C

NO! E knot values can only change when you inverse the reaction. If you have to multiple to get the electrons to cancel out, the E knot values remain the same.

Sarah Zhao 4C

The post is titled LYNDON'S PORK RAMEN REVIEW. It was the very last result for me.

Sarah Zhao 4C

a = 100% or 1

Sarah Zhao 4C

You can't multiply it by four but you can square it by four!
Break down the math:
1/2 x 4 = 2
vs
(1/2)^4 = 1/16

Sarah Zhao 4C

Can someone explain the problems and provide the answer?

Sarah Zhao 4C

M/s and mol/(L*s) are the same and used interchangeably so either one will be fine

Sarah Zhao 4C

Electrolytic cells just mean that electrolysis is occurring in that cell. The cell overall is a non-spontaneous reaction being driven to perform via an outside voltage.
If anything, I would say that galvanic cells can power electrolytic cells, thus helping to drive a non-spontaneous reaction

Sarah Zhao 4C

nevermind, it's moles of electrons transferred in the reaction

Sarah Zhao 4C

For the equation DELTA G = -N F E, how do you know what number to use for n? I know its moles but moles of what?!

Sarah Zhao 4C

In a Cu/Zn galvanic cell, why can we use Cu as an electrode but must use Pt as the other?

Sarah Zhao 4C

I wouldn't think so for this class.

Sarah Zhao 4C

You use delta G = standard delta G + RTlnQ

Sarah Zhao 4C

Use the Gibb's Free Energy equation to determine spontaneity. While is is usually true that delta G follows the sign for delta H, please do not use this as a rule of thumb.

Sarah Zhao 4C

Non-spontaneous does not mean that it cannot happen. It rather means that it requires an input of energy to happen.

Sarah Zhao 4C

Yep yep

Sarah Zhao 4C

We know which R to use based off what pressure unit is being used in the problem

Sarah Zhao 4C

all compounds will have bond enthalpies. the only ones that won't are elements!

Sarah Zhao 4C

3/2R is for Cv and 5/2R is for Cp. It's on the constants sheet

Sarah Zhao 4C

Pistons moving affects the volume and thus the pressure of the system. If PV=nRT, then yes, very much affected

Sarah Zhao 4C

It's open because you can change the amount of tea. If you are able to pour more tea into it, it's because it is open!

Sarah Zhao 4C

Yep, and you can multiple the reaction coefficients and reverse the reaction so they cancel out. Just make sure you do the same to the enthalpy, respectively, multiple them or change the sign.

Sarah Zhao 4C

Nope! Just make sure that if you are canceling things out, that they are the same state.

Sarah Zhao 4C

I know for work that the positive and negative just mean that work is done on or done by the system. Meaning that the total amount of work is the absolute value of work done on and work done by added up.

Sarah Zhao 4C

Strong acids you will just need to memorize. Strong bases on the other hand is metal hydroxide where the metal is from the alkaline metals (Group 1) or alkaline earth metals (Group 2)

Sarah Zhao 4C

In terms of water, the ionization constant is the same as the equilibrium constant. In the breaking down of water, it creates ions H+ and OH-. So we are able to interchangeable use the words ionization constant.

Sarah Zhao 4C

I would use whichever one gets you to the answer in the solution manual. You made need to do the problem with both concentrations to determine if it was a typo or if they used the 10^-3 number throughout the whole problem.

Sarah Zhao 4C

-ate if for when the entire coordination compound has a negative charge aka when there are metals present before the coordination compound. -ide is for when the compound charge is positive or net neutral

Sarah Zhao 4C

No, bond length is within the molecule while an intermolecular force is between the molecules

Sarah Zhao 4C

These words are actually interchangable!

Sarah Zhao 4C

I have never seen my grades online before we've gotten them back so I'm assuming that it is second week of winter quarter.

Sarah Zhao 4C

Sometimes it can be either one and you may not know if the central atom is a transition metal with no roman numeral

Sarah Zhao 4C

OH2 has a charge of 0. Its water: H20 or OH2. So having 5 of them would still make the charge 0. Cl has a charge of -1. It is a halogen, so it will always have a charge of -1 The total charge of the coordinate compound is +1. So to get the compound from the -1 provided by the Cl to the +1 of the com...

Sarah Zhao 4C

They go by different definitions but they identify the same molecules as bases
tldr; they are the same

Sarah Zhao 4C

So besides water, they get kind of weird.
Hydrogen carbonate, bisulfate, amino acids, BUT MOST IMPORTANTLY (and probably the only one you will need to know) WATER

Sarah Zhao 4C

Yes you will
But pretty much everything except for transition metals will be the charge of the neutral atom.

Sarah Zhao 4C

greek-prefix ligand name (for all ligands, IN ALPHABETICALLY ORDER) and then the metal name (roman number)

Sarah Zhao 4C

If I'm understanding your question correctly, there is zero possibility to find an electron in the center because the p orbital takes a infinity sign shape and in the middle, there is a nodal plane where no electron can exist.

Sarah Zhao 4C

So carbon will be the central atom because it is the least electronegative.
And it will be have 4 elements around it. It does not matter where it goes. But CH2F2 is a non-polar molecule so by putting the H opposite each other and the F opposite each other, it gaurentees that.

Sarah Zhao 4C

Yes, Test 3 includes bonding trends, shapes, molecular shape, polarity, and hybridization.

Sarah Zhao 4C

Replying assuming that you mean AX2E3: AX2 is also linear

Sarah Zhao 4C

Does not matter. All ends up being the same VSEPR structure.

It just might be easier to identify if you do it horizontally.

Sarah Zhao 4C

Nitrogen can only have a maximum of 8 electrons; its in period 2. If you give it two double bonds, it will have 10!

Sarah Zhao 4C

Or in a simpler manner of explaining, trigonal planar has 3 bonding regions while trigonal pyramidal has 4! The only difference is the lone pair of electrons on trigonal pyramidal, which forces the bonds to be repelled.

Sarah Zhao 4C

First bond will always be sigma because they need to have a sigma bond in order for the electrons to be oriented in a way to form a pi bond.

Yes there can be more than 3 bonds but that gets complicated and I'm assuming we don't need to know it for this chapter.

Sarah Zhao 4C

I don't think we need to know how to calculate it for this class.

At most, just know the relationship.
It has an inverse relationship with bond length (the longer the bond, the easier to break) and thus is directly related to atomic radius (the greater the atomic radius, the longer the bond)

Sarah Zhao 4C

Polarizability is the ease to release an electron. A higher electronegativity means that electrons are more tightly held together. So polarizability and electronegativity are inversely related.

Sarah Zhao 4C

So yes, H-bonds are the weakest types of bonds. Key word here being BONDS. So it's being compared to stronger covalent bonds and even stronger ionic bonds.

Dipole-dipole is an inter molecular force!

Sarah Zhao 4C

Thank you Lyndon for pushing through today's review session. Feel better and good luck on your own midterms :)

Sarah Zhao 4C

Yes, it's the same thing!

Sarah Zhao 4C

Anions are larger than their parent ion because there is one more electron with the same nuclear charge.
Cation are smaller than their parent ion because there is less electrons with the same nuclear charge.

Sarah Zhao 4C

So we know that a Lewis base is an electron donor and a Lewis acid is a lone pair acceptor. So in most cases, you can just look at it this way:

The cation will be the Lewis acid. The anion will be the Lewis base.
Ex. OH- + H+ -> H20

OH- is the Lewis base
H+ is the Lewis acid

Sarah Zhao 4C

Degenerate orbitals are orbitals of the same energy level

Any s-orbital would have 1 degenerate orbital
Any p-orbital would have 3 degenerate orbitals
Any d-orbital would have 5 degenerate orbitals
Any f-orbital would have 7 degenerate orbitals

Sarah Zhao 4C

It's the function used to calculate the energy of an electron

Sarah Zhao 4C

In the simplest form, principle quantum number (n) = the shell

Sarah Zhao 4C

I understand that for the p orbital, you can determine based off the magnetic quantum number if it is Px, Py, or Pz. But for the s, d, or f orbitals, are we supposed to be able to recognize which value of m lines up with which axis pairs?

I'm sorry if that wording made no sense.

Sarah Zhao 4C

Negative because the energy of the electron is decreasing but the energy is positive because it is being released as a photon

Sarah Zhao 4C

Just memorize it for the sake of doing so

Sarah Zhao 4C

Mass of a photon is on the constants/equations sheet!

Sarah Zhao 4C

Multiply anything that isn't less than .2 away from a whole number

Sarah Zhao 4C

Multiply anything that isn't less than .2 away from a whole number

Sarah Zhao 4C

What do you get when you put Avogadro's number in the blender?

GuacaMOLE

Sarah Zhao 4C

Formula units is the equivalent of molecules for different compounds.

Molecules are for molecular compounds. Formula units are for atomic compounds.

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