CHEMISTRY COMMUNITY

Angela Cong 3C

yah specific heat capacity is joules kelvin, there doesnt exist a grams in it since it depends on how much of the thing is

Angela Cong 3C

Does a concentration cell always have to have a porous disk?

Angela Cong 3C

I believe when a galvanic cell is negative then it will favor the reactants rather than the products

Angela Cong 3C

The collision model basically states that molecules must collide with a great enough energy to break bonds. The activated complex is an intermediate states when reactants convert into products

Angela Cong 3C

n is the number of electrons used within the redox reaction

Angela Cong 3C

The first order half life equation is .693 over k so the greater k value means smaller or shorter half life time

Angela Cong 3C

Catalyst can be present within the rate law

Angela Cong 3C

Thank you so much for everything you have done for us lyndon!

Angela Cong 3C

Should problem 1a be to the negative 6th power instead of negative 5th power?

Angela Cong 3C

In lecture, Lavell mentioned that catalyst are present at the beginning of the equation as they are needed for the reaction to take place. Whereas an intermediate is produced as a product but then used up as an reactant.

Angela Cong 3C

So in a galvanic cell, whichever one is more positive, that means its more likely to be reduced and thus gains electrons (having e on the reactant side), and the more negative one is likely to be oxidized, and thus lose electrons (having e on the product side)?

Angela Cong 3C

Thank you so much!

Angela Cong 3C

Sometimes there are cases where you simplify the balanced redox reaction, would n be the number of moles before simplification or would it be the number of moles after simplification?

Angela Cong 3C

would there be no units for n since its just the # of moles then?

Angela Cong 3C

Potential is basically the cell potential in which how much voltage exists between the cathode and the anode. Thats why when there is "very little current flow" as said in the lecture (meaning before most of the reaction has taken place), the potential is the greatest.

Angela Cong 3C

A simple acronym that helps to remember which is OIL RIG
OIL= Oxidation Is Loss (of electrons)
RIG= Reduction Is Gain (of electrons)

Angela Cong 3C

It's basically just the drawing on the board that Lavelle had where a spontaneous redox reaction (the cathode and the anode) converts chemical energy into electrical energy through the transfers of electrons

Angela Cong 3C

The notes area also extremely important. If you can, try to memorize even the small details that might seem arbitrary. I remember in 14a Lavelle put some questions on the test that were briefly mentioned in class.

Angela Cong 3C

Yah for number six, im confused as well. Internal energy is dependent on temperature and the work function for a reversible reaction has temperature for one of the unknown variables. Is there a way around this?

Angela Cong 3C

Thank you so much!

Angela Cong 3C

There are also other work equations such as work=-P*delta V where work is done by the system causing energy to decrease

Angela Cong 3C

There are charts that you can search up in which it gives you if T is a high number when delta H is positive and so is delta s then it will be spontaneous and so on. It can somewhat help you conceptually. However, essentially if you just plug in big or small values for the equation you can get a gag...

Angela Cong 3C

The R constant can be determined with which equation you have to use. For example in the pV=nrt function it will be 8.314*10^7 while the rydberg formula for finding energy states would be 1.097*10^7.

Angela Cong 3C

the information given is always the biggest clue, what units are and what fits into the equation will help you solve for what you need to find.

Angela Cong 3C

When they ask you the question the information should be enough for you to determine whether or not to calculate specific, molar, or just plain heat capacity

Angela Cong 3C

The information present in the question given will allow you to determine which method to use

Angela Cong 3C

you will be given the enthalpy with the initial rxns but just keep in mind you will also need to use that to find the final reaction enthalpy.

Angela Cong 3C

steam does cool down but it's still immediately displacing the energy that was necessary to change water into steam in the heating curve.

Angela Cong 3C

they're almost similar to math equations. Whatever you do to one you have to do to another, so if the rxn in the second equation is multiplied by two or divided by two you much also do the same to the enthalpy. It will be more convenient to keep track of if you add them together

Angela Cong 3C

even if kw is not equal to 1*10^-14, [H3O+][OH-] is still equal to kw and to find concentration, you just sqaureroot the kw

Angela Cong 3C

The change in liquids such as water is so small in even in equilibrium there is large excess of it so it would cancel out in K and thus is not included. Solids also don’t affect the constant and is left out as well

Angela Cong 3C

There is no change since the number of moles balance on both sides. Equilibrium would not shift either way

Angela Cong 3C

in the modules he also mentioned you can tell if a reaction is exo or endo by looking at the lewis structure depending on whether or not they form or break bonds

Angela Cong 3C

the concentrations and ratio do not change since youre using the concentration of product over reactant to find the ratio which is the equilibrium constant

Angela Cong 3C

yes. only homework one is due during class the rest of the homeworks are all due during your discussion section

Angela Cong 3C

For the final exam, would we need to know the common names of metals? Such as ferrate or ferrous for iron and cuprous for copper?

Angela Cong 3C

For the final exam, would we need to know the chemical formula for ethylenediamine or do we just need to write en?

Angela Cong 3C

Thank you so much to my favorite UA. I greatly appreciate your practice problems!

Angela Cong 3C

In bonding and vsepr models, the central atom dictates shape since its the atom that pairs with all other valence electrons. The other lone pairs are not significant enough in repulsion to affect the shape since they are essentially on the outskirts of the atom. The lone pairs on the central atom ho...

Angela Cong 3C

The backwards reaction causes the equation to produce reactants that are on the left side of the equation as well as products. They are not strong enough to completely dissociate

Angela Cong 3C

The lewis structures could also help you visualize which atoms give or receive an electron. Depending on the lone pairs and the electronegativity of the atom you can get an idea of which ones will be more likely to donate.

Angela Cong 3C

Dear Dr. Lavelle,
Thank you for your explanations in chem that make the material more understandable. I never thought it would be a subject that I would understand and your jokes are pretty funny! I look forward to next quarter with you in chem 14b :) Happy holidays

Angela Cong 3C

will test three specify whether molecular structures will be cis or trans?

Angela Cong 3C

The lone pairs also play a part in determining molecular shape due to their repulsion. For trigonal pyramidal there is only one lone pair while t shaped has two

Angela Cong 3C

would we also need to include the 180 degree angle when they ask for the bond angles?

Angela Cong 3C

im confused too, if its occupying three orbitals then wouldnt that make it sp3 instead of sp2 and have another electron in an unhybridized orbital?

Angela Cong 3C

the sigma bond is the first bond between the two elements and thus any bond created after that can only pair side by side, creating the different pi bonds. The triple bond has the same concept where the electrons pair side by side.

Angela Cong 3C

pi bonds are bonded side by side different than sigma bonds, because of the physical structure, rotating the molecule along the sigma bond would cause the pi bond to snap.

Angela Cong 3C

you can think of it as kind of the "_" that are drawn for the electron orbitals. There are only three p orbitals and thats why it does not go higher than sp3

Angela Cong 3C

Because lone pairs are unbound electrons, they have a much larger electron cloud and repulsion energy, thus push down the other electron densities such as the bond angles. In class lavelle showed us that by replacing a molecule (taking it off the stick), the area becomes much more occupied and resul...

Angela Cong 3C

Pi bonds break if they are rotated. This is due to their rigidness and the way that they are bonded side by side, different than sigma bonds.

Angela Cong 3C

Dr. Lavelle should tell us in class soon but so far it's going to be everything after the midterm like the lewis structures, bond energy, types of bonds and such

Angela Cong 3C

additionally, the central atom is alway the least electronegative so the surrounding atoms bonded would much rather have the more negative charge

Angela Cong 3C

Chemistry is Fluorine, Uranium, Nitrogen

Angela Cong 3C

would we need to know the difference between angular and radial planes on the midterm?

Angela Cong 3C

hello! does anyone know how soon the solutions sheet will be up?

Angela Cong 3C

Dr. Lavelle also mentioned Li and Be in addition to H and He as never fulfilling the octet rule

Angela Cong 3C

The four H atoms are on the outside of N and since N has five valence electrons, there will be a bond connecting the two NH4 structures with the SO4

Angela Cong 3C

The exceptions are H, He, Li, and Be since they will always be the elements giving their electrons instead of receiving them

Angela Cong 3C

If avagrado calls, tell him to leave his number ;)

Angela Cong 3C

Since the nodal plane is a plane, don't the electrons cross over it at one point to the orbital on the other side? I understand that there's zero possibility but in cases of the p orbital where there's two orbital won't the electron have to circulate both?

Angela Cong 3C

Chemistry? More like Chemystery

Angela Cong 3C

Thank you so much for all your advice! This will definitely help us all out years from now :)

Angela Cong 3C

Take all your lame chemistry jokes, and Barium.

Angela Cong 3C

Test 2 will begin Tuesday Oct 23rd in our discussion, similar to how Test 1 was. So it would be the 10/22-10/26, depending on what day your discussion is. @danny

Angela Cong 3C

I understand the difference between intensity and frequency but in an actual experiment, how would you physically raise the frequency of the of the light source?

Angela Cong 3C

I'm pretty sure you're suppose to use the least amount of sig figs found in the problem to avoid any "false accuracy". If there isn't any numbers given in the problem then a good amount would be three sig figs.

Angela Cong 3C

Is there a system where they can automatically track if we had posted or not?

Angela Cong 3C

I tried to tell a chemistry joke but it got no reaction

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