CHEMISTRY COMMUNITY

nicole-2B

https://www.toppr.com/content/concept/z ... ns-203348/
here is a link with an example

nicole-2B

Tai Metzger 3K wrote:Yes, in other words, catalysts are present before and after a reaction whereas intermediates are only present during the reaction.

this is helped thank you!

nicole-2B

Qiu Ya Wu 4I wrote:For the image above, it's good to know that only one intermediate will be formed since the reaction profile indicates a 2 step process and the intermediate will be created in the first step and used as a reactant for the second step.

Thank you for clarifying on this

nicole-2B

Thank you Dr.Lavelle for yet another amazing quarter!!

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Dr.Lavelle should send out an email soon but I feel like they might be

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Angela Patel 2J wrote:Would the slope of the graph be k?

yes the slope would be k

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When the chemical kinetics specialist is asked why he ran slowly, his reply was “I always wanted to be the significant rate-determining step”.

nicole-2B

The rate-determining step is equivalent to the slow step. Therefore, by comparing each of the elementary steps' rate laws with the overall reaction rate law, you can determine which step is the rate-determining step: it's whatever step gives you a rate law identical to the overall reaction rate law...

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should look linear and have a negative slope which is -k

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Congrats for doing so great in these classes!!

nicole-2B

JosephineF wrote:chem final outfit ideas

I love this so much !!

nicole-2B

For cells that involve gases, such as hydrogen gas or chlorine gas, the pressure of these species matters. In these cases, the partial pressures of gases would probably be used over concentrations. Depending on the partial pressures, E would differ because of the nernst equation, E = Enot - (RT/NF)...

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Dr.Lavelle always picks good songs to end the lecture with

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galvanic cells have a positive potential difference so find the cathode and anode that makes E (naught) cell positive using the equation E(naught) cell= E (naught) cathode- E(naught) anode

nicole-2B

a) MnO4-(aq) +8H+(aq)+5e- yields Mn2+(aq) +4H2O (cathode half reaction)
5[Fe2+ (aq) yields Fe3+(aq)+e-] anode half reaction
Two equations together:
MnO4-(aq)+fFe2+(aq)+8H+(aq) yields Mn2+(aq) + Fe3+(aq) +4H20(l)

nicole-2B

Lydia Luong 4L wrote:Cathode is always on the right side of a cell diagram and anode is always on the left side.

Thank you!!

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Why was the electrochemical cell arrested?
Because it was charged with battery.

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Matthew Tran 1H wrote:You need a solid platinum electrode when there is no conducting solid (except liquid mercury) in the cathode or anode reaction. That's all you need to know.

THANKS!!

nicole-2B

Thanks for clarifying what n was. I was lost when doing the homework problems

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Gibbs free energy is related to cell potential by the equation: ΔG°cell = −nFE°cell. If E°cell > 0, then the process is spontaneous. If E°cell < 0, then the process is nonspontaneous

nicole-2B

Did you hear that Oxygen and Magnesium hooked up last night?
OMg

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CynthiaLy4F wrote:Work will be negative when the system is doing the work, such as through expansion. Work is positive when is being done on the system, such as through compression.

this helps a lot thank you! I have been confused about this

nicole-2B

Thanks for sharing your experience !!

nicole-2B

If it is under constant pressure C equals Cp=5/2*R for a monatomic gas

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TarynD_1I wrote:qp is equal to delta h when a system is at constant pressure, so no nonexpansion work is being done.

Thank you for clarifying!!

nicole-2B

Brianna Becerra 1B wrote:When w is negative, it means that work is being done (expansion), while when it is positive, it is compression.

thanks for clarifying I have been so confused!!

nicole-2B

The equation sheet on Lavelle's website should have all the equations you need to use on an exam.

nicole-2B

and this equation is used for reversible reactions only?

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Brooke Yasuda 2J wrote:a bomb calorimeter is tightly sealed and insulated which means that heat cannot be transferred with the surroundings. Also, the volume of the system cannot change so there can be no work done. This means that it is an isolated system.

thanks for explaining so well!!

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Nathan Rothschild_2D wrote:Will we have to know these terms for the test?

I believe so because they can be used to describe something. For example yesterday during Lyndon workshop one of these words was used to describe the system and it was needed to solve the problem.

nicole-2B

why do white bears dissolve in water?
because they are polar

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everything after the midterm until test 2 begins

nicole-2B

thanks for clarifying I was also confused about this

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Luis_Yepez_1F wrote:Work would be equal to zero, since volume is constant.

so when volume is constant work is equal to 0 in any case?

nicole-2B

I would follow outline three from Lavelle's website

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we do not have to know this for the test since we did not learn this in class

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you usually ignore the -x when the Ka or Kb is less than 10^-3 because it has little effect to the concentrations

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significant figures for pH/pOH only counts after the decimal.

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when performing a ice table you should only worry about the gasses and aqueous molecules

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homework three can probably be on chemical equilibria as well since it will be on test one so it can be helpful to prepare with the hw questions

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Why does hamburger yield lower energy than steak?
A: Because it's in the ground state.

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It is called partial pressure instead of just pressure because there are several gases in a given volume at once. Each gas has a certain amount of moles that occupies part of the total pressure. The sum of all the partial pressures of the gases present equals the total pressure. If only one gas was...

nicole-2B

You should use ICE charts when needed! In my discussion, we mostly did ICE charts for weak acids and bases.

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To add on, we don't include a pure liquid in an equilibrium calculation because it acts as the solvent in a chemical reaction and its change in concentration is relatively insignificant so in the K expression, the product concentration and reactant concentration would just cancel out. Thanks for ex...

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When using PV=nRT you see there is an inverse relationship between P and V so when P increases V decreases and the reverse is also true.

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You solve for Q the same way you solve for K.

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Gas constant, R = 8.314 J·K-1·mol-1 = 8.206 x 10-2 L·atm·K-1·mol-1 = 8.314 x 10-2 L·bar·K-1·mol-1= 62.364 L·Torr·K-1·mol-1
This is what was on the constants and formualas sheet on Dr. Lavelle's website.

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If Q<K, then we know that the reaction will favor the forward reaction because there is not enough product for the reaction to be at equilibrium. If Q>K, then we know the reaction will favor the reverse reaction because there is not enough reactant for the reaction to be at equilibrium. Thanks for ...

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NatBrown1I wrote:Because the concentration of solids and liquids are constant throughout the reaction.

Thank you!

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What animal is made up of calcium, nickel and neon?
A: A CaNiNe

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I think it would be good to know it because in lecture Dr.Lavelle notes state to look at the acid rain topics in the textbooks

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the hybridization for the C atom is sp

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What do you call an acid with an attitude?
a-mean-oh-acid

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Can someone explain when do you use the prefixes bis,-tris-,tetrakis-, pentakis-?

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Thank you Dr. Lavelle for being such an amazing professor and can not wait to be in chem 14B with you next quarter!

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In this case, you are looking at the HF bond length vs the HCL bong length. Since Florine is more elctronegative than Cl, it will have a stronger pull on the H make it harder to donate the H. The longer the bond, the easier it is to remove the H. It follows one of three rules in the book for strong...

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Why did the military use acid?
To neutralize the enemy base.

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Here is a list of the strong bases:
LiOH = lithium hydroxide, NaOH = sodium hydroxide, KOH = potassium hydroxide, RbOH = rubidium hydroxide, CsOH = cesium hydroxide, Ca(OH)2 = calcium hydroxide , Sr(OH)2 = strontium hydroxide, Ba(OH)2 = barium hydroxide

nicole-2B

Every time my TA does a problem he always tells us to follow sig fig rules so I do not think you would get a lot of points taken off but it is important to know

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a single bond has one sigma bond, a double bond has one sigma and one pi bond, and a triple bond has one sigma and two pi bonds

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it is the lowest energy state of an atom

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Why can you never trust atoms?
A: They make up everything!

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To find the hybridization of an atom, you need to find its steric number. The steric number is calculated by adding the number of atoms bonded to the central atom plus the number of lone pairs on the central atom. In this case, because oxygen has 1 carbon bonded to it + 2 lone pairs, its steric num...

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I plan on doing the homework questions, reviewing the midterm, and looking at past final tests if they are available.

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looks to be all correct

nicole-2B

Kassidy Ford 1J wrote:If you have a molecule like CHF3, it will be polar because not all of the atoms surrounding the C are the same, but will that affect the bond angles or do you still assume that it is 109.5

I believe it will have bond angles of 109.5 since the shape is still tetrahedral.

nicole-2B

London forces are always present in each molecule.

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Hydrogen bonds are formed when H is bonded to F,O,N. Easy way I was taught to remember if it is a hydrogen bond was if Hydrogen was bonded to Freak Of Nature.

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TA's have been saying to study everything we have learned after the midterm until lecture this Friday.

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What do you call a tooth in a glass of water?
A one molar solution.

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It is not totally necessary but can be helpful to determine the shape of the molecule.

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I think two factors that help determine whether or not an element forms coordinate covalent bonds is electronegativity and the octet rule. Atoms that accept the two electrons should be "hungry" enough to take them, but this can also mean that they don't have a complete electron shell. Tha...

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There are more electrons being shared so there is a greater attraction causing for shorter bonds.

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kevinolvera1j wrote:nice joke,
Helium Helium Helium

This made me hehehe!! haha

nicole-2B

There is more than one way to draw a lewis structure. For example the double bonds can move to another same element in the drawing.

nicole-2B

I feel like the question would ask for you to include the dipole moment but maybe include it just in case.

nicole-2B

A neutron walks into a bar. He asks the bartender, "How much for a beer?"
The bartender gives him a smile and says, "For you, no charge"

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Zoya Mulji 1F wrote:since formal charge indicates the gain/loss of electrons while forming a covalent bond, it serves as a predictor for stability in a lewis structure. The structure with the least formal charge should be lower in energy and thereby be the better Lewis structure.

Thank you for explaining very well.

nicole-2B

Why did the attacking army use acid?
To neutralize the enemy's base!

nicole-2B

since he has not gone over it I would not worry to much about it

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Did you hear about oxygen’s date with potassium?
It went OK.

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Did you hear about oxygen’s date with potassium?
It went OK.

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This should help in writing electron configurations

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Since s-block has a much lower ionization energy than the p-block so they lose electrons with less energy making them highly reactive

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There are no rules but I was taught that you should put a pair of valence electrons on each element before putting another pair on the first element you did

nicole-2B

I feel like everything we have learned so far will be on the midterm, but hopefully they mention what the midterm will consist of soon.

nicole-2B

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

nicole-2B

There are other exceptions but Dr.Lavelle mentioned that we will only be looking at the first row of the d-block so Cr and and Cu are the only ones we need to know.

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Adelpha Chan 1B wrote:Q: Wanna hear a joke about sodium hypobromite?

A: NaBrO.

This was such a good joke. Thanks for the laugh.

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I heard Potassium and Oxygen went on a date....It went OK Q: What do you do with a sick chemist? A: If you can't helium, and you can't curium, then you might as well barium Q: What is the name of 007's Eskimo cousin? A: Polar Bond My high school chemistry had the first joke up all year and it alway...

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Chantel_4B wrote:The G orbital does exist, but in their ground state, electrons are not in the G orbital, so it is therefore not represented on the periodic table.

Thank you for saying this. I had never heard of the G orbital before

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Why does 3d go before 4s in the electron configuration? I learned before it was 4s then 3d.

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andrewcj 4I wrote:One additional thing for my reply, make sure you convert nm to m.

thanks for clarifying this.

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The photoelectric effect is an experiment that discovered light has the properties of particles. The equation of calculating the energy of a photon E=hv comes from this experiment. The electrons will only be ejected when the energy is greater than or equal to the threshold energy (work function), a...

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Planck's constant is 6.626 x10^-34 J s. It is used to relate the energy of a particle to its frequency. The equation E=hv, we can be manipulated to h=E/v. Therefore, h or Planck's constant gives the ratio of energy to frequency and its relationship between these two variables. Thank you for your ex...

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APatel_4A wrote:He said that it is 720 to 400 but that we can just remember 700 to 400 since it's easier!

Thank you for clarifying .

nicole-2B

For week 3 we should only be submitting problems from the quantum section. We were allowed to submit fundamentals problems for week 2 because so many students were still preparing for the test, and he didn't want us to have to confuse ourselves with new material before it. Yes you should be doing t...

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What was the scam for workshops that Dr. Lavelle mentioned in lecture? Something to do with asking for our phone numbers? Yeah he mentioned it in my lecture which was at 2. He said in one of his earlier lectures there was a piece of paper going around to sign up for workshops. It asked for your nam...

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The electrons have both wave-like and particle-like properties, and the photoelectric effect is a key example showing the particle-like property. The diffraction pattern observed during the experiment we went over in class is evidence that electrons have wave-like properties. As for the particle na...

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In terms of the original question you asked - the relationship between velocity and wavelength for light is given by this equation: V = f\lambda Where V is the velocity of the wave in meters per second, \lambda (lambda) is the wavelength in meters, and f is the frequency, or cycles per second. I be...

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