CHEMISTRY COMMUNITY

abby hyman

A zero order reaction has a rate that is independent of the concentration of a reactant

abby hyman

I am taking Chem 14C and wanted to get into BL but couldn'.

abby hyman

n is the number of electrons transferred once the equations are balanced.

abby hyman

The activation energy of the reverse reaction is the activation energy of the forward, plus delta H

abby hyman

On the right will be the reduction (cathode) and on the right will be the oxidation (anode)

abby hyman

They are due Sunday as per Dr. Lavelle's email

abby hyman

Yes this is true. You do include catalysts in the rate law for the steps but the catalyst will not show up in the overall reaction, so will not be included in the overall rate law.

abby hyman

I think if we were given it on the test they would have to tell you which is the slow step. If that is not the case then, if you know the overall rate law, you can find the rate law for each step in the mechanism and determine which is the slow step because it will match the overall. Sometimes we ar...

abby hyman

The calculations are usually in seconds but can easily be converted and should always tell you the unit if used in a question

abby hyman

I think the sapling questions are great to refresh on concepts and remember the particulars for how to solve problems

abby hyman

The equations are all specific to the order of the reaction. Once you know the order, you can use those equations to figure out anything you need to solve for

abby hyman

I do not believe you would include intermediates in the rate law in any case.

abby hyman

I agree, I think it would be a typo because the convention is to always put the anode on the left side

abby hyman

An elementary reaction is a chemical reaction in which one or more species reacts directly to form products in a single reaction step with a single transition state. -If a reaction is elementary, the rate will be proportional to the concentrations of the reactants -Elementary reactions do not have a...

abby hyman

A catalyst is a species that is consumed and then produced
An intermediate is a species that is produced and then consumed
You would include the catalyst in the rate law but you would not include an intermediate

abby hyman

Zero order means that the reaction rate does not depend on the concentration of the reactants
First order means that the reaction rate depends on the concentration of one reactant
Second order means that the reaction rate depends on the concentration of 2 reactants

abby hyman

I am pre-dent and have found the majority of the required classes are very manageable if you know how to study and distribute your time

abby hyman

Did you know that you can cool yourself to -273.15˚C and still be 0k?

abby hyman

I also was confused on how to go about splitting up the reaction for this question

abby hyman

When you do the half reactions, the number of moles is the number of electrons transferred in the equation

abby hyman

I think it will be based on the amount of time we covered each topic but I also think that there will be a significant amount of questions from after midterm 2 specifically

abby hyman

at equilibrium Delta E is equal to 0 since the reaction quotient isn't changing

abby hyman

I agree^^ I think you can interpret them the same but usually the A is at least written as a subscript for Activation Energy , if not also lowercase

abby hyman

Wilberth is the best!!!!

abby hyman

My TA went over this problem in class so hopefully I can help. For the cathode, you have Au+ + e- -----> Au(s) For the anode you have Au+ --------> Au3+ + 2e- He then added the above anode rxn to Au(s) -------> Au+ + e- By doing this, it canceled out the Au+ and resulted in Au(s) ------> Au3+ + 3e f...

abby hyman

Imagine if two people were running a race together but their finishing time was determined by the second person to cross the finish line. The rate then is determined by the the slower person and it does not matter how fast the fast person completed the race.

abby hyman

New girl is one of the best shows
Also Big Little Lies is very good

abby hyman

An intermediate is a species that is a product in one reaction and then a reactant in the next. In other words, it is produced and then consumed.

abby hyman

All the review sessions are super helpful. I find it very helpful to also go through the textbook sections and read the ones on the outline and then try the problems

abby hyman

The slow step compared to the fast means that one reaction is able to happen quickly and one more slow. The rate is determined by the slow reaction because the overall reaction will not be able to occur until the slow step has

abby hyman

Does anyone know if the majority of questions will be focused on electrochemistry and kinetics since we haven't been tested on them yet? I think there will definitely be multiple questions form electrochem and kinetics but I am not sure I would say the majority. I would expect it to be a mix of tho...

abby hyman

I dont think there will be exactly the same questions as a midterm but there will be similar. In addition, there will be exact questions from the textbook!

abby hyman

Yes, this does have to do with equilibrium in the way that if you increase the concentration of products, rather then there being a strong tendency to form more reactants, there is instead a desire to form more reactants .

abby hyman

You must use the specific half life equation for a zero order reaction which is t1/2 = [A]0/2k

abby hyman

I think the slow step will be identified as such in the question, and you use the slow step to determine the rate law.

abby hyman

I would also like to know the answer to this question as I am confused why we do not need it on the left side too since there is not a solid

abby hyman

K, the rate constant, can only be changed by the temperature

abby hyman

Can someone tell me if you use the coefficient as the exponent for rate laws?

abby hyman

Yay! Good luck with the rest of your midterms !!

abby hyman

The textbook problems and Step Up and Workshop sessions are without a doubt the keys to success in this class. It is such an advantage to be able to work through problems and familiarize yourself with the wording of questions. I also don't learn this type of material by reading the textbook but for ...

abby hyman

I feel like the midterm was fair but did have more wordy/complicated questions than we had seen in the textbook or the UA workshops but I felt like if you had a good understanding of the material then you had an okay chance for a good score

abby hyman

I listen to a lot of Rex Orange County, Vampire Weekend, and Brockhampton

abby hyman

K and Kc are essentially the same thing. c is a subscript of K, denoting that it is the equilibrium constant for the concentration. Kp is also the same essentially but this is with partial pressures of gases instead.

abby hyman

Yeah last quarter they took about a week to get back to us.

abby hyman

If someone could help me with this one I would be so appreciative! I have tried so many times and can't figure out what I am doing wrong so if you could use my numbers that would be great!!

abby hyman

I think Le CHatelier's principle would be one you would need to memorize for the midterm. Similar to how we had to remember Pauli Exclusion and Hund's rule ect.

abby hyman

As explained above, the chart with initial concentration, change in concentration, and equilibrium concentration is very helpful for this problem

abby hyman

Yes that would be the equation. It would be helpful for this question to set up the table to determine the values in terms of x and then can use the quadratic formula to solve for x

abby hyman

Can someone explain to me how you would be able to figure out the partial pressure of a gas if you are not given the temperature?

abby hyman

To begin, you would need to use the wavelength given (converted to meters) to find the velocity of the ejected electron. The equation for this would be deBroglie's so wavelength=planks constant/(mass)(velocity) Once you have the velocity of the electron, you can use 1/2mv^2 to find the Kinetic energ...

abby hyman

Coordination number is the number of bonds but you must keep in mind that some ligands are bidentate/tridentate/tetradentate ect and would contribute 2 or more bonds. These additional bonds must be taken into account to find the correct coordination number.

abby hyman

It does not matter really how you write it. I remember in lecture that Lavelle wrote it as OH2 to show that the oxygen was what was donating the electrons rather than the Hydrogen

abby hyman

I am starting by doing 10 problems from each section on the outlines and then checking them and the sections where I struggled I will go back and re-read the textbook section and try more problems.

abby hyman

Resonance structures are determined to be more stable because they represent delocalized electrons and the fact that they can be found in multiple places. In general delocalized electrons are spread out over the molecule which makes it more stable than if it was fixed location.

abby hyman

I think of hybridization in terms of the electron configuration where the hybridization orbitals are the combination of the orbitals with electrons in them

abby hyman

I find flashcards very helpful for this class in general. I have the name of a compound on one side and the lewis structure and properties on the other and write down what I think the answer is on a piece of paper and then check it with the back after.

abby hyman

I think the way that it is most similar to high school chemistry is in the fact that a lewis acid is electron-deficient and the lewis base is electron-rich and the electron-rich donates to the electron-deficient.

abby hyman

An amphoteric substance is one that is able to react as both an acid and a base. Amphiprotic is a substance that could accept or donate H+ ions.

abby hyman

NH3 is neutral because the N has a charge of -3 and each H has a charge of +1 creating an overall charge of 0 for the compound.

abby hyman

I do not think any questions would be asked in this class about what state of matter an atom or molecule would be in. Other than knowing that metals are solid and the obvious gasses, you should be solid

abby hyman

Yes in Lavelle's reviews he should talk about the format and details for the final but it should be the same format and set up as the midterms.

abby hyman

I believe it is the case that a ligand is a lewis base but all lewis bases are not ligands. A ligand is specifically the lewis base as part of a coordination compound.

abby hyman

Myoglobin is found in the tissues of the body while hemoglobin is found in the blood. They both serve the same purpose of transporting oxygen around the body but hemoglobin carried 4 times the amount of oxygen as myoglobin

abby hyman

For the s and p orbitals, you can use the group number to tell you how many valence electrons an element has, and for the d block, you can think about writing the halogen electron configuration and see how many electrons are written

abby hyman

This is so helpful. I was struggling with naming a lot and these videos helped me out a ton.

abby hyman

As stated, a coordination covalent bond connects a ligand to a transition metal ion. The ligand contributes both electrons to the transition metal which is why it is a coordination covalent bond.

abby hyman

I believe the fact that they are the same atom does not make a difference in this case. You have to take into account the bound atoms and lone pairs to determine the geometry

abby hyman

The reason that a molecule with 6 electron regions has an octahedral geometry is that the shape that is made in which the atoms would be the most stable is called an octahedron. This shape has 6 vertices which would represent the positions of the 6 electron regions. As for trigonal bipyramidal, a mo...

abby hyman

I think it is very helpful to know them and have them memorized.

abby hyman

I am doing pretty well. Finals feel more stressful this quarter than usual for some reason.

abby hyman

Hi I was wondering if anyone could explain to me how you would go about naming [Co (NH3)3Cl3]
I thought it would be triamminetrichlorocobalt(II)

abby hyman

Hey! So AsF3 has a tetrahedral arrangement but a pyramidal shape due to the fourth electron region being a lone pair rather than an atom. The tetrahedral arrangement means that there is a hybridization of the one S and three P orbitals which is why it is sp3. You can also think of it as s + p*p*p.

abby hyman

Hi can someone explain to me what it means that the acid donates protons to the base?

abby hyman

I have also used organic chem tutor on youtube! I found that really helpful.

abby hyman

He has not said how the final will be proctored. I assume it will be similar to the earlier midterms and I believe it is in the same multiple-choice format as the midterms.

abby hyman

As the person above said, you would be correct that seesaw geometry has four bonds and thus a coordination number of 4, it is not the most common geometry for molecules with four bonds.

abby hyman

The exceptions for the octet rule include examples such as SF6 where Sulfur can accommodate more than 8 valence electrons and BCl3 where Boron has less than 8 electrons in its valence shell.

abby hyman

No an A+ and A have the same GPA

abby hyman

Does anyone know if there is any way to review the ones you missed on midterm 2?

abby hyman

Don’t stress too much! The chemistry community points along with the homework make up a good portion of the grade and you can do better on the next tests!!

abby hyman

Anions are just atoms that gain electrons or become more negative to be in a more stable state. cations are similar except for they lose electrons or become more positive to reach a more stable state.

abby hyman

The number of valence electrons is found by going across the period of the element and counting how many. So carbon would be 4, oxygen 6 etc.

abby hyman

I found the text book problems, step up sessions, and workshops so helpful because you get to see most of the types of questions that will be asked on the midterm.

abby hyman

Yes, the number of spectral lines is equal to the number of possible transitions from n=7 to n=1. To find the wavelength range you just have to find the wavelength corresponding to the transition from n=7 to n=6 and the wavelength corresponding to the transition from n=7 to n=1. These would be the m...

abby hyman

To solve this, make sure you remember to convert nanometers to m in order to do the proper calculations. To find the frequency from the wavelength you would first use c= frequency/wavelength. Once you have the frequency, you plug it into the equation f= (Rydberg's constant) (1/n(final) - 1/n(initial...

abby hyman

I think there is a lot of information we will need to know requiring the orbitals. Mainly, it is important to be able to identify an atom from its ground-state electron configuration, (which is where the 2s and 3s come from). The periodic table is separated into blocks, corresponding to the type of ...

abby hyman

Yes, you have the right idea about it. since you do not want a coefficient to be 15/2 you have to multiply every coefficient by 2 so they are all in whole numbers and maintain the correct ratio

abby hyman

As they stated above, the wavelength and frequency do not change based on the number of photons. The value you get for energy is per photon so you must only multiply this value by 100 to get the total energy.

abby hyman

hey again kendall!! still missing you! Wish we were back in class with sam and brandee! I would love to do some midterm review over zoom with you! Text me and let me know when works best!

abby hyman

Hey Kendall! Miss you from last year's ls7b class! Do you know if the first midterm will cover weeks 1-3 only or if the beginning of week 4 is included?

abby hyman

Protons and neutrons have around the same mass of about 1.67 x 10^-24 grams while electrons are only 9.109 x 10^-28g. Protons and neutrons determine the mass of an atom, while electrons move from atom to atom without a significant change in mass

abby hyman

Although I believe for this quarter the exams are multiple-choice so it is not as important, usually, it is good to have your answers in 3 or 4 sig figs. Also, it does depend on the TA since they are grading but usually there is a range for the answers to account for rounding errors.

abby hyman

I think the problems on the audiovisual topics are the most helpful for studying. It is helpful to see many different problems for each topic so you will be prepared for the kinds of questions being asked on the midterm. Also, of course, it is important to have a good background for what you are doi...

abby hyman

I am assuming we can be muted for the exam as I have two roommates who would be using the space I would be taking the exam. My TA said that they want to be monitoring your workspace rather than your face. He recommended getting a webcam that would attach to your computer.

abby hyman

I would love to be part of the virtual study group my Instagram is _abbyhyman

abby hyman

The state of the molecule is not required for balancing equations right now. I believe Lavelle will discuss more of this later on in the quarter, but not something that is tested on I don't think.

abby hyman

Along with the conversion factor link on the website, I believe you are given some conversions on the formula sheet for tests.

abby hyman

I believe the periodic table is always provided to you if you need it for exams so memorizing would be unnecessary. It does save time to know the molar masses for some of the commonly used elements though, so you do not have to refer back every time.

abby hyman

Although the molecular formula is directly related to the molar mass of elements and the compound, there is not a common multiple that would take you from molar mass to molecular formula. If you meant how to get from empirical formula to molecular formula using the total molar mass, then you would a...

abby hyman

I believe for this class you just need to recognize the common ones but will not be asked to produce the name based on only the empirical formula.

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