CHEMISTRY COMMUNITY

Samantha Pacheco 2K

Will the half life equations be given to us or will we have to derive them?

Samantha Pacheco 2K

What exactly is a pseudo rate law and when would we use it?

Samantha Pacheco 2K

1 atm= 760 torr

Samantha Pacheco 2K

Do we need to know how to derive the Nerst Equation or will it be given to us?

Samantha Pacheco 2K

You reverse the half reaction that will given help produce the desired overall reaction. If you are using the Ecathode-Eanode then you do not need to flip the sign of E. Ex our reaction is Fe3+ + Cu ---> Cu2+ + Fe2+ our half reactions are Fe3+ + e- ---> Fe2+ E= .77V Cu2+ + 2e- -----> Cu E= .34 V We ...

Samantha Pacheco 2K

What exactly is an activated complex model and how does it account for temperature dependence of a reaction?

Samantha Pacheco 2K

What is the unit used for ∆S

Samantha Pacheco 2K

Adiabatic means there is no heat flow, no heat is being transferred between the system and the surroundings

Samantha Pacheco 2K

n stands for the number of electrons and it has no units.

Samantha Pacheco 2K

You would use
∆Hrxn=∆H(bonds broken)-∆H(bonds formed)

Samantha Pacheco 2K

The outline says we should know how to derive the rate laws so it is possible it may appear.

Samantha Pacheco 2K

On the outline it says know how to derive the rate law so a question involving/requiring derivation can potentially appear on the final.

Samantha Pacheco 2K

Acidic: If you are balancing in an acidic solution you would use H2O to balance the O and balance H by using H+.
Basic: If you are balancing in a basic solution use H2O to balance the O, balance H by using H2O to side of reaction that needs H and Add OH- to other side

Samantha Pacheco 2K

For naming molecularity you only consider the reactants taking part in a reaction.

Samantha Pacheco 2K

If you reverse a half reaction and you do not change sign of E° then we use that equation Ecathode-Eanode, you will always subtract . If you do flip the sign of the E° in the reaction you reversed then you would add the 2 cell potentials.

Samantha Pacheco 2K

You do not include a zeroth order in the overall rate because anything to the power of zero is one. [A]^0=1 so it does not need to be included

Samantha Pacheco 2K

For E° when is the case that we do not flip its sign even if we reversed the reaction?

Samantha Pacheco 2K

Will we always use platinum as our inert conductor? If not which other conductor would we use?

Samantha Pacheco 2K

I don't think it will, it should only cover the information in the outlines that are in this category. It might require the knowledge of previous concepts.

Samantha Pacheco 2K

Does Wmax always equal G or is that only when temperature and pressure are constant?

Samantha Pacheco 2K

I don't think so, the outline has the information that we need to know.

Samantha Pacheco 2K

I'm pretty sure that any standard enthalpy of formation that we will need will be given.

Samantha Pacheco 2K

Why does going from a liquid to a gas have a larger enthalpy than going from a solid to a liquid?

Samantha Pacheco 2K · Re: Lecture notes 2/8/19 I have a picture of the slides

I have a picture of the slides

Samantha Pacheco 2K

I think a good way to prepare for the midterm is by doing the homework questions. There are usually multiple review sessions held by the TA's which he will probably announce in class or on his website.

Samantha Pacheco 2K

He solved this example using the equation
Δu=ΔH-PΔV=ΔH-ΔnRT (assuming P=1 atm)

Δu=(-50kJ)- (8 mol)(8.3124)(298K)
Δu=-50kJ-(-20kJ)
Δu=-70kJ

Samantha Pacheco 2K

It is best to draw out the structures so that you can see all the bonds in the reaction. This will help figure out which bonds have been broken and which have been formed.

Samantha Pacheco 2K

I believe it is best to calculate the molarities before, this will make it easier when trying to solve for your unknown value.

Samantha Pacheco 2K

On page 461 there is an acid chart and on page 462 there is a base chart. They don't specifically indicate which is strong or weak but it gives K. We know anything smaller than 10^-3 is weak and anything greater is strong.

Samantha Pacheco 2K

When K=1 this means that when equilibrium is reached, the concentration of products and reactants is the same.

Samantha Pacheco 2K

What does a polydentate ligand allow us to do? What is its function?

Samantha Pacheco 2K

If we are trying to determine hybridization of an atom and we are given a structure but an atom in that structure does not have a full octet, do we assume that their is/are lone pairs?

Samantha Pacheco 2K

How do we determine that something is an oxoacid?

Samantha Pacheco 2K

A conjugate acid results when a base accepts a proton. A conjugate base results when an acid gives up a proton.

Samantha Pacheco 2K

A) K₃[Cr(CN)₆]
B) [Co(SO4)(NH3)5]
C) [Co(NH3)4(H2O)2]Br3
D)Na[Fe(OH2)2(C2O4)2]

Samantha Pacheco 2K

Yes a triple bond will have 1 sigma bond and 2 pi bonds.

Samantha Pacheco 2K

You can draw an arrow toward the partial negative end and if these partial negatives cancel the molecule will be nonpolar.

Samantha Pacheco 2K

How do we know when to use hybridization?

Samantha Pacheco 2K

When determining lewis structure resonance you should keep resonance in mind but it does not affect VSEPR models. The number of electron densities around the central atom is the same in all the resonance structures and those regions of e- density determine the VSEPR model. So they if the regions of ...

Samantha Pacheco 2K

The farther away the electrons are from each other, the less repulsion there is between them. Therefore the shape where electrons are farthest apart will have the lowest amount of repulsion and will be the most stable.

Samantha Pacheco 2K

How do we determine whether the VSEPR model will be polar or nonpolar? Is it only based on symmetry?

Samantha Pacheco 2K

How are sigma and pi bonds related to bond strength?

Samantha Pacheco 2K

This is a radical because it has one unpaired electron on carbon.

Samantha Pacheco 2K

If there is a dipole attraction then there must be a negative and positive part of the molecule. One end of the molecule will be delta negative and the other will be delta positive. I believe you can include the delta negative/positive on the lewis structure and this will help you see how the molecu...

Samantha Pacheco 2K

When the electronegativity is between 1.5-2 the bond will exhibit ionic and covalent characteristics. The bond is neither completely covalent nor completely ionic. These bonds are also usually good in polar solvents.

Samantha Pacheco 2K

Ground state atoms are going to be atoms where their electrons are at normal energy level. All atoms at ground state have their electrons in the lowest possible energy levels, and they are said be at the zero energy level. An excited atom will have be in a higher energy level. They will be more unst...

Samantha Pacheco 2K

When an atom has a 3+ charge that means they have lost electrons therefore you must subtract electrons not add them. The question is asking you to identify the element that would have that specific electron configuration after losing 3 electrons. For example a neutral Co has and electron configurati...

Samantha Pacheco 2K

You would usually add a double bond when the central atom does not have a full octet but you have to keep the exceptions in mind. In order to know how many double bonds to put you need to calculate the formal charge for each atom. The formal charges all need to add up to the overall charge of the mo...

Samantha Pacheco 2K

Another example is electronegativity, as it increases it affects how electrons will act in a bond. If atoms are close in electronegativity they will equally share the electron and it will create a nonpolar covalent bond. If their is a big difference in electronegativity there will be an unequal shar...

Samantha Pacheco 2K

Be and Br have a similar electronegativity therefore they both pull on the electron equally. In order for it to be ionic one would have to have a significantly greater electronegativity so that it could pull the electron from the other atom, but because the electronegativity is similar between these...

Samantha Pacheco 2K

When writing out the configuration and there is only 1 electron in the orbital does the spin always have to be an up spin? can it be a down spin?

Samantha Pacheco 2K

As distance between e- and the nucleus increases the electrostatic attraction between the two will decrease.

Samantha Pacheco 2K

As n increases the energy of the electron increases as well. As n increases the e- moves farther away from the nucleus which means that the attraction between the nucleus and the e- will be weaker and the e- will be more unstable(as energy increases stability of e- decrease). Therefore the electron ...

Samantha Pacheco 2K

First you are going to convert the wave length from nm to meter. 1850nm= 1.85x10^-6 m. In order to find the # of photons first calculate the energy of each photon using E =hc/λ. =(6.626 × 10−34 J · s)(3 × 108 m/s) /1.85 × 10−6 m = 1.07449 × 10−19 J (per photon) Now that you have the energy of one ph...

Samantha Pacheco 2K

We went over an example that included threshold energy in the problem but what exactly is threshold energy of an electron and how does that factor into calculating the energy of a photon?

Samantha Pacheco 2K

I'm pretty sure all the equations and constants will be provided for every test/exam.

Samantha Pacheco 2K

If you make it into a fraction it will be easier to see

Samantha Pacheco 2K

Julia Lindner 1I wrote:Where in the book (7th ed.) can I find the formula for calculating energy of a photon? A question requires you to use it but I can't seem to find it anywhere.

The equation can be found on page 13 it falls under Topic 1B Quantum Theory and in the sub section 1B.1 Radiation, Quanta, and Photons

Samantha Pacheco 2K

My TA also recommended using as many digits as possible during the calculation to avoid any rounding errors and use sig figs for the final answer

Samantha Pacheco 2K

Rounding while calculating can lead to a different answer so it is best to round until you reach your final step/answer

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