CHEMISTRY COMMUNITY

Rachel Yoo 1F

I believe it is because the rate law is in terms of the products so reactants are the ones affecting the production rate

Rachel Yoo 1F

Did anyone get #6 part c right and if you did could you give me the answer and how you got it because I got a and b right but c wrong and I'm not sure what I did wrong

Rachel Yoo 1F

Are the k reaction rates swithced too? Because if k is switched too then it is fine

Rachel Yoo 1F

The 1st order reaction should look like an exponential decay function

Rachel Yoo 1F

check to see the order for the reactant C. If reactant C iz zero order, than it doesn't matter what concentration C is because it has no effect on the rate

Rachel Yoo 1F

Calculate the potential of a cell constructed with two nickel electrodes. The electrolyte in one compartment is 1.0 M Ni(NO3)2. In the other compartment, NaOH has been added to a Ni(NO3)2 solution until the pH = 11 at 298 K. Use Table 6I.1 I got the [OH-} concentration but I'm not really sure how to...

Rachel Yoo 1F

in this equation n = the number of moles of electrons being transferred

Rachel Yoo 1F

For the cell diagram the answer doesn't include a platinum(s) on the anode side when there is no solid. It only has Hg(l) and Hg2 2+(aq). I thought we had to always include Pt(s) when there's no solid so why does the answer not include it on this side?

Rachel Yoo 1F

For the people with 7th edition textbooks will anything in topic 6N be in test 2?

Rachel Yoo 1F

Which of the following compounds become less stable with respect to the elements as the temp is raised: (a) PCl5 (b) HCN (c) NO(g) (d)SO2?

Rachel Yoo 1F

I read a post saying that thermodynamics will be on test 2 so does that mean isobaric, isothermal, and isochoric equations for test 2?

Rachel Yoo 1F

The larger the molecule, the more ways it can rearrange itself and create different shapes. This increases entropy

Rachel Yoo 1F

I dont think it matters whether you use specific heat of molar heat as long as your consistent in what you use.
For this problem make sure you include the energy it takes to change the solid to a liquid into the equation

Rachel Yoo 1F

3/2 R=Cv
5/2R=Cp
this is used in the equation to find heat
q=ncdeltaT
those values only apply to ideal gases

Rachel Yoo 1F

It will cover everything until 4J I believe because he said entropy is on the midterm

Rachel Yoo 1F

If you go to any TA office hour, they will tell you what topics are on the midterm and generally help with any questions you have for the midterm.

Rachel Yoo 1F

I'm struggling with trying to understand which equation to use when I'm reading the homework problems so does anyone have any tips or advice on how to memorize which work,q, or delta u equation to use for the different types of different processes?

Rachel Yoo 1F

Does anyone know when we will receive our finals from last quarter?

Rachel Yoo 1F

Does anyone know if Chem 14BL should be taken with Chem 14C? If not when is it recommended to take Chem 14 BL?

Rachel Yoo 1F

air in a bicycle pump is compressed by pushing in the handle. the inner diameter of the pump is 3.0cm and the pump is depressed 20. cm with a pressure of 2.0 atm. part c) what is the change in internal energy of the system?

Rachel Yoo 1F

What are the common bond enthalpies that I should memorize?

Rachel Yoo 1F

So I'm trying to do the problems in the 7th edition book section 4A but I don't really think Lavelle's lecture today or last Friday covered section 4A. Which sections did Lavelle cover so far in thermochemistry so I can do for this week's hw?

Rachel Yoo 1F

Since its a weak acid you have to make an ICE Table. You can find the Ka values on the tables in section 6C.

Rachel Yoo 1F

For problem 6D.13 I used tables 6c1, 6c2, and 6c3 to find ka and kb values

Rachel Yoo 1F

For part a with the H+ concentration, you can also use the Table 6c1 and 6c2 to find Ka for HClO. Use ICE table to set up an equation and find the initial concentration of the weak acid

Rachel Yoo 1F

You can use PV=NRT in any situation when given any three out of the four: pressure, volume, number of moles, or temperature. R=.08206. In this instance, we use it to convert Kc to Kp or vice versa

Rachel Yoo 1F

Kp is for partial pressure with units like atm, bar, torr, etc. Kc is for concentrations and will have mol/L for units

Rachel Yoo 1F

They aren't online so if you ever miss a lecture I would say to either ask a friend for their notes on the lecture or go into his office hours and ask what you topics you missed.

Rachel Yoo 1F

For questions like 5G.11 when it asks you to write the reaction quotient Q for a certain equation, does it matter to answer with Qc or Qp?

Rachel Yoo 1F

Just change your username by clicking on your name on the top right corner of the page and click user control panel

Rachel Yoo 1F

I know that we don't include solids and liquid in our K expression but what if its aqueous ?

Rachel Yoo 1F

The cation/anion and water would be the reactants and depending on which reactant is the acid, it will donate the H+ to the base

Rachel Yoo 1F

The question is to identify the salt that is produce from the acid-base neutralization reaction between potassium hydroxide and acetic acid. write the complete ionic equation for each reaction. I am confused as how to approach the problem and what salts can be produced

Rachel Yoo 1F

For our class right now I believe that we are focusing on Bronsted acids

Rachel Yoo 1F

The cis configuration is polar which means it can create dipole dipole interactions and create a stronger bond compared to the trans configuration

Rachel Yoo 1F

It has 3 bonds and two lone pairs which means its hybridization is sp3d

Rachel Yoo 1F

Nitrogen is in row 2 which means it cant disobey the octet rule. By adding a double bond to chlorine, it would make nitrogen not follow this rule.

Rachel Yoo 1F

Today in lecture Dr. Lavelle talked about unhybridized 2p orbitals but I was unsure of what unhybridized orbitals are and the difference between these and hybridized orbitals.

Rachel Yoo 1F

When drawing lewis structures, it is good to first make sure every element has a complete octet( unless it's in row 3 or after). Then I would start paying attention to how to create the most stable structure.

Rachel Yoo 1F

Yes Dr. Lavelle said in class that it was fine if you put d before or after the sp

Rachel Yoo 1F

Test 3 is on the week after Thanksgiving

Rachel Yoo 1F

I think stable charge refers to the formal charge of the most stable structure for the specific molecule

Rachel Yoo 1F

I think bond angles is something you just need to memorize by VSEPR

Rachel Yoo 1F

Polar bonds have an unequal sharing of electrons while nonpolar bonds do have equal sharing

Rachel Yoo 1F

To know how to solve the problem, you want to find the most stable lewis structure so guess and check until you find a structure with the lowest formal charge.

Rachel Yoo 1F

A dipole induced dipole means that the molecule by itself doesn't have a dipole moment but with the bonding of a second molecule, it will have become dipole,

Rachel Yoo 1F

The question asks to draw the lewis structure for COCl2. I drew mine and put oxygen in the middle but when I checked the answers carbon was the central atom. How would you be able to know this?

Rachel Yoo 1F

Since the question is asking for the electron configuration of Cu+ it means that Cu lost an electron. Originally it would be [ar]3d84s2 but the 2 electrons from the 4s shell move to the 3d shell making the electron configuration [Ar]3d10

Rachel Yoo 1F

The way I figure it out is I first look at the position of the element. If it is in Group1-3 it will lose the electron, so it will have a positive charge. If its in Group 15-17 it will gain electrons and have a negative charge. The amount of electrons it loses/gains represents the number.

Rachel Yoo 1F

Also where did you get the study guide

Rachel Yoo 1F

I think it might be talking about e-p distribution and that the p orbital has a 0 probability of electron density

Rachel Yoo 1F

The ionization energy(energy required to lose one electron) of p-block are quite high because they need one more to fill a shell . So they are less reactive than s-blocks in which has a low ionization energy

Rachel Yoo 1F

The f orbital is included after the 6s2 orbital is filled. When looking at the periodic table, you can see that the f block starts in period 6.

Rachel Yoo 1F

Photons do influence the amount of energy. Each photon is like a packet of energy so if the light produces a certain amount of photons, the energy radiation is influenced upon that.

Rachel Yoo 1F

A lower frequency means a longer wavelength. Since the wavelengths are longer, it allows less oscillations to be completed in a time frame compared to a small wavelength. "extent of the change" means the slope so since the wavelength is longer, the slope changes less.

Rachel Yoo 1F

Use the 32J/s to find the total amount of J in 2 seconds. Then use the equation E=(hc)/lambda to find the energy of one photon. With this you should be able to find the number of photons of a violet light. Then you can find the number of moles of photons by using Avogadro's number

Rachel Yoo 1F

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6*10^3 km*s^-1. part c. what is the wavelength of the radiation that caused photoejection of the electron? I got part a and b but I'm not really sure how to do this part but I tried both the equations lambda=c/v and...

Rachel Yoo 1F

To find the wavelength you first convert the frequency of MHz to Hz. Then using the equation c=(lambda)v, you can find the wavelength.

Rachel Yoo 1F

the "extent of the change" refer to the slopes of the wavelength and because the wavelengths are longer, it allows less oscillations to be completed within a time frame

Rachel Yoo 1F

I have the 7th edition and the chart on Table 1A.1 says that a 1m wavelength is both microwave and radio wave

Rachel Yoo 1F

When finding empirical or molecular formula, its important that we know the mass percentage of each element. For example, we find the mass percentage is H 4.58%, O 54.5%, and C 40.9%. Since these percentages all equal to 100% it is the easiest procedure to imagine the sample mass being 100g because ...

Rachel Yoo 1F

When adding and subtracting, you use the least number of sig figs AFTER the decimal place.
For example, 1.823+9.75=11.57

9.57 has only 2 sig figs after the decimal place which means the answer will only have 2 sig figs after the decimal.

Rachel Yoo 1F

In my opinion, the prefixes that will most likely be used is kilo, deci, centi, and milli but like the comment above I think its probably best to memorize them all.

Rachel Yoo 1F

Doing the modules posted on Dr. Lavelle's website is actually really good review. The videos are him teaching the topics/lectures and he gives good and easy examples to follow along.

Rachel Yoo 1F

Yea when I did the modules they don't ask for our name or UID so I'm assuming that its just review for self benefit. It was actually a good refresher from summer break.

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