CHEMISTRY COMMUNITY

NinaSheridan

Dear Dr. Lavelle, You have actually made me enjoy learning about chemistry and I did not know that was possible! I feel like I have so many resources at my disposal, and using them has made me confident in my own abilities and made me aspire to really understand everything, because I know it's possi...

NinaSheridan

The book says the "largest" is more stable in the equatorial position, so I would say size. However, I'm confused about 3.16 because it doesn't state whether the conformation is more stable when methyl is equatorial or not. I'm assuming it's more stable when it is equatorial, because CH3 i...

NinaSheridan

Also, for electrophilic addition, we often have a main molecule with a double bond and a molecule with two element s. If a double bond is broken and an atom from the two-element molecule has been added, the other part of the two-part molecule will be added to the other side of the double bond.

NinaSheridan

There was also a thing Lavelle mentioned about not using a dash sometimes for the second to last term? It's in our course reader but was different on the powerpoint or something like that.

NinaSheridan

Because we aren't being tested on it, should we still do the 20 or so problems on it? Is it likely to show up on future tests?

NinaSheridan

If anyone can explain why we look at molar mass rather than the possible positions of the molecule that would be great :)

NinaSheridan

That's the constant used when the ln is changed to log.

NinaSheridan

But (298)(8.314)/(964853) = .025678, not .05916, so where is .05916 coming from? A different form of the gas constant? A different temperature??

NinaSheridan

As I understand it, you split up the equation into the oxidation reaction and the reduction reaction. First, put them in their reduction form because E(standard) values are given for reduction reactions. Then, depending on which reaction is actually an oxidation reaction in the equation (you can fin...

NinaSheridan

If you're still confused about why entropy of the system and entropy of the surroundings aren't both zero (why option A and B aren't correct if entropy in general is a state function), the situation with isothermal reversible reactions having a net change of zero while irreversible reactions have an...

NinaSheridan

For question 51 in chapter 8, the problem tells us the enthalpy of formation for TNT (-67kJ/mol) and the density (1.65g/cm^3). It then gives us the equation 4 C7H5N3O6 + 21 O2 --> 28 CO2 + 10 H20 + 6N2. It asks to find its enthalpy density. I understand how to find the enthalpy of the equation, but ...

NinaSheridan

When would we use one constant over the other? Does it have to do with units?

NinaSheridan

Also why do we completely ignore the masses that are given? Isn't the equation (m)(c)(deltaT)? Why do we disregard the masses and the moles?

NinaSheridan

I'm a little confused about the idea of "standard states" to begin with. For example, a gas is only in its standard state at 1 atm. So what if it isn't at 1 atm? What does that make it? Does that just mean the reaction enthalpy isn't the standard reaction enthalpy?

NinaSheridan

I looked this up too and also found that in the case of liquids going to solids (the opposite of fusion) it's technically called solidification or crystallization if that ever comes up anywhere :)

NinaSheridan

I've been told the test might be more conceptual (more like the practice final from 2015 than the ones from earlier years) so it might be helpful to look at the practice test from 2015, and the conceptual problems and the concepts at the beginning of each chapter. Knowing calculations wouldn't be a ...

NinaSheridan

If that's the case though, why isn't KF neutral as well?

NinaSheridan

Jk, just answered my own question, but if anyone else has this problem, here's what's going on. The answer key is using a different method that uses the reaction stoichiometry rather than the concentrations, but the concentration method works too, so it's just a different method.

NinaSheridan

So on 11.57 the answer key says the initial concentration for H2 is 3 moles per liter, but the problem itself says it's 3 moles for 10 L, which would make the concentration .3 instead of 3, wouldn't it? It does the same thing for CO, it says 2 moles are put into a 10L vessel, which would make the co...

NinaSheridan

As to the above comment ^^, you mean electronegativity of a specific element like the central element? Or all the average of the elements overall?

NinaSheridan

This is related, if someone can explain this, can they also explain why oxalato is only bidentate?

NinaSheridan

What do the (sigma2p)^22 and (sigma2p)^11 mean at the end of #61 on the chapter 4 homework?

NinaSheridan

When we used NH2 in class, several times we referred to it as having on electron pair, but shouldn't NH2 have two pairs of unbound valence electrons?

NinaSheridan

It depends on electronegativity, not formal charge :)

NinaSheridan

So based on this logic, any bond with small ionic character (such as elements of the same group, or the same element bonding with another atom of the same element) would have the highest covalent character, and elements far apart from one another on the periodic table would have low covalent charact...

NinaSheridan

Wait I just answered my own question, but in case other people are also confused by this, maybe it will help. Effective nuclear charge has to do with the pull from the nucleus on electrons in their respective orbitals, so an electron in an s orbital will have a stronger attraction to the nucleus tha...

NinaSheridan

I also have a question on 2.37 but it's for part d. So an electron in an s orbital has a lower energy than an electron in a p orbital, but it has a higher effective nuclear charge. What exactly is effective nuclear charge and does it have an inverse relationship to the energy of the electron?

NinaSheridan

For later quizzes, should we have specific polyatomic ions memorized?

NinaSheridan

Does the roman numeral between copper and oxide mean the oxygen atom is negatively charged or the copper atom?

NinaSheridan

Hey guys! I'm Nina, and I'd love to join too. Maybe we could all just exchange numbers when we have a few more people; we could meet once a week/before tests for anyone who wants to and that way we can text each other for small things/if we can't make it to a scheduled time?

CHEMISTRY COMMUNITY

Search found 30 matches

Re: Saying Thank You to Dr. Lavelle

Re: Question 3.15 plus 3.16 Question

Re: Transition Steps

Re: Naming [ENDORSED]

Re: Quiz prep 2 #11

Re: Midterm Winter 2013 problem 5B

Re: .05916 In Nernst Equation

Re: Nernst Equation [ENDORSED]

Re: General Guidelines for Writing Half Reactions

Re: Quiz 1 prep #9

Homework Problem 8.51

Re: Homework Help 8.9

Re: Homework 8.25

Re: Different enthalpy of vaporizations for water

Re: Sublimiation

Re: Most efficient way to study w/ only 3 days until the midterm

Re: Homework 12.65

Re: Homework Problem #57

Homework Problem #57

Re: Strong Acid or Weak Acid

Re: Homework 17.33

Homework problem 4.61

NH2 Bonds

Re: Dipole Moment

Re: Ionic and Covalent Character

Re: Textbook Question 2.37 part b [ENDORSED]

Re: Textbook Question 2.37 part b [ENDORSED]

Re: QUIZ 1 [ENDORSED]

Copper (I) Oxide [ENDORSED]

Re: Dykstra Hall Study Group (Fall 2016)