Hey everyone :) I'm getting ready for my first Organic test this Monday (Wish me luck!), and I am having trouble with a couple questions.
1) Provide the conjugate acid of the following base: CH3CH2OH
I chose a) CH3-CH2-OH2+...Now my thinking was, if CH3CH2OH is a base, it has to donate a lone pair of electrons...meaning O needs to bond to another H+....
The key says that c) CH3-CH2-O- is the correct answer...but this indicates that the molecule acted as an ACID and gained an e- pair from the H atom...I think he may have marked the wrong one...
2) Which of the following is most likely to behave as a lewis acid?
a)NH3 b)AlCl3 c)PBr3 d)CF3-
Now I eliminated A and D because they have no vacant orbitals to accept and e- pair. Being left with B and C, I chose B because it had the lower e- negativity (Opps now that I've typed this out I see my error...should have chosen the one with higher e- negativity, right?) Meaning C is the correct answer.
3) Which is more stable?
a) CH3O- b) HC(=O)-O-
Now the only distinct features are:
1) B has a double bonded O to the central atom.
I don't really even have a hunch to this question...my though was that since B has 2 O atoms...they'd both carry a negative charge and repel eachother making the molecule unstable... but that is obviously incorrect as the correct answer is B..Any insight here would be much appreciated---I'm obviously missing a concept.
4) Alkanes are ________ dense than/as water
a) more b) less c) as
Okay...d=m/v, but where does this play in? The most simple alkane, methane...CH4 has a mass of about 16g/mole, where as H2O has a mass of about 18g/mole. Now assuming they both occupy the same volume...water is more dense....But what about anything larger than methane....then the alkane is more dense...so how am I supposed to determine this?
5) Energy is released when bonds are broken.
a) true b) false.
I'm really frustrated with this question. Teachers need to stop asking this, the answer tends to change from person to person.
Now is it not true that: Energy needs to be put into a bond to break a bond...BUT after it is broken, some energy is released?
Now, I'm not saying that the system will have an overall energy gain, as more energy may be needed to break the bond than what is released....(would this be endergonic?)
Anyways...He says that enery is NOT relesed when bonds are broken..and would like to defy all cases of where ATP--> Energy+ADP in our bodies...
Thanks for everyone's help!!