Strong/Weak Acid/base question

[joonkimdds]

1. which is the strongest acid?
a) CH3C=CH
b) CH3OH
c) CH3CH2F
d) CH3CH2CH3
e) CH3NH2

2. H2O2 + CN- <==> HCN + HO2-
which is the strongest acid?

3. In which solvent would you expect benzoic acid to be least acidic?
a) CH3CH2OH
b) HOH
c) CH3CH2-O-CH2CH3
d) CH3CH2NH2

please help me, and could you explain the reasons too?

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[dudewhensmydat]

1. which is the strongest acid?
a) CH3C=CH
b) CH3OH
c) CH3CH2F
d) CH3CH2CH3
e) CH3NH2

2. H2O2 + CN- <==> HCN + HO2-
which is the strongest acid?

3. In which solvent would you expect benzoic acid to be least acidic?
a) CH3CH2OH
b) HOH
c) CH3CH2-O-CH2CH3
d) CH3CH2NH2

please help me, and could you explain the reasons too?

Alright homie,

1) C b/c F>O>N (in terms of electronegativity) and there's 2 fluorines as well.

2) H202, b/c the it has 2 electronegative atoms (the 2 oxygens) whereas HCN has only one (CN-).

3) I think it's D b/c an ether would not be very miscible with an acid.

*I'm not really sure about Question #3, though.

 

[joonkimdds]

Alright homie,

1) C b/c F>O>N (in terms of electronegativity) and there's 2 fluorines as well.

2) H202, b/c the it has 2 electronegative atoms (the 2 oxygens) whereas HCN has only one (CN-).

3) I think it's D b/c an ether would not be very miscible with an acid.

*I'm not really sure about Question #3, though.

I am so sorry, but they are all wrong

 

[dudewhensmydat]

I am so sorry, but they are all wrong

Wow, that sucks. Minus 3 points for me. What are the answers?

 

[joonkimdds]

Wow, that sucks. Minus 3 points for me. What are the answers?

I have the answers but can I just wait for other people to answer and explain? because if ppl know the answer their explanations become less convincing sorry~

 

[erichen]

1. which is the strongest acid?
a) CH3C=CH
b) CH3OH
c) CH3CH2F
d) CH3CH2CH3
e) CH3NH2

2. H2O2 + CN- <==> HCN + HO2-
which is the strongest acid?

3. In which solvent would you expect benzoic acid to be least acidic?
a) CH3CH2OH
b) HOH
c) CH3CH2-O-CH2CH3
d) CH3CH2NH2

please help me, and could you explain the reasons too?

i think number 1 is B, A and C's molecular form is larger than B, so probably does not dissociate as quickly, D is a complete hydrocarbon, and E has an ammine group (amino acids aren't strong bases)

number 2 should be HCN, because CN- and H- would dissociate quickly and grab other conjugate acids/bases whereas H202 would not.

im not sure if number three is asking if benzoic acid would be less acidic relative to the solutions below or would the solution titrate the benzoic acid making it less acidic ?

 

[joonkimdds]

i think number 1 is B, A and C's molecular form is larger than B, so probably does not dissociate as quickly, D is a complete hydrocarbon, and E has an ammine group (amino acids aren't strong bases)

number 2 should be HCN, because CN- and H- would dissociate quickly and grab other conjugate acids/bases whereas H202 would not.

im not sure if number three is asking if benzoic acid would be less acidic relative to the solutions below or would the solution titrate the benzoic acid making it less acidic ?

you first two answers are correct.
since u are confused with third question, let me just tell u that answer is C even though I still don't know why.

By the way, I m taking organic chemistry now and I still don't know anything about it and I guess I am still confused with ur explanation(i m really sorry)

for Number2, you said CN- and H- would dissociate quickly and grab each other whereas H2O2 would not. How do you know that CN- and H- would dissociate quickly and H2O2 would not?? and where do you see H-?

according to your explanation to number1, the smaller one dissociates quicker and thus it's strongest acid so I guess finding out the size of the ions and rate of dissociation are the method you use to find strongest acid? am I right?

 

[bruinpredent]

isn't #3 C because for benzoic acid to be acidic, it needs to donate a proton (bronsted-lowry acid), and it can't donate a proton to the non-reactive ether?

 

[joonkimdds]

isn't #3 C because for benzoic acid to be acidic, it needs to donate a proton (bronsted-lowry acid), and it can't donate a proton to the non-reactive ether?

yep it's C.
my teacher wrote the explanation with crappy hand writing but what I can read is

"polar protic solvents, polar aprotic solvents decreases acidity"

anyway could you also explain number 1 and 2 if you can explain in a different way that the other guy did? becuz i m really bad at organic chemistry and I hope you can explain it to me as if u r teaching a elementary school kid

 

[joonkimdds]

Oh by the way, since all of the choice in 1 has CH3, can I just get rid of them?
a) CH3C=CH
b) CH3OH
c) CH3CH2F
d) CH3CH2CH3
e) CH3NH2


so it makes them
a) C=CH
b) OH
c) CH2F
d) CH2CH3
e) NH2

without CH3.

and the next step is....what....comparing the size? is that right?

 

[erichen]

sorry for the confusing answers. i haven't even taken G chem, i just kinda know it from AP. so ur way ahead of me.

by the way Bruinpredent, are u still at UCLA? cuz im a first year at UCLA .