Which pairs of molecules can form a hydrogen bond with one another? (Select all that apply.)

Question

A.)CH3CH2SH and CH3CH2SH

B.)CH3OCH3 and CH3OCH3

C.)CH3OH and CH3OH

D.)CH2=CHCH3 and CH2=CHCH3

Answer 1

Hydrogen bonding is a type of intermolecular interaction. Hydrogen bonding occurs in polar molecules containg hydrogen atoms bonded directly to small electronegative atoms (flourine (F), nitrogen (N) and oxygen (O).

 

Now that you know the criteria for hydrogen bonding you can eliminate choices A and D because these molecules has H but does not contain F, N or O. We are left with choices B and C, which contains both H and O. However, we must draw the structural formula of the molecules to see if the O is directly bonded to the H:

 

   

H₃C-O-CH₃    *Notice that in this structure (dimethyl ether) H is not bonded directly to O, hence will not hydrogen bond. This eliminates B.

 

H₃-C-O-H     *Notice that methanol has 4 hydrogens, but only one can participate in hydrogen bonding, the one that is directely bonded to oxygen. the answer choice is C

 

 

 

 

 

 

 

 

Answer 2

C is the answer.. 

 

Hydrogen bond can only be formed with the FON atoms (Fluorine, Oxygen and Nitrogen). answer A does not have these atoms. B is a ketone molecule, there are not hydrogen to form this bonds.. D has same reason why A is not the answers. Hope this helps.