For each of the following pairs of molecules, determine which is most polar:

Question

C2H4 or C2H5OH
C2H6 or CH3OCH3
CCl4 or CF4
H2O or HsS
Question 8 options:

a) C2H4 , C2H6 , CF4, HsS
b) C2H5OH, CH3OCH3, CCl4, HsS
c) C2H5OH, CH3OCH3, CF4, HsS
d) C2H4, C2H6, CF4, H2O
e) C2H5OH, CH3OCH3, CF4, H2O

Answer 1

The most polar molecule in each pair is the one that has a greater electronegativity difference between the atoms. This means that the atom with the higher electronegativity will have a greater pull on the shared electrons, resulting in a more polar bond.

a) C2H4 or C2H5OH
C2H4: This molecule is nonpolar because there is no significant electronegativity difference between carbon and hydrogen.
C2H5OH: This molecule is polar because there is a significant electronegativity difference between carbon and oxygen in the alcohol functional group.

b) C2H6 or CH3OCH3
C2H6: This molecule is nonpolar because there is no significant electronegativity difference between carbon and hydrogen.
CH3OCH3: This molecule is polar because there is a significant electronegativity difference between carbon and oxygen in the ether functional group.

c) CCl4 or CF4
CCl4: This molecule is nonpolar because there is no significant electronegativity difference between carbon and chlorine.
CF4: This molecule is polar because fluorine is more electronegative than carbon, resulting in a polar bond.

d) H2O or H2S
H2O: This molecule is highly polar because there is a significant electronegativity difference between oxygen and hydrogen.
H2S: This molecule is less polar than H2O because there is a smaller electronegativity difference between sulfur and hydrogen.

Comparing the most polar molecules from each pair, we can see that the answer is:

e) C2H5OH, CH3OCH3, CF4, H2O