Question

which bond in ethanol is most polar?
a) C-O
b)O-H
c) C-H​

Answer 1

•Polarity is decided on the basis of electronegativity.

•The atoms that have most electronegativity difference are considered to be most polar.

Here we have to consider 3 bonds:C-O, O-H, C-H

•The electronegativities of carbon ,hydrogen and oxygen are as given below

Carbon-2.5

Hydrogen-2.2

Oxygen-3.4

•The difference in electronegativities of will be

C-O: 3.4 - 2.5 = 0.9

O-H: 3.4-2.2 = 1.2

C-H: 2.5-2.2= 0.3

O-H bond has the most •electronegativity difference hence will be the most polar.

Answer 2

As we know that the Polarity is decided on the basis of electronegativity.

So, The atoms that have the most electronegativity difference are considered to be the most polar.

Here we have to consider 3 bonds: C-O, O-H, C-H

The electronegativities of carbon, hydrogen, and oxygen are as given below:  

• Carbon - 2.5  
• Hydrogen-2.2  
• Oxygen-3.4  

The difference in electronegativities will be,  

• C-O: 3.4 - 2.5 = 0.9  
• O-H: 3.4-2.2 = 1.2  
• C-H: 2.5-2.2= 0.3  
• O-H bond has the most electronegativity difference hence will be the most polar.

Fluorine has the highest electronegativity while iodine has the least electronegativity among group 17 elements.

Thus the electronegativity difference between fluorine and iodine is highest due to which they form the most polar bond.

Hence, The most polar bond in C2H5OH is the OH bond.