(ii) What is the approximate chlorine-carbon-chlorine bond angle in C2Cl4?

∠

O

−

C

−

C

l

≅

120

∘

The central carbon is  

s

p

2

−

hybridized

Explanation:

And thus  

∠

C

l

−

C

−

C

l

and  

∠

O

−

C

−

C

l

≅

are  

120

∘

to a first approximation.

Why this value? We look to  

VSEPR theory

. There are 3 regions of electron density around the central carbon, and the most stable geometry is a trigonal plane. While there is a  

carbonyl

group, i.e. a  

C

=

O

bond, the  

π

bond is conceived to lie above and below this trigonal plane.

The  

carbonyl oxygen

is likewise conceived to be  

s

p

2

-hybridized

, however, here, there are 2 lone pairs on the oxygen centre.

3

explanation: