How to calculate relitive molecular polarity of a large molecule with electro negitivity?

By doing the vector sum of the polar bonds.

Explanation:

The relative polarity of a molecule is the vector sum of the polarities of the bonds in the molecule. Thus, in large molecules, first, we need to identify which of the bonds are polar (with elements with a huge difference of electronegativity), and them calculate the polarity in each polar bond which will be the difference in the electronegativities.

Then, we identify the vector, which will be directed to the most electronegative element. Thus, the vectors must be summed following the rules of the vector sum.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.