Why does the mass of a polysaccharide increase when linking monosaccharides?

[Shakattack12]

Hey guys. When a polysaccharide (e.g. starch) is made I understand that monosaccharides are linked together and a water molecule is removed. In the final product the polysaccharide has a mass of n times its empirical formula plus a water molecule. Like the mass of 300 starches from 300 glucose molecules is 300(C₆H₁₀O₅) + H₂O. Why is this?

 

[DoItForYourself]

I think you mean why a starch molecule from 300 glucose molecules is 300(C₆H₁₀O₅) + H₂O.

Because the water from each molecule has already been subtracted [the molecule of monomer was initially (C₆H₁₂O₆)]. You must add one water molecule because the polymer has an -OH in the one end and -H in the other end.

 

[Borek]

It is all in the structure - just count the atoms:

 

[Shakattack12]

Thanks guys you were extremely helpful!