Why is Specific Rotation Not a Colligative Property? Answers Here

[pseudogirl]

Why is specific rotation not a colligative property?
i just read that it depends on concentration(gm/litre)
but i feel that it should depend on molarity considering the fact that rotation is due to changes in molecular structure...do i have a point or am i just being silly ...can someone help me?

 

[Borek]

Looks to me like you are confusing rotation with specific rotation.

 

[pseudogirl]

i am sorry .i did confuse them both
so does rotation depend on number of moles per liter?this is the formula in the book

specific rotation=rotation/l*cl=length of polarimeter tube
c=concentration of optically active solution in (gm/l)why is molarity not there in the formula?

 

[Borek]

so does rotation depend on number of moles per liter?

Yes.

c=concentration of optically active solution in (gm/l)

why is molarity not there in the formula?

Does it have to be there? Concentration in the definition is expressed in g/L, g/L and molarity are easily interconvertible.