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Rotation of PPL by opticaly active compounds (mathematical feeling) 
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#1
May614, 12:40 AM

P: 69

i read formulae in textbook :
[α]^{λ}_{t°C} = Θ/L*C ........(i) where Θ is rotation in light and L is length of tube and C is concentration in gm/litre if we consider tube of lenth L and cross section area 'A' then C= M/A*L M is mass of sample so (i) becomes [α]^{λ}_{t°C} = Θ/[M/A] so are scientist so blind to observe or i am doing something wrong. 


#2
May614, 01:01 AM

Sci Advisor
Thanks
PF Gold
P: 1,908

This appears to be a variation on Verdet's equation for measuring the concentration of an optically active substance, allowing for temperature variations.
You have neatly removed the variable for concentration. 


#3
May614, 01:17 AM

Sci Advisor
P: 3,593

To blind to observe what?
Your formula is correct, however, I doubt that it is more practical. The point is that you would have to fill the sample of the given mass in a tube which has precisely the cross section you sprecified. Have you tried to fill a tube with precisely the amount of substance you want and to put glass windows on it without neither liquid spilling out or gas bubbles remaining inside? 


#4
May714, 12:47 AM

P: 69

Rotation of PPL by opticaly active compounds (mathematical feeling)
the older equation has a feeling that if length of tube is increased one of factor will have to change and my equation marks that rotation(θ) and [α] are both independent of length of tube. I am just a bit confused for example help out with this Q) if length of tube is doubled what will be the effect on Θ? 


#5
May714, 01:32 AM

Sci Advisor
P: 3,593

Depends on what you hold constant. If M is constant, nothing, if c is constant, theta will double.



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