A plant virus is found to consist of uniform cylindrical particles of 150 angstrom in diameter and 5000 angstrom long. The specific volume of the virus is 0.75cm3/g.If the virus is considered to be a single particle, find its molar mass.
Ans given: 70.96 x 106g/mol.
How do u go about with this question?
1radius of particle = d/2 = 7.5 * 10 -7 cm
length of the particle = 5 * 10 -5 cm
so volume = Î rl = 8.83 * 10 -17 cm3
mass of particle = vol./sp. vol. = 1.18 * 10 -16g
hence molar mass = M = NA * mass of particle ≈ 7.096 * 10 7 gmol-1
1VOLUME OF THE PARTICLE=Ï€R2H
WHERE 'r' = 1502 A
h= 5000
MASS = Volume*Specific density*
...
* VOLUME = (88312500 * 10-30 m3 )
*Specific density = 0.75 * 10-6 m3 per gram
.. this will give mass of one particle
MOLAR MASS= 6.02 * 1023 * mass of one particle
= 70.96 * 106 gram per mole