139.
Calculate the mass of a non-volatile solute (molecular mass 40 g mol–1) which should be dissolved in 114 g octane to reduce its vapour pressure to 80%.
Answer:
molar mass of solute, M
2 =40g mol
-1
mass of octane, w
1= 114g
molar mass of solute, M
1 = 114 g mol
-1Let the vapour pressure of pure octane be
then, the vapour pressure of the octane after dissolving the non volatile solute is
applying the relation,
or
or
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