NEET Questions Solved


The boiling point of acetic acid is 118.1°C and its latent heat of vaporisation is 121 cal/gm. A solution containing 0.4344 gm anthracene in 44.16 gm acetic acid boils at 118.24°C. What is the molecular wt. of anthracene ?

(a) 122

(b) 178

(c) 105

(d) 154

 

(b) Now Tb=118.24-118.1=0.14°

If a gm solute be dissolved in b gm solvent, then 

M2=Kb×a×1000b×TbM2=RTb2l×1000×a×1000b×Tbor M2=2×10-3×391.102121×0.4344×100044.16×0.14or M2=178

Hence, mol. wt. of anthracene = 178.

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