Solutions Question 354

Question: A solution containing 1.8 g of a compound (empirical formula CH2O ) in 40 g of water is observed to freeze at 0.465C . The molecular formula of the compound is ( Kf of water =1.86kgKmol1 )

Options:

A) C2H4O2

B) C3H6O3

C) C4H8O4

D) C6H12O6

Show Answer

Answer:

Correct Answer: D

Solution:

ΔTf=Kf×m

M=1000×Kf×w2(solute)ΔTf×w1(solvent)

=1000×1.86×1.80.465×40M=180 Molecular formula = (empiricalformulae)n

n=MolecularmassEmpiricalformulamass=180g30=6 Molecular formula =(CH2O)6=C6H12O6



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