# 0.75 g of an unknown substance is dissolved in 200 g solvent. If the elevation of boiling point is 0.15 K and molal elevation constant is 7.5K

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0.75 g of an unknown substance is dissolved in 200 g solvent. If the elevation of boiling point is 0.15 K and molal elevation constant is 7.5K kg more then, calculate the molar mass of unknown substance.

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∆Tb = Kb m = Kb x W2 x $\frac{1000}{M_2}$ x W1

M2 = Kb x W2 x $\frac{1000}{\Delta T_b}$ x W1

= 7.5 x 0.75 x $\frac{1000}{0.15}$ x 200 = 187.5 g mol-1