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Question
0·70g of an organic compound, when dissolved in 32g of acetone, produces an elevation of 0·25°C in the boiling point. Calculate the molecular mass of the organic compound (Kb for acetone = 1·72 K kg `mol^(-1)`).
Solution
Given
Mass of solute = 0.70 g (`w_2`)
Mass of solvent = 32 g (`w_1`)
`DeltaT_b = 0.25 °C`
`K_b = 1.72 K.Kg mol^(-1)`
To find = `M_2`(molecular mass of organic compound)
Formula => `M_2 = (1000 K_bw_2)/(w_1 Delta T_b)`
`M_2 = (1000 xx 1.72 xx 0.70)/(32xx 0.25)`
`M_2 = 150.5 g`
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