A Chemist Is Given a White Solid That Is Suspected $\Delta$

question 98

Essay

A chemist is given a white solid that is suspected of being pure cocaine (molar mass = 303.35 g/mol).When 1.22 g of the solid is dissolved in 15.60 g of benzene,the freezing point is lowered by 1.32°C.The molar mass is calculated from these data to be 303 g.Assuming the following uncertainties,can the chemist be sure the substance is not codeine (molar mass 299.36)? K_f for benzene is 5.12°C/m.
Uncertainties
Mass of solid = ±0.01 g
Mass of benzene = ±0.01 g
$\Delta$ T (freezing point lowering)= ±0.04°C
K_f = ±0.01
Support your answer with calculations.

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