Amysterious white powder could be powdered sugar (c12h22o11), cocaine (c17h21no4), codeine (c18h21no3), norfenefrine (c8h11no2), or fructose (c6h12o6). when 82 mg of the powder is dissolved in 1.50 ml of ethanol (d = 0.789 g/cm3, normal freezing point −114.6 ∘c, kf = 1.99 ∘c/m), the freezing point is lowered to −115.5 ∘c. what is the identity of the white powder?

norfenefrine

Explanation:

Depression in freezing point is given by:

= Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte)

= freezing point constant =

m= molality

Weight of solvent (ethanol)=

Molar mass of unknown non electrolyte = M g/mol

Mass of unknown non electrolyte added = 82 mg = 0.082 g (1g=1000mg)

The molecular mass of norfenefrine is near to 154 and thus the identity of the white powder is norfenefrine .

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