Question

substance A tetramerises in water to the extent of 80%. A solution of 2.5 g of A in 100 g of water lowers the freezing point of 0.3celsius the molar mass of A is

Answer 1

Mass of solution = (2.5 + 100)g = 102.5 g

​Molality of solution = No. of moles of solute / kg of solvent
= (Mass/Molar mass) / kg of solvent =(m/M)Mass of solvent= (2.5/M)100/1000

Depression in freezing point =ΔTf =i Kfm
ΔTf = 0.3 K
0.3 =i Kfm

α =i -1im-1ori =α(1m-1)+1 =0.8(14-1) + 1 =0.4


0.3 =0.4 × 1.86 × mm=0.30.4×1.86 0.30.4×1.86=2.5/M0.1Molar mass(M) = 2.5×0.4×1.860.1×0.3=62 g/mol

Answer 2

Explanation:

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