The Total solution for NCERT class 6-12
Calculate the mass of ascorbicacid (Vitamin C, C6H8O6) to be dissolved in75 g of acetic acid to lower its melting point by 1.5┬░C.┬аKf┬а=3.9 K kg molтИТ1.
of acetic acid,┬аw1┬а=75 g
Molar mass of ascorbic acid (C6H8O6),┬аM2┬а=6 ├Ч 12 + 8 ├Ч 1 + 6 ├Ч 16
= 176 g molтИТ1
Lowering of melting point, ╬ФTf┬а=1.5 K
We know that:┬а
= 5.08 g (approx)
Hence, 5.08 g of ascorbic acid isneeded to be dissolved.