How much ethyl alcohol must be added to 1 litre of water so that the solution will freeze at– 14°C ? (Kf for water = 1.86°C/mol)
(a) 7.5 mol
(b)8.5 mol
(c)9.5 mol
(d)10.5 mol
(a) 7.5 mol
Explanation:
`"T"_{f}` = `"K"_{f}`m
`"T"_{f}` = `"K"_{f}` `\frac{"n"_{2}\times1000}{"W"_{1}}`
14 = 1.86 `\times` `\frac{"n"_{2}\times1000}{1000}`
`"n"_{2}` = 7.5 mol
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