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) | Bzziii

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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