How much ethly alcohol must be added to 1.0 L of water so that solution will not freeze at `-4^(@)` ? (`K_(f) = 1.86^(@)C//m`)

Explanation

`W_(B) = ?`
`M_(B) = 62 g mol^(-1)`
`W_(A)= 10 kg`
`K_(f) = 1 . 86 L kg mol^(-1)`
`Delta T_(f) = 0 - (-1 0 "" ^(@)C) = 10^(@) C `
= 10 K
`Delta T_(f) = K_(f) xx (W_(B))/( M_(B) ) xx (1)/( W_(A) (kg))`
`W_(B) = (Delta T_(f) xx M_(B) xxW_(A) (kg))/( K_(f))`
`= (10 K xx 62g mol ^(-1) xx 10 kg)/(1 . 86 K kg mol^(-1))`
`= (1000)/( 3) g = (10)/( 3) kg = 3 . 33 kg `