Calculate the weight of ethylene glycol (an effective antifreeze) that must be added to 25 litre water to protect its freezing at `-24^@C. (K_f= 1.86^@C m^(-1))`

Options

A. 20 kg
B. 322.5 kg
C. 200 kg
D. 32.25 kg

Answer

A

Explanation

`DeltaT_f= K_f xxm, m= 24/(1.86) = 12.9`
It means 1 kg of water requires 12.9 moles of ethylene glycol. 25 litre = 25 kg of water require = `12.9 xx 25` moles of ethylene glycol
Weight of ethylene glycol `(CH_2OHCH_2OH)`
`= 12.9 xx 25 xx 62` (inolar weight = 62)
`~~20000 g = 20 kg`.