Question

Ethylene glycol, C2H6O2, is infinitely miscible (soluble) in water. It is a nonelectrolyte that is used as antifreeze. What is the lowest possible melting point for engine coolant that is 26.1% ethylene glycol

Answer 1

Answer: The lowest possible melting point for engine coolant that is 26.1% ethylene glycol is
`-7.83^0C`

Step-by-step explanation:

Depression in freezing point or melting point is given by:

`\Delta T_f=i* K_f* m`

`\Delta T_f=T_f^0-T_f=(0-T_f)^0C` = Depression in freezing point

i= vant hoff factor = ( 1 for non electrolyte)

`K_f` = freezing point constant for water=
`1.86^0C/m`

m= molality

`\Delta T_f=i* K_f* \frac{\text{mass of solute}}{\text{molar mass of solute}* \text{weight of solvent in kg}}`

Given : 26.1 g of ethylene glycol in 100 g of water

Weight of solvent (water)= 100 g = 0.1 kg (1kg=1000g)

Molar mass of solute (ethylene glycol) = 62 g/mol

Mass of solute (ethylene glycol) added = 26.1 g

`(0-T_f)^0C=1* 1.86* (26.1g)/(62g/mol* 0.1kg)`

`(0-T_f)^0C=7.83`

`T_f=-7.83^0C`

Thus the lowest possible melting point for engine coolant that is 26.1% ethylene glycol is
`-7.83^0C`