Respuesta :
Answer: The lowest possible melting point for engine coolant that is 26.1% ethylene glycol is [tex]-7.83^0C[/tex]
Explanation:
Depression in freezing point or melting point is given by:
[tex]\Delta T_f=i\times K_f\times m[/tex]
[tex]\Delta T_f=T_f^0-T_f=(0-T_f)^0C[/tex] = Depression in freezing point
i= vant hoff factor = ( 1 for non electrolyte)
[tex]K_f[/tex] = freezing point constant for water= [tex]1.86^0C/m[/tex]
m= molality
[tex]\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}[/tex]
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
[tex](0-T_f)^0C=1\times 1.86\times \frac{26.1g}{62g/mol\times 0.1kg}[/tex]
[tex](0-T_f)^0C=7.83[/tex]
[tex]T_f=-7.83^0C[/tex]
Thus the lowest possible melting point for engine coolant that is 26.1% ethylene glycol is [tex]-7.83^0C[/tex]
