how many grams of ethylene glycol (c2h6o2) must be dissolved in 200 grams of water to lower the freezing point to -29.75 Celsius? if the density of ethylene glycol is 1.12g/m1, how many milliliters of ethylene glycol are required?

Respuesta :

Answer:

mass of ethylene glycol = 198. 562 g

Volume of ethylene glycol = 177.2875 ml

Explanation:

The freezing point depression of the solvent can be expressed by the formula:

[tex]\delta T = K_fmi[/tex]

where

[tex]K_f[/tex] = molar freezing point depression constant of water = 1.86 °C/m

[tex]\delta T[/tex] = freezing point depression = 0°C -(-29.75°C)

    = 29.75°C

m = molarity of ethylene glycol

i = the value of Van't Hoff Factor = 1

replacing our value into above expression; we have:

[tex]29.75^0C= (1.86)*m*(1)[/tex]

[tex]m = \frac{29.75^0C} {(1.86)}[/tex]

m = 15.995 M

Also. Molarity = [tex]\frac{Mass(g) of solute}{Molar mass (g/mol) of solute}*\frac{1000}{mass of solvent(g)}[/tex]

[tex]15.995m = \frac{mass (g) of solute}{62.07g/mol C_2H_6O_2}*\frac{1000}{200}[/tex]

mass of ethylene glycol = 198. 562 g

Density = [tex]\frac{mass}{volume}[/tex]

Given that;

the density of ethylene glycol is 1.12g/ml

and our derived mass of ethylene glycol = 198. 562 g; we can determine how many milliliters of ethylene glycol  are required by calculating the volume

Volume of ethylene glycol = [tex]\frac{mass}{density}[/tex]

Volume of ethylene glycol = [tex]\frac{198.562}{1.12}[/tex]

Volume of ethylene glycol = 177.2875 ml