The ethylene glycol molecule has the following composition: CH 2 (OH)CH 2 (OH).

Question

The ethylene glycol molecule has the following composition: CH2(OH)CH2(OH). It is a liquid at room temperature with a density of 1.11 g/mL. Ethylene glycol is commonly used as automotive antifreeze, where it's mixed with water in the car's cooling system (the radiator)

a) How many liters of ethylene glycol should you add to your car's radiator containing 8.25 L of water, if the coolest winter temperature in your areais -15 degress Celsius?

b) Calculate the boiling point of this water-ethylene glycol mixture.

Explanation / Answer

a) using depression in freezing point

delta Tf = Kf x molality

= Kf x (mass/molar mass) x (1/mass of solventKg)

15 = 1.86 x(m/62)(1/8.25)

mass of solute = 4125 g

volume of ethylene glycol = mass/ density

= 4125g/1.11g/mL

= 3716.22mL

Part B

to calculate the boiling point we use elevation of boiling point

Delta Tb = Kb x m

= 0.512K.Kg.m-1 x (4125g/62g/mol) /8.25 Kg

= 4.129 K or 4.129C

Thus boiling point of that solution = 104.129 C

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