Question

A 50/50 blend of engine coolant and water (by volume) is usually used in an automobile\'s engine cooling system. If your car\'s cooling system holds 6.20 gallons, what is the boiling point of the solution? Make the following assumptions in your calculation; at normal filling conditions, the densities of engine coolant and water are 1.11 g/mL and 0.998 g/mL respectively. Assume that the engine coolant is pure ethylene glycol (HOCH2CH2OH), which is non-ionizing and non-volatile, and that the pressure remains constant at 1.00 atm. Also, you\'ll need to look up the boiling-point elevation constant for water. ? _______ deg C

Answer 1

Answer:

109.173 °C

Explanation:

For the given system, there is 50/50 (per volume) blend of engine coolant and water. Therefore,

We need to convert the volume to moles of solute/kg of solvent.

Assuming 1 liter of solution:

500 ml * 1.11 g/ml = 555 g ethylene glycol

500 ml * 0.998 g/ml = 499 g water

The number of moles of the solute (ethylene glycol) = mass/molar mass = 555/62.08 = 8.94 moles

There is 8.94 moles of ethylene glycol in 499 g of water. Thus, in 1000 g of water, there is 8.94*1000/499 = 17.92 moles/kg of water = 17.92 molal.

Therefore, the boiling point of the solution = 100°C + 0.512 °C/molal*17.92 molal = 100 + 9.173 = 109.173 °C