Question

4. Ethylene glycol (C2H6O2) is used as an antifreeze in cars. If 400 g of ethylene glycol is added to 4.00 kg of water, what is the molality? Calculate how much the freezing point of water will be lowered. The freezing-point depression constant for water is Kf = –1.86°C/m. Show your work.

Answer 1

The molality of a solution is expressed as the amount of the solute in moles per mass of the solvent in kilograms. In this case, the molality is equal to 400 g/62.07 g/mol/ 4 kg water. The molality is equal to 1.61 molal. The freezing point depression is determined through Tf- Kb*molality. Substituting, 0 deg - 1.86 * 1.61 m is equal to -2.99 degrees celsius.