3 Question (1 point) The liquid used in automobile cooling systems is prepared b
ID: 1083880 • Letter: 3
Question
3 Question (1 point) The liquid used in automobile cooling systems is prepared by dissolving ethylene glycol (HOCH2CH2OH) in water. Ethylene glycol has a molar mass of 62.07 g/mol and a density of 1.115 g/mL at 50.0°C. See page 553 v 3rd attempt see Periodic Table See Hint Calculate the vapor pressure at 50 C of a coolant solution that is 58.0-42.0 ethylene glycol-to-water by volume. At 50.0°c, the density of water is 0.9880 g/mL, and its vapor pressure is 92 torr. The vapor pressure of ethylene glycol is less than 1 torr at 50.0°c. 65.974 torrExplanation / Answer
let us consider 100 ml coolant
volume of water = 42 ml
mass of water = 42*0.988 = 41.5 g
no of mol of water = 41.5/18 = 2.3 mol
volume of ethylene glycol = 58 ml
mass of ethylene glycol = 58*1.115 = 64.67 g
no of mol of ethylene glycol = 64.67/62.07 = 1.042 mol
molefraction of ethylene glycol(x1) = 1.042/(1.042+2.3) = 0.312
molefraction of water(x2) = 1-0.312 = 0.688
vapor pressure of coolant = pwater + pethylene glycol
pethylene glycol <<<<<< pwater
so that,
vapor pressure of coolant = pwater
pwater = x2*p0
= 0.688*92
= 63.3 torr
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