Question

Ashmita pours 425 mL of Methanol into an insulated cup. (The density of Methanol is 0.792 g/mL, and the specific heat of liquid Methanol is 2.597 J/g/deg C.) She measures the initial temperature to be 18.0 deg C. She puts the cup of Methanol into her freezer for 1.50 hours. When she pulls it out of the freezer, she measures the temperature to be -5.0 deg C. Calculate the amount of heat energy Q removed from the liquid Methanol.

Answer 1

Answer:

Mol. mass of ethyl alcohol =C2H5OH=46

No. of moles of ethyl alcohol =4660=1.304

Mol. mass of methyl alcohol =CH3OH=32

No. of moles of methyl alcohol =3240=1.25

′XA′, mole fraction of ethyl alcohol =1.304+1.251.304=0.5107

′XB′, mole fraction of methyl alcohol =1.304+1.251.25=0.4893

Partial pressure ethyl alcohol =XAp˙A0=0.5107×44.5=22.73mmHg

Partial pressure methyl alcohol =XBp˙B0=0.4893×88.7=73.40mmHg

Total vapour pressure of solution =22.73+43.40=66.13mmHg

Mole fraction of methyl alcohol in the vapour

=Total vapour pressurePartial pressure of CH3OH

Explanation:

I HOPE THIS HELPS YOU