Asked by tim

The total pressure in a flask containing air and ethanol at 257C is 878 mm Hg. The pressure of the air in the flask at 257C is 762 mm Hg. If the flask is immersed in a water bath at 400C, the total pressure is 980 mm Hg. The vapor pressure of ethanol at the new temperature is ? mm Hg.
drwls
At 257 C (which is 530 K), 878-762 or 116 mm Hg is the partial pressure of ethanol, and 762 mm Hg is the partial pressure of air.

At 400 C (673 K), the air's partial pressure increases to (673/530)*762 = 967.6 mm Hg. That would leave only 12.4 mm Hg for the partial pressure of ethanol if the total pressure is 980 mm Hg.

These numbers don't make sense. The partial pressure of ethanol should go up, not down, with temperature and I don't see how one could have a water bath at 400 C. Are sure you copied the numbers correctly?
Kevin
The total pressure in a flask containing air and ethanol at 257C is 878 mm Hg. The pressure of the air in the flask at 257C is 762 mm Hg. If the flask is immersed in a water bath at 400C, the total pressure is 980 mm Hg. The vapor pressure of ethanol at the new temperature is mm Hg.
Hint: you will need to correct the pressure of air at the new temperature using the Gas Law: P1T1 = P2T2

Anonymous
he meant 25.70 and 40.00 degrees celsius