Ethanol is produced for use as a fuel from corn and agricultural waste. Ethanol plant engineers need to know at what temperature ethanol boils at different pressures. The vapor pressure of ethanol at 34.9 °C is 13.3 kPa. Use the data in Table 4C.1 to estimate the boiling temperature of ethanol at 2.00 atm.

ANTICIPATE In Table 4C.1, you can see that the normal boiling point of ethanol is 351.5 K (78.4 °C). At the higher pressure ethanol molecules must reach a higher temperature to break free and boil, so you should expect a boiling temperature greater than 351.5 K.

PLAN Use the Clausius–Clapeyron equation to find the temperature at which the vapor pressure has risen to 2.00 atm (203 kPa).

What should you assume? Assume that DH_vap° and DS_vap° are constant over the temperature range of interest, that the boiling point at 1 bar is approximately the same as at 1 atm, and that the vapor behaves as an ideal gas (so that the Clausius– Clapeyron equation can be used).