Question

The vapor pressure of a liquid is the pressure exerted by its vapor when the liquid and vapor states are in equilibrium. The relationship between vapor pressure P and temperature T is expressed by the Clausius-Clapeyron equation. lnP2P1=ΔHvapR(1T1−1T2) where P1 and P2 are the vapor pressures at the absolute temperatures T1 and T2, respectively, ΔHvap is the heat of vaporization of the substance in joules per mole, and R is the ideal gas constant, which is equal to 8.3145 J/(mol⋅K). The heat of vaporization of water is 4.07×104 J/mol. The boiling point of a liquid increases as the pressure above the liquid increases. In contrast to boiling food in an open pot, pressure cookers trap the steam, which raises the internal pressure, which raises the boiling point of water, causing a higher cooking temperature. A higher cooking temperature means that the food will cook faster.

The instruction booklet for your pressure cooker indicates that its highest setting is 12.8 psi . You know that standard atmospheric pressure is 14.7 psi, so the booklet must mean 12.8 psi above atmospheric pressure. At what temperature in degrees Celsius will your food cook in this pressure cooker set on "high"? Express your answer numerically in degrees Celsius.

Answer 1

Temperature = 119 ^oC

(exact value is 118.71 ^oC)