Question

The instruction booklet for your pressure cooker indicates that its highest setting is 13.5 psi . You know that standard atmospheric pressure is 14.7 psi, so the booklet must mean 13.5 psi above atmospheric pressure. At what temperature in degrees Celsius will your food cook in this pressure cooker set on "high"?

Also how do I work the equation out with the ln?

Answer 1

the heat of vapourization is 40.65 kj/mol.we can leave the pressure in psisince p2/p1 is a ratio

p2 = the highest pressure setting = 14.7 psi + 13.5 psi = 28.2 psi the normal BP of H2O = 14.7 psi ( 1 atm) and 373 k

using clausius - clapeyron equation

ln( p2 / p1) = ( delta H / R) ( 1 / T1 - 1 / T2)

ln( 28.2 psi / 14.7 psi ) = ( 40,650 j/mol) / ( 8.314 j/mol k) ( 1/373 - 1/ T2)

0.65 = ( 4890) ( 1/373 - 1/T2)

0.65 = 13.1 - 4890 / T2

-12.45 = -4890 / T2

T2 = -4890 / -12.45

T2 = 392 k = 119 C