Question

Chemists sometimes carry out reactions in liquid ammonia as a solvent. With adequate safety protection, these reactions can be done at temperatures above ammonia's boiling point in a sealed, thick-walled glass tube. If the reaction is being carried out at 22 °C, what is the pressure of ammonia inside the tube? Vapor pressures of NH () at several temperatures are given in the table below. Vapor Pressure (atm) Temperature (C) 0.132 68.4 0.526 45.4 1.000 -33.6 2,00 -18.7 4.7 5.00 10.00 25.7 20.00 50.1 Pressure atm

Answer 1

Given that,

temperature = 22⁰C

According to Clausius Equation,

ln(P2 / P1) = ∆H / R(1 / T1 - 1 / T2)

ln(20 / 10) = ∆H / 8.314(1 / 298.5 - 1 / 323.1)

0.6931 = ∆H / 8.314 ( 0.00026)

5.762 = ∆H ( 0.00026)

∆H = 22.16 kJ/mol

So now for 22°c

ln(10/P1) = 22.16×1000 / 8.314(1/295 - 1 / 298.5)

ln(10/P1) = 2665.38( 0.003389 - 0.0033500 )

ln(10/P1) = 2665.38 ( 0.000039 )

ln(10/P1) = 0.1039

10 / P1 = 1.1094

P1 = 9.01 atm

Therefore, the pressure of ammonia inside the tube is 9.01 atm