Question

A 4.60 L vessel contains 24.5 g of PCl3 and 3.00 g of O2 at 15.0 ⁰C. The vessel is heated to 195 ⁰C, and the contents react to give POCl3.What is the final pressure in the vessel,assuming that the reaction goes to completion and that all reactants and products are in the gas phase?

Answer 1

The final pressure in the vessel is 2.270atm

Step-by-step explanation:

Mass of PCl3 = 24.5g, MW of PCl3 = 137.5g/mole, number of moles of PCl3 = 24.5/137.5 = 0.178mole

Mass of O2 = 3g, MW of O2 = 32g/mole, number of moles of O2 = 3/32 = 0.094moles

Total moles of rectant (n) = 0.178mole + 0.094mole = 0.272mole

From ideal gas equation

PV = nRT

P (pressure of reactants) = nRT/V

n = 0.272mole, R = 82.057cm^3.atm/gmol.K, T = 15°C = 15+273K = 288K, V = 4.6L = 4.6×1000cm^3 = 4600cm^3

P = 0.272×82.057×288/4600 = 1.397atm

From pressure law

P1/T1 = P2/T2

P2 (final pressure in the vessel) = P1T2/T1

P1 = 1.397atm, T1 = 288K, T2 = 195°C = 195+273K = 468K

P2 = 1.397×468/288 = 2.270atm