Question

One mole of $NH_4Cl$ (s) is kept in an open container & then covered with a lid. The container is now heated to 600 K where all $NH_4Cl$ (s) dissociates into $NH_3$ & $HCl$ (g). The Volume of the container 24.6 litres Assume that outside air is at 300 K and 1 atm pressure.

Answer 1

(i) 6.007 atm (ii) The lid would stay.

Answer 2

The container traps approximately 1 mole of air when covered. Upon heating to 600 K, 1 mole of $NH_4Cl$ dissociates, producing 2 moles of gas ($NH_3$ and $HCl$). The total moles of gas inside becomes 3 moles. Using the ideal gas law, the final pressure is calculated to be approximately 6.007 atm. The pressure difference between the inside and outside (1 atm) is about 5.007 atm, which is less than the 5.5 atm the lid can withstand. Therefore, the lid stays.