Ammonium hydrogen sulphide dissociates as follows : NH_(4) HS(s) hArr H_(2) S(g) = NH_(3)(g) If solid NH_(4) HS is placed in an evacuated flask at a certain temperature, it will dissociate until the total gas pressure is 500 torr. Calculate the following : ( a) Equilibrium constant for the dissociation reaction ( b) If the additional NH_(3) is introduced into the equilibrium mixture without change intemperature until the partial pressure of ammonia is 700 torr. (i) What is the partial pressure of H_(2)S under the conditions. (ii) What is the total pressure in the flask ?

Ammonium hydrogen sulphide dissociates as follows : NH_(4) HS(s) hArr

1.	Ammonium hydrogen sulphide dissociates as follows : NH_(4) HS(s) hArr H_(2) S(g) = NH_(3)(g) If solid NH_(4) HS is placed in an evacuated flask at a certain temperature, it will dissociate until the total gas pressure is 500 torr. Calculate the following : ( a) Equilibrium constant for the dissociation reaction ( b) If the additional NH_(3) is introduced into the equilibrium mixture without change intemperature until the partial pressure of ammonia is 700 torr. (i) What is the partial pressure of H_(2)S under the conditions. (ii) What is the total pressure in the flask ?
Answer» <P> Solution :SINCE, `P_(H_(2)S)= P_(NH_(3)) = ( 250)/( 760) = 0.329 `atm ( a) `K_(p ) =P_(H_(2)S) P_(NH_(3)) = 0 .108"atm"^(2)` ( b) `K_(p ) = P_(H_(2)S ) P_(NH_(3))` `P_(H_(2)S) = ( 0.108)/( 700 // 760 ) = 0.117` atm (ii)Total pressure `= P_(H_(2) S) + P_(NH_(3)) = 789 ` torr