Most Important Selected Qs for JEE AdvancedChemistryStates of Matter
Gas A ( mol . Mass =16) and gas B ( mol . Mass =4) are confined in to a vessel at partial pressure of 2 atm each at 27^ C . The gases are then allowed to effuse out at 27^ C through a valve till the pressure inside the vessel becomes 2 atm after which the valve is closed and the gases are heated to 127^ C and allowed to react as A + B C for which k _ p =0.1 ~atm ⁻¹ . By assuming that C is not formed till the effusion
Options
- AThe no. of moles of A and B diffused out are in the ratio 1:2.
- BThe no. of moles of A and B left after diffusion at 27^ C are in the ratio 2: 1
- CPartial pressure of B at 127^ C is 8 9 ~atm .
- DPartial pressure of C at 127^ C is 1 8 ~atm
Correct answer
D. Partial pressure of C at 127^ C is 1 8 ~atm
Step-by-step solution
At 27^ C , total pressure P _ A + P _ B =2+2=4 ~atm r_A r_B = n_A n_B = P_A P_B M_B M_A n_A n_B = 1 2 moles diffused out at 27^ C are in the ratio 1: 2 Initial moles a a moles left a-x a-2 x Total moles after diffusion =a-x+a-2 x=a ( P drops from 4 atm to 2 ~atm moles should decrease from 2 a to a) a =3 x After diffusion moles of A and B are 3 x - x =2 x and 3 x -2 x = x moles of A and B left are in the ratio 2: 1 Partial pressures after diffusion at 27^ C For A it is 2 3 P = 2 3 2= 4 3 For B it is 1 3 P = 1 3 2= 2