(NH4)2Cr2O7(s) ---> N2(g) + 4 H2O(g) +
Cr2O3(s)
1 mole (NH4)2Cr2O7 = 1 mole N2 = 4 mole H2O = 1 mol
Cr2O3
no of mole of (NH4)2Cr2O7 = w/mwt = 0.7/252.07 = 0.00278
mol
no of mole of N2(g) = 0.00278 mol
no of mole of H2O(g) = 4*0.00278 = 0.01112
mol
total no of mol of gas mixer = 0.00278 + 0.01112 =
0.0139 mol
total pressure of gas (Ptotal) = nRT/V
  =
0.0139*0.0821*(28+273.15)/13.3
= 0.026 atm
partial pressure of N2 gas = Xn2*Ptotal
                         Â
= (0.00278/0.0139)*0.026
                         Â
= 0.0052 atm
partial pressure of H2O gas = XH2O*Ptotal
                          Â
= (0.01112/0.0139)*0.026
                          Â
= 0.0208 atm
