1500 mL flask contains `400 mg O_(2) " and " 60 mg H_(2) " at " 100^(@)C`.
(a) What is the total pressure in the flask ?
(b) If the mixture is permitted to react to form water vapour at `100^(@)C`, what will be left and what will be their partial pressure ?

Explanation

(a) No. of moles of `O_(2) = (400)/(1000 xx 32) = 0.0125`
No. of moles of `H_(2) = (60)/(1000 xx 2) = 0.03`
Partial pressure of `O_(2) = (0.0125 xx 0.0821 xx 373)/(1.5) = 0.255 atm`
Partial pressure of `H_(2) = (0.03 xx 0.0821 xx 373)/(1.5) = 0.612 atm`
Total pressure `= 0.255 + 0.612 = 0.867 atm`
(b) `{:(,2H_(2),+O_(2),= 2H_(2) O),("Initital",0.03,0.0125," "0),("After reaction",0.005,0," "0.025):}`
Partial pressure of `H_(2) = (0.005 xx 0.0821 xx 373)/(1.5) = 0.102 atm`
Partial pressure of `H_(2) O = (0.025 xx 0.0821 xx 373)/(1.5) = 0.51 atm`