25. When 2 gm of a gas A is introduced into an evaluated flaskkept at 25Â°C, the pressure is found to be one atmosphere. If3 gm of another gas B is then added to the same flask, thetotal pressure becomes 1.5 atm. Assuming ideal gasbehaviour, calculate the ratio of the molecular weightsA.B

25. When 2 gm of a gas A is introduced into an evaluated flaskkept at

1.	25. When 2 gm of a gas A is introduced into an evaluated flaskkept at 25Â°C, the pressure is found to be one atmosphere. If3 gm of another gas B is then added to the same flask, thetotal pressure becomes 1.5 atm. Assuming ideal gasbehaviour, calculate the ratio of the molecular weightsA.B
Answer» When 2 grams of a gas A is introduced in an evacuated flask kept at 25 C; the pressure was found to be 1 atm .i.e.Partial Pressure of gas A = 1 atm.And let moles be nA = 2/Maif 3 g of another gas B is then added to the same flask;Partial Pressure of gas B =1.5 atm – 1 atm. = 0.5 atmmoles of gas B = 3/MbAgain the temp and volume are constant therfore,P1/n1 = P2/n2hence,1/(2/Ma) = 0.5/(2/Mb)Ma/2 = 0.5Mb/2Ma/2 = Mb/4Ma = Mb/2orMa/Mb = ½ => 1:2