At 27^@C, a cylinder of 20 L capacity contains three gases He, O_2 " and " N_2. Their masses are 0.502 g, 0.250 g and 1.00 g respectively. If all these gases behave ideally, calculate the partial pressure of each gas as well as the total pressure.

At 27^@C, a cylinder of 20 L capacity contains three gases He, O_2 " a

1.	At 27^@C, a cylinder of 20 L capacity contains three gases He, O_2 " and " N_2. Their masses are 0.502 g, 0.250 g and 1.00 g respectively. If all these gases behave ideally, calculate the partial pressure of each gas as well as the total pressure.
Answer» Solution :Calculation of moles : Moles of helium = `(0.502)/4 =0.125` Moles of oxygen = `(0.250)/32 = 7.81xx10^(-3)` Moles of NITROGEN = `(1.00)/28 = 3.57xx10^(-2)` Calculation of partial PRESSURES : `:. "" PV=nRT` `:. ""P= (nRT)/V` Given V=20L and T=27+273=300K HENCE, `P_(H_e)=(0.125xx0.0821xx300)/20 = 0.154` atm `P_(O_2)= (7.81xx10^(-3)xx0.0821xx300)/20 = 9.62xx10^(-3)` atm `P_(N_2) = (3.57xx10^(-2)xx0.0821xx300)/20 = 0.0440` atm Calculation of total pressure : ACCORDING to Dalton.s law of partial pressure, `P_(mixture) = P_(He)+P_(O_2)+P_(N_2)=0.154+9.62xx10^(-3)+0.0440 = 0.208` atm