750 mL of nitrogen are collected over water at 25^@C and 740 mm pressure. If the aqueous tension at this temperature is 23.8 mm Hg, calculate the mass of the dry gas.

750 mL of nitrogen are collected over water at 25^@C and 740 mm pressu

1.	750 mL of nitrogen are collected over water at 25^@C and 740 mm pressure. If the aqueous tension at this temperature is 23.8 mm Hg, calculate the mass of the dry gas.
Answer» SOLUTION :According to Dalton.s law of partial pressure, `P_(gas) = P_(obs). - " aqueous TENSION " = 740 - 23.8 = 716.2 mm Hg` The given gas thus occupies a volume of 750 mL at `25^@C " and " 716.2 mm Hg`. According to the ideal gas equation, `PV =nRT= m/M RT` `m=(PVM)/(RT)` In the present case, `P =716.2 mm = (716.2)/760 =0.9424` atm `V=750 mL = 0.750 L, "" T=25+273 =298 K` `M = 28 " and " R =0.0821 L " atm " K^(-1) mol^(-1)` `m=(0.9424xx0.750xx28)/(0.0821xx298) = 0.809 g` Hence, the mass of the given gas = 0.809 g