Calculate the number of moles present in 9 g of ethane Calculate the number of molecules of oxygen gas that occupies a volume of 224 ml at 273 K and 3 atm pressure.

Calculate the number of moles present in 9 g of ethane Calculate the

1.	Calculate the number of moles present in 9 g of ethane Calculate the number of molecules of oxygen gas that occupies a volume of 224 ml at 273 K and 3 atm pressure.
Answer» Solution :MASS of ethane = 9 G Molar mass of ethane `C_(2)H_(6)`= 30 g `mol^(-1)` . No. of moles = `("Mass")/("Molar mass") = 9/30 =`0.3 mol. Molar volume of oxygen = 22400 ML. 22400 ml of oxygen contains `6.023 xx 10^(23)` MOLECULES. `:.` 224 ml of oxygen contain `(6.023 xx10^(23))/222400 xx 224` at 1 atm.pressure For 3 atm.pressure = `(60.23x10^(23))/100 = 6.023 xx 10^(21)` molecules `xx` 3 = `18.069 xx 10^(21)` molecules (or) `1.8069 xx 10^(22)` molecules