Given, Volume of ammonia at STP = 5000 mL= 5 L
Molar volume at STP (litres) = 22.4 L
In case of gases at STP,
Number of moles = Volume at STP (litres)Molar volume at STP (litres) .... (i)
[1 Mark]
Putting the values of the volume of ammonia at STP and molar volume at STP (litres) in equation (i) we have:
Number of moles = 5.022.4
Number of moles = 0.22
Also, number of moles = Given massMolar Mass .... (ii)
Therefore, given mass = Number of moles x Molar mass ....(iii)
Molar mass of ammonia = Gram atomic mass of Nitrogen + (3 x Gram atomic mass of Hydrogen)
[1 Mark]
Molar mass of ammonia (NH3) = 14 + 3 = 17 g
Substituting the values of number of moles and molar mass of ammonia in equation (iii) we get:
Mass of ammonia = 0.22 x 17 = 3.74 g
∴ The mass of 5000 ml of NH3 gas at STP is 3.74 g [1 Mark]