Question

Calculate the volume of 68.0 g of NH3 gas at standard temperature and pressure (STP). Use a molar mass with at least as many significant figures as the data given.

Answer 1

Ans--- Given,

mass of NH3 is 68 g , and the temperature and pressure is at STP . so solving this problem , firstly we have to convert mass of NH3 to number of moles , and we have to use molar volume of gas at STP as a conversion factor.

for calculating volume we use the formula, volume(V)= molar volume at STP (v^-) / moles of gas (n) -----------(1)

we know,  gas kept under STP conditions will have a molar volume of 22.7 L mol−1.

molar mass of NH3= 17 g/mol

mole of NH3 = mass / molar mass

= 68/17

= 4 moles of NH3

Now, using equation (1) we get ,

volume(V) = 22.7 / 4

V=5.67L

Hence volume = 5.6L