N2+3H2⇌2NH3Let mass of N2 be x g
Then mass of H2 will be (34−x)g
moles of N2=x28, moles of H2=34−x2
as their molar ratio is 1:3
So, x28(34−x)2=13⇒6x28=34−x
⇒6x=34×28−28x
⇒34x=34×28
⇒x=28⇒ Mass of N2
⇒34−x=34−28=6⟶ Mass of H2
Number of moles of N2=2828=1
Number of moles of H2=62=3
N21+3H23⇌2NH3−
1−y 3−3y 2y
As NH3 required 0.5 moles of H3PO4
So, n×nf(H3PO4)=n×nf(NH3)
(as nf for H3PO4 is 3)
⇒0.5×3=n×1
n=1.5 moles of NH3
Thus 2y=1.5
⇒y=1.52=0.75 moles of NH3
Number of moles remain in solution Mass remain in solution
N2⟶1−0.75=0.25 0.25×28=7g
H2⟶3−3×0.75=0.75 0.75×2=1.5g
NH3⟶2×0.75=1.5 1.5×31=46.5g
Vapour density=EffectiveMolarmass(EMM)2
⇒EMM=m1+m2+m3n1+n2+n3=7+1.5+46.50.25+0.75+1.5
⇒EMM=22
Vapour density of mixture= 222=11 .