When 1 g each of compounds AB and AB ₂ are dissolved in 15 g of water separately, they increased the boiling point of water by 2.7 K and 1.5 K respectively. The atomic mass of A (in amu) is ____ 10⁻¹ (Nearest integer) (Given : Molal boiling point elevation constant is .0.5 ~K ~kg ~mol ⁻¹ )

Step-by-step solution

For AB aligned & T _ b =2.7 ~K & 2.7=1 0.5 m & ~m = 27 5 aligned Let molar mass of AB = x . aligned & So 1 / x 15 1000= 27 5 & x=12.34 aligned For AB ₂ aligned & T _ b =1.5 ~K & 1.5=1 0.5 m & ~m =3 aligned Let molar mass of AB ₂= y So 1 / y 15 1000=3 aligned & y= 1000 45 & y=22.22 aligned Now let a and b be atomic masses of A and B respectively, then aligned & A + b =12.34 ...(i) & ~A +2 ~b =22.22 ...(ii) & ~B =22.22-12.34=9.88 & Now a =12.34-9.88=2.46 & =24.6 10⁻¹=25 10⁻¹ aligned