Question

A compound which contains one atom of X and two atoms of y for every three atoms of z is made of mixing $5gm$ of x, $1.15\times {10}^{23}$ atoms of y and $0.03$ moles of Z atoms. Given that only $4.40gm$ of compound results, calculate the atomic weight of Y if the atomic weight of X and Z are $60$ and $80$, respectively.

Answer 1

Molecular formula $=X{Y}_2{Z}_3$

${10}^{23}$ , atomic weight of $Y=y$

Molecular mass $=60+240+2y$

$=300+2y$

$1.15\times {10}^{23}$ atoms of $Y\simeq$2 mol of $Y$

$\therefore$ Limiting agent is $Z$ .

$\therefore$ No. of moles of compound $=\frac{0.03}{3}=0.01$

$\therefore$ Molecular mass $=\frac{4.40}{0.01}=440$

$\Rightarrow 300+2y=440$

$\Rightarrow y=70$