Question

The percentage composition (by weight) of a solution is $45\%X$, $15\%Y$ and $40\%Z$. If the mole fraction of $X=a,Y=b$ and $Z=c$, then find the value of $a,b$ and $c$. (Molecular mass of $X=18,Y=60$ and $Z=60$)

• A. $a=0.73,b=0.073,c=0.195$
• B. $a=0.63,b=0.073,c=0.295$
• C. $a=0.73,b=0.173,c=0.095$
• D. None of these

Answer 1

The correct option is A $a=0.73,b=0.073,c=0.195$

According to given data,
$X=45$%, $n_1=\frac{45}{18}=2.5$
$Y=15$%, $n_2=\frac{15}{60}=0.25$
$Z=40$%, $n_3=\frac{40}{60}=0.666$
${\chi }_1=\frac{n_1}{n_1+n_2+n_3}=\frac{2.5}{2.5+0.25+0.666}$ $=\frac{2.5}{3.416}=0.73$
${\chi }_2=\frac{n_2}{n_1+n_2+n_3}=\frac{0.25}{3.416}=0.073$
${\chi }_3=[1+({\chi }_1+{\chi }_2\left)\right]=(1-0.73-0.073)=0.195$