Question

If X is the degree of dissociation of $PC{l}_5$
$PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$
at a given temperature and if 2 moles of $PC{l}_5$ are taken in a vessel, then at equilibrium the total number of moles of various species would be -

• A. 4
• B. 2+x
• C. 2(1-x)
• D. 2(1+x)

Answer 1

The correct option is D 2(1+x)

Given that

degree of dissociation $\left(\alpha \right)=x$

Now,

$PC{l}_5\left(g\right)\rightleftharpoons PC{l}_3\left(g\right)+C{l}_2\left(g\right)$

$t=0$ $2$mol $0$ mol $0$ mol

$t_{eq}$ $2(1-x)$ $2x$ $2x$

$\therefore n_T\left(eq\right)=n_{PC{l}_5}+n_{PC{l}_3}+n_{C{l}_2}$

$=2(1-x)+2x+2x$

$=2-2x+2x+2x$

$=2+2x$

$=2(1+x)$. Option D.