Question

Ammonia in $0.224gm$ of a compound, $Zn{(N{H_3})_x}C{l_2}$ is neutralised by $30.7ml$ of $0.20M$ $HCl$ . The value of $x$ in the formula is:
A.4
B.5
C.6
D.8

Answer 1

Hint: A chemical substance composed of atoms of more than one element which is held together by chemical bonds is known as chemical compound. Mainly these exist in two categories, organic compounds (carbon and its derivatives) and inorganic compounds.

 Complete step by step answer:
Given:
Weight of compound = $0.224gm$
Concentration of $HCl$ = $0.20M$
Volume of $HCl$ required to neutralize the compound = $30.7ml$
Molecular weight of $Zn{(N{H_3})_x}C{l_2}$ =\[65.30 + 17x + 35.5 \times 2\; = 136.30 + 17x\;gm/mol\]
\[136.30 + 17x\;gm\] of compound contains $x$ mole of ammonia.
Therefore,
$0.224gm$ of compound contains $\dfrac{x}{{17x + 136.30}} \times 0.224$ moles.
And we know that $x$ equivalent of ammonia = $x$ mole of ammonia
So,
Eq. of $HCl$ $ = \dfrac{{MV}}{{1000}} = $Eq. of $N{H_3}$
$\dfrac{{0.224x}}{{17x + 136.30}} = \dfrac{{30.7 \times 0.2}}{{1000}}$
$x = 6.75 \approx 6$
We will take the integral value of $x$ because the molecule can’t be fractional.
So the obtained integer value of $x$ is $6$ .

Hence option (C) is correct.

Note:
Equivalent is basically the amount of substance that reacts with an arbitrary amount of another substance in a given chemical reaction. It is also defined as the mass of a substance which displaces one gram of hydrogen or eight gram of oxygen from a compound.