The first and second ionisation enthalpies of a metal are 496 and 4560kJmo l ^ - 1 , respectively. How many moles of HCl and H _ 2 S O _ 4 , respectively, will be needed to react completely with 1 mole of the metal

Question

Quantrex Academy · Accepted Answer

Correct answer: D. 1 and 0.5

Ionization Enthalpy values indicate that the metal belongs to

{I}^{st}

group, since the second ionization enthalpy is very high.
(Q - only one valence electron)
Metal hydroxide will be of the type,

MOH

.

\mathop{\text{MOH}}_{\left(1\text{mol}\right)} + \mathop{\text{HCl}}_{\left(1\text{mol}\right)} \to \text{MCl} + {\text{H}}_{\text{2}} \text{O}

\text{MOH} + \dfrac{1}{2} {\text{H}}_{2} {\text{SO}}_{4} \to \dfrac{1}{2} {\text{M}}_{2} {\text{SO}}_{4} + {\text{H}}_{2} \text{O}

( 1\text{mol} )

\left(\dfrac{1}{2} \text{mol}\right)

So, one mole of

HCl

is required to react with one mole of

MOH

.<br /><br />So,

\dfrac{1}{2}

mole of

{\text{H}}_{\text{2}} {\text{SO}}_{\text{4}}

is required to react with one mole of

MOH.

The first and second ionisation enthalpies of a metal are 496 and...

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