If NaCl is doped with 10^{–3} mol % SrCl ₂, ...

NCERT Class XII Chemistry
Chapter - The Solid State
Questions with Solutions

Question : 25 of 50

Marks: +1, -0

If NaCl is doped with 10

^{–3}

mol % SrCl

_{2}

, what is the concentration of cation vacancies ?

Solution:

Let moles of NaCl = 100

∴

Moles of SrCl

_2

doped = 10

^{–3}

Each Sr

^{2+}

will replace two Na

^{+}

ions. To maintain electrical neutrality it occupies one position and thus creates one cation vacancy.

∴

Moles of cation vacancy in 100 moles NaCl = 10

^{–3}

Moles of cation vacancy in one mole NaCl = 10

^{–3}

× 10

^{–2}

= 10

^{–5}

∴

Number of cation vacancies = 10

^{–5 }

× 6.022 × 10

^{23}

= 6.022 × 10

^{18}

mol

^{–1}

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