1.

If NaCl is doped with 10^(-4) mol % of SrCl_2, the concentration of cation vacancies will be (N_A=6.02xx10^23 mol^(-1))

Answer»

`6.02xx10^14 "mol"^(-1)`
`6.02xx10^15 "mol"^(-1)`
`6.02xx10^16 "mol"^(-1)`
`6.02xx10^17 "mol"^(-1)`

Solution :For each `Sr^(2+)` ion INTRODUCED, one cation vacancy is created because `2 NA^+` ions are removed and one VACANT site is occupied by `Sr^(2+)` . Doping with `10^(-4)` mol % of `SrCl_2`means 100 moles of NaCl are doped with `10^(-4)` mole of `SrCl_2`.
`therefore SrCl_2` doped per mole of NaCl=`10^(-4)//100`
=`10^(-6)` mole
=`10^(-6)xx (6.02xx10^23) Sr^(2+)` ions
`=6.02xx10^17 Sr^(2+)` ions
Hence, concentration of cation vacancies =`6.02xx10^17 mol^(-1)`


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