1. Tardigrade
  2. Question
  3. Chemistry
  4. Consider the following information about rock salt type of structure (a) Potassium has a unit cell length of 50pm lesser than that of the corresponding Rb salt of the same halogen. (b) The ionic radius of Rb+ is 158pm. Calculate the ionic radius of K+ based on above information.

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Q. Consider the following information about rock salt type of structure
(a) Potassium has a unit cell length of 50pm lesser than that of the corresponding $Rb$ salt of the same halogen.
(b) The ionic radius of $Rb^{+}$ is 158pm.
Calculate the ionic radius of $K^{+}$ based on above information.

NTA AbhyasNTA Abhyas 2020

Solution:

For rock salt type structure
Edge length
$=2\left(r_{c} + r_{a}\right)$
$x^{\ominus}=\frac{158}{0.414}=381.6 \, pm$
$k^{+}+x^{\ominus}=\frac{1079 - 50}{2}$
$k^{\oplus}=\frac{1079 - 50}{2}-381.6=133.6 \, pm$