Concept explainers
(a)
Interpretation:
The crystalline structure of MnO whether it is NaCl type or CsCl type needs to be identified.
Concept Introduction :
Simple cubic, face-centered cubic and body centered cubic are the kinds of cubic cells explained on the basis of arrangement of spheres. All of them contains the identical volume thus the packing efficiency of these can be differentiated by calculating the number of spheres which best suited in the unit cell.
(a)
Answer to Problem 74E
MnO crystallizes in the NaCl type
Explanation of Solution
The NaCl unit cell contains a face-centered cubic arrangement of cations and anions. There are 4 NaCl units present per unit cell. The CsCl unit cell contains a simple cubic structure of anions with the cations in the cubic holes.There are 1CsCl units present per unit cell.
Therefore, we have to estimate how many units of MnO are present in the unit cell.
By using below formula, we can calculate:
Due to the 4 formula units of MnO per unit cell, MnO crystallizes in the NaCl type.
(b)
Interpretation:
The ionic radius of manganese in MnO needs to be calculated.
Concept Introduction :
Simple cubic, face-centered cubic and body centered cubic are the kinds of cubic cells explained on the basis of arrangement of spheres. All of them contains the identical volume thus the packing efficiency of these can be differentiated by calculating the number of spheres which best suited in the unit cell.
(b)
Answer to Problem 74E
The radius of manganese is 84 pm.
Explanation of Solution
As we know that MnO crystallizes in the NaCl type, the edge length of Face-centered cubic is related to the ionic radii as shown below:
Radius of oxygen = r- = 140 pm
Radius of Mn = r+= ?
a =
thus, putting all the values in the above formula:
Thus, the radius of manganese is 84 pm.
(c)
Interpretation:
Explanations require for the cation-to-anion ratio for MnO.
Concept Introduction :
Simple cubic, face-centered cubic and body centered cubic are the kinds of cubic cells explained on the basis of arrangement of spheres. All of them contains the identical volume thus the packing efficiency of these can be differentiated by calculating the number of spheres which best suited in the unit cell.
(c)
Answer to Problem 74E
The radius ratio value is 0.60.
Explanation of Solution
The cation-to-anion ratio can be calculated as below:
We know from the data given in textbook, that octahedral holes should be filled when the radius ratio is
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Chapter 16 Solutions
Chemical Principles
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