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Govind Dhiraj Vaidya
Asked: 2022-11-09T10:04:54+05:30 In:

What fraction of the surface of a crystal of `Cd` at `T = 298 K` consists of vacancies? Assume that the energy needed to form a vacancy `= 0.5 Delta_(“sub”)H^(Θ)`. For `Cd(s), Delta_(“sub”)H^(Θ) = 112.0 kJ mol^(-1)`.
A. `1.5 xx 10^(-10)`
B. `3 xx 10^(-5)`
C. `2 xx 10^(-6)`
D. `3 xx 10^(-2)`

What fraction of the surface of a crystal of `Cd` at `T = 298 K` consists of vacancies? Assume that the energy needed to form a vacancy `= 0.5 Delta_(“sub”)H^(Θ)`. For `Cd(s), Delta_(“sub”)H^(Θ) = 112.0 kJ mol^(-1)`.
A. `1.5 xx 10^(-10)`
B. `3 xx 10^(-5)`
C. `2 xx 10^(-6)`
D. `3 xx 10^(-2)`
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  1. Correct Answer – A
    The number of vacancies (or Schottky defects )
    (n) is given by.
    `n=Ne^(-E//2KT)` or `(n)/(N)=e^(-E//2KT)`
    But fraction of the surface of a crystal vacancy is given by `(n)/(N)=e^(-E//RT)`
    `=”exp”[(-(0.5)(112.0xx10^(3)J”mol”^(-1)))/(8.314JK^(-1)”mol”^(-1)(298K))]=1.5xx10^(-10)`

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Ehsaan Jani
Asked: 2022-11-07T02:09:52+05:30 In:

What fraction of the surface of a crystal of `Cd` at `T = 298 K` consists of vacancies? Assume that the energy needed to form a vacancy `= 0.5 Delta_(“sub”)H^(Θ)`. For `Cd(s), Delta_(“sub”)H^(Θ) = 112.0 kJ mol^(-1)`.

What fraction of the surface of a crystal of `Cd` at `T = 298 K` consists of vacancies? Assume that the energy needed to form a vacancy `= 0.5 Delta_(“sub”)H^(Θ)`. For `Cd(s), Delta_(“sub”)H^(Θ) = 112.0 kJ mol^(-1)`.
Parabola
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Leave an answer

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1 Answer

  1. The number of vacancies (or Schottky defects) `(n)` is given by.
    `n = Ne^(-E//2KT)` or `(n)/(N) = e^(-E//2KT)`
    But fraction of the surface of a crystal vacancy is given by
    `(n)/(N) = e^(E//2KT)`
    `= exp[(-(0.5)(112.0xx10^(3)Jmol^(-1)))/((8.314JK^(-1)mol^(-1))(298 K))] = 1.5 xx 10^(-10)`

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