The number of vacancies in some hypothetical metal increases by a factor of 3 when the temperature is increased from 1020 ˚C to 1290 ˚C. Calculate the energy for vacancy formation (in J/mol) assuming that the density of the metal remains the same over this temperature range.

Answer :

umohduke14

Answer:

first step here is to substitute the 3 of your two equations into the second;

3 Ne^(-Q_v/k(1293)) = Ne^(-Q_v/k(1566))

Since 'N' is a constant, we can remove it from both sides.

We also want to combine our two Q_v values, so we can solve for Q_v, so we should put them both on the same side:

3 = e^(-Q_v/k(1293)) / e^(-Q_v/k(1566))

3 = e^(-Q_v/k(1293) + Q_v/k(1566) ) (index laws)

ln (3) = -Q_v/k(1293) + Q_v/k(1566) (log laws)

ln (3) = -0.13Q_v / k(1566) (addition of fractions)

Q_v = ln (3)* k * 1566 / -0.13 (rearranging the equation)

Now, as long as you know Boltzmann's constant it's just a matter of substituting it for k and plugging everything into a calculator.

MrRoyal

Energy for vacancy formation literally means the change in energy when breaking atom bonds. The energy for vacancy formation in J/mol is 68371.38 J/mol

Given that

[tex]T_1 = 1020^oC[/tex]

[tex]T_2 = 1290^oC[/tex]

Since the hypothetical metal increases by a factor of 3, then:

[tex]NV_1 = 1[/tex] --- the initial number of vacancies

[tex]NV_1 = 3[/tex] --- the final number of vacancies

The energy for vacancy formation is calculated using:

[tex]Q_v = \frac{R \times \ln(NV_1/NV_2)}{1/T_2 - 1/T_1}[/tex]

Where:

[tex]R = 8.3145[/tex] ----- molar gas constant

Convert temperatures to kelvin

[tex]T_1 = 1020+273 = 1293[/tex]

[tex]T_2 = 1290+273=1563[/tex]

So, we have:

[tex]Q_v = \frac{R \times \ln(NV_1/NV_2)}{1/T_2 - 1/T_1}[/tex]

[tex]Q_v = \frac{8.3145 \times \ln(1/3)}{1/1563 - 1/1293}[/tex]

[tex]Q_v = \frac{-9.13441187413}{-0.00013359993}[/tex]

[tex]Q_v = 68371.3821866[/tex]

Approximate

[tex]Q_v = 68371.38[/tex]

Hence, the energy for vacancy formation is 68371.38 J/mol

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https://brainly.com/question/15053879

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