Question

What is the vacancy concentration of Fe at 850 °C and 1250 °C given the density...

What is the vacancy concentration of Fe at 850 °C and 1250 °C given the density (7.65g/cm3 ), and activation of energy for vacancy formation (1.08eV/atom).

Science   Chemistry   
0 0
Add a commentTranscribed image text
Next >

Homework Answers

Answer #1

Determination of the number of vacancies per cubic meter in iron at 850°C (1123 K) and 1250 °C (1523 K ) requires the utilization of following equation:

Nv = N * exp(-Qv/KT) = NA * ρfe / Afe *exp(-Qv/KT)

Nv = number of vacancies per cubic meter

NA = Avogadro's number = 6.022 * 1023 atoms/mol

ρfe = Density of iron = 7.65g/cm3

Afe = Atomic mass of iron = 55.85g/mol

Qv = activation of energy for vacancy formation (1.08eV/atom)

K = Boltzmann constant = 8.62 *10-5 ev/atom.K

At temperature 850°C (1123 K)

Nv = NA * ρfe / Afe *exp(-Qv/KT)

Nv = 6.022 * 1023 atoms/mol *( 7.65g/cm3/55.85g/mol) * exp(-1.08eV/atom/( 8.62 *10-5 ev/atom.K * 1123 K)

Nv = 1.18 *1018 cm-3 or 1.18 *1024 m-3

At temperature 1250°C (1523 K)

Nv = NA * ρfe / Afe *exp(-Qv/KT)

Nv = 6.022 * 1023 atoms/mol *( 7.65g/cm3/55.85g/mol) * exp(-1.08eV/atom/( 8.62 *10-5 ev/atom.K * 1523 K)

Nv = 2.20 *1015 cm-3 or 1.18 *1021 m-3

0 0
Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Log In

Sign Up

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
Calculate the energy (in eV/atom) for vacancy formation in some metal, M, given that the equilibrium...
Calculate the energy (in eV/atom) for vacancy formation in some metal, M, given that the equilibrium number of vacancies at 476oC is 3.61E+23 m-3. The density and atomic weight for this metal are 20.1 g/cm3 and 92.40 g/mol, respectively.
(a) Calculate the activation energy, QV, for vacancy formation in silver, given that the equilibrium number...
(a) Calculate the activation energy, QV, for vacancy formation in silver, given that the equilibrium number of vacancies at 1073°K is 3.6 x 1023 m-3. The atomic weight and density (at 1073°K) of silver are, respectively, 107.9 g/mol and 9.5 g/cm3 . (b) Suppose that CaO is added as an impurity to Li2O. If the Ca2+ substitutes for Li+ , what kind of vacancies would you expect to form? How many of these vacancies are created for every Ca2+ added?
Compute the concentration (number density, count per volume) of vacancies in copper at room temperature if...
Compute the concentration (number density, count per volume) of vacancies in copper at room temperature if the lattice parameter of FCC copper is 0.3615 nm at room temperature (25oC, 298 K), and the activation energy to form a single vacancy is 0.9 eV. Use 8.617x10-5 eV/(atom-K), exactly, as Boltzmann's Constant. Note: You could look up the density and atomic weight of copper to compute the intermediate value of atom concentration you need for this problem. But here I give you...
Given that for a typical metal the energy for vacancy formation is on the order of...
Given that for a typical metal the energy for vacancy formation is on the order of 1 eV/atom, melting point is 10^3 K, molar mass is 10^2 g/mol and density is 10 g/cm3. 1.) Near melting point the fraction of vacant lattice sites is: a) <10^-5 b) 10^-5 to 10^-3 c) 10^-3 to 10^-2 d) 10^-2 to 10^-1 2.) The number of vacant sites per cm^3 is typically: a) <10^3 b)10^3 to 10^6 c) 10^6 to 10^9 d) > 10^9...
Consider a hypothetical metal that has a simple cubic structure, a density of 9.62 g/cm3, and...
Consider a hypothetical metal that has a simple cubic structure, a density of 9.62 g/cm3, and an atomic weight of 90.5 g/mol. If, at the melting temperature, one out of every 104 atom sites is a vacancy, determine the number of vacancies in one cubic meter of this material. Assume that the energy for the vacancy formation is 96,000 J/mol. Answer should be in units of vacancies/m^3
The energy for vacancy formation in Al is 0.66 eV. Calculate the number of vacancies in...
The energy for vacancy formation in Al is 0.66 eV. Calculate the number of vacancies in a 1 cm3 of Al at 300°C and 600°C
Problem 1) In a certain crystalline material, the vacancy concentration at 45°C is twice that at...
Problem 1) In a certain crystalline material, the vacancy concentration at 45°C is twice that at 25°C. At what temperature would the vacancy concentration be one-half that at 25°C?
The concentration of vacancies in niobium (Nb) at 765˚C is 9.836 x 1018 cm-3. If niobium...
The concentration of vacancies in niobium (Nb) at 765˚C is 9.836 x 1018 cm-3. If niobium has a BCC crystal structure and a lattice parameter of 0.3302 nm, calculate the energy for vacancy formation in niobium.
The density of solid Fe is 7.87 g/cm3. How many atoms are present per cubic centimeter...
The density of solid Fe is 7.87 g/cm3. How many atoms are present per cubic centimeter of Fe? As a solid, Fe adopts a body-centered cubic unit cell. How many unit cells are present per cubic centimeter of Fe? What is the volume of a unit cell of this metal? What is the edge length of a unit cell of Fe?
Calculate the radius of iridium atom, given that Ir has an FFC crystal structure, a density...
Calculate the radius of iridium atom, given that Ir has an FFC crystal structure, a density of 22.4 g/cm3 and atomic weight of 192.2g/mol.
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT