Calculating the Density of a BCC Crystal with Ta Substitution

AI Thread Summary
To calculate the density of a BCC crystal with 7.5 atomic % tantalum substitution for chromium, start by determining the mass of the unit cell. The mass is calculated by multiplying the number of atoms in the cell by the adjusted atomic mass, considering the 7.5% replacement of chromium with tantalum. The volume of the BCC crystal can be found using the given lattice parameter of 0.29158 nm. Density is then calculated as mass divided by volume. Understanding the substitution percentage is crucial for accurate mass calculations.
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how would i start this solution off?

we replace 7.5 atomic % of the chromium atoms in its BCC crystal with tantalum. X ray diffraction shows that the lattice parameter is 0.29158 nm find the density.
 
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Well the crystal is bcc, and one is given the length of the side of the cube.

Density is simply mass divided by volume.


The mass is simply the number of atoms in the cell times the mass per unit atom (think amu, which can be converted into grams.). Also, since 7.5% of the Cr atoms are replaced with Ta atoms, simply adjust the atomic mass by the proportions of each element.
 
thank you I am going to try and work it out now the 7.5% Ta was confusing me but i think i get it now
 
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