How Do You Calculate Molar Mass from BCC Packing?

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To calculate the molar mass of an element with body-centered cubic (bcc) packing, the density (862 kg/m^3) and unit cell volume (1.51 x 10^-28 m^3) are used. The correct molar mass is determined to be 39.2 g/mol. The calculation involves converting density to grams and using Avogadro's number, but confusion arose regarding the packing density factor. The participant initially miscalculated the value, leading to an incorrect result. Understanding the unit conversions and the relevance of packing density is crucial for accurate calculations.
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Homework Statement



An element has bcc packing with a body-centered cubic unit cell. Its density is 862 kg/m^3 and the unit cell volume is 1.51 x 10-28 m^3. Calculate the molar mass (g/mol) of the element to three significant figures.

Homework Equations



Known: D= 862 kg/m^3, V=1.51 x 10-28 m^3 , MM=??

The Attempt at a Solution



Ok the correct answer is 39.2, but I don't know how to arrive to that answer.

(862kg/m^3)(1.51e-28m^3)(1000g/1kg)(6.022e23atoms/1mol)(1/2 atoms)
(0.68) but instead I get 26.6504.

The 0.68 is the density packing.
 
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vipertongn said:
The 0.68 is the density packing.

Are you sure it is relevant to the question?
 
ah, htat wasn't required, thanks
 
The real question is: do you understand what you did and why?
 
Yes, I pretty much converted to the proper units I needed, the only problem was getting the right units.
 
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