# Chemistry

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An element has bcc packing with a body-centered cubic unit cell. Its density is 19300 kg/m3 and the unit cell volume is 3.17 x 10-26 L. Calculate the molar mass (g/mol) of the element to three significant figures.

The element rubidium has bcc packing with a body-centered cubic unit cell. The volume of the unit cell is 1.85 x 10-22 cm3. Calculate the density (g/cm3) of the element.

• Chemistry -

# atoms/unit cell * molar mass/Avogadro's number = mass unit cell.
Calculate mass unit cell from
mass = volume x density. The only unknown is molar mass.
Post your work if you get stuck. The second problem is done essentially the same way. Try it. Repost if you run into trouble but show your work to the point you don't know how to continue.

• Chemistry -

thats wrong. don't listen to him

• Chemistry -

No that's correct. Im having trouble finding the # atoms/unit cell.

• Chemistry -

Remember these.
A bcc unit cell has 2 atoms/unit cell.
A fcc unit cell has 4 atoms/unit cell.
A simple cubic unit cell has 1 atom/unit cell.