Chromium forms a crystalline solid with a body-centered cubic unit cell. The edge length of its unit cell is 291 pm. Calculate the density of chromium metal in g/cm^3. a. 7.84 g/cm^3
b. 6.33 g/cm^3
c. 7.01 g/cm^3
d. 8.23 g/cm^3
e. 5.08 g/cm^3

c. 7.01 g/cm³

Explanation:

To dinf density of the Chromium we need to find first the mass of the unit cell and then its volume.

A body-centered cubic unit cell has:

2 atoms per cubic unit cell.

Volume = Edge length³

Mass of 2 atoms of Cr - Molar mass: 51.9961g/mol-:

2 atoms Cr * (1mol / 6.022x10²³ atoms) = 3.321x10⁻²⁴ moles Cr * (51.9961g/mol) =

1.72687x10⁻²²g

Volume:

291pm = (291x10⁻¹²m)³= 2.4642x10⁻²⁹m³* (1cm³/1x10⁻⁶m³) =

2.4642x10⁻²³cm³

Density, ratio of mass and volume is:

Density: 1.72687x10⁻²²g / 2.4642x10⁻²³cm³ =

7.01g/cm³

Right option is:

c. 7.01 g/cm³

For cyclohexane compounds drawn in a chair conformation:   -axial bonds are vertical  -equatorial bonds are parallel to two bonds within the ring.  thus, as i assume the chair conformation is drawn:   -the x group is in an axial position, as are the five other vertical bonds.  -three axial bonds are on the top face of the ring  -the other three axial bonds are on the bottom face  the position of the second substituent on each ring carbon is equatorial.  gauche groups must be on an adjacent carbon such as carbon 6 and carbon 2, and also gauche groups are rotated by 60 degrees relative to each other.  drawing the newman projections for c1–c2 and c1–c6 aids in visualizing the groups that are gauche to the y group on c1.  click this link and watch some academic videos that may you more understand the topic