What is closest packing? what is the difference between hexagonal closest packing and cubic closest packing? what is the unit cell for each closest packing arrangement?

In crystal structure close packing is define as space efficient arrangement of constituent particles to form a crystal lattice.

Explanation:

closest packing

In crystal structure close packing is define as space efficient arrangement of constituent particles to form a crystal lattice.

Difference between hexagonal closest packing and cubic closest packing

In cubic closest packing arrangement, each sphere is surrounded by 12 other spheres on the other hand in case of hexagonal close packing, layers of spheres are packed so that spheres in alternating layers overlie one another.

unit cell for each closest packing arrangement

The hexagonal closest packed arrangement has a coordination number of 12 and it consists of 6 atoms per unit cell. The face centered cubic lattice has a coordination number of 12 and it consists of 4 atoms per unit cell. In case of body centered cubic crystal the coordination number is 8 and it consists of 2 atoms per unit cell.

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml