Boron phosphide, BP, is a semiconductor and a hard, abrasion-resistant material. It is made by reacting boron tribromide and phosphorus tribromide in a hydrogen atmosphere at high temperature (>750 °C).
(a) Write a balanced chemical equation for the synthesis of BP.
(b) Boron phosphide crystallizes in a zinc-blend structure, formed from boron atoms in a face centered cubic lattice and phosphorus atoms in tetrahedral holes. How many tetrahedral holes are filled with P atoms in each unit cell?
(c) The length of a unit cell of BP is 478 pm. What is the density of the solid in g/cm³?
(d) Calculate the closest distance between a B and a P atom in the unit cell. (Assume the B atoms do not touch along the cell edge. The B atoms in the faces touch the B atoms at the corners of the unit cell.)