Since 1891 lighting lamps have been manufactured in the Netherlands. The improvement today in comparison to the first lamp is enormous , especially with the intorduction of the gas discharge lamps. The life- time has increased by orders of magnitude . the colour is also an important aspect. Rare earth metal compunds like CeBr_(3) are now included to reach a colour temperature of 6000K in the lamp the compounds are ionic solids at room temperature , and upon heating they sublime partially to give a vapour of neutral metal halide molecules . To achieve a high vapour pressure, the sublimation enthalpy should be as low as possible. Calculate the enthalpy of sublimation fo CsCeBr_(4) (in integers) Use the Born-Lande formula for all steps in the process and report the separate energies also (be aware of the signs). The CeBr_(4)^(-) anion is a teteahedron and in which the ratio between the edge and the destance between a corner of the tetrahedron and the centre of gravity (body - radius) amounts to (2sqrt(6))//3 = 1.33 . The Born exponent of the CsBr is 11.The radius of Cs is 0.181 nm.