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Determine the density of cesium chloride which crystallizes in bcc type structure with the edge length 412.1 pm. The atomic masses of Cs and Cl are 133 and 35.5 respectively. |
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Answer» re of CESIUM chloride is body centre cubic TYPE in which Cs+ placed within centre and Cl- placed at corner of lattice. number of Cl- ions PER unit CELL = 8 × 1/8 = 1 number of Cs+ ions per unit cell = 1 so, there is only one molecule of CsCl in a lattice .so, mass of one molecule of CsCl = MOLAR mass of CsCl/Avogadro's number= (133 + 35.5)/(6.023 × 10²³) = 168.5/6.023 × 10²³ = 2.8 × 10^-22 g volume of lattice = a³ , where a is edge length= (412.1 × 10^-12)³ = 7 × 10^-23 cm³ so, density of CsCl crystal = 2.8 × 10^-22/7 × 10^-23 = 4 g/cm³ |
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