8.2 Specific Heat 283 Raman active active Silent Figure 8.3.Various modes of vibration in graphite Table 8.2.Specific heat values(p)of various materials Material p (g-IK-1) Water(25C) 4.1813 Ice(-10C) 2.050 Paraffin wax 2.5 Magnesium 1.02 Aluminum 0.897 Graphite 0.710 Diamond 0.5091 Glass 0.84 Silica(fused) 0.703 Table 8.2 shows a comparison of the cp values for various materials.cp is higher for water than ice.This is because there are more degrees of freedom for vibra- tions/rotations in the liquid,which has a disordered structure,than in the ordered structure of ice.cp of paraffin wax is higher than that ofice,due to the disordered structure of solid wax,which is a molecular solid.Magnesium has a higher cp than aluminum(which is next to magnesium in the periodic table of the elements),be- cause it has a hexagonal crystal structure.In contrast,aluminum has a cubic(fcc) crystal structure.A hexagonal structure is less symmetrical than a cubic structure, resulting in more modes of lattice vibration.Similarly,graphite (hexagonal)has a higher cp than diamond(cubic),even though graphite and diamond are both 100%carbon.Glass has a higher cp than fused silica due to the lower degree of8.2 Specific Heat 283 Figure 8.3. Various modes of vibration in graphite Table 8.2. Specific heat values (cp) of various materials Material cp (Jg−1 K−1) Water (25°C) 4.1813 Ice (−10°C) 2.050 Paraffin wax 2.5 Magnesium 1.02 Aluminum 0.897 Graphite 0.710 Diamond 0.5091 Glass 0.84 Silica (fused) 0.703 Table 8.2 shows a comparison of the cp values for various materials. cp is higher for water than ice. This is because there are more degrees of freedom for vibra￾tions/rotations in the liquid, which has a disordered structure, than in the ordered structure of ice. cp of paraffin wax is higher than that of ice, due to the disordered structure of solid wax, which is a molecular solid. Magnesium has a higher cp than aluminum (which is next to magnesium in the periodic table of the elements), be￾cause it has a hexagonal crystal structure. In contrast, aluminum has a cubic (fcc) crystal structure. A hexagonal structure is less symmetrical than a cubic structure, resulting in more modes of lattice vibration. Similarly, graphite (hexagonal) has a higher cp than diamond (cubic), even though graphite and diamond are both 100% carbon. Glass has a higher cp than fused silica due to the lower degree of