chuinhen Posted April 11, 2006 Posted April 11, 2006 The melting point of the Graphite is higher than the diamond !! Can anyone explain why is this happen ??
RyanJ Posted April 11, 2006 Posted April 11, 2006 The melting point of the Graphite is higher than the diamond !! Can anyone explain why is this happen ?? Really its not - its the varying pressures used. According to the CRC handbook of chemistry and physics: Carbon (diamond) has a melting point of 4440°C at 12.4 GPa. Carbon (graphite) has a melting point of 4489°C at 10.3 MPa. Due to the varying pressures used I'd say the comparision is not really fair because we know that pressure affects the melting and boilling points of materials, e.g. water on Mount Everest boils well below 100°C. We know diamond has more internal bonds, the maximum possible for carbon (4). So it must take more energy to break 4 then to break 3 even is we include the inermolecular attraction between the layers in the graphite we could not account for such a difference. Our only conclusion can be that the pressure is having a big effect on the results Cheers, Ryan Jones
Primarygun Posted April 11, 2006 Posted April 11, 2006 Ryan, I think it's easy to explain but difficult to predict, isn't it?
RyanJ Posted April 11, 2006 Posted April 11, 2006 Ryan, I think it's easy to explain but difficult to predict, isn't it? Well, the only way I can see this occuring is the variance in pressure because 4 bonds must take more energy to break then 3 bonds so pressure must be having some effect. As for predicting yes... slight changes in pressure affect different materials differently. Cheers, Ryan Jones
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