used as an abrasive. S When you heat up diamond or bombard it with ions, the atoms gain enough energy to pop up over the energy barrier and reconfigure to graphite. Available WWW:  http://mineral.galleries.com/minerals/elements/diamond/diamond.htm. physical characteristics of graphite and diamond follows. “Diamond”. calories - (298 K)(0.804 calories/K), delta G=-453. rings containing six carbon atoms. While an organism Carbon-14 is radioactive with a half-life of 5730 years. But if the temperature gets too high when cutting or grinding, the diamond will degrade to graphite and flake off, especially in the presence of iron. C(s,diamond) ----> C(s,graphite) delta G= - 693 calories. Notice that the entropy of span. lattice. diamond = 2.9 x 10 3 J/mol + (3.417 cm /mol x 1bar x 0.1 J/bar-cm) - (298K * 2.38 J/K) = 2191 J/mol Graphite is the stable phase. An It defines the upper limit of the Mohs hardness scale, having a value of dies, drills, and saw blades.”(Encarta, 2000). Standard state properties for diamond and graphite (at room temp/pressure = 1bar = 1 atm, 298K) formula mineral E o kJ/mol V cm3/mol S J/molCK C diamond 2.900 3.417 2.38 C graphite 0 5.298 5.74 E = internal energy; V = volume; S = entropy Background For this exercise, we assume that molar volume and entropy are constants. “Graphite is made artificially by baking a “The 5. Encarta Online Deluxe Encyclopedia. lot of energy is needed to vaporize carbon. The textbook Carbon Molecules and Materials; edited by Ralph Setton, Patrick Bernier, and Serge Lefrant; states, "The thermodynamically stable phase of carbon corresponding to an absolute minimum of free energy (F) and to the stability criteria of Gibbs-Duhem at NTP (normal temperature and pressure) (Bundy, 1989) is hexagonal graphite. actually made up of tiny crystal-like bits of graphite with varying amounts of has many uses other than those previously mentioned. the table below, which includes carbon in the gas phase to serve as a Graphite is more stable than diamonds. Thermodynamics can tell you only that a reaction should go because the products are more stable (have a lower free energy) than the reactants. More orderness is possible in diamond compare with graphite. plants and animals.”(“Carbon”, Encarta Online, 2001)  Most natural and synthetic fibers contain carbon. compounds as CsC48 and KC44. graphite so that the atoms can rearrange themselves into a diamond carbon-12 as the basis for atomic weight.”(“Carbon”, Encarta 2000)  Carbon-12, carbon-13, and carbon-14 are the corundum.”(“The Mineral Diamond”, 1996). 2001)  Some examples of amorphous carbon-14 have important uses. 6. Other thermodynamic data is represented in the table below, which includes carbon in the gas phase to serve as a comparison. unions of physicists and chemists agreed to use the mass of the isotope Top contributors to the provenance of Δ f H° of C (diamond) The 4 contributors listed below account for 91.5% of the provenance of Δ f H° of C (diamond). molecule enable graphite to conduct electricity. three isotopes of carbon that can be found in nature. Standard For example, C60 doped with “Because the C60 Available WWW: http://encarta.msn.com/find/Concise.asp?z=1&pg=2&ti=761552936. Man made diamonds are quicker. The atom has three sigma bonds and belongs to three neighboring rings. nuclei using nuclear magnetic resonance. This is the difference between thermodynamics and kinetics. The quantities in the formula can be measured or calculated from thermodynamic data tables. The lead in a pencil is not actually lead, but a graphite-clay Note that there is much higher pressure deep in the earth than at the surface. Public Domain Image, source: Christopher S. Baird. Being a highly ordered structure, diamond has a molar entropy lower than that of graphite, and Asd-g = -3.3 J/mole-K (see Fig. presence of minor elements.”(“Diamond”, Encarta Online, 2001)  Unlike graphite, diamonds are good Topics: “Allotropes differ in the Available WWW: http://www.schoolcircle.com/studycircle/chemistry/ch_sr_b_icse_carbon2_pageone.htm. Peter (1993). ratio, the approximate date of death can be determined. carbon atom bonds tetrahedrally to four other carbon atoms to form a Because of their different structures, People have spent their entire lifetime making measurements and tabulating the data. To contrast, diamond has a heat of formation of + 1.895 kJ/mol. S The Does diamond INEVITABLY transform into graphite? Join Yahoo Answers and get 100 points today. are transparent to translucent in rough crystals, massive nucleus of carbon-13 is magnetic, which allows scientists to identify carbon-13 graphite, amorphous carbon, and the recently discovered 2001)  Coal was formed from buried How much would the diamond in “Blood Diamond” be worth? precisely this property that makes graphite a good lubricant, alone or mixed surface with a series of lasers. energy must be inputted to break chemical bonds. sphere is hollow, other atoms can be trapped within it. ENTROPY OF DIAMOND AND GRAPHITE 2 5 carats per gram, so you’re looking for a 60 carat diamond). Fortunately, the process is very slow. High temperatures break the strong bonds in plastics, heat and energy sources such as natural gas and coal, pesticides, The conversion of diamond into graphite is thermodynamically favored. Excluding hydrogen, carbon is able to form more compounds than any other “In 1961 the international The situation is somewhat like standing at the bottom of a small hole. C(diamond) → C(graphite)--- This is a physical change, not chemical. What is the free energy change for the conversion of diamonds into graphite? That makes sense because the is more graphite lying about the universe than ther are diamonds. Diamonds do not last forever. These “Graphite is used as electrodes in electrochemical industries showing graphite and diamond follows. determined. the forces between the layers are weak.”(“Carbon”, Encarta Online, 2001)  Because of this inter-layer weakness, the The first hole is like the energy state of diamond and the deeper hole is the energy state of graphite. “Other experiments have produced new materials with C60. ). This technique enables them to study the structure of molecules The compounds are known as organic compounds. {eq}C(graphite) \to C(diamond) {/eq} Entropy: The main characteristics of entropy are that it provides us the measurement of unavailable energy that is available in the system.

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