(Solved): Problem 7: Use the phase diagram of silicon to answer the following questions. For the y-axis of th ...

Problem 7: Use the phase diagram of silicon to answer the following questions. For the $y$-axis of the plot, $1\mathrm{bar}?1\mathrm{atm}=100,000\mathrm{Pa}$. Figure from Lawrence Livermore Laboratory (1975) a) From the phase diagram rank the relative densities of the 3 forms of Silicon near the triple point (such as: $?$ tetragonal $<?$ cubic $<?$ liquid ). Explain how you decided that. b) Can cubic silicon convert spontaneously to liquid silicon at $1600\mathrm{K}$ and $1\mathrm{atm}$ ? c) Use the values on the graph. Estimate the enthalpy of fusion when liquid silicon freezes to cubic silicon at $1700\mathrm{K}$ and $1\mathrm{atm}$. The difference in molar volume between liquid and cubic silicon is $1.13\mathrm{cm}3/\mathrm{mol}$. Note the data point(s) you used from the plot for your calculation. Also specify the correct sign of the enthalpy of fusion.