CHM 1101 2014LectureNotesModuleHNov5
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Transcript of CHM 1101 2014LectureNotesModuleHNov5
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Module H: The Solid State Nov 5
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Radius
Structure Coordination # Radius & Length
Simple Cubic 6 = /2
Body-centred Cubic (bcc) 8 4 = 3
Face-centred Cubic (fcc) 12 4 = 2
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Radius of a Metal atom Example 1:
At room temperature, iron crystallizes in a bcc structure. The edge of the cubic cell corresponding to Figure is found to be 287 pm. What is the radius of an iron atom?
Ans: 124 pm 3
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Density Use data from Example 1, together with the molar mass of Fe
and the Avogadro constant, to calculate the density of iron in g/cm3.
1. Find mass of Unit cell.
2. Determine volume of unit cell.
3. Find density.
Density = mass/volume
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Phase Diagrams A phase is any sample of matter with definite composition and
uniform properties that is distinguishable from other phases with which it is in contact.
A process in which the physical form but not the chemical identity of a substance changes is called a phase change or a changes of state.
Triple point - the unique temperature and pressure at which the three states of matter, solid, liquid, and gas, coexist in equilibrium.
Critical point - At the critical point the liquid and vapour become indistinguishable
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Sketch a plausible phase diagram for hydrazine (N2H4) from the following data:
triple point = 2.0C and 3.4 mmHg,
the normal melting point = 2.0C,
the normal boiling point = 113.5C and
the critical point 380C and 145 atm.
The density of the liquid is less than that of the solid. Label significant data points on this diagram.
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