Melting point of gallium

From the ventilation point of view, the fixed points -38.83 °C (triple-point of mercury), 0.010 °C (triple-point of water), 29.76 °C (melting point of gallium), and 156.60 °C (freezing point of indium) are of relevance. The triple-point of water is relatively simple to achieve and maintain with a triple-point apparatus. Some freezing point cells are covered in standards. In practical temperature calibration of measuring instruments, the lTS-90 fixed points are not used directly. 

Mendeleev predicted that the melting point of gallium would fall between those of aluminium (660°C) and indium (115°C). In fact gallium has an anomalously low melting point of 30°C. 

The exceptionally low melting point of gallium has no simple explanation. Since its boiling point (2070°) is not abnormal, gallium has the longest liquid range of any known substance and finds use as a thermometer liquid. 

Gallium is used as a fixed thermometric standard to calibrate thermistor probes of electronic thermometers used in clinical chemistry and experimental laboratory analyses (Scansetti 1992). This standard is appropriate because (i) the melting point of gallium (29.78 °C) falls within the region of critical importance to laboratory biological determinations (25-37°C) and (ii) the melt can be maintained accurately and constantly for several hours (Mangum 1977). 

Figure 8.16 The Group 3A elements. The low melting point of gallium (29,8 °C) causes It to melt when held In hand.

Elemental gallium is another substance whose solid floats on its liquid the density of Ga(s) is 5.91 g/cm while the density of Ga( ) is 6.09 g/cm. The melting point of gallium under normal pressure is 302.9 K. What pressure is necessary to reduce the melting point to 298.1 K The entropy of fusion of Ga is 18.45 J/mol K. 

Now substimte C into the equation and calculate the answer. Note The number of digits reported in this answer follows significant figure conventions, covered in Section 1.7. FOR PRACTICE 1.2 Gallium is a solid metal at room tanperature but will melt to a liqi What is this tonperature on (a) the Celsius scale aud (b) the Kelvi °F = 1.8(°C) + 32 T = 1.8(40.00 °C) + 32 = 104.00 °F rid in your hand. The melting point of gallium is 85.6 °F. n scale ... 

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