Physical Properties of Potassium
Atomic Number
19
Atomic weight (based on C=12)
39.102
Natural isotopes (mass number)
39, 40, 41
Istotopic abundance
93.1%, 0.012%, 6.88%
Absorption cross-section to 0.025-ev (thermal) neutrons
2.1 barns
Total cross-section to 0.025-ev (thermal) neutrons
4.3 barns
Ionization potential
4.318 Volts
Melting point
63.2 °C
Boiling point
756.5 °C
Volume increase on melting
2.4%
Latent heat of fusion
14.2 cal/g
Latent heat of vaporization at the boiling point
474 cal/g
Critical temperature
2287°K (estimate)
Critical pressure
167 atm (estimate)
Critical volume
0.216 cm³/g-mole (estimate)
Density (solid)
20°C - 0.855 g/cm³
m.p. - 0.848 g/cm³
Density (liquid)
m.p. - 0.828 g/cm³
100°C - 0.819 g/cm³
400°C - 0.75 g/cm³
550°C - 0.715 g/cm³
b.p. - 0.664 g/cm³
Specific volume (saturated vapor)
400°C - 1.7 x 10⁵g/cm³
550°C - 0.22 x 10⁵cm³
b.p. - 1.8 x 10³ g/cm³
Viscosity (liquid)
100°C - 0.472 cP
400°C - 0.216 cP
550°C - 0.167 cP
b.p. - 0.13 cP
Surface tension
m.p. - 111 dynes/cm
100°C - 109 dynes/cm
400°C - 90 dynes/cm
550°C - 80 dynes/cm
b.p. - 67 dynes/cm
Electrical resistivity (solid)
20°C - 4.7 µΩcm
m.p. - 6.5 µΩcm (estimate)
Electrical resistivity (liquid)
m.p. - 12 µΩcm
100°C - 14.3 µΩcm
400°C - 34.5 µΩcm
550°C - 47.3 µΩcm
b.p. - 70.5 µΩcm
Thermal conductivity (solid)
20°C - 1.08 W/cm-°C (estimate)
m.p. - 1.05 W/cm-°C (estimate)
Thermal conductivity (liquid)
m.p. - 0.54 W/cm-°C
100°C - 0.522 W/cm-°C
400°C - 0.408 W/cm-°C
550°C - 0.364 W/cm-°C
b.p. - 0.307 W/cm-°C
Specific heat (solid)
20°C - 0.184 cal/g-°C
m.p. - 0.193 cal/g-°C
Specific heat (liquid)
m.p. - 0.197 cal/g-°C
100°C - 0.194 cal/g-°C
400°C - 0.182 cal/g-°C
550°C - 0.182 cal/g-°C
b.p. - 0.187 cal/g-°C