# At what temperature is bismuth the densest?

Both water and bismuth have denser liquids compared to solid forms, and we know water is the densest at the temperature of about 4°C.

Does the same thing apply to bismuth? Of course, I know the melting point of bismuth is about 271° C. So the temperature of interest should be around it I think.

• The reasons that water has that density anomaly do not apply to bismuth. NIST has tabulated density values to peruse at your leisure. Commented Jun 15, 2023 at 1:47
• So what's the reason for bismuth?
– user85778
Commented Jun 15, 2023 at 1:52
• I guess I'm a bit confused - do you mean the liquid being denser than the solid, or that water is densest at about 4C? Commented Jun 15, 2023 at 13:10
• Both. And in the case of bismuth it's densest at about 310C based on the paper in Nilay Ghosh's answer. While in the case of antimony there's no such an anomaly but its liquid form is also denser.
– user85778
Commented Jun 15, 2023 at 13:15
• For water at 4C, see chemistry.stackexchange.com/questions/81756/…. For the rest, you need to understand that thermal expansion coefficients of many (well, all really) materials are not a constant and can even change sign. Why? the shape of the potential well the atoms find themselves in. Commented Jun 15, 2023 at 13:22

The densities of Sb and Bi melts were investigated by an improved Archimedean method. The results show that the density of the Sb melt decreases linearly with increasing temperature, but the density of the Bi melt firstly increases and then decreases as the temperature increases. There is a maximum density value of $$\pu{10.002 g/cm^3}$$ at 310 ℃ ,about 39 ℃ above the melting point. The temperature dependence of the Sb melt is well fitted with the expression $$\pu{ρ = 6.8590 - 5.8105 × 10^{-4} T}$$ , and that of the Bi melt is fitted with $$\ce{ρ = 10.3312 - 1.18 ×10^{-3} T}$$.

Source: Geng, Haoran & Sun, Chunjing & Wang, Rui & Qi, Xiaogang & Zhang, Ning. (2007). Temperature dependence of densities of Sb and Bi melts. Chinese Science Bulletin. 52. 2031-2034. DOI: 10.1007/s11434-007-0309-7

Also see:

1. Greenberg, Y. & Yahel, Eyal & Caspi, E. & Benmore, Chris & Beuneu, B. & Dariel, M.P. & Makov, Guy. (2009). Evidence for a temperature-driven structural transformation in liquid bismuth. EPL (Europhysics Letters). 86. 36004. DOI: 10.1209/0295-5075/86/36004.
2. Tournier, R.F. Multiple Glass Transitions in Bismuth and Tin beyond Melting Temperatures. Metals 2022, 12, 2085. DOI: 10.3390/met12122085
• Why does this say the density of liquid bismuth is 10.067 g/cm$^3$ which is bigger than 10.002? Also, there is another article saying the number as 10.022.
– user85778
Commented Jun 15, 2023 at 2:59
• @SnackExchange You should check latest papers which has improved measurement techniques. Density of bismuth around melting point is just above 9.9 g/cm3 which goes to maximum value of 10.002 g/cm3 at around 310 C (the ref.2 has a better graph). The Wikipedia article needs to have the values corrected. Commented Jun 15, 2023 at 3:02
• When I plugged temperatures in the density formula of bismuth, I found the temperature should be about 280 K in order to have a density of about 10 g/cm$^3$. But when we put 583 K (310 C) the answer is about 9.6! How can it be explained?
– user85778
Commented Jun 15, 2023 at 13:26
• @SnackExchange If you follow the paper, it says that in the range of m.p. and 310 C, the equation is $\mathrm{ρ = 9.44903+1.73×10^{−3} T}$ giving density value within 1.3% error. Above 310 C, the equation is $\mathrm{ρ =10.3312−1.18×10^{−3} T}$ Commented Jun 17, 2023 at 3:58