NIST Standard Reference Database 30
Last Update to Data Content: 2002
"The Heat Capacities of Quartz, Cristobalite and Tridymite at Low Temperatures," C. T. Anderson, Journal of the American Chemical Society, Vol. 58, pp. 568-570 (1936), published by American Chemical Society.Language: English
The sample of quartz was obtained from Utah, through the Bureau of Mines Intermountain Experiment Station at Salt Lake. It was crushed and screened to pass a 28-mesh and remain on a 35-mesh screen. It was washed with hydrochloric and nitric acids, with water and dried. An analysis of the quartz, by decomposition with hydrofluoric acid gave the impurities as 0.07%, indicating that the quartz had a purity of at least 99.93% SiO2. Its density was found to be 2.6378 g/cm3 at 22.2 °C. The calorimeter was filled with 164.9 g. The starting material for the samples of cristobalite and tridymite was a very pure sample of vein quartz from Lake Toxaway, North Carolina. The sample was ground to pass through a 60-mesh screen, repeatedly washed with hydrochloric acid and then dried. Analysis of the silica with hydrofluoric acid showed 99.99% SiO2. The residue, when tested with sodium thiocyanate, showed a red coloration indicating the presence of iron. ... the sample of cristobalite was prepared by placing the quartz in a platinum cone set into a magnesia block into which a Pt-Pt + Rh thermocouple had been inserted. The cone was covered with platinum foil resting on two porcelain rods. The assembly was placed inside a graphite tube, heated by an induction furnace for ninety minutes at 1600 °C. After cooling in the furnace it was removed. An analysis showed 99.99% SiO2, the residue again showing iron. ... It had a density of 2.3201 g/cm3 at 23.3 °C. A 98.9 g sample was studied. The preparation of the tridymite was more difficult as it was necessary to use a flux. The purified quartz was mixed with carefully purified sodium tungstate in the proportion of 6 SiO2 to 1 Na2WO4, by weight. The mixture was ground in an agate mortar to pass a 200-mesh screen, placed in the platinum cone, described above, and heated in a high temperature furnace, provided with silicon carbide heating elements, for twenty-four hours at 1250 °C. ... Analysis of the sample showed 98.7% SiO2, the remainder Na2WO4. ... the sample was reground in an agate mortar to pass through a 400-mesh screen. After screening it was ground for ten minutes longer. ... this sample showed 99.46% SiO2. 107.8 g of this sample was used in the specific heat measurements. Its density was 2.2777 g/cm3 at 23.7 °C. The average deviation from the mean of the densities in six determinations each of all three materials was ±0.0001 g/cm3."
The authors cite C.T. Anderson, Journal of the American Chemical Society, Vol. 52, 2296, 2712 (1930), Vol. 54, 107 (1932), Vol. 55, 3621 (1933).
| Phase |
Temperature ( K ) |
Molar Heat Capacity ( J mol-1 K-1 ) |
Specific Heat ( J kg-1 K-1 ) |
|---|---|---|---|
| Quartz | 53.4 | 6.481 | 107.9 |
| Quartz | 56.4 | 7.046 | 117.3 |
| Quartz | 60.3 | 7.757 | 129.2 |
| Quartz | 65.4 | 8.812 | 146.7 |
| Quartz | 72.8 | 10.47 | 174.3 |
| Quartz | 80.0 | 11.97 | 199.3 |
| Quartz | 87.5 | 13.25 | 220.7 |
| Quartz | 98.9 | 15.40 | 256.4 |
| Quartz | 107.9 | 16.84 | 280.5 |
| Quartz | 122.1 | 19.92 | 331.7 |
| Quartz | 134.1 | 22.26 | 370.7 |
| Quartz | 143.8 | 24.02 | 399.9 |
| Quartz | 156.2 | 26.07 | 434.1 |
| Quartz | 169.1 | 28.18 | 469.3 |
| Quartz | 184.8 | 30.67 | 510.6 |
| Quartz | 197.7 | 32.45 | 540.2 |
| Quartz | 216.1 | 34.97 | 582.2 |
| Quartz | 234.7 | 37.55 | 625.2 |
| Quartz | 252.1 | 39.74 | 661.7 |
| Quartz | 272.0 | 42.59 | 709.2 |
| Quartz | 285.0 | 43.14 | 718.2 |
| Quartz | 296.1 | 44.27 | 737.0 |
| Cristobalite | 54.8 | 7.276 | 121.1 |
| Cristobalite | 57.8 | 7.791 | 129.7 |
| Cristobalite | 61.3 | 8.364 | 139.3 |
| Cristobalite | 69.9 | 10.14 | 168.9 |
| Cristobalite | 73.7 | 10.97 | 182.7 |
| Cristobalite | 77.7 | 11.85 | 197.3 |
| Cristobalite | 83.9 | 12.86 | 214.1 |
| Cristobalite | 88.0 | 13.51 | 224.9 |
| Cristobalite | 99.8 | 15.88 | 264.4 |
| Cristobalite | 112.0 | 18.21 | 303.2 |
| Cristobalite | 120.4 | 17.05 | 283.9 |
| Cristobalite | 136.8 | 22.79 | 379.5 |
| Cristobalite | 150.7 | 25.33 | 421.7 |
| Cristobalite | 164.0 | 27.41 | 456.4 |
| Cristobalite | 178.2 | 29.70 | 494.5 |
| Cristobalite | 193.7 | 31.89 | 531.0 |
| Cristobalite | 210.9 | 34.40 | 572.7 |
| Cristobalite | 229.5 | 37.03 | 616.5 |
| Cristobalite | 241.4 | 38.41 | 639.6 |
| Cristobalite | 257.1 | 40.15 | 668.5 |
| Cristobalite | 272.2 | 41.72 | 694.6 |
| Cristobalite | 297.2 | 44.10 | 734.3 |
| Cristobalite | 297.3 | 44.43 | 739.8 |
| Tridymite | 54.2 | 7.364 | 122.6 |
| Tridymite | 57.6 | 7.962 | 132.6 |
| Tridymite | 61.5 | 8.581 | 142.9 |
| Tridymite | 68.6 | 10.05 | 167.4 |
| Tridymite | 80.5 | 12.62 | 210.2 |
| Tridymite | 90.8 | 14.34 | 238.8 |
| Tridymite | 100.4 | 16.48 | 274.5 |
| Tridymite | 108.8 | 17.95 | 298.9 |
| Tridymite | 117.7 | 19.58 | 326.0 |
| Tridymite | 131.4 | 22.19 | 369.5 |
| Tridymite | 149.3 | 25.38 | 422.5 |
| Tridymite | 164.3 | 27.94 | 465.3 |
| Tridymite | 181.6 | 30.64 | 510.1 |
| Tridymite | 187.9 | 31.60 | 526.2 |
| Tridymite | 202.6 | 33.63 | 560.0 |
| Tridymite | 219.5 | 35.90 | 597.8 |
| Tridymite | 235.4 | 38.05 | 633.5 |
| Tridymite | 249.1 | 39.66 | 660.3 |
| Tridymite | 271.8 | 42.17 | 702.2 |
| Tridymite | 278.1 | 42.80 | 712.7 |
| Tridymite | 290.8 | 44.14 | 735.0 |
| Tridymite | 294.9 | 44.43 | 739.8 |