Density of Common Substances — Elements, Compounds, and Materials
| Substance | Formula | Density (g/cm³) | State (25 °C) | Category |
|---|---|---|---|---|
| Hydrogen | H₂ | 0.0000899 | Gas | Element (gas) |
| Helium | He | 0.000179 | Gas | Element (gas) |
| Nitrogen | N₂ | 0.00125 | Gas | Element (gas) |
| Oxygen | O₂ | 0.00143 | Gas | Element (gas) |
| Chlorine | Cl₂ | 0.00321 | Gas | Element (gas) |
| Lithium | Li | 0.534 | Solid | Metal |
| Sodium | Na | 0.971 | Solid | Metal |
| Magnesium | Mg | 1.738 | Solid | Metal |
| Aluminum | Al | 2.7 | Solid | Metal |
| Titanium | Ti | 4.507 | Solid | Metal |
| Iron | Fe | 7.874 | Solid | Metal |
| Nickel | Ni | 8.908 | Solid | Metal |
| Copper | Cu | 8.96 | Solid | Metal |
| Zinc | Zn | 7.134 | Solid | Metal |
| Silver | Ag | 10.49 | Solid | Metal |
| Tin | Sn | 7.287 | Solid | Metal |
| Gold | Au | 19.32 | Solid | Metal |
| Platinum | Pt | 21.45 | Solid | Metal |
| Lead | Pb | 11.34 | Solid | Metal |
| Mercury | Hg | 13.53 | Liquid | Metal |
| Carbon (diamond) | C | 3.513 | Solid | Nonmetal |
| Carbon (graphite) | C | 2.267 | Solid | Nonmetal |
| Sulfur | S₈ | 2.07 | Solid | Nonmetal |
| Silicon | Si | 2.329 | Solid | Metalloid |
| Water | H₂O | 0.997 | Liquid | Compound (liquid) |
| Ice | H₂O | 0.917 | Solid | Compound (solid) |
| Ethanol | C₂H₅OH | 0.789 | Liquid | Compound (liquid) |
| Methanol | CH₃OH | 0.792 | Liquid | Compound (liquid) |
| Acetone | C₃H₆O | 0.791 | Liquid | Compound (liquid) |
| Acetic acid | CH₃COOH | 1.049 | Liquid | Compound (liquid) |
| Sulfuric acid (conc.) | H₂SO₄ | 1.84 | Liquid | Compound (liquid) |
| Hydrochloric acid (conc.) | HCl (aq) | 1.18 | Liquid | Compound (liquid) |
| Glycerol | C₃H₈O₃ | 1.261 | Liquid | Compound (liquid) |
| Diethyl ether | C₄H₁₀O | 0.713 | Liquid | Compound (liquid) |
| Chloroform | CHCl₃ | 1.489 | Liquid | Compound (liquid) |
| Carbon tetrachloride | CCl₄ | 1.594 | Liquid | Compound (liquid) |
| Sodium chloride | NaCl | 2.165 | Solid | Compound (solid) |
| Calcium carbonate | CaCO₃ | 2.711 | Solid | Compound (solid) |
| Sodium hydroxide | NaOH | 2.13 | Solid | Compound (solid) |
| Glucose | C₆H₁₂O₆ | 1.54 | Solid | Compound (solid) |
| Sucrose | C₁₂H₂₂O₁₁ | 1.587 | Solid | Compound (solid) |
| Air (dry, sea level) | — | 0.0012 | Gas | Mixture |
| Seawater | — | 1.025 | Liquid | Mixture |
Solids and liquids are tabulated at roughly 25 °C and 1 atm; gases at STP (0 °C, 1 atm). Density falls with rising temperature for nearly everything except water near 4 °C, where the density anomaly gives a maximum. Concentrated-acid entries refer to commercial reagent grades (98% H2SO4, 37% HCl); diluting changes the density substantially, so use a tabulated concentration-vs-density chart when preparing dilutions by mass. Carbon's two phases differ (diamond 3.51 vs graphite 2.27 g/cm³) because of their different bonding networks. Sources: CRC Handbook of Chemistry and Physics, NIST Chemistry WebBook.
Frequently Asked Questions
Why does ice float on water?
Ice is about 9% less dense than liquid water (0.917 vs 0.997 g/cm³) because the hexagonal hydrogen-bonded lattice of solid water packs each molecule into a fixed tetrahedral cage with substantial empty space. Liquid water above the freezing point has the same hydrogen-bonded geometry locally but trades the rigid open framework for a denser, jostling network of broken-and-reformed bonds. The anomaly continues into the liquid: water density actually peaks at about 4 °C, then falls again as you approach 0 °C. That's why lakes freeze top-down rather than bottom-up.
How is density used in chemistry calculations?
Density (d = m/V) is the bridge between what you can measure with a graduated cylinder and what you actually need on a balance. Worked example: 50.0 mL of concentrated H2SO4 at d = 1.84 g/mL contains m = 1.84 × 50.0 = 92.0 g of solution. To get the molarity of that solution you'd combine density with the mass percent (98% for concentrated H2SO4) and the molar mass. Density is also how you convert molarity (mol per L of solution) to molality (mol per kg of solvent), and the only way to identify an unknown liquid by physical properties.
Which element has the highest density?
Osmium tops the list at about 22.59 g/cm³, edging out iridium at 22.56 — the two have been swapped in textbooks over the years as measurement precision improved, but osmium is the current consensus winner. Among elements you'll handle in a typical chemistry course, platinum (21.45) and gold (19.32) are the densest. At the opposite extreme, lithium (0.534 g/cm³) is the least dense metal and floats on water (where it also reacts vigorously). The pattern reflects atomic mass plus crystal-packing efficiency, not just one or the other.