The molar mass of calcium oxide (CaO) is 56.077 g/mol.
Case matters: CO is carbon monoxide, Co is
cobalt. Brackets and hydrates are fine — try
or
.
| Element | Atoms | Atomic mass | Mass contributed | Percent |
|---|---|---|---|---|
| Calcium (Ca) | 1 | 40.078 | 40.078 | 71.47% |
| Oxygen (O) | 1 | 15.999 | 15.999 | 28.53% |
| Total | 2 | 56.077 | 100.00% |
40.078 + 15.999 = 56.077 g/mol
Grams and moles
25 g of calcium oxide is 0.4458 mol, because 25 ÷ 56.077 = 0.4458.
This element has no single atomic weight. Their isotopic mix varies slightly depending on where on Earth the sample came from, so the figure used here is the conventional value IUPAC publishes for when one number is needed: oxygen is 15.999, and really lies between 15.99903 and 15.99977.
Quicklime is 56.077 g/mol, made up of 71.47% calcium and 28.53% oxygen. It is one of the oldest manufactured chemicals, produced by roasting limestone in a kiln.
The name quicklime refers to how violently it reacts with water, an older sense of quick meaning living. Adding water releases about 63 kilojoules per mole as heat, enough to raise steam and to ignite paper in contact with it. Self-heating food cans use the reaction deliberately.
Its industrial importance is almost entirely about mass. Steelmaking uses it as a flux to carry off silicon and phosphorus impurities as slag, and the tonnage consumed per tonne of steel is calculated directly from the impurity content of the ore. Cement production is the other large consumer.
The compound is strongly basic and caustic on skin, and it is the active component of the burial lime once used to reduce odour, though contrary to the usual story it slows decomposition rather than accelerating it.