Molar Mass Calculator
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Molar Mass
The molar mass of some substance represents the mass of 1 mole of a substance. A mole is the SI (International System of Units) standard for measuring the number of some individual units that make up some substance.
Just like one dozen represents the number twelve, so does one mole represent another number. This number is Avogadro's number and is equal to 6.02214076*10^23. So, where a dozen eggs is twelve eggs, a mole eggs would be 6.02214076*10^23 eggs.
However, one mole is quite the quantity and is therefore used to represent extremely small units, such as atoms or molecules. For example, one mole of a water molecule, chemically denoted as H2O, means 6.02214076*10^23 molecules of water.
The molar mass indicates what the mass is of one mole of a substance, usually expressed in grams per mol. One water molecule weighs roughly 2.99 × 10^-23 grams. This means that one mole of water weighs 6.02214076*10^23 × 2.99*10^-23 g = 18.01 grams. The molar mass, or molecular weight, of water is thus 18.01 g/mol
Each atom in the periodic table has a "molar mass", but because the mass describes a single atom, it is called the atomic mass. Even though it is the same thing, the unit of mass for a single atom can also be expressed as u, rather than g/mol. Hydrogen has an atomic mass of 1.01 u, whereas oxygen has an atomic mass of 16 u. Water contains two hydrogen atoms and one oxygen atom. 1.01 * 2 + 16 * 1 = 18.01, which is the molar mass of water as calculated above.
This calculator
This calculator takes in some molecule and shows the molar mass of each atom group of the molecule. It also gives the total molar mass of the molecule, which is just the sum of its individual atom groups. For example, take the molecule for Methane, chemically denoted as CH4. It contains one Carbon atom, having a molar mass of 12.01 g/mol. It contains four Hydrogen atoms, having a molar mass of 1.01 g/mol per Hydrogen atom, so 4.04 g/mol for the atom group.
The total molar mass of CH4 is thus 12.01 + 4*1.01 = 16.04 g/mol.