How do you calculate the mass of one mole of a compound?

Answer 1

To find the molecular weight (also called the molecular mass or molar mass) of a compound or chemical, you need two things: the molecular formula of the compound and a periodic table.

The molecular formula tells you how many atoms of each element is present in the compound. To find the molecular weight, just add up the atomic weights of each element present in the compound, being sure to multiply by the number of times that atom appears. The atomic weight of each element is found on a Periodic Table.

See the Related Questions and the Web Links to the left for a periodic table with the atomic weight of each element.

Here are some examples:

1) What is the molecular weight of methane, CH4?

The formula for methane is CH4, which means there is one carbon atom (C) and 4 hydrogen atoms. From the periodic table, the atomic weight of carbon is 12.011 grams per mole, and the atomic weight of hydrogen is 1.01 grams per mole. Adding them up, we have

12.01 + (4 × 1.01) = 16.05 grams per mole

2) What is the molecular weight of table salt, or sodium chloride?

The formula for sodium chloride is NaCl. The molecular weight of NaCl is just the sum of the atomic weights of sodium (Na) and chlorine (Cl):

22.99 + 35.45 = 58.44 grams/mole

3) What is the molar mass of octane, C8H10?

Answers: The molar mass of octane is just 8 times the mass of carbon plus 10 times the mass of hydrogen:

(8 × 12.01) + (10 × 1.01) = 106.18 grams/mole

Answer 2

The molecular mass can be calculated as the sum of the individual isotopic masses (as found in a table of isotopes) of all the atoms in any molecule. This is possible because molecules are created by chemical reactions which, unlike nuclear reactions, have very small binding energies compared to the rest mass of the atoms ( < 10-9) and therefore create a negligible mass defect. The use of average atomic masses derived from the standard atomic weights found on a standard periodic table will result in an average molecular mass, whereas the use of isotopic masses will result in a molecular mass consistent with the strict interpretation of the definition, i.e. that of a single molecule. However, any given molecule may contain any given combination of isotopes, so there may be multiple molecular masses for each chemical compound.

-cj

Answer 3

You would take the molar mass of each element that is in the compound and add them up. For example, H2O would be 2 hydrogen atoms and one oxygen. 1+1+16 equals 18.

........................................................................................................................................

in order to calculate the molar mass of a compound, multiply the mass of 1 mole of each element by the ratio of that element to one mole of the compound then add the resulting masses.

Answer 4

To find the mass of one mole of a compound you must find the mass of a mole of the component elements and add them together.

Just as an added side note the molar mass of any element is that elements standard Atomic Mass as listed on the periodic table in grams.

An example of this would H2O, hydrogen: 1 mole = 1.0794g/mol, Oxygen: 1 mole = 16.00g/mol.

Based on these numbers one calculates the molar mass of H2O to be two moles of Hydrogen and one mole of Oxygen or ~18.16g/mol.

I will also offer a second example to help further clarify this idea. For this the chemical compound is glucose C6H12O6. hydrogen: 1 mole = 1.0794g/mol, Oxygen: 1 mole = 16.00g/mol, Carbon: 1 mole = 12.0g/mol.

So one calculates that Glucose has a molar mass of six moles of carbon, twelve moles of hydrogen, and six moles of oxygen or ~ 181g/mol.

Well hope this helps.

Answer 5

The molecular mass of a compound is the sum of the atomic weights of the elements in this compound.

Example: methane, CH4

Atomic weight of hydrogen: ca. 1,007 98

Atomic weight of carbon: ca. 12,106

The molecular mass of methane: (1,00798 x 4) + 12,106 = 16,137 92

Answer 6

To calculate the mass of one mole of a compound, take the molar mass (which is the same as atomic mass) of the elements used to make the compound and add them together. The atomic mass can be found directly under the elements' symbol in the periodic table.

For example, the chemical formula for water is H2O. That's two atoms of hydrogen and one atom of oxygen. The molar mass of hydrogen is 1.0794g/mole. There's two atoms of hydrogen, so multiply it by two: 1.0794 x 2 = 2.1588. Then, get the molar mass of oxygen, which is 16g/mole. There's only one atom of oxygen, so you don't need to multiply it. Lastly, add the two numbers together (2.1588+16) and you have the answer: 18.16.

Answer 7

Molar mass or molar wieght of a substance is the molecular mass of the substance written in gram units.

For example- the molecular mass of water (H2O) is 18u. Therefore the molar mass of water is 18 grams.

Molar mass could be also defined as the mass of 1 mole of a substance.

( 1 mole of a substance has NA number of particles which may be ions, atoms or molecules. NA represents Avogadro's constant.)

Answer 8

To calculate the mass of one mole of a compound, you need to add up the atomic masses of all the elements in the compound as given on the periodic table. This sum represents the molar mass of the compound in grams per mole.

Answer 9

use the sum of the stoms that compose it