# What do you mean by molecular mass?

Molecular mass. It is calculated as the sum of the atomic weights of each constituent element multiplied by the number of atoms of that element in the molecular formula. The molecular mass of small to medium size molecules, measured by mass spectrometry, determines stoichiometry.
A.

### How do you calculate the molecular mass?

The molar mass is the mass of all the atoms in a molecule in grams per mole. To calculate the molar mass of a molecule, we first obtain the atomic weights from the individual elements in a periodic table. We then count the number of atoms and multiply it by the individual atomic masses.
• #### What is molar mass measured in?

Molar mass is the mass of a given substance divided by the amount of that substance, measured in g/mol. For example, the atomic mass of titanium is 47.88 amu or 47.88 g/mol. In 47.88 grams of titanium, there is one mole, or 6.022 x 1023 titanium atoms.
• #### How do you calculate the molecular mass?

It is easy to find the molecular mass of a compound with these steps.
1. Determine the molecular formula of the molecule.
2. Use the periodic table to determine the atomic mass of each element in the molecule.
3. Multiply each element's atomic mass by the number of atoms of that element in the molecule.
• #### What is the weight of a formula?

Formula weight, in chemistry, the sum of the atomic weights of all atoms appearing in a given chemical formula. It is generally applied to a substance that does not consist of individual molecules, such as the ionic compound sodium chloride.
B.

### What is the molar mass of a substance?

The molar mass is the mass of a given chemical element or chemical compound (g) divided by the amount of substance (mol). The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.
• #### How do you go from grams to molecules?

So, step one is to convert molecules to moles by dividing by Avogadro's number (6.022*10^23). Second step, once you have a number of moles, is to multiply it by the molar mass of the compound. You can find this by adding the molar mass of each atom in the formula.
• #### How do you find molar mass of a gas?

Example #1: The density of a gas is measured at 1.853 g / L at 745.5 mmHg and 23.8 °C. What is its molar mass? Solution #1: Convert mmHg to atm and °C to K. Use 1.000 L. Plug into PV = nRT and solve for n. Then divide 1.853 g by n, the number of moles, for your answer.
• #### How do you get from molecules to Grams?

So, step one is to convert molecules to moles by dividing by Avogadro's number (6.022*10^23). Second step, once you have a number of moles, is to multiply it by the molar mass of the compound. You can find this by adding the molar mass of each atom in the formula.
C.

### Why is it important to know the molecular mass of a substance?

However, because densities of different substances vary, weight and volume aren't very good guidelines to amount. A small, dense object may weigh a lot, and have more molecules of substance than a large, hollow object. The molar mass of a substance is defined relative to the mole.
• #### How do you convert grams to moles?

Using a calculator, divide the number of grams by the molar mass. The result is the number of moles in your element or compound. For example, imagine you have 2 g of water, or H2O, and you want to convert it to moles. The molecular mass of H2O is 18g/mol.
• #### How many molecules are in an atom?

The chemical formula for water is H2O which means that every molecule of water has 2 atoms of hydrogen (H) and one atom of oxygen (O). Here comes the key part. From the Periodic Table of Elements, one sees that one mole of hydrogen atoms weighs 1 gram while one mole of oxygen atoms weighs 16 grams.
• #### How do you find molar mass of a gas?

Example #1: The density of a gas is measured at 1.853 g / L at 745.5 mmHg and 23.8 °C. What is its molar mass? Solution #1: Convert mmHg to atm and °C to K. Use 1.000 L. Plug into PV = nRT and solve for n. Then divide 1.853 g by n, the number of moles, for your answer.

Updated: 21st October 2019