# 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 10^{23}titanium atoms.#### How do you calculate the molecular mass?

**It is easy to find the molecular mass of a compound with these steps.**- Determine the molecular formula of the molecule.
- Use the periodic table to determine the atomic mass of each element in the molecule.
- 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 H_{2}O, and you want to**convert**it to**moles**. The molecular mass of H_{2}O is 18g/**mol**.#### How many molecules are in an atom?

The chemical formula for water is H_{2}O 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