Molar Mass Calculator

What is Molar Mass?

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is a fundamental concept in chemistry that relates the mass of a substance to the number of particles it contains. Molar mass is essential for stoichiometric calculations and understanding the composition of chemical compounds.

How to Calculate Molar Mass

To calculate the molar mass of a compound, follow these steps:

1. Identify the chemical formula of the compound
2. Look up the atomic masses of each element in the periodic table
3. Multiply each element's atomic mass by its subscript in the formula
4. Sum up all the calculated masses

Formula

The molar mass of a compound is calculated using the following formula:

\[ M = \sum_{i} (n_i \times A_i) \]

Where:

• \(M\) is the molar mass of the compound (g/mol)
• \(n_i\) is the number of atoms of element \(i\) in the compound
• \(A_i\) is the atomic mass of element \(i\) (g/mol)

Calculation Steps

Let's calculate the molar mass of water (H₂O) as an example:

1. Identify the elements: Hydrogen (H) and Oxygen (O)
2. Look up atomic masses: H = 1.008 g/mol, O = 15.999 g/mol
3. Apply the formula: \[ M_{H_2O} = (2 \times M_H) + (1 \times M_O) \] \[ M_{H_2O} = (2 \times 1.008 \text{ g/mol}) + (1 \times 15.999 \text{ g/mol}) \] \[ M_{H_2O} = 2.016 \text{ g/mol} + 15.999 \text{ g/mol} \] \[ M_{H_2O} = 18.015 \text{ g/mol} \]

Example and Visual Representation

Let's visualize the molar mass of water (H₂O):

In this representation:

• The large blue circle represents the oxygen atom (O)
• The two smaller red circles represent the hydrogen atoms (H)
• The total molar mass is the sum of these components: 15.999 g/mol (O) + 2 × 1.008 g/mol (H) = 18.015 g/mol

This visual helps to understand how the molar mass of a compound is derived from its constituent elements, each contributing its atomic mass to the total.