Calculate The Molar Mass of Each of The Following Substances

The molar mass of a substance is the mass of one mole of that substance. It's calculated by summing the atomic masses of all atoms in the molecular formula. This calculation is essential in chemistry for stoichiometry, solution preparation, and reaction yield analysis.

What is Molar Mass?

Molar mass (also called molecular weight) is the mass of one mole of a substance. It's expressed in grams per mole (g/mol). The molar mass of a compound is the sum of the atomic masses of all the atoms in its molecular formula.

For example, the molar mass of water (H₂O) is calculated by adding the atomic masses of two hydrogen atoms and one oxygen atom. The atomic masses are typically found on the periodic table.

Molar mass is different from molecular mass. Molecular mass refers to the mass of a single molecule, while molar mass refers to the mass of a mole (6.022 × 10²³ molecules) of that substance.

How to Calculate Molar Mass

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

Write down the molecular formula of the substance.
Determine the atomic mass of each element in the formula from the periodic table.
Multiply each atomic mass by the number of atoms of that element in the formula.
Sum all the values to get the molar mass.

Formula: Molar Mass = Σ (Number of atoms of each element × Atomic mass of each element)

Example Calculation

Let's calculate the molar mass of sodium chloride (NaCl):

Molecular formula: NaCl
Atomic mass of sodium (Na): 22.99 g/mol
Atomic mass of chlorine (Cl): 35.45 g/mol
Molar mass = (1 × 22.99) + (1 × 35.45) = 58.44 g/mol

Common Substances and Their Molar Masses

The following table shows the molar masses of some common substances:

Substance	Formula	Molar Mass (g/mol)
Water	H₂O	18.02
Sodium chloride	NaCl	58.44
Glucose	C₆H₁₂O₆	180.16
Ethanol	C₂H₅OH	46.07
Carbon dioxide	CO₂	44.01

These values are approximate and may vary slightly depending on the specific isotopes present.

Frequently Asked Questions

What is the difference between molar mass and molecular mass?: Molecular mass refers to the mass of a single molecule, while molar mass refers to the mass of a mole (6.022 × 10²³ molecules) of that substance.
How do I find the atomic masses of elements?: You can find atomic masses on the periodic table, which is typically available in chemistry textbooks or online resources.
Why is molar mass important in chemistry?: Molar mass is essential for stoichiometry calculations, solution preparation, and determining reaction yields.
Can molar mass be used to identify substances?: Molar mass alone cannot identify a substance, but it can help confirm the identity when combined with other analytical techniques.