What is the molar mass of sodium nitrate?


Sodium nitrate, with the chemical formula NaNO3, is a commonly used inorganic compound. It is an important ingredient in fertilizers, food preservatives, and as a component in solid rocket propellants. The molar mass of a compound is the mass of one mole of that compound and is expressed in grams per mole (g/mol). In this article, we will explore the concept of molar mass and calculate the molar mass of sodium nitrate.

Understanding Molar Mass

Molar mass is a fundamental concept in chemistry, and it is defined as the mass of one mole of a substance. A mole is a unit that represents a specific number of atoms, molecules, ions, or other particles, which is approximately 6.022 x 10^23 (Avogadro’s number). The molar mass of a compound is calculated by summing the atomic masses of all the atoms present in the compound.

Atomic Mass

Atomic mass is the mass of an atom relative to the mass of a carbon-12 atom, which is assigned a mass of exactly 12 atomic mass units (amu). The atomic masses of elements are listed on the periodic table, usually below the element’s symbol. These atomic masses represent the average mass of the naturally occurring isotopes of an element, taking into account their relative abundance.

Atomic Mass of Sodium (Na)

Sodium (Na) is a chemical element with atomic number 11. It has several isotopes, but the most common isotope is sodium-23, which accounts for approximately 100% of naturally occurring sodium. The atomic mass of sodium-23 is 22.99 amu.

Atomic Mass of Nitrogen (N)

Nitrogen (N) is a chemical element with atomic number 7. It has two stable isotopes, nitrogen-14 (99.63% abundance) and nitrogen-15 (0.37% abundance). The atomic mass of nitrogen-14 is 14.01 amu, while the atomic mass of nitrogen-15 is 15.00 amu.

Atomic Mass of Oxygen (O)

Oxygen (O) is a chemical element with atomic number 8. It has three stable isotopes, oxygen-16, oxygen-17, and oxygen-18, which have atomic masses of 15.99 amu, 16.99 amu, and 17.99 amu, respectively. Oxygen-16 is the most abundant isotope, accounting for approximately 99.76% of naturally occurring oxygen.

Calculating the Molar Mass of Sodium Nitrate

To calculate the molar mass of sodium nitrate (NaNO3), we need to sum the atomic masses of sodium, nitrogen, and oxygen atoms in the compound. The chemical formula of sodium nitrate indicates that it contains one sodium atom, one nitrogen atom, and three oxygen atoms.

Element Atomic Symbol Atomic Mass (amu) Number of Atoms Total Mass (amu)
Sodium Na 22.99 1 22.99
Nitrogen N 14.01 1 14.01
Oxygen O 16.00 3 48.00

The total mass of one mole of sodium nitrate can be calculated by summing the masses of the individual atoms:

Molar mass of NaNO3 = 22.99 g/mol + 14.01 g/mol + 48.00 g/mol = 84.00 g/mol

Frequently Asked Questions (FAQs)

  1. What is the significance of molar mass?

    The molar mass of a substance is essential for various calculations in chemistry, such as determining the amount of substance present in a given mass or volume, converting between grams and moles, and balancing chemical equations.

  2. Why is sodium nitrate commonly used in fertilizers?

    Sodium nitrate is a valuable source of nitrogen, an essential nutrient for plant growth. It provides the necessary nitrogen for plants to produce proteins, enzymes, and chlorophyll, promoting healthy and vigorous growth.

  3. Is sodium nitrate harmful to humans?

    In large quantities, sodium nitrate can be harmful to human health. It is classified as a toxic substance and exposure to high levels can cause methemoglobinemia, a condition that reduces the ability of blood to carry oxygen. However, when used in regulated amounts as a food preservative, it is considered safe.

  4. Can sodium nitrate be used as a rocket propellant?

    Yes, sodium nitrate can be used as an oxidizer in solid rocket propellants. When combined with a fuel source, such as powdered aluminum, it can produce a high-energy combustion reaction, generating thrust for propulsion.

  5. How is the molar mass of a compound determined experimentally?

    The molar mass of a compound can be determined experimentally using techniques such as mass spectrometry, which measures the mass-to-charge ratio of ions, or vapor density measurements, which involve comparing the density of a vapor to that of a reference gas.

  6. What is the difference between molar mass and molecular mass?

    Molar mass refers to the mass of one mole of a substance, whereas molecular mass is the sum of the atomic masses of all atoms in a molecule. Molecular mass is specific to compounds with covalent bonding, while molar mass can be applied to any substance.

  7. Can the molar mass of a compound be less than the sum of the atomic masses?

    No, the molar mass of a compound is always greater than the sum of the atomic masses. This is because the molecular formula represents the ratio of atoms in the compound, and the molar mass takes into account the number of each type of atom present.

  8. What are some other uses of sodium nitrate?

    Aside from its role in fertilizers and food preservatives, sodium nitrate is also used in glass manufacturing, fireworks, and as a component in some medications.

  9. Can sodium nitrate be substituted with other compounds in its applications?

    In some cases, sodium nitrate can be substituted with other nitrogen-containing compounds, such as ammonium nitrate or potassium nitrate, depending on the specific application and requirements.

  10. Is sodium nitrate soluble in water?

    Yes, sodium nitrate is highly soluble in water. It readily dissolves to form a clear, colorless solution.


The molar mass of sodium nitrate (NaNO3) is 84.00 g/mol. Molar mass is a crucial concept in chemistry that allows for various calculations and conversions. Sodium nitrate, with its diverse applications in fertilizers, food preservatives, and rocket propellants, plays a significant role in our lives. Understanding the molar mass of compounds helps us comprehend their properties and behavior in chemical reactions.

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