Browse and retrieve precise chemistry constants by selecting a Constant Category and your preferred Unit System, then set Decimal Places to control how many digits appear in your displayed constants — including Avogadro's Number (NA), the Gas Constant (R), and the Faraday Constant (F).
Constants Displayed
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Avogadro's Number (NA)
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Gas Constant (R)
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Faraday Constant (F)
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Avogadro's number (6.022 × 10²³ mol⁻¹) represents the number of particles (atoms, molecules, ions) in one mole of a substance. It's fundamental for converting between atomic scale and macroscopic quantities in chemistry.
The gas constant R has the same value but different units: 8.314 J/(mol·K), 0.08206 L·atm/(mol·K), or 1.987 cal/(mol·K). Choose the unit that matches your pressure, volume, and temperature units in calculations.
Faraday's constant (96,485 C/mol) equals Avogadro's number multiplied by the elementary charge. It represents the charge of one mole of electrons and is essential in electrochemistry calculations.
The atomic mass unit (u) equals 1.661 × 10⁻²⁷ kg and is defined as 1/12 the mass of a carbon-12 atom. It's more convenient for expressing atomic and molecular masses than kilograms.
Constants have different numerical values in SI and CGS systems due to different base units. For example, the gas constant R is 8.314 J/(mol·K) in SI but 8.314 × 10⁷ erg/(mol·K) in CGS units.
Boltzmann's constant (1.381 × 10⁻²³ J/K) relates energy to temperature at the particle level. It equals the gas constant R divided by Avogadro's number: k = R/NA.
These constants are based on the most recent CODATA values and are accurate to their stated precision. Some constants like Avogadro's number are now defined exactly, while others have experimental uncertainty in their final digits.
The most frequently used constants are Avogadro's number (6.022 × 10²³), gas constant R (8.314 J/(mol·K)), and atomic mass unit (1.661 × 10⁻²⁷ kg). These appear in most stoichiometry and thermodynamics problems.