What is the molar gas constant R?
The molar gas constant is R = 8.314462618 J/(mol·K), exact by SI definition (zero uncertainty). It equals N_A times the Boltzmann constant.
Open the interactive PhysRef tool →Key facts
| Value | 8.314462618 J mol^-1 K^-1 |
|---|---|
| Symbol | R |
| Relation | R = N_A · k_B |
| Exactness | Exact by SI definition (uncertainty 0) |
| Source | CODATA 2018 |
Frequently asked questions
What is the value of the gas constant R?
R = 8.314462618 J/(mol·K), the proportionality constant in the ideal gas law PV = nRT.
Is the gas constant exact?
Yes. Because N_A and k_B are now exact, R = N_A·k_B is exact at 8.314462618 J/(mol·K).
What is R in L·atm units?
R is about 0.082057 L·atm/(mol·K), commonly used in chemistry; the SI value is 8.314462618 J/(mol·K).
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