Avogadro proposed in 1811 that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. So volume is proportional to the amount of gas – one mole of ideal gas fills about 22.4 L at 0 °C and 1 atm.
How to use the Avogadro’s Law Calculator
- Find
- Initial volume V₁
- Initial amount n₁ (mol)
- Final amount n₂ (mol)
- Final volume V₂
Results update as you type, every field has its own unit menu, and everything is calculated in your browser.
How it works
Choose what to find and enter the initial volume and amount and the known final value.
Tips
- Use absolute temperature (K) in gas laws and efficiency formulas.
- Temperature differences are the same in K and °C.
- Heat = mass × specific heat × temperature change when no phase change occurs.
- Phase changes need latent heat at a constant temperature.
Common mistakes to avoid
- Using °C in pV = nRT.
- Forgetting latent heat during melting or boiling.
- Confusing heat capacity (J/K) with specific heat (J/(kg·K)).
Inputs explained
| Field | What to enter |
|---|---|
| Find | Choose one: Final volume V₂, Final amount n₂ |
| Initial volume V₁ | Units: L, m³, mL, ft³ |
| Initial amount n₁ (mol) | A number |
| Final amount n₂ (mol) | A number |
| Final volume V₂ | Units: L, m³, mL, ft³ |
What each result means
- Final volume V₂ = [Initial volume V₁]×[Final amount n₂ (mol)]÷[Initial amount n₁ (mol)]
- Final amount n₂ = [Initial amount n₁ (mol)]×[Final volume V₂]÷[Initial volume V₁]
Example values
How the main result changes when Initial volume V₁ changes and everything else stays at the example values above:
| Initial volume V₁ (L) | Final volume V₂ (L) |
|---|---|
| 11.2 | 22.4 |
| 16.8 | 33.6 |
| 22.4 | 44.8 |
| 28 | 56 |
| 33.6 | 67.2 |
| 44.8 | 89.6 |
Formula
V₁/n₁ = V₂/n₂Worked example
Inputs — Find: Final volume V₂; Initial volume V₁: 22.4 L; Initial amount n₁ (mol): 1; Final amount n₂ (mol): 2.
Results — Final volume V₂ = 44.8 L.
Key terms
- Mole
- 6.022 × 10²³ particles.
Frequently asked questions
What does Avogadro's law state?
At constant T and p, gas volume is proportional to the number of moles.
What is the molar volume?
About 22.414 L/mol at 0 °C and 1 atm (STP).
Does it work for real gases?
Approximately, at moderate pressures.
How does it relate to the ideal gas law?
It is the n-dependence of pV = nRT.
What formula does the Avogadro's Law Calculator use?
V₁/n₁ = V₂/n₂.