Avogadro Law Calculator

Calculator Form

Solve for

Gas sample name

Decimal precision

Initial volume (V1)

V1 unit

Initial moles (n1)

Final volume (V2)

V2 unit

Final moles (n2)

Temperature condition

Pressure condition

Avogadro Law Graph

This graph shows the direct proportional relationship between moles and volume under constant temperature and pressure.

Example Data Table

Case	Initial Volume	Initial Moles	Final Moles	Calculated Final Volume
Example 1	2.0 L	0.50 mol	1.25 mol	5.0 L
Example 2	750 mL	0.30 mol	0.60 mol	1500 mL
Example 3	0.90 L	0.15 mol	0.10 mol	0.60 L
Example 4	1.20 m³	40 mol	55 mol	1.65 m³

Formula Used

Avogadro’s law states that, at constant temperature and pressure, gas volume is directly proportional to the number of moles.

V₁ / n₁ = V₂ / n₂

Rearranged forms:

V₂ = (V₁ × n₂) / n₁
n₂ = (V₂ × n₁) / V₁
V₁ = (n₁ × V₂) / n₂
n₁ = (V₁ × n₂) / V₂

The calculator first converts volume inputs into liters for consistent computation, solves the selected unknown, then reports scale factors, percent changes, and ratio consistency checks.

How to Use This Calculator

Select which variable you want to solve.
Enter the three known values for two gas states.
Choose the units for both volume fields.
Keep temperature and pressure constant for valid results.
Set output precision for the report.
Click Calculate to view the result above the form.
Review the graph, scale factors, and consistency metrics.
Export your report using the CSV or PDF buttons.

FAQs

1. What does Avogadro’s law describe?

It describes a direct proportional relationship between gas volume and number of moles when temperature and pressure remain constant.

2. When should I use this calculator?

Use it when one gas state is known and one variable in another state is missing, with unchanged temperature and pressure.

3. Why are volume units converted internally?

Internal conversion keeps calculations consistent and prevents ratio errors when initial and final volumes are entered using different units.

4. Can this tool solve for all four variables?

Yes. You can solve for initial volume, initial moles, final volume, or final moles by selecting the missing variable.

5. What happens if temperature changes too?

Then Avogadro’s law alone is not sufficient. You should use a combined gas law or ideal gas law approach instead.

6. Why does the graph look linear?

Because volume is directly proportional to moles. Doubling moles doubles volume, so the relationship forms a straight line.

7. What is the proportionality constant shown in results?

It is the volume-per-mole ratio, V/n. For valid constant conditions, this ratio should remain nearly identical between both states.

8. Why export CSV or PDF reports?

Exports help with lab records, homework checking, engineering notes, and sharing clean documentation of the solved gas-state comparison.