Avogadro's Law Calculator
Enter any three of initial volume, initial moles, final volume and final moles, and this calculator finds the fourth using Avogadro's Law, V1/n1 = V2/n2, at constant temperature and pressure. Volume units are relative, so use any consistent unit.
How to use the Avogadro's Law calculator
- Pick which quantity you want to solve for.
- Enter the other three values, using any consistent volume unit.
- Read the missing value, solved from V1/n1 = V2/n2.
Examples
Solve for final volume
V1 = 10, n1 = 2, n2 = 4
V2 = 20
Solve for final moles
V1 = 5, n1 = 1, V2 = 15
n2 = 3
Frequently asked questions
What is Avogadro's Law?
Avogadro's Law states that at constant temperature and pressure the volume of a gas is directly proportional to its amount in moles, so V1/n1 = V2/n2.
What units should I use?
Use any consistent volume unit because only the ratio matters. Amounts are in moles, and the same volume unit applies to both V1 and V2.
Do temperature and pressure stay constant?
Yes. Avogadro's Law assumes constant temperature and pressure. If those change, use the combined or ideal gas law instead.
How many values do I need to enter?
Exactly three of the four. From any three of V1, n1, V2 and n2 the fourth is fully determined.
Why must the values be positive?
Volume and amount of gas are always greater than zero, so the calculator rejects zero or negative inputs.
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