Boyle's Law Calculator

Solve for pressure or volume at constant temperature using P₁V₁ = P₂V₂. Leave one field blank.

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What is Boyle's Law?

Boyle's Law, formulated by Robert Boyle in 1662, states that the pressure of a gas is inversely proportional to its volume when temperature remains constant. As pressure increases, volume decreases proportionally.

P₁V₁ = P₂V₂

Boyle's Law Formula — Rearranged Forms

P₂ = P₁V₁ / V₂
V₂ = P₁V₁ / P₂
P₁ = P₂V₂ / V₁
V₁ = P₂V₂ / P₁

Step-by-Step Examples

Example 1: Find P₂

Given: P₁ = 2.0 atm, V₁ = 6.0 L, V₂ = 3.0 L. Find P₂.

1. Formula: P₂ = P₁V₁ / V₂
2. Substitute: P₂ = (2.0)(6.0) / 3.0
3. Calculate: P₂ = 12.0 / 3.0 = 4.0 atm

Example 2: Find V₂

Given: P₁ = 1.0 atm, V₁ = 10.0 L, P₂ = 5.0 atm. Find V₂.

1. Formula: V₂ = P₁V₁ / P₂
2. Substitute: V₂ = (1.0)(10.0) / 5.0
3. Calculate: V₂ = 10.0 / 5.0 = 2.0 L

Real-World Applications

  • Scuba diving: As a diver descends and pressure increases, the volume of air in the lungs and equipment decreases.
  • Syringes: Pulling the plunger increases volume, decreasing pressure and drawing fluid in.
  • Vacuum pumps: Expanding the chamber volume reduces pressure inside.
  • Breathing: The diaphragm expands the chest cavity (volume up), reducing lung pressure and drawing air in.

Frequently Asked Questions

  • Boyle's Law states that for a fixed amount of gas at constant temperature, the pressure and volume are inversely proportional. When pressure increases, volume decreases, and vice versa. The formula is P₁V₁ = P₂V₂.

  • P₁V₁ = P₂V₂. This can be rearranged: P₂ = P₁V₁/V₂, V₂ = P₁V₁/P₂, etc.

  • Use Boyle's Law when temperature is constant and you need to find how pressure or volume changes. Common examples include compressing gas in a syringe, scuba diving depth changes, and vacuum pump calculations.

  • According to Boyle's Law, pressure and volume have an inverse relationship at constant temperature. If you double the pressure, the volume is halved. If you triple the volume, the pressure drops to one-third.