basic

Moles of Gas Collected Over Water from Total Pressure and Volume Calculator

P_gas = P_total − P_water; n = P_gas·V / (R·T).

Compute the moles of dry gas collected by water displacement: subtract the water-vapour partial pressure at the experiment temperature from the measured total pressure, then apply ideal-gas n = P_gas·V / (R·T). Uses R = 0.08206 L·atm·mol⁻¹·K⁻¹.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

Inputs

atm
atm
L
K

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

n = (P_total − P_water)·V / (R·T).

In depth

Compute the moles of dry gas collected by water displacement: subtract the water-vapour partial pressure at the experiment temperature from the measured total pressure, then apply ideal-gas n = P_gas·V / (R·T). Uses R = 0.08206 L·atm·mol⁻¹·K⁻¹.