Dalton's Law Calculator Formula

Understand the math behind the dalton's law calculator. Each variable explained with a worked example.

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Formulas Used

Total Pressure

p_total = p_a + p_b + p_c

Mole Fraction of Gas A

mole_frac_a = p_a / (p_a + p_b + p_c)

Variables

VariableDescriptionDefault
p_aPartial Pressure of Gas A(atm)0.5
p_bPartial Pressure of Gas B(atm)0.3
p_cPartial Pressure of Gas C (0 if none)(atm)0.2

How It Works

Dalton's Law of Partial Pressures

Formula

P_total = P_A + P_B + P_C + ...

Each gas in a mixture exerts pressure independently as if it alone occupied the container. The partial pressure of each gas equals its mole fraction times the total pressure:

P_i = x_i × P_total

Worked Example

A mixture of N₂ (0.5 atm), O₂ (0.3 atm), and CO₂ (0.2 atm).

p_a = 0.5p_b = 0.3p_c = 0.2
  1. 01P_total = P_A + P_B + P_C
  2. 02P_total = 0.5 + 0.3 + 0.2
  3. 03P_total = 1.0 atm
  4. 04Mole fraction of A = 0.5 / 1.0 = 0.50

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