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Dalton Law Of Partial Pressures Calculator

Work out dalton law of partial pressures instantly with clear inputs, formula shown and shareable results.

About Dalton Law Of Partial Pressures Calculator

Dalton's law says each gas in a mixture exerts its own pressure independently and the total is their sum. 60, 25 and 15 kPa give 100 kPa, with mole fractions of 60%, 25% and 15%. This is why the oxygen partial pressure at altitude matters more than the percentage, which stays at 21% all the way up.

Formulas

Dalton's law

P(total) = p1 + p2 + p3 + ...

Mole fraction

x(i) = p(i) / P(total)

Worked example

With the default values below, Dalton Law Of Partial Pressures Calculator returns Total Pressure of 100.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Partial pressure of the first gasminimum 0 kPa
60 kPa
Partial pressure of the second gasminimum 0 kPa
25 kPa
Partial pressure of the third gasminimum 0 kPa
15 kPa

Results

Total Pressure
100.000 kPa
Share From The First Gas
60.00%
Share From The Second Gas
25.00%
Share From The Third Gas
15.00%

Step by step

  1. 1Values used
  2. 2Dalton's law
  3. 3Mole fraction
  4. 4Total Pressure= 100.000 kPa
  5. 5Share From The First Gas= 60.00
  6. 6Share From The Second Gas= 25.00
  7. 7Share From The Third Gas= 15.00

Assumptions and limits

  • The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 3 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does altitude cause hypoxia if oxygen is still 21%?

Because total pressure falls, so oxygen's partial pressure falls with it. At 5500 m it is about half its sea-level value.

Does water vapour count?

Yes. Saturated vapour pressure must be subtracted before applying the dry-gas fractions, which matters in respiratory physiology and gas collection over water.

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