Dalton’s Law of Partial Pressures| Real life examples

Dalton’s Law of Partial Pressures states that in a mixture of non-reacting gases, the total pressure exerted by the mixture is equal to the sum of the partial pressures of individual gases in the mixture. Each gas in the mixture exerts a pressure as if it were the only gas present in the same volume and under the same conditions. This law is particularly useful for understanding how gases behave in various real-life situations, such as those mentioned in the previous responses, by considering the individual contributions of each gas to the total pressure in a mixture.

The total pressure of a mixture of gases is equal to the sum of the partial pressures of the component gases.

Pressure_Total = Pressure_{Gas 1} + Pressure_{Gas 2} + Pressure_{Gas 3} + … Pressure_{Gas n}

An alternative of this equation can be used to determine the partial pressure of an individual gas in the mixture.
If the total pressure is known and the moles of each component gas are known, the partial pressure can be computed using the formula:

P_x = P_Total ( n_x / n_Total )

where:

• P_x = partial pressure of gas x
• P_Total = total pressure of all gases
• n_x = number of moles of gas x
• n_Total = number of moles of all gases

This relationship applies to ideal gases but can be used in real gases with very little error.

Real Life Examples

1. Scuba Diving: Adjusting gas mixtures to prevent issues at different depths, following Dalton’s Law to calculate partial pressures.
2. Medical Oxygen Therapy: Regulating oxygen levels for patients by using Dalton’s Law to control the gas mixture’s partial pressure.
3. Air Travel: Maintaining cabin pressure at high altitudes using Dalton’s Law to ensure passenger comfort and safety.
4. Industrial Gas Storage: Safely storing and using gases in manufacturing processes by controlling partial pressures as per Dalton’s Law.
5. Chemical Reactions: Predicting how gases behave in chemical reactions using Dalton’s Law to calculate partial pressures.
6. Weather Balloons: Measuring atmospheric conditions at different altitudes and interpreting the data with Dalton’s Law.
7. Food Packaging: Extending the shelf life of food products by controlling gas mixtures as per Dalton’s Law to preserve freshness.

Deviation From Dalton’s law

• Dalton’s law is an ideal gas law. It is an approximation for real gases.
• Deviation from the law increases with higher pressure as high pressure makes the volume occupied by a gas significant compared to free space.
• In addition, intermolecular forces become more important at high pressures.