How To Calculate Partial Pressure A Level Chemistry

Dalton's Law of Partial Pressures:

\[ P_i = \frac{n_i}{n_{total}} \times P_{total} \]

Partial Pressure (P_i):

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1. What is Dalton's Law of Partial Pressures?

Dalton's Law states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. The partial pressure of each gas is proportional to its mole fraction in the mixture.

2. How Does the Calculator Work?

The calculator uses Dalton's Law equation:

\[ P_i = \frac{n_i}{n_{total}} \times P_{total} \]

Where:

\( P_i \) — Partial pressure of gas i (Pa)
\( n_i \) — Moles of gas i (mol)
\( n_{total} \) — Total moles of gas mixture (mol)
\( P_{total} \) — Total pressure of gas mixture (Pa)

Explanation: The equation calculates the pressure that each individual gas would exert if it alone occupied the entire volume of the mixture at the same temperature.

3. Importance of Partial Pressure Calculation

Details: Partial pressure calculations are essential in understanding gas behavior in mixtures, predicting chemical reactions involving gases, and applications in respiratory physiology, industrial processes, and environmental science.

4. Using the Calculator

Tips: Enter moles of the specific gas, total moles of the gas mixture, and total pressure. All values must be positive numbers, and moles of specific gas cannot exceed total moles.

5. Frequently Asked Questions (FAQ)

Q1: What units should be used for pressure?
A: While Pascals (Pa) are used here, any pressure unit can be used as long as consistency is maintained throughout the calculation.

Q2: Does Dalton's Law apply to reacting gases?
A: Dalton's Law applies specifically to mixtures of non-reacting gases. For reacting gases, the equilibrium composition must be considered.

Q3: How does temperature affect partial pressure?
A: Temperature affects the total pressure according to the ideal gas law, which in turn affects all partial pressures proportionally.

Q4: Can this be used for real gases?
A: Dalton's Law is most accurate for ideal gases. For real gases, deviations occur at high pressures and low temperatures.

Q5: What is the relationship between partial pressure and concentration?
A: For ideal gases, partial pressure is directly proportional to concentration (P_i = (n_i/V)RT).