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Atmospheric Pressure Formula:
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Atmospheric pressure is the force per unit area exerted on a surface by the weight of the air above that surface in the Earth's atmosphere. It is a fundamental concept in chemistry and physics, particularly in gas law calculations.
The standard atmospheric pressure is defined as:
This value is equivalent to:
Explanation: This standard value represents the average atmospheric pressure at sea level at a temperature of 15°C (59°F).
Details: Atmospheric pressure is crucial in chemistry for gas law calculations (Boyle's Law, Charles's Law, Ideal Gas Law), determining boiling points of liquids, and understanding partial pressures in gas mixtures.
Examples: Used in calculating gas volumes at STP (Standard Temperature and Pressure), determining vapor pressures, and calibrating laboratory equipment like barometers and manometers.
Q1: Why is 101325 Pa considered standard atmospheric pressure?
A: This value was established internationally as the average atmospheric pressure at sea level and serves as a reference point for scientific calculations.
Q2: How does atmospheric pressure affect chemical reactions?
A: Pressure affects reaction rates, equilibrium positions (especially for reactions involving gases), and boiling points of solvents.
Q3: Does atmospheric pressure change with altitude?
A: Yes, atmospheric pressure decreases with increasing altitude due to the decreasing weight of the air column above.
Q4: How is atmospheric pressure measured?
A: Typically measured using barometers, with mercury barometers and aneroid barometers being the most common types.
Q5: Why do we use Pascals as the SI unit for pressure?
A: Pascals (Newton per square meter) are the SI derived unit for pressure, providing a consistent measurement system for scientific calculations.