At standard atmospheric conditions, what is the specific volume of 1kg of air?

• A. 0.509m³
• B. 0.840m³
• C. 1.0m³
• D. 1.25m³

Answer: (B)

To determine the specific volume of 1 kg of air at standard atmospheric conditions, it's essential to reference the Ideal Gas Law, which is used to describe the behavior of gases. The specific volume is defined as the volume occupied by a unit mass of a substance, typically expressed in cubic meters per kilogram (m³/kg).

At standard atmospheric pressure (101.325 kPa) and a temperature of approximately 20 °C (often used as standard conditions), the density of air is about 1.225 kg/m³. The specific volume can be calculated as the reciprocal of density:

Specific Volume = 1 / Density.

Given the density of approximately 1.225 kg/m³, we can calculate the specific volume:

Specific Volume = 1 / 1.225 kg/m³ ≈ 0.816 m³/kg.

This value aligns closely with the choice of 0.840 m³, which is a commonly accepted rounded figure used in calculations for specific volume under standard atmospheric conditions. Therefore, this choice best represents the specific volume of 1 kg of air, making it the correct answer.

Understanding specific volume is crucial for various applications within HVAC and refrigeration systems, as it helps professionals comprehend air flow characteristics and system performance at