1. Understand STP (Standard Temperature and Pressure)
* Temperature: 0°C (273.15 K)
* Pressure: 1 atm (101.325 kPa)
2. Use the Ideal Gas Law
The ideal gas law is a fundamental relationship that describes the behavior of gases:
PV = nRT
Where:
* P: Pressure (in atm)
* V: Volume (in liters)
* n: Number of moles
* R: Ideal gas constant (0.0821 L·atm/mol·K)
* T: Temperature (in Kelvin)
3. Calculate Moles of Hydrogen Gas
* Molar mass of H₂: 2 g/mol
* Moles (n): (20 g) / (2 g/mol) = 10 moles
4. Rearrange the Ideal Gas Law to Solve for Volume
V = nRT / P
5. Plug in the Values and Solve
V = (10 mol) * (0.0821 L·atm/mol·K) * (273.15 K) / (1 atm)
V ≈ 224.14 L
Therefore, approximately 224.14 liters of hydrogen gas are present in 20 grams at STP.
Important Note: This calculation assumes ideal gas behavior. In reality, gases may deviate slightly from ideal behavior, especially at high pressures or low temperatures.
