Final answer:
All gases occupy the same volume at the same temperature and pressure because of Avogadro's hypothesis, which posits that equal volumes of any gases contain equal numbers of particles; at standard temperature and pressure, one mole of any gas occupies 22.4 liters.
Step-by-step explanation:
The reason all gases occupy the same volume at the same temperature and pressure is based on Avogadro's hypothesis. This hypothesis states that equal volumes of all gases, when held at the same temperature and pressure, contain an equal number of particles, regardless of the size of the particles or their molecular mass. It's crucial to understand that the majority of a gas's volume is composed of empty space, which means the particle size itself is negligible when considering the volume a gas occupies.
At standard temperature and pressure (STP), which is 0°C (273.15 K) and 1 atm, one mole of any gas will occupy a volume of 22.4 liters. Therefore, whether one is measuring a mole of hydrogen or a mole of sulfur hexafluoride, the volume at STP will be the same due to the vast space between gas particles. Furthermore, the ideal gas law, which states the product of pressure and volume is constant for a given amount of gas at a constant temperature, supports this concept.
Understanding these principles is vital for conducting volume-volume stoichiometry calculations in chemistry, as they allow us to easily convert volumes to moles, facilitating the comparison and reaction of different gases under controlled conditions.