Here's why:
* Kinetic Molecular Theory: This theory describes gas behavior. It states that gas molecules are constantly in random motion, colliding with each other and the walls of their container.
* Pressure: Pressure is defined as the force exerted per unit area. In a gas, this force is caused by the collisions of gas molecules with the container walls.
* More molecules, more collisions: If you have more gas molecules in the same container, there will be more collisions with the walls per unit of time. This means a higher force is exerted on the walls, leading to higher pressure.
Think of it like this: Imagine a room full of people. If more people enter the room, there will be more collisions between people and the walls. The walls will feel more pressure because of the increased number of collisions.
Mathematical Relationship:
The relationship between pressure (P), number of moles (n), and volume (V) of a gas is described by the Ideal Gas Law:
PV = nRT
Where:
* R is the ideal gas constant
* T is the temperature in Kelvin
This equation shows that pressure (P) is directly proportional to the number of moles (n) of gas, assuming constant volume and temperature.
Practical Examples:
* Inflating a tire: Adding more air to a tire increases the number of gas molecules inside, leading to higher pressure.
* Cooking in a pressure cooker: The pressure cooker traps steam, increasing the number of water molecules in the container and thus increasing the pressure.
* Oxygen tank: An oxygen tank holds a high concentration of oxygen molecules, resulting in high pressure.
In summary: The pressure exerted by a gas is directly proportional to the number of gas molecules present. The more molecules, the more collisions, and the higher the pressure.
