1.3.3. THE GASEOUS STATE

Have you ever observed a balloon seller filling a large number of balloons from a single cylinder of gas? Enquire from him how many balloons is he able to fill from one cylinder. Ask him which gas does he have in the cylinder.

In this introduction, we engage with a real-world observation—balloons being filled with gas. It prompts students to think about gases in practical terms and how they are stored and utilized in everyday life. The focus on a single cylinder highlights the compressibility of gases, as many balloons can be inflated using just one cylinder of gas, which can contain a considerable volume of gas in a smaller space.

Think about a bicycle pump. When you push down on the pump, the air gets compressed into a small space before it fills the tire. In a similar way, a gas cylinder can hold a lot of gas in a compact form.

Activity _____________ 1.11 • Take three 100 mL syringes and close their nozzles by rubber corks, as shown in Fig.1.4. • Remove the pistons from all the syringes. • Leaving one syringe untouched, fill water in the second and pieces of chalk in the third. • Insert the pistons back into the syringes. You may apply some vaseline on the pistons before inserting them into the syringes for their smooth movement. • Now, try to compress the content by pushing the piston in each syringe.

This activity illustrates the compressibility of gases compared to liquids and solids. When you attempt to push in the piston of the syringe filled with gas (the untouched syringe), it will easily move down because gases are highly compressible. In contrast, when you push the piston in the syringe filled with water or chalk, the resistance will be felt much more compared to the gaseous syringe. This principle is crucial in understanding the behavior of different states of matter.

Consider an inflated balloon. When you squeeze it, the air inside gets compressed and the balloon changes shape. This happens because gases can be easily compressed, unlike liquids and solids, which maintain their volume and resist compression.

We have observed that gases are highly compressible as compared to solids and liquids. The liquefied petroleum gas (LPG) cylinder that we get in our home for cooking or the oxygen supplied to hospitals in cylinders is compressed gas. Compressed natural gas (CNG) is used as fuel these days in vehicles.

Gases have a unique property: they can be compressed significantly due to the large spaces between their particles. This feature is utilized in various applications, such as LPG and CNG, where gases are stored under pressure for practical use. This compressibility allows for the efficient storage and transportation of gas.

Imagine trying to carry a bag full of air versus a bag full of marbles. You can easily squish the air bag down to a tiny size, but the marble bag stays firm. This is similar to how gases can be compressed into small cylinders, while solids and liquids cannot.

The smell of hot cooked food reaches us in seconds; compare this with the rate of diffusion of solids and liquids. Due to high speed of particles and large space between them, gases show the property of diffusing very fast into other gases.

Gases mix rapidly with other gases because their particles are in constant, random motion. The larger spaces between gas particles allow for quicker dispersion, which is why smells can travel from one room to another almost instantly. This property is fundamental in understanding how gases interact with one another in open environments.

Think about when you spray perfume in one corner of a room. You might notice the fragrance quickly spreading to the opposite side. This is essentially diffusion in action, showcasing how gaseous particles move swiftly and fill available space.

In the gaseous state, the particles move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container. The pressure exerted by the gas is because of this force exerted by gas particles per unit area on the walls of the container.

Gas particles are in constant motion, colliding with each other and the walls of their container. This movement results in gas pressure—essentially, the force acting per unit area as these particles strike the walls. Understanding this behavior helps explain why gases, unlike solids and liquids, will expand to fill their container completely.

Consider a group of children running around in a room. They bounce off each other and the walls, creating a lively atmosphere. This is similar to how gas particles behave in a container—constantly moving and colliding, creating pressure within that space.

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