Question 1: Define the Particle Model of matter and explain how it describes the states of solids, liquids, and gases.

Answer: The Particle Model of matter states that all matter is made up of tiny particles (atoms, molecules, or ions) that are in constant motion. In solids, particles are tightly packed and vibrate in fixed positions; in liquids, particles are close but can move past each other; in gases, particles are far apart and move freely.

Question 2: Describe how the motion and arrangement of particles change when a substance melts from a solid to a liquid.

Answer: In melting, particles gain energy, vibrate more vigorously, and the ordered structure of the solid breaks down, allowing particles to move past each other, forming a liquid.

Question 3: Explain why gases are compressible based on the Particle Model.

Answer: Gases are compressible because their particles are far apart with lots of space between them; applying pressure reduces the space, bringing particles closer together.

Question 4: Calculate the number of particles in 2 mol of a substance. (Avogadro's number = 6.02 x 10^23 particles/mol).

Answer: 1.204 x 10^24 particles

Question 5: Identify three variables that could affect the rate of diffusion of particles in a gas.

Answer: Temperature, particle mass, and concentration gradient.

Question 1: Design a simple experiment to demonstrate that gases diffuse faster at higher temperatures. Outline the key variables, safety precautions, and expected observations.

Answer: Use two gases, such as ammonia and hydrogen chloride, in separate test tubes connected by a tube with a cotton wool plug. Place the setup in a warm environment and observe the formation of a white ring (ammonium chloride). Variables include temperature (independent), rate of diffusion (dependent), and gas type (control). Safety precautions involve handling gases in a well-ventilated area and wearing safety glasses.

Question 2: Identify two safety precautions that must be followed when heating gases in a laboratory to observe particle behaviour.

Answer: Ensure proper ventilation and avoid direct inhalation of gases; always use heat-resistant equipment and protective safety glasses.

Question 3: State how the Particle Model explains the expansion of gases when heated.

Answer: Heating increases the energy of gas particles, causing them to move faster and collide more forcefully, which results in an increase in volume (expansion) if the container allows.

Question 1: A sample of gas shows an increase in pressure when the temperature is raised while keeping the volume constant. Explain this observation using the Particle Model.

Answer: According to the Particle Model, increasing temperature increases the energy and speed of particles, leading to more frequent and forceful collisions with the container walls, thus raising the pressure.

Question 2: In an industrial process, understanding the behaviour of particles at different states of matter helps improve efficiency. Give an example of such an application.

Answer: In the production of liquefied gases, understanding how particles behave allows engineers to optimise cooling and compression processes to liquefy gases efficiently.

Question 3: Describe how the Particle Model can be used to explain the process of boiling in water.

Answer: Boiling occurs when particles in the liquid gain enough energy to overcome intermolecular forces, forming vapour bubbles throughout the liquid. The Particle Model explains this as particles moving rapidly and separating to form a gas phase at the boiling point.