Properties of Waste Material

• Waste materials have different properties which must be considered when recycling or disposing of them.
• Corrosive, flammable, and toxic materials pose hazards and require careful handling.
• Waste exists in three states of matter: solid, liquid, and gas, handled differently during recycling and disposal.

Solids

• Generally, solids don't flow or change shape; they stay in place unless moved.
• Volume is measured in cubic centimetres (cm³).
• Solids are hard to compress.
• Solid waste like metals, paper, and plastic is easily transported in open lorries to landfill sites.

Liquids

• Liquids take the shape of their container and can flow.
• It would be difficult to transport them in an open truck because they slosh and spill
• Liquids don't change volume and are hard to compress.
• Liquid wastes can be pumped along pipelines due to flow.

Gases

• Gases change their shape and volume, spreading in all directions and easily compressing.
• Gas cylinders store gases under pressure.
• Flammable gases in cylinders pose explosion or fire risks in recycling plants.
• The release of many waste gases into the atmosphere can harm the environment
• Power stations burn fossil fuels and produce acidic gases.

Density

• Density helps identify a substance
• Mass of a certain volume of material, is measured in kilograms per cubic metre (kg/m³) or grams per cubic centimetre (g/cm³).
• Iron has a density of 7.9 g/cm³, meaning 1 cm³ has a mass of 7.9 g.
• Iron is denser than water (1 g/cm³), so 1 cm³ of iron weighs more than 1 cm³ of water.
• Generally, solids are denser than liquids, and liquids are denser than gases.
• The density of gases can be changed by squashing them.

Solids-Particles

• Particles in solids are tightly packed, cannot be compressed and arranged in a regular way.
• Attraction forces between particles hold them in place.
• Solids expand when heated.
• Particles vibrate in a fixed position, giving solids fixed shape and meaning they cannot flow.

Liquids- Particles

• Particles are arranged randomly but close, touching neighbours.
• Liquids cannot be compressed.
• Particles have enough energy to overcome some attraction forces, allowing movement and pouring.

Gases- Particles

• Particles are widely spaced and randomly arranged so the gases can be easily compressed or squashed.
• Particles have enough energy to overcome attraction, moving freely in straight lines and colliding with container walls

Particle Theory

• All matter consists of tiny particles in constant motion, held together by varying forces of attraction.
• In solids, particles are closely held by strong forces, vibrating but not moving past each other.
• In liquids, particles are close with moderate forces, allowing them to move past each other, like marbles in a bucket.
• In gases, particles are far apart with weak forces, allowing quick, random movement to fill the container.

Diffusion

• Brownian motion was first observed in 1827 by Robert Brown, studying pollen grains in water and discovering they moved randomly.
• Air consists of moving particles that collide with smoke specks, pushing them in different directions to demonstrate diffusion
• Diffusion is the process where particles spread from high to low concentration areas
• It occurs in liquids and gases due to random particle collisions like smelly substances spreading through the air

Nanoscale

• Though pollen grains and smoke specks are only visible using a microscope, they are more than 100,000 times larger than molecules in water or air.
• Nanometres (nm) are used to measure such small particles; 1 nm equals 0.000000001 meters.
• Brownian motion is important to scientists, including those studying paints, air pollution, and electronics.

Gas pressure

• Gas pressure is the result of gas particles constantly colliding with surfaces.
• More collisions equate to more pressure.
• Gas pressure is increased when the temperature increases or volume decreases
• Decreasing the volume of a sealed container containing a gas, results in more frequent collisions with the walls, which results in increasing the pressure.

Scientific Method

• Scientific Method begins with observation, forming a hypothesis, and making a prediction
• Experimentation then tests the hypothesis, and results are compared to the prediction
• A hypothesis supported by many experiments becomes a theory.
• Salty water takes longer to boil, boiling point of water depends on amount of salt added, predictions should be "if" "then" statements