Physical and Chemical Change Flashcards
Explain what a physical change is.
A physical change is a change in which the substance’s appearance or state changes, but its chemical composition remains the same. No new substances are created.
List some examples of physical changes.
Melting ice
Boiling water
Breaking a glass
Dissolving sugar in water
Crushing a can
Explain what a chemical change is.
A chemical change occurs when a substance undergoes a reaction that changes its chemical composition, producing one or more new substances. These changes are usually irreversible.
List some examples of chemical changes.
Burning wood
Rusting of iron
Digestion of food
Cooking an egg
Baking a cake
What are the main roles of the stomach chemicaly?
The stomach produces gastric acid and digestive enzymes that chemically break down food into simpler compounds, such as proteins being converted into amino acids.
& Outline the main steps involved in recycling aluminium. Are they chemical or physical?
Step 1: Collecting and sorting aluminum products (physical).
Step 2: Cleaning and shredding the aluminum (physical).
Step 3: Melting the aluminum (physical).
Step 4: Reforming the aluminum into new products (physical).
Recycling aluminum is a physical change because the aluminum maintains its chemical properties and can be reused.
Outline the Particle Model.
The Particle Model describes how matter is made up of tiny particles (atoms or molecules) that are in constant motion. In solids, particles are closely packed and vibrate in place; in liquids, they are close but can move around each other; in gases, particles are far apart and move freely at high speeds.
Draw and describe the arrangement of particles in a solid, liquid, and gas.
Solid: Particles are tightly packed in a regular pattern and vibrate in place. (e.g., ice)
Liquid: Particles are close but can move past one another. The arrangement is irregular. (e.g., water)
Gas: Particles are far apart and move freely. The arrangement is random and spread out. (e.g., air)
Explain why something expands when heated, using the Particle Model.
When a substance is heated, its particles gain energy and move faster. As they move faster, they push farther apart, causing the substance to expand. This occurs because the particles are vibrating more and need more space.
. Explain what pressure is and why it increases when a gas is heated.
Pressure is the force exerted by gas particles when they collide with the walls of their container. When a gas is heated, its particles move faster and collide more frequently with the container walls, causing an increase in pressure.
Explain what happens to particles when they are heated and a solid changes into a liquid.
When a solid is heated, the particles gain energy and start to vibrate more intensely. As the temperature rises, the particles’ vibrations become strong enough to overcome the forces holding them together, causing the solid to melt into a liquid.
Describe the arrangement of particles in a solution.
In a solution, the solute (solid) is dissolved in the solvent (liquid). The particles of the solute are evenly distributed throughout the solvent at the molecular level, forming a homogeneous mixture.
Explain what diffusion is.
Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. It continues until the particles are evenly spread out.
Explain what a chemical reaction is.
A chemical reaction is a process in which one or more substances (reactants) are transformed into new substances (products) through the breaking and forming of chemical bonds.
Write a word equation.
A word equation represents a chemical reaction using the names of the reactants and products. Example:
Hydrogen + Oxygen → Water
h02
