UNIT 12: PHYSICAL & CHEMICAL CHANGES PHASES CHANGES SYNTHESIS DISSOLUTION DECOMPOSITION DEFORMATION OXIDATION PRECIPITATION Page 43

PHYSICAL CHANGES Does not affect the nature or the characteristic properties of a substance or matter Are reversible 3 Types: 1 – Changes of State 2 – Dissolution 3 – Deformation

CHANGES OF STATE There are three states (or phases): 1 – Gas 2 – Liquid 3 – Solid A phase change occurs when matter transforms from one state to another This form of change IS reversible (Physical)

CHANGES OF STATE ROLE OF ENERGY Adding Energy 1- Increases movement 2- Releases attraction Subtracting Energy 1- Decreases movement 2- Creates attraction

DISSOLUTION Creating a solution by dissolving a SOLUTE into a SOLVENT Why is this a PHYSICAL CHANGE? EX. When a cube of sugar dissolves into water, the sugar molecules break up and are uniformly distributed within the water. BUT, the sugar molecules and water molecules DO NOT CHANGE

DISSOLUTION ROLE OF ENERGY Affects Temperature of solution Affects Solubility of solution ENERGY TRANSFER RESULT DISSOLUTION RELEASES ENERGY TEMPERATURE INCREASES DISSOLUTION ABSORBS ENERGY TEMPERATURE DECREASES

DEFORMATION Changes the shape of the material Some are reversible. Some are permanent

DEFORMATION ROLE OF ENERGY: Always involves ENERGY Transfer One force imposing on another object transferring that energy it had

CHEMICAL CHANGES Changes the nature and characteristic properties of a substance or matter. Are Irreversible Creates new material or substance 4 TYPES: 1- SYNTHESIS 2- DECOMPOSITION 3- OXIDATION 4- PRECIPITATION

CHEMICAL CHANGES 𝐻 2 + 𝐶𝑙 2 = 2 HCl + energy + = + 2 HCl breaks down proteins in your stomach to prepare them for digestion and kills bacteria that enter your stomach. + = + ENERGY

CHEMICAL CHANGES There are many clues that help tell the difference between CHEMICAL & PHYSICAL changes 1- the release of gas 2- greater changes of heat 3- the generation of light 4- a change of colour 5- the formation of a precipitate

SYNTHESIS The formation of a complex molecule from atoms or simpler molecules 2 𝐻 2 + 𝑂 2 2 𝐻 2 𝑂 + Energy (synthesis of water releases a lot of energy) 𝑁 2 + 2 𝑂 2 + Energy 2 𝑁𝑂 2 (synthesis of Nitrous Dioxide absorbs energy)

SYNTHESIS A major chemical reaction is the process of PHOTOSYNTHESIS CARBON DIOXIDE and WATER along with the suns energy come together to make SUGAR and OXYGEN. 6 𝐶𝑂 2 + 6 𝐻 2 𝑂 + Sun 𝐶 6 𝐻 12 𝑂 6 + 6 𝑂 2

DECOMPOSITION The transformation of complex molecules into simpler molecules or atoms The opposite of SYNTHESIS. Role of Energy: Breaks down the molecules 2 𝐻 2 𝑂 + electrical energy 2 𝐻 2 + 𝑂 2

DECOMPOSITION The opposite of PHOTOSYNTHESIS is CELLULAR RESPIRATION. A process that involves Oxidation. 𝐶 6 𝐻 12 𝑂 6 + 6 𝑂 2 6 𝐶𝑂 2 + 6 𝐻 2 𝑂 + energy SUGAR and OXYGEN becomes CARBON DIOXIDE and WATER plus ENERGY Respiration releases energy. Photosynthesis absorbs energy.

OXIDATION A chemical reaction involving oxygen or a substance that has similar properties to oxygen IRON combines with OXYGEN to form IRON OXIDE (RUST) 4 Fe + 3 𝑂 2 2 𝐹𝑒 2 𝑂 3 + energy

PRECIPITATION The formation of a solid that is less soluble, or not soluble, following the mixing of the two solutions. Addition of ENZYMES. (milk curdles into cheese)