Physical and chemical change Physical change –the altering of the physical form but not composition of matter –ex. Pounding, pulling, changes of state Knowledge of physical change leads to… –the understanding of separation of mixtures –ex. Distillation, crystallization, chromatography, filtration

Chemical change –change in which the matter is converted into matter with different composition and properties

Indicators of chemical change 1.heat and/or light energy –Energy changes within the system 2.Production of gas - release of gas from the system

3. Formation of a precipitate - when two (or more) solutions are put together an insoluble solid is produced 4. Color change - the system changes color - not always an indicator of chemical change (can be physical

MIXTURES mixture: - combination of two or more kinds of matter each of which retains its own composition and properties - physical blend of two or more substances

heterogeneous mixture : - a mixture containing substances that are not evenly distributed - different from point to point ex. granite ---> quartz, feldspar, and mica More of Mixtures: Phase mixtures that are obviously heterogeneous and have separate, distinct parts Ex. Oil forming layers in water is another Interface – the region where two or more phases meet

M o M homogeneous mixture - a mixture containing substances that are uniformly distributed with the particles blended completely - composition and properties are uniform throughout - also called solutions (mixed on a scale of individual particles) ex. I molar copper II sulfate To the eye, the mixture appears to be pure substance.

Solutions (Homogeneous Mixtures) Can you tell the difference?

Parts of a Solution SOLUTE – the part of a solution that is being dissolved (usually the lesser amount) SOLVENT – the part of a solution that dissolves the solute (usually the greater amount) Solute + Solvent = Solution SoluteSolventExample solid Brass: Copper and Zinc solidliquidSeawater: NaCL in water gassolidMoth balls: naphthalene liquid Ethyl alcohol and water (miscible) gasliquidSODA: CO 2 gas in water gas AIR: O 2 gas, N 2 gas DO NOT NEED TO COPY CHART

Definitions Solutions can be classified as saturated or unsaturated. A saturated solution contains the maximum quantity of solute that dissolves at that temperature. An unsaturated solution contains less than the maximum amount of solute that can dissolve at a particular temperature

Definitions SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved in a given amount of solvent Supersaturated solutions are unstable. -- the supersaturation is only temporary -- need to warm the solvent so that it will dissolve more -- then need to cool the solution slowly

Separation of Mixtures types of… Filtration –Separation of mixture on the basis of differences in the size of the particles –Mostly used to separate solids from liquids (but filtration is used to separate all phases of matter from one another) Ex. Air filters separate gas (air) from solid (dirt particles)

Distillation –Based on the tendency of a substance to vaporize (turn to a gas) –Based on boiling point differences –The substance in the mixture with the lowest boiling point will vaporize first from the mixture Ex. Crude oil

Crystallization –Separation of the mixture is based on solubility differences –Temperature changes within the mixtures change solubility of parts of the mixture Solubility – the amount of a solute that is able to dissolve in a given amount of solvent Ex. Rock candy

Chromatography –Based on the differences in solubility –Two types  Gas and Paper –Mixture separates as it travels (most soluble separates first) Solute – substance that gets dissolved Solvent – substance that does the dissolving Ex. Separating ink in a marker

Concentration: amount of solute in a given amount of solvent (can be determined quantitatively) Dilute: a solution with a small amount of solute per solvent amount (relative term) Concentrated: a solution with a large amount of solute per solvent amount (relative term) BOTH DILUTE AND CONCENTRATED ARE QUALITATIVE SOLUTION CHEMISTRY

Concentration of Solute The amount of solute in a solution is given by its concentration The amount of solute in a solution is given by its concentration. Molarity (M) = moles solute liters of solution The concentration of a solution is said to be its molarity. Ex. 1 M CuSO 4 “1 molar copper II sulfate