Unit 5: Matter and Energy

I. Classification of Matter

Classification of Matter

Pure Substances A “pure substance” is one that has the same composition throughout All parts of this substance has the same properties, regardless of shape, size, or state Examples: water silver sodium chloride nitrogen helium sucrose

B.Mixtures Mixtures are physical combinations of more than one compound and/or element These are 2 or more distinct substances properties May have varying properties throughout Two major categories of mixtures: 1) Heterogeneous 2) Homogeneous

Mixtures Heterogeneous Mixtures = those that are not the same throughout; vary in composition; can see the separate parts Examples: sand & water, ??? Homogeneous Mixtures = those that look the same throughout, but can still be separated physically Examples: 14kt gold, sugar water, ???

C. Properties of Matter Physical Property those that can be observed without changing the identity or composition Ex] density, solubility, phase, etc. Chemical Property describes how a substance reacts; composition changes Ex] flammability, oxidation, etc.

Intensive vs. Extensive Properties depend upon the amount Extensive Properties depend upon the amount present Mass, shape, volume, etc. remain the same regardless Intensive Properties remain the same regardless of amount Density, boiling point, solubility, etc.

Website reference pre/matter.html

D. Physical and Chemical Changes Physical changes are generally are reversible The substance may look differently, but has the same intensive properties

D. Chemical Changes Chemical changes generally alter the composition of the substance End product has different properties Sample is destroyed

II.Particle Diagrams of Matter [drawings of types and phases] Identify the type of substance and the phase in each diagram below. Draw a particle diagram of nitrogen gas and iodine.

III. Separation Techniques These methods separate mixtures that are physically combined End result, or products, are the compounds or elements that composed the mixture Four major methods: A) FiltrationC) Evaporation B) DistillationD) Chromatography

A. Filtration Filtration is used to separate a solid from a liquid or a solution; starts with suspension Materials: filter paper, funnel, collection beaker Advantages: easy, common, fast, recovers all parts Disadvantages: inaccurate, difficult with small particles, depends on technique, human error common

B. Distillation This is a method of separating components of a liquid mixture based on different boiling points Materials: boiling flask, collection flask, condenser, water, heat source Advantages: recovers all parts, collects pure substances, separate complex mixtures Disadvantages: costly equipment, slow, can be difficult

Evaporation is the removal of a solvent by evaporating it, leaving behind the solute Materials: Evaporating dish, heat source Advantages: easy, common, usually fast Disadvantages: lose solvent, solute may be contaminated, inaccurate, can be difficult C.Evaporation

D. Chromatography This uses solubility rules and mass to separate components of a complex solution Materials: stationary phase [paper], mobile phase [solution], sample Advantages: very accurate, rater fast, can separate hundreds of components Disadvantages: expensive, must have the proper solvent, destroys sample Several different types: paper, gas, or liquid

IV. Laws of Matter and Energy A. Law of Conservation of Energy B. Law of Conservation of Matter C. Law of Constant Composition Exception: Exception: nuclear reactions

V.Energy

B. Changes in Energy Endothermic a reaction or change that ABSORBS heat energy Exothermic a reaction or change that RELEASES heat energy

C. Temperature vs. Heat Temperature = the average kinetic energy of the particles within an area Heat = energy transferred between two objects of different temperatures Heat moves from hotter object to the colder one

V. Heat Transfer and Calculations Specific Heat (C) The amount of heat energy lost/gained by a specific mass of a substance over a certain temperature change or The larger the value of specific heat, the more energy it takes to heat the object, or the longer time it takes for the object to cool

Specific Heat substances with LOW specific heats: Metals Alloys Substances w/ high thermal conductivity substances with LOW specific heats: glass Some Polymers water Air, inert gases Substances w/ low thermal conductivity

B.Heat Equation and Calculations q = m C Δ T q= heat [J or kJ] C = specific heat [J/gC] Δ T = change in temperature = T f - T i