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MIXTURES, ELEMENTS, COMPOUNDS AND SOLUTIONS CHEMISTRY MS. ZIMMER 2005 CLASSES OF MATTER • Matter exists as mixtures, solutions, elements or compounds • Classified by their make up • Not classified by their phases, because several can exist in more than one phase. CLASSES OF MATTER REVIEW • What are the four classes of matter? – Mixtures, solutions, compounds, elements • How are the classes classified? – They are classified by their make up. • Why isn’t matter classified by their phases? – They are not classified by their phases because some matter can exist in more than one phase. MIXTURES • Mixtures consists of two or more substances • Mixture are not chemically combined • Each substance in a mixture maintains its physical properties PROPERTIES OF MIXTURES • Substances in a mixture are not chemically combined. – Sugar dissolved in water is still sugar • Substances may change in physical appearance, but the chemical properties do not. – You can’t see the sugar in the water but it is there. PROPERTIES OF MIXTURES CONT. • Substances in a mixture can be present in any amount. – There can be a little sugar or a lot of sugar dissolved in the water. • Substances in a mixture can be separated by physical means. – Dissolve water and you have the sugar left. – No chemical reaction needed to separate mixtures HETEROGENEOUS MIXTURE • “least-mixed” • Particles are large enough to see • Does not appear the same throughout • Easy to separate the particles • Not only solid-solid mixtures • Can be liquid-liquid HOMOGENEOUS MIXTURES • “Well-mixed” • Particles are small and not easily recognizable • Do not settle when the mixture stands • Particles are mixed • Appears to be the same throughout COLLOIDS • Particles are mixed together but are not dissolved • Particles are large and kept suspended • Particles will not separate when left standing • Bombarded by other particles – Often appears cloudy SOLUTIONS • Homogeneous mixture formed when one substance dissolves into another. • Solutions have a substance that is dissolved called the solute • Solutions have a substance that does the dissolving called a solvent SOLUTIONS CONT. • Particles in a solution are not visible • Hard to separate physically • Solutions appear to be clear • Particles are evenly spread out SOLUBILITY • A substance that dissolves in water is soluble –Salt, sugar • A substance that can’t dissolve in water is insoluble –Mercury, oil SOLUBILITY CONT. SOLUBILITY OF SOLUBILITY OF SOLIDS GASES • As the temperature • As the of a solvent temperature increases, the increases, the solubility of the solubility of the solute increases gas decreases – More sugar can – The warmer the dissolve in warm soda, the less water than in cold “fizz” due to less water CO2 in solution ALLOYS • Metal solutions • Solids dissolved in solids • Gold jewelry is a solid solution of gold and brass • Brass is a solution of copper and zinc REVIEW • What is a mixture? – A combination of 2 or more substances mixed together but not chemically combined • How does a heterogeneous mixture differ from a homogeneous mixture? – Heterogeneous mixtures have large particles and do not appear the same throughout – Homogeneous mixtures have small particles that are well blended and are the same throughout. Review Cont. • What is a colloid? – A homogeneous mixture where the particles are mixed together but are not dissolved and are permanently suspended • What is a solution? – A type of homogeneous mixture formed when one substance dissolves in another substance. • What are the two parts of a solution? – Solute (what dissolves) and solvent (what does the dissolving) Review Cont. • What are two properties of a solution – The particles are not easily separated – Particles are so small they are not visible • What is solubility? – The ability to absorb in water • What is an alloy? Give an example. – A metal solution of two or more metals. – Gold jewelry, brass, stainless steel
"MIXTURES_ ELEMENTS_ COMPOUNDS AND SOLUTIONS"