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HONORS CHEMISTRY

HONORS CHEMISTRY. Chapter 3 MATTER. CLASSIFICATION OF MATTER. Classification of Matter. Matter - anything that has mass and occupies space anything that has the prop. of intertia Material - a specific kind of matter Mixture - matter that contains 2 or more diff. materials

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HONORS CHEMISTRY

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  1. HONORS CHEMISTRY Chapter 3 MATTER

  2. CLASSIFICATION OF MATTER

  3. Classification of Matter • Matter - anything that has mass and occupies space • anything that has the prop. of intertia • Material - a specific kind of matter • Mixture - matter that contains 2 or more diff. materials • Ex. wood, granite, concrete, air, milk

  4. Classification of Matter • Heterogeneous Materials - nonuniform material • has different properties throughout • made of separate phases • Phase - Physically separate part of a material having a uniform set of properties • Interface - boundary betw. phases

  5. Classification of Matter • Heterogeneous Mixture - composed of more than one phase • Homogeneous Materials - consist of only 1 phase • same props. throughout • Heterogeneous materials are always mixtures. • Homogeneous mixtures are called solutions.

  6. Mixtures • Mixtures can vary in composition • Solutions consist of: Solute - dissolved material Solvent - dissolving material • Same phase - solvent is in greater proportion • Molarity - indicates amt. of solute in a specific amt. of solvent - Concentration

  7. Classification of Matter • Substances - homogeneous materials which always have the same composition • Divided into 2 classes 1. Elements - substs. composed of 1 kind of atom 2. Compounds - substs. composed of 2 or more diff. kinds of atoms chemically combined

  8. MIXTURES not chemically combined separated by physical means proportions may vary COMPOUNDS chemically combined separated only by chemical means proportions can not vary (look up Law of Definite Proportions) Mixture Vs. Compound

  9. Classification of Matter • Organic Substs. - compounds which contain carbon • Inorganic Substs. - elements and compounds of all elements other than carbon

  10. PHYSICAL AND CHEMICAL CHANGES

  11. Physical Changes • changes in a material in which no new properties appear • Ex. boiling, melting, breaking, etc.

  12. Useful Physical Changes • Distillation - means of separating substs. by boiling pt. differences • Fractional Crystallization - means of separating substs. dissolved in the same soln. by using differences in solubilities • Solubility - the amt. of solute that will dissolve in a specific amt. of solvent at a specific temp. (see graph p. 58)

  13. Chemical Changes • Changes in which new substs. with new props. are formed. • Ex. burning, digestion, baking, etc. • Separation of a compound requires chemical change

  14. Conservation of Mass • During any chemical reaction, the mass of the products is always equal to the mass of the reactants.

  15. RULE OF THUMB • If a precipitate, gas, color change, or energy change occurs, a chemical change has probably taken place.

  16. Precipitate - a solid subst. that forms from a soln.

  17. PHYSICAL AND CHEMICAL PROPERTIES

  18. Physical Property • A property that can be observed w/out a change of subst. • A discription of the behavior of a subst. undergoing a physical change • Extensive Properties - Depend on amt. of matter present • Intensive Properties - Do not depend on amt. of matter

  19. LOOK UP… • Malleability • Ductility • Tensile Strength (tenacity) • Conductivity

  20. Chemical Property • A prop. characteristic of a subst. when it is involved in a chemical change • Defined in terms of interactions w/ other substs. • It is just as important to find out if a subst. does not react as it is to discover if it does react.

  21. ENERGY

  22. SYSTEM • Part of the universe under consideration • Surroundings - everything else • Surroundings do work on the system • System does work on the surroundings

  23. HEAT (q) • Energy transferred betw. 2 objects bec. of a diff. in temp. • flows from high temp. to low temp.

  24. Quantitative measurements of energy changes are expressed in Joules (J). • - derived SI unit • 1 J = 1kg*m2/s2 • 1 calorie = 4.18 J • 1 Calorie = 1000 calories = 1 kilocal. = 4180 J

  25. Chemical changes are always accompanied by energy change. • Endothermic Reaction - Rxn. in which energy is absorbed • Products have more energy than reactants. • Exothermic Reaction - Rxn. in which energy is given off • Products have less energy than reactants.

  26. Rule of thumb for reacting systems Nature tends to run downhill (exothermic). Exothermic rxns tend to take place spntaneously (w/out outside help). Endothermic rxns. usually need external source of energy to take place.

  27. Activation Energy - minimum amt. of energy needed to start a rxn. • Calorimeter - device used to meas. energy change in a chem rxn. or physical change

  28. Specific Heat (cp) • heat needed to raise the temp. of 1 g of a subst. by 1 Co • In an insulated syst., heat lost by one quantity of matter = heat gained by another. • assume no heat lost to surroundings • energy flows until 2 reach same temp

  29. q = mDtcp or q = mcDt • q = heat lost or gained (J) • m = mass (usually in grams) • cp or c = specific heat (J/g Co) • Dt = change in temp. (Co)

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