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How can we describe matter? Page 39

How can we describe matter? Page 39. Extensive Properties – depend on the amount of matter in a sample Ex. Mass, Volume Intensive Properties – depends on the type of matter, not the amount Ex. Density, Boiling Point, Freezing Point. Identifying Substances.

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How can we describe matter? Page 39

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  1. How can we describe matter? Page 39 Extensive Properties – depend on the amount of matter in a sample Ex. Mass, Volume Intensive Properties – depends on the type of matter, not the amount Ex. Density, Boiling Point, Freezing Point

  2. Identifying Substances Substance - matter that has a uniform and definite composition Physical Property – a property that can be observed without changing the substance’s composition • Color, Luster, Malleability, Boiling/Melting/Freezing Point, Density, conductivity,

  3. States of Matter and Phase Changes P. 41 Exothermic Exothermic P. 59 Q - 60-64 Exothermic

  4. Is it a gas or a vapor? Vapor – the gaseous state of a substance that is generally a solid or gas at room temperature Question 40 - P. 58

  5. Physical Change – a property of a substance that changes but the identity of the substance does not Ex. Melting, freezing, splitting, grinding Density of water (l) – 1.00 g/cm3 Density of water (s) - .92 g/cm3

  6. Classifying Mixtures– a blend of two or more substances P. 58 Q-44-46, P. 59 Q 66

  7. Separating Mixtures • Density • Filtration – separates a solid from a liquid in a heterogeneous mixture • Distillation – separates a homogenous mixture of water and another substance (Boiling Points) P. 58 Q - 47

  8. Representing Elements and Compounds Element – first letter capital, second letter lower case K = Potassium Na = Sodium Aspirin – C8H9O2N Subscript – indicates the number of atoms, follows the element P. 58 Q - 50,52

  9. Compounds - continued Cu(NO3)2 • Multiply the subscripts inside and outside the parentheses to determine the number of atoms • Subscript outside the parentheses only refers to the elements inside

  10. Indicate the names of each element and the total number of atoms in each compound. MgCl2 Ca3(PO4)2 CrCO3 Ca(C2H3O2)

  11. Breaking Down Compounds Chemical change –produces matter with a different composition than the original matter Heating – raw egg vs. fried egg Electricity – decomposes water into H2 and O2 gas.

  12. Indicators of a Chemical Change • color change • production of a gas • formation of a precipitate (solid) • transfer of energy • Production of light • Change in Temperature • Exothermic – release in heat, increase in temp. • Endothermic – heat absorption, decrease in temp. • multiple forms of evidence are needed P. 59 Q - 69-71

  13. Chemical Property – the ability of a substance to undergo a specific chemical changeEx. Reactivity with acids, flammability, decomposition Coefficients – state the number of individual atoms, compounds or molecules 4Fe(s) + 3O2(g)  2Fe2O3(s) rust State of matter – before and after the reaction s = solid, l = liquid, g = gas, aq = aqueous P. 59 Q - 67

  14. Chemical and Physical Properties

  15. Law of Conservation of Matter • Mass is neither created nor destroyed in a chemical reaction it is conserved Mass reactants = Mass products • Antoine Lavoisier (1743-1794)

  16. Applying the Law of Conservation of Matter 4Fe (s) + 3O2 (g)  2Fe2O3 (s) 3.5 kg x kg 3.7 kg + = x = .2 kg

  17. Sn (s) + 4HCl (aq)  SnCl4 (s) + 2H2 (g) When 5.0 g of tin reacts with hydrochloric acid, the mass of the products tin chloride and hydrogen totals 8.1 g. How many grams of hydrochloric acid were used? How many atoms of hydrogen are present on the reactants side of the equation? Products? How many atoms of tin are present on the reactants side of the equation? Products? How many atoms of chlorine are present on the reactants side of the equation? Products? Identify the state of each reactant. Identify the state of each product. How many molecules of HCl are present? H2? P. 55 #34, P. 58 # 56 P. 61 #10-14

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