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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. - PowerPoint PPT Presentation
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How can we describe matter? Page 39
Extensive Properties – depend on the amount of matter in a sampleEx. Mass, Volume
Intensive Properties – depends on the type of matter, not the amountEx. Density, Boiling Point, Freezing Point
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,
States of Matter and Phase Changes P. 41
ExothermicExothermic
ExothermicP. 59 Q - 60-64
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
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
Classifying Mixtures – a blend of two or more substances
Mixture
Heterogeneous
Not uniform throughout
Ex. Salad dressing, Sand, chocolate
chip cookie dough
Homogeneous
Uniform throughout
Solution – liquid or gas
Coke, Sea water, gold jewelry, air
P. 58 Q-44-46, P. 59 Q 66
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
Element• Simplest form of matter that has a
unique set of properties• Ex. Carbon, Oxygen, Iron
Compound• A substance that contains 2 or more
elements chemically combined in a fixed proportion
• Ex. Salt – NaCl, Glucose C6H12O6
• Can be broken down into simpler substances by chemical means
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
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
Indicate the names of each element and the total number of atoms in each compound.
MgCl2Ca3(PO4)2
CrCO3
Ca(C2H3O2)
Breaking Down CompoundsChemical 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.
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
Chemical Property – the ability of a substance to undergo a specific chemical change
Ex. Reactivity with acids, flammability, decomposition
4Fe(s) + 3O2(g) 2Fe2O3(s)
rust
State of matter – before and after the reaction
Coefficients – state the number of individual atoms, compounds or molecules
s = solid, l = liquid, g = gas, aq = aqueous
P. 59 Q - 67
Chemical and Physical Properties
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)
Applying the Law of Conservation of Matter
4Fe (s) + 3O2 (g) 2Fe2O3 (s)
3.5 kg x kg 3.7 kg+ =
x = .2 kg
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.
1. How many grams of hydrochloric acid were used?2. How many atoms of hydrogen are present on the reactants
side of the equation? Products?3. How many atoms of tin are present on the reactants side of the
equation? Products?4. How many atoms of chlorine are present on the reactants side
of the equation? Products?5. Identify the state of each reactant.6. Identify the state of each product.7. How many molecules of HCl are present? H2?
P. 55 #34, P. 58 # 56 P. 61 #10-14