how can we describe matter? page 39 extensive properties – depend on the amount of matter in a...

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