MATTER Chapter 3

Definitions from Matter Tree Matter – anything that has space or takes up volume Matter – anything that has space or takes up volume Mixture – 2 or more materials NOT chemically combined Mixture – 2 or more materials NOT chemically combined

Mixtures Heterogeneous – mixtures composed of more than one phase Heterogeneous – mixtures composed of more than one phase Ex: oil and water Ex: oil and water Ex: granite Ex: granite Homogeneous – mixtures consisting of one phase Homogeneous – mixtures consisting of one phase Each piece has the same properties Each piece has the same properties Ex: air, Kool-Aid Ex: air, Kool-Aid Another name for a homogeneous mixture is SOLUTION Another name for a homogeneous mixture is SOLUTION

Pure Substance Always has the same composition Always has the same composition Element – substance composed of only one kind of atom Element – substance composed of only one kind of atom Ex: S, Ca, O, He, N Ex: S, Ca, O, He, N Compound – Substances composed of 2 or more elements chemically combined ex: Water, salt, hydrochloric acid

Physical Properties Properties of a substance that can be observed WITHOUT changing the substance Properties of a substance that can be observed WITHOUT changing the substance Ex: Length, color, temp. Ex: Length, color, temp. Two types of Physical Properties Two types of Physical Properties Intensive – DOES NOT depend on the size of the sample Intensive – DOES NOT depend on the size of the sample Ex: color, malleability, ductility, conductivity, MP, BP, density Ex: color, malleability, ductility, conductivity, MP, BP, density Extensive – DOES depend on the size of the sample Ex: mass, length, volume

Chemical Properties Describes the behavior of a substance undergoing a chemical change Describes the behavior of a substance undergoing a chemical change Ex: Cl reacts with Na  NaCl Ex: Cl reacts with Na  NaCl Ex: Fe + O 2  Fe 2 O 3 (rust) Ex: Fe + O 2  Fe 2 O 3 (rust)

Physical Changes Change that DOES NOT result in a new substance being formed Change that DOES NOT result in a new substance being formed Ex: Cutting, dissolving sugar in H 2 O, phase changes Ex: Cutting, dissolving sugar in H 2 O, phase changes

Chemical Changes Changes that produce a new substance Changes that produce a new substance Ex: Rust, CuCl 2 + Al foil Ex: Rust, CuCl 2 + Al foil

Energy Physical and chemical changes are always accompanied by energy changes Physical and chemical changes are always accompanied by energy changes Most common form of energy involves heat Most common form of energy involves heat

Types of Heat Endothermic – absorbs heat Endothermic – absorbs heat Exothermic – releases heat Exothermic – releases heat

Calculating Heat Q = mC∆T Where: Q = heat (Joules or calories) m = mass (g) C = specific heat (J/g o C) ∆T = change in temp(T final – T initial )

Calculating Heat How much heat is lost when 25.6g of water cools from 87.4 o C to 34.5 o C?

Calculating Heat Aluminum has a specific heat of 0.97 J/g o C. 30,006 J of heat are added to change the substance from 67.3 o C to 87.2 o C. What is the mass?

Calculating Heat What is the final temperature of 33.3 g of water when 67,456 J of heat are added at 55.3 o C?

Calculating Heat How many calories of heat are needed to change 98g of water 12 o C?