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 – Ex. wood, granite, concrete, air, milk

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

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.

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

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

Mixture Vs. Compound

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)

Classification of Matter

  Organic Substs. - compounds which contain carbon

  Inorganic Substs. - elements and compounds of all elements other than carbon

PHYSICAL AND CHEMICAL CHANGES

Physical Changes

  changes in a material in which no new properties appear – Ex. boiling, melting, breaking, etc.

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)

Chemical Changes

  Changes in which new substs. with new props. are formed.

•  Ex. burning, digestion, baking, etc. – Separation of a compound requires chemical

change

Conservation of Mass

  During any chemical reaction, the mass of the products is always equal to the mass of the reactants.

RULE OF THUMB

  If a precipitate, gas, color change, or energy change occurs, a chemical change has probably taken place.

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

PHYSICAL AND CHEMICAL PROPERTIES

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

LOOK UP…

  Malleability   Ductility   Tensile Strength (tenacity)   Conductivity

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.

ENERGY

SYSTEM

  Part of the universe under consideration – Surroundings - everything else

  Surroundings do work on the system   System does work on the surroundings

HEAT (q)

  Energy transferred betw. 2 objects bec. of a diff. in temp. –  flows from high temp. to low temp.

  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

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.

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.

  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

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

q = mΔtcp or q = mcΔt

  q = heat lost or gained (J)   m = mass (usually in grams)   cp or c = specific heat (J/g Co)

 Δt = change in temp. (Co)