Chapter 2 Energy & Chapter 2 Energy & MatterMatter

Energy – the capacity to do Energy – the capacity to do work or produce heatwork or produce heat

– Examples of energy: moving car, Examples of energy: moving car, sunlight, food, oilsunlight, food, oil

3 categories of energy:3 categories of energy:1.1. Radiant – all forms of lightRadiant – all forms of light2.2. Kinetic energy – movement energyKinetic energy – movement energy3.3. Potential energy – stored energyPotential energy – stored energy

Gravitational energy – energy of positionGravitational energy – energy of positionElectrical energyElectrical energyChemical energyChemical energy

Measuring energyMeasuring energy1 calorie (cal) – amount of heat 1 calorie (cal) – amount of heat

to raise 1 gram of water 1 Cto raise 1 gram of water 1 Coo

1 food calorie (Cal) = 1000 cal = 1 food calorie (Cal) = 1000 cal = 1 kcal1 kcal

Chocolate bar is about 200 Cal Chocolate bar is about 200 Cal (200 kcal)(200 kcal)

SI unit of heat is the joule (J) SI unit of heat is the joule (J) 1 cal = 4.184 J1 cal = 4.184 J

Law of Conservation of Law of Conservation of energy energy

Energy cannot be created or Energy cannot be created or destroyed but can be changed destroyed but can be changed from one form to another.from one form to another.

Energy transformationEnergy transformation

Food chemical potential

Kinetic Gravitational

potential

Energy is not lost

but changes forms.

Kinetic

Heat and sound as arrow

strikes the ground

Temperature (3 temp. scales)Temperature (3 temp. scales)Fahrenheit, Celsius, KelvinFahrenheit, Celsius, Kelvin

Develop equations to convert F Develop equations to convert F to C and C to Fto C and C to F TT 180 F180 Foo = 100 C = 100 Coo

9 F9 Foo

F = F = C + 32 C + 32 ooFF5 C5 Coo

5 C5 Coo C =C = (F – 32 F (F – 32 Foo))

9 F9 Foo

Kelvin temp scale – there are Kelvin temp scale – there are no negative temperaturesno negative temperatures– The coldest temperature is 0 K The coldest temperature is 0 K

which is -273 which is -273 ooCC ooK = K = ooC + C +

273273((see page 64 “Pursuing Absolute Zero”)see page 64 “Pursuing Absolute Zero”)

If matter reached absolute zero, all If matter reached absolute zero, all motion would stopmotion would stopThe closer any thing gets to absolute zero the harder it is to remove any more heat.

It is a natural limit in nature (like the speed of light)

MatterMatterAnything that has mass and occupies volumeAnything that has mass and occupies volume

States of MatterStates of Matter• Solid – holds a particular Solid – holds a particular shape and has definite shape and has definite volumevolume• Liquid – no particular shape Liquid – no particular shape but has definite volumebut has definite volume• Gas – no definite shape or Gas – no definite shape or volume, fills all available volume, fills all available spacespace• Plasma – like gas only Plasma – like gas only exists at high temps (millions exists at high temps (millions of degrees)of degrees)On the sun and in a lightning boltOn the sun and in a lightning bolt

HEATING

Changes in state – by heating and coolingChanges in state – by heating and coolingProperties of matter – anything that can be Properties of matter – anything that can be used to describe matterused to describe matter

1.1. Physical properties – properties that can Physical properties – properties that can be determined without a chemical be determined without a chemical reactionreaction

2.2. Chemical properties – properties that Chemical properties – properties that can only be determined by a chemical can only be determined by a chemical reactionreaction

Physical change – no new substance Physical change – no new substance producedproducedChemical change – new substance Chemical change – new substance produced produced (something that was not there before)(something that was not there before)Law of Conservation of Matter – matter Law of Conservation of Matter – matter cannot be created or destroyedcannot be created or destroyed

Antwan Lavoisier (luhv-wahz-ee-ay) – father of Antwan Lavoisier (luhv-wahz-ee-ay) – father of modern chemistry, careful experiments and modern chemistry, careful experiments and precise measurementsprecise measurements

Elements and CompoundsElements and Compounds• Element – a Element – a substance that cannot substance that cannot be separated into be separated into simpler substances by simpler substances by a chemical changea chemical change

- Is listed on the - Is listed on the Periodic Periodic

ChartChart• Compound – two or Compound – two or more elements more elements

combinedcombined Na H2O Sc SC O2 O3

Element Compound Element Compound Element Element

MixtureMixture – two or more – two or more substances stirred substances stirred together but not together but not chemically combinedchemically combined– Heterogeneous Heterogeneous

mixture – contains mixture – contains visibly different parts visibly different parts (even very small (even very small particles)particles)

– Homogeneous mixture Homogeneous mixture – the same throughout– the same throughout

Separating MixturesSeparating Mixtures– Can be separated by Can be separated by

physical means; physical means; filtration, filtration, crystallization, crystallization, distillation, distillation, chromatographychromatography