chapter 1 the chemical world
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Chapter 1 The Chemical World. What Is Chemistry?. The science that deals with the materials of the universe and the changes these materials undergo. The science that seeks to understand what matter does by studying what atoms and molecules do. What Is Chemistry?. - PowerPoint PPT PresentationTRANSCRIPT
Chapter 3Matter and Energy
Matter Matter is defined as anything that occupies
space and has mass–things you can see, touch, taste, or smell.
States of Matter Matter can be
classified as solid, liquid, or gas based on what properties it exhibits.
States of Matter
State Particle Spacing Shape Volume Compress
Solid close fixed fixed no
Liquid close indefinite fixed no
Gas far apart indefinite indefinite yes
Composition of Matter Matter that is composed of only one kind of
atom or molecule is called a pure substance. Matter that is composed of different kinds of
atoms or molecules is called a mixture.
Pure SubstanceConstant Composition
MixtureVariable Composition
Matter
Composition of Matter Pure substance
Element—a substance that cannot be broken down into other substances by chemical methods.
Compound—a substance composed of a given combination of elements that can be broken down into those elements by chemical methods.
Composition of Matter Element: made of one
type of atom. Compound: made of
one type of molecule, or array of ions—more than one type of atom.
Composition of Matter Mixture
Mixtures that are uniform throughout are called homogeneous. Also known as solutions.
Mixtures that have regions with different characteristics are called heterogeneous.
Composition of Matter Homogeneous—appears to be
one substance, all portions of a sample have the same composition and properties.
Heterogeneous—presence of multiple substances can be seen, portions of a sample have different composition and properties.
Composition of Matter Mixtures can be separated
based on different physical properties of the components. Filtration
Composition of Matter Distillation
Composition of Matter
Composition of Matter Classify each of the following as a pure
substance (compound or element) or mixture (homogeneous or heterogeneous).1. Pure water2. Gasoline3. Jar of jelly beans4. Soil5. Copper metal
Physical and Chemical Properties The characteristics of a substance that
distinguish that substance are called its properties.
Physical and Chemical Properties Physical Properties are the characteristics of
matter that can be changed without changing its composition. Characteristics that are directly observable.
Physical and Chemical Properties Chemical Properties are the characteristics
that determine how the composition of matter changes as a result of contact with other matter or the influence of energy. Characteristics that describe the behavior of
matter.
Physical and Chemical Changes Changes that alter the state
or appearance of the matter without altering the composition are called physical changes.
Physical and Chemical Changes Changes that alter the
composition of the matter are called chemical changes.
Physical and Chemical Properties1. Classify each of the following as a physical or chemical property.
a. Ethyl alcohol boils at 78oCb. Sugar ferments to form ethyl alcoholc. Salt is stable at room temperature, it does not decomposed. 36 g of salt will dissolve in 100 g of water
2. Classify each of the following as a physical or chemical change.a. Sugar fermenting to form ethyl alcohol b. Dissolving of sugar in waterc. Iron metal meltingd. Iron combining with oxygen to form rust
Conservation of Mass Matter is neither created nor destroyed in a
chemical reaction.
Conservation of Mass 15 g elemental
magnesium is burned in the presence of oxygen; 25 g white magnesium oxide result. What mass oxygen was used up?
Energy Energy is anything that
has the capacity to do work.
All chemical and physical changes result in the matter changing energy.
Energy Potential energy is energy that is stored. Kinetic energy is energy of motion, or energy
that is being transferred from one object to another.
Energy Energy can neither be created nor destroyed.
Energy calorie (cal) is the amount of energy needed to raise
one gram of water by 1 °C.
Energy Conversion Factors1 calorie (cal) = 4.184 joules (J)
1 Calorie (Cal) = 1000 calories (cal)
1 kilowatt-hour (kWh) = 3.60 x 106 joules (J)
Energy and Chemical/Physical Change Exothermic process—when a chemical or
physical change results in the release of energy
Pote
ntia
l ene
rgy
Reactants
Products
Surroundings
reaction
Amount of energy released
Energy and Chemical/Physical Change Endothermic process—when a chemical or
physical change requires the absorption of energy
Surroundings
reaction
Pote
ntia
l ene
rgy
Products
Reactants
Amount of energy absorbed
Energy and Chemical/Physical Change Classify each process as exothermic or
endothermic1. Your hand gets cold when you touch ice.2. The ice gets warmer when you touch it.3. Water boils in a kettle being heated on a stove.4. Water vapor condenses on a cold pipe.5. Ice cream melts.
Temperature A measure of the random motions of the
components of a substance. Fahrenheit, Celsius, Kelvin
Heat: a flow of energy between two objects due to a temperature difference between the objects.
Temperature
Temperature Converting between scales
1. The normal body temperature for a dog is approximately 102oF. What is this equivalent to on the Kelvin temperature scale?
2. If the outside temperature is 298 K, what would you wear? What is this equivalent to on the Fahrenheit temperature scale?
K C C K
FC F C
+ 273 273
32 1.80 + 32
1.80
T T T T
TT T T
Heat Capacity Energy (Heat) Required to Change the
Temperature of a Substance Depends On: The amount of substance being heated (grams) The temperature change (degrees). The identity of the substance.
Heat Capacity Heat capacity is the amount of heat a
substance must absorb to raise its temperature by 1 °C.
Specific heat = heat capacity of 1 gram of the substance.
Heat Capacity Specific Heat
Capacities
Substance Specific Heat J/g°C
Aluminum 0.903 Carbon (dia) 0.508 Carbon (gra) 0.708
Copper 0.385 Gold 0.128 Iron 0.449 Lead 0.128 Silver 0.235
Ethanol 2.42 Water (l) 4.184 Water (s) 2.03 Water (g) 2.02
Summary of Topics: Chapter 3 Matter Pure substances: compounds and elements Mixtures: homogeneous and heterogeneous Chemical, Physical properties Chemical, Physical changes Energy, exothermic and endothermic Temperature conversions Heat Capacity (qualitative)