Download Chapter 3- Matter and Energy

Chapter 3- Matter and Energy
Properties
• Characteristics of the substance under observation
• Properties can be either
¬ directly observable or
¬ the manner something interacts with other substances in the universe
Universe Classified
• Matter is the part of the universe that has mass and volume
• Energy is the part of the universe that has the ability to do work
• Chemistry is the study of matter
– The properties of different types of matter
– The way matter behaves when influenced by other matter and/or energy
Properties of Matter
• Physical Properties are the characteristics of matter that can be changed without changing its
composition
– Characteristics that are directly observable
• 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
States of Matter
State
Super Cooled Solid
Solid
Liquid
Gas
Plasma
Shape
Keeps Shape
Keeps Shape
Takes Shape of
Container
Takes Shape of
Container
Takes Shape of
Container
Volume
Keeps Volume
Keeps Volume
Keeps Volume
Compress
NO
NO
NO
Flow
NO
NO
YES
Takes Volume of
Container
Takes Volume of
Container
YES
YES
YES
YES
Changes in Matter
• Physical Changes are changes to matter that do not result in a change the fundamental components that
make that substance
– State Changes – boiling, melting, condensing
• Chemical Changes involve a change in the fundamental components of the substance
– Produce a new substance
– Chemical reaction
– Reactants  Products
Elements and Compounds
• Substances which can not be broken down into simpler substances by chemical reactions are called
elements
• Most substances are chemical combinations of elements. These are called compounds.
– Compounds are made of elements
– Compounds can be broken down into elements
– Properties of the compound not related to the properties of the elements that compose it
– Same chemical composition at all times
Classification of Matter
Pure Substances vs. Mixtures
• Pure Substances
– All samples have the same physical and
chemical properties
– Constant Composition  all samples have the
same composition
– Homogeneous
– Separate into components based on chemical
properties
• Mixtures
– Different samples may show different properties
– Variable composition
– Homogeneous or Heterogeneous
– Separate into components based on physical
properties
• All mixtures are made of pure substances
Mixture- a sample of matter containing two or more substances not chemically combined. (air, saltwater)
• Homogeneous mixture- the components of the mixture are evenly distributed. (seawater)
– Also known as a solution- a substance (solute) dissolved in a solution (solvent).
• Heterogeneous mixture- the components of the mixture are not evenly distributed- different components
are concentrated in different regions (granite)
Separation of Mixtures
• Separate mixtures based on different physical properties of the components
– Physical change
Different Physical Property
Separation Technique
Boiling Point
Distillation
State of Matter (solid/liquid/gas) or Particle Size
Filtration
Adhere to a surface
Chromatography
Volatility
Evaporation
Solubility
Recrystalization
Energy and Energy Changes
• Capacity to do work
– chemical, mechanical, thermal, electrical, radiant, sound, nuclear
• Energy may affect matter
– e.g. raise its temperature, eventually causing a state change
– All physical changes and chemical changes involve energy changes
Heat
• Heat: a flow of energy due to a temperature difference
1. Exothermic = A process that results in the evolution of heat.
• Example: when a match is struck, it is an exothermic process because energy is produced
as heat.
2. Endothermic = A process that absorbs energy.
• Example: melting ice to form liquid water is an endothermic process.
Units of Energy
• One calorie is the amount of energy needed to raise the temperature of one gram of water by 1°C
– kcal = energy needed to raise the temperature of 1000 g of water 1°C
• joule
– 4.184 J = 1 cal
• In nutrition, calories are capitalized
– 1 Cal = 1 kcal
Energy and the Temperature of Matter
• The amount the temperature of an object increases depends on the amount of heat added (Q).
– If you double the added heat energy the temperature will increase twice as much.
• The amount the temperature of an object increases depends on its mass
– If you double the mass it will take twice as much heat energy to raise the temperature the same
amount.
Specific Heat Capacity
• Specific Heat (s) is the amount of energy required to raise the temperature of one gram of a substance by
one Celsius degree
By definition , the specific heat of water is 4.184
J
g C
Amount of Heat = Specific Heat x Mass x Temperature Change
Q = s x m x T