Transcript PS Unit 5 Matter and Temperature

Matter and Temperature
Chapters: 2,3 and 14
Standards
• SPS2. Students will explore the nature of matter, its
classifications, and its system for naming types of
matter
• SPS2a. Calculate density when given mass and volume
• SPS5. Students will compare and contrast the phases
of matter as they relate to atomic and molecular
motion
• SPS5a. Compare and contrast the atomic/molecular
motion of solids, liquids, gases and plasmas
• SPS5b. Relate temperature, pressure and volume of
gases to the behavior of gases
Classifying Matter
Matter: anything with mass and volume:
• Atom: smallest unit of an element
• Element: cannot be broken down into
anything simpler (by chemical means)
ex hydrogen, oxygen, carbon…
Classifying Matter
• Molecule: two or more different elements
chemically bound; smallest unit of a
compound
• Compound: made up of molecules
-formula
ex NaCl
Pure Substances
• Fixed composition and definite properties
ex: water, salt, nitrogen, oxygen
Mixtures
• combination of substances:
-homogenous: parts are evenly distributed
ex vinegar
-heterogeneous: parts are not evenly
distributed
ex vegetables in a salad
Mixtures (cont’d)
• Miscible: can mix
ex gasoline
• Immiscible: cannot mix
ex oil and water
Physical Properties of Matter
• Physical Properties: can be observed without
changing the identity of the substance
ex melting point, boiling point, dissolving
magnetism, ability to conduct electricity
Physical Properties (cont’d)
• mass: amount of matter in an object
• volume: amount of space an object takes up
• density: ratio between mass and volume
-D= m/V
-measured in g/cm3 or g/mL
m
D
V
Chemical Properties
• describes how a substance changes into
another substance (cannot be reversed)
ex flammability: ability to burn,
reactivity: capacity to combine with another
substance,
rusting, effervescence
(bubbling)
Matter and Energy
Matter- anything that has mass and volume
• 4 states: solids, liquids, gases, plasma
Energy- ability to do work:
• Potential
• Kinetic
Kinetic Molecular Theory
Kinetic Molecular Theory (KMT):
• All matter is made of constantly moving
particles (atoms, molecules)
• All particles have kinetic energy (KE)
Temperature and Kinetic Energy
Temperature
• measure of average kinetic energy
• the more KE an object has, the higher its
temperature
Thermal energy= total KE; depends on:
• particle speed- faster particles have more KE
• number of particles- more particles have
greater thermal energy
Thermal Energy Quiz
• Which beaker of water has more thermal
energy?
B - same temperature, more mass
80ºC
A
80ºC
B
200 mL
400 mL
States of Matter
1. solid: definite shape and volume
2. liquid: changes shape but not volume
3. gases: changes shape and volume
4. plasma: no definite shape or volume and
full of moving charged particles
Energy and Solids
Solids
• low KE - particles vibrate but can’t move
around
• definite shape, volume:
*crystalline - repeating geometric pattern
*amorphous - no pattern (e.g. glass, wax)
Energy and Liquids
Liquids
• higher KE - particles can move, but are still
close together
• indefinite shape, not volume
• flows-fluid
Energy and Gases
Gases
• high KE – particles move freely
• indefinite shape and volume
• flows- fluid
Energy and Plasma
Plasma
• very high KE- particles collide with enough
energy to ionize (break into charged particles)
• lacks definite shape or volume
• can conduct electric current (unlike gases)
• most common state of matter
Changes of State Releasing Energy
• Condensation- gas to liquid
• Freezing- liquid to solid
• Temperature is constant during all changes in
state of matter
(ex: If energy is added to ice, the temperature
of ice will not rise until all the ice has melted)
Changes of State
• Sublimation
Evaporation
Condensation
Melting
Freezing
• substance does not change during a phase
change, but the energy does.
Changes of State Requiring Energy
• Melting Point: temperature at which a
substance changes from a solid to a liquid
• Boiling Point: temperature at which a
substance changes from a liquid to a gas
Energy Transfer Methods
• Conduction: when objects in direct contact are
unequal in temperature
• Convection: occurs in fluids (liquids or gases)
-convection currents: rise and fall of fluids due to
temperature differences (plate tectonics, wind)
• Radiation: transfer of energy by EM waves;
no physical contact
Energy Transfer
• Heat: thermal energy that flows from a
warmer material to a cooler material (energy
transfer)
-measured in joules (J)
Heat Transfer
Why does A feel hot and B feel cold?
 Heat flows from A to your hand = hot.
 Heat flows from your hand to B = cold.
80ºC
A
10ºC
B
Energy Transfer
• Conductor: material that can transfer energy
easily as heat
ex metals
• Insulator: material that cannot transfer
energy easily
ex. plastic, foam, wood
Temperature Scales
• T conversions:
• Fahrenheit: water boils- 212◦ F
water freezes- 32◦F
• Celsius:
water boils- 100◦ C
water freezes- 0◦ C
◦F = 1.8C + 32.0
◦C = F – 32.0
1.8
Temperature Scales (cont’d)
• Kelvin: based on absolute zero (-273.15 ◦C,
when molecular energy is at a minimum)
- theoretically, KE = 0 at absolute zero (but
particles actually never stop moving!)
K = ◦C + 273.0
Tκ = Tс + 273
Specific Heat
• Specific Heat (Cp)
– amount of energy required to raise the temp.
of 1 kg of material by 1 degree Kelvin
– units: J/(kg·K) or J/(kg·°C)
E = cmΔ T
E =energy
c = specific heat
m = mass
delta T = temp. change
Specific Heat Practice
How much energy must be transferred as heat
To 200kg of water in a bathtub to raise the
water’s temperature from 25◦C to 37◦C?
Given:
Known:
Solution:
ΔT= 37◦C - 25◦C E = cmΔ T
ΔT= 12K
m= 200kg
c= 4186 J
E= 4186J x 200kg x 12K
kg·K
E= 1.0 x 10⁴ kJ
Law of Thermodynamics
• First Law of Thermodynamics: total energy
used in any process is conserved
• Second Law of Thermodynamics: energy
transferred as heat moves from higher T to a
lower T
- energy decreases in all energy transfers
- entropy: measure of disorder within a
system when left to itself
Heat Engines
• Heat engines: convert chemical energy to
mechanical energy through combustion
- mechanical energy: transferred by work
- internal combustion: burns fuel inside
engine; always generate heat
Fluids
• gases, liquids
• Exert pressure, bouyancy,
• 3 basic principles govern fluids: Archimedes’,
Pascal’s, and Bernoulli’s
Pressure
• Amount of force exerted on a given area
force
pressure 
area
• P=F
A
• SI unit = Pascal; 1P = 1N/m²
• Fluids exert pressure in all directions
Buoyant Force
• All fluids exert an upward buoyant force on
matter
• Due to increased pressure with increased
depth
Archimedes’ Principle
• Archimedes’ principle: buoyant force on an
object in fluid is an upward force equal to the
weight of the fluid that the object displaces
Buoyancy and Density
• Objects with D = 1.00g/cm³ or less will float
Pascal’s Principle
• Pascal’s principle: if pressure is increased at
any point in a container, the pressure
increases at all points by the same amount
• P₁ = P₂ or F₁ = F₂
A₁ A₂
Pascal’s Principle Practice
A hydraulic lift lifts a 19,000 N car. If the area of
the small piston (A₁) equals 10.5 cm² and the area of
the large piston (A₂) equals 400 cm², what force needs
to be exerted on the small piston to lift the car?
Given:
Known:
Solution:
F₂ = 19,000N F₁ = F₂
F₁ = (F₂)(A₁)
A₁ = 10.5 cm² A₁ A₂
A₂
A₂ = 400 cm²
F₁ = (19,000N)(10.5cm²)
F₁=?
400cm
F₁ = 500N²
Fluids in Motion
• Move faster in smaller areas than large ones
(think water through a partially blocked hose)
• Viscosity: the resistance of fluids to flow
Bernoulli’s Principle
• Fluid pressure decreases as speed increases
Behavior of Gases
Properties:
• Fill container
• Mix with each other
• Low density
• Compressible
(unlike solids or liquids, gases are mostly empty
space)
Gas Laws
Describe how the behavior of gas is affected by:
• Pressure
• Volume
• Temperature
(laws help predict the behavior of gases under
certain circumstances)
Boyle’s Law
• Boyle’s Law: volume and pressure of a gas are
inversely related
• P₁V₁ = P₂V₂
P₁ = initial pressure
V₁ = initial volume
P₂ = final volume
V₂ = final volume
P
V
Boyle’s Law Practice
A cylinder has a volume of 7.5 L and contains a
gas at a pressure of 100 kPa. If the volume
changes to 11 L, what is the final pressure?
Given:
Known:
Solve:
P₁ = 100 P P₁V₁ = P₂V₂
P₂ = P₁V₁
V₁ = 7.5 L
V₂
V₂ = 11 L
P₂ = (100 kPa)(7.5 L)
P₂ = ?
11L
P₂ = 68 kPa
Gay-Lussac’s Law
• Gay-Lussac’s Law: pressure and temperature are
directly related
• P₁ = P₂
T₁ T₂
P₁ =initial pressure
T₁ = initial temp
P₂ = final pressure
T₂ = final temp
P
T
Charles’ Law
• Charles’ Law: volume and temperature are
directly related (at constant pressure) V₁ = V₂
• V₁ = V₂
T₁ T₂
T₁ = initial temp
V₁ = initial volume
T₂ = final temp
V₂ = final volume
V
T