Download powerpoint

Unit I: Matter & Energy
Textbook Chapters 1,2,11 & 12
What is Chemistry?
Concerned with the properties of chemicals and the
changes chemicals can undergo
Physical vs. Chemical Changes
• Physical Change
change in appearance
but the substance itself
is not changed.
• Chemical Change
produces new
substances with
different properties.
H2O (l)  H2O (s)
H2O + ½O2  H2O2
• Aka Chemical Reaction
Paper Demo
Image taken from http://www.chem4kids.com/files/art/matter_intro_2_240.gif on 8/11/11.
Evidence of a Chemical
Change/Reaction
1.
2.
3.
4.
Evolution of a Gas
Formation of a Precipitate
Release or Absorption of Energy
Color Change in the Reaction System
Image taken from http://toastyscience.edublogs.org/2011/02/02/1para-reactions-lab-1/ on 8/11/11.
Properties of Matter
• Physical property
– Can be recognized without changing the
substance to anything else.
– Examples: color, odor, density, melting pt.
• Chemical property
– Describes how a substance reacts to form a
new substance.
– Examples: stable, reactive, flammable, inert
Image taken from warningsignsdirect.co.uk on 8/11/11.
Common States (Phases) of Matter
•
•
•
•
Solid
Liquid
Gas
Plasma
Image taken from
http://ds9.ssl.berkeley.edu/themis/m
ission_sunearth_closeup1.html on
8/11/11.
Solids
•
•
•
•
•
•
•
Particles close together
Particles vibrate but do not move
Strong attractive forces between particles
Crystalline structure (regular geometric pattern)
Definite shape
Definite volume
Lowest PE
Image taken from http://itl.chem.ufl.edu/2045_s99/lectures/FG11_001.GIF on 8/11/11.
Liquids
•Particles still close together.
•Particles vibrate and rotate allowing for movement.
•Weaker attractive forces between particles
•No regular pattern of particles
•Take shape of container
•Definite Volume
Image taken from http://itl.chem.ufl.edu/2045_s99/lectures/FG11_001.GIF on 8/11/11.
Gases
•Particles are very far apart and move all over.
•Particles vibrate, rotate and translate (move from
place to place).
•Weakest attractive forces between particles.
•Take shape and volume of container.
•Greatest disorder
•Highest PE
Image taken from http://itl.chem.ufl.edu/2045_s99/lectures/FG11_001.GIF on 8/11/11.
Phase Changes
{Change in Position of Particles (PE)}
•
•
•
•
•
•
•
Types of Physical Change
Melting
Freezing (Solidification)
Vaporization (Boiling)
Condensation
Sublimation
Deposition
Sublimation of Iodine
Image taken from http://www.splung.com/heat/images/phases/phasediagram.png on 8/11/11.
•Triple point
•At this temperature and pressure, substance can
exist as a solid, liquid or gas.
•Under higher pressure, harder for a solid to melt or a
liquid to boil.
•Under lower pressure, melting and boiling points lower
(easier to change).
Exception is water:
increasing pressure,
lowers freezing/melting
point (think ice
skating).
Endothermic vs. Exothermic
• Endothermic
– Heat energy is absorbed.
– Chemical Bonds broken in chemical rxn.
– 6 kcal + H2 + I2  2HI
• Exothermic
– Excess heat is given off (released).
– Chemical Bonds formed in chemical rxn.
– CaO(s) + H2O(l)  Ca(OH)2(s) + 986 kJ/mol
Images taken from uline.com and en.wikipedia.org on 8/11/11.
Demo
• Is this reaction exothermic or endothermic?
• Ba(OH)2.8H2O + 2NH4NO3+ 170kj/mol Ba(NO3)2 + 2NH3 + 10 H2O
Heating Curves
• Endothermic or exothermic?
• Be able to label all phases, phase changes,
changes in temperature, PE and KE.
Animated Heat Curve
Cooling Curves
• Endothermic or
exothermic?
• Be able to label
all phases,
phase changes,
changes in
temperature, PE
and KE.
2 Factors Affecting Phase of a
Material
• Temperature
• Pressure
n.f.p.= solid-liquid equilibrium point
n.b.p.= liquid-gas equilibrium point
Image taken from http://invsee.asu.edu/srinivas/liquidmod/states.html on 8/11/11.
• Evaporation
Vapor Pressure
• LG that takes place at the surface of the liquid and occurs
at all temp’s.
• From evaporation, vaporization & boiling, the
gas (vapor) produced exerts a pressure called
vapor pressure.
• ↑Temp of liquid, ↑vapor pressure
• Each substance has its own vapor pressure at
differing temperatures.
• Ref Table H
Vp animation
Image taken from http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/imgkin/vapp2.gif on 8/11/11.
Boiling Point
• Liquid will boil at temperature at which vapor
pressure = pressure on liquid.
• Point of equilibrium between gas and liquid
• If vapor pressure = 1 atm (std pressure) then
called the normal boiling point.
• Ref Table H
Image taken from http://images.tutorvista.com/content/solutions/manometer-vapour-pressure.jpeg on 8/11/11.
Low pressure lowers b.p. demo
7 Diatomics
• Di = 2
• Atomic = atoms
• 7 elements that exist in nature as paired
atoms in a molecule.
•To identify them, go to PT start
with element #7 and make the
shape of a #7
•
N2,O2,F2,Cl2,Br2,I2
•Missing one? Whose #1?
•
H2
Image taken from
http://ths.talawanda.net/~BrambleN/classroom/Pictures/periodictablediatomic.JPG
on 8/11/11.
Temperature vs. Heat
• Which one has more heat, a pot of boiling water
or the Arctic Ocean?
• Describe the temperature and heat of a 4th of
July sparkler.
Sparklers
Temperature
Δ of 1oC= Δ of 1K
• Measure of the
average kinetic
energy (KE) of the
particles of a
substance.
• Instrument
• thermometer
• Units
• Fahrenheit (o F)
• Celsius (o C)
• Kelvin (K) (SI Unit)
• Ref Table T
Temperature Animation
Animated Temp Movie
Image taken from http://www.visionlearning.com/library/module_viewer.php?mid=48 on 8/11/11.
Heat
• Energy transferred
between objects that
are at different
temperatures.
• Energy always flows
from source to sink.
• Instrument
Sink ↓(Temp)
• calorimeter
• Units
• Calories
• Joules (SI Unit)
Source ↑(Temp)
Image taken from http://www.g9toengineering.com/resources/heattransfer.jpg on 8/11/11.
Specific Heat
• Amount of heat energy required to raise the
temperature of 1 gram of a material 1oC
• What is the specific heat capacity of water?
• Ref Table B
4.18 J/goC or 4.18 J/gK
• Equal to 1 calorie/goC
ESCI connection metals vs. water
Boiling water in a paper cup
Using a bomb calorimeter to determine calories of an almond (4min)
Image taken from http://media.web.britannica.com/eb-media/54/7054-004-8062DB49.gif on 8/11/11.
3 Heat Formulas (Ref Table T)
•
•
•
•
Q=mHf
Q=mHv
Q=mcΔT
Try
examples!
• Ref Table B
Em Cee Delta Tee video
Animated Heating Curve
• Energy
Energy Conversion
– Ability to do work or
transfer heat
• Law of Conservation of
Energy
• Energy can not be created
nor destroyed, just
converted from one form to
another.
• 2 Types of Energy
• Kinetic and Potential
• Forms of Energy
• Kinetic (motion, electrical,
sound, radiant, thermal)
• Potential (chemical,
nuclear, gravitational,
stored mechanical)
Image taken from http://www.ngdir.ir/sitelinks/kids/html/energy_mfahem_science_forms%20of%20energy.html.htm on 8/11/11.
Classifying Matter
• Matter
– Anything that has mass and volume.
• Should remember terms mass, weight, volume
and density (Ref Table T) from esci. [Text 1-2]
Image taken from http://www.meta-synthesis.com/webbook/31_matter/matter2.jpg on 8/11/11.
Elements
• Substances that can not be broken down into
simpler substances by chemical means.
• Each element is composed of one type of atom.
Examples:
Review diatomics. allotropes
Image taken from http://www.starkeith.net/coredump/wp-content/uploads//2008/06/the-elements.jpg on 8/11/11.
Compounds
• 2 or more different elements chemically
combined in a definite ratio
• Can be decomposed chemically into elements.
Image taken from http://wiki.district87.org/images/9/91/Compounds.jpg on 8/11/11.
Pure Substances
• A sample of matter that has definite chemical
and physical properties.
• All samples of a single pure substance are
identical in their properties.
• Examples:
– elements &
– compounds
Image taken from http://www.m2c3.com/chemistry/VLI/M1_Topic2/la_01_02.jpg on 8/11/11.
Mixtures
• 2 or more substances physically combined with
no definite proportions.
• In a mixture, each substance retains its own
properties.
• Homogeneous or Heterogeneous
Image taken from http://www.m2c3.com/chemistry/VLI/M1_Topic2/la_01_02.jpg on 8/11/11.
Heterogeneous Mixtures
• Physical combination of substances that are
NOT uniform in composition throughout.
• Examples: sand & water, tossed salad, milk
Milk under a microscope
Image taken from
http://scienceprojectideasforkids.com/wpcontent/uploads/2010/06/challenge-1-sep-mix-clue.jpg
on 8/11/11.
Image taken from http://chestofbooks.com/reference/Facts-For-Everybody/images/Milk-474.png on 8/11/11.
Homogeneous Mixtures
• Physical combination of substances that
are uniform in composition and properties
throughout.
• Examples: salt & water, all solutions and
alloys
Image taken from
http://apbrwww5.apsu.edu/thompsonj/Anatomy%20&%20Physiology/2010/2010%
20Exam%20Reviews/Exam%201%20Review/salt_in_solution.jpg on 8/11/11.
Separating Mixtures
• Because mixtures are not chemically
combined, they can be separated physically.
• Such as….
– Filtration
– Centrifugation
– Chromatography
– Magnetism
– Distillation
Image taken from http://images.tutorvista.com/content/chemistry-concepts/magnetic-separationprocess.jpeg on 8/11/11.
Image taken from
http://library.thinkquest.org/11430/research/images/
filtration.gif on 8/11/11.
Distillation
Fractional Distillation of Petroleum
• Process by which a
mixture of liquids or a
liquid and a solid can
be separated by
different boiling
points.
Distillation of Saltwater
Image taken from http://www.tutorvista.com/content/chemistry/chemistryiii/organic-compounds/distillation.php on 8/11/11.
Image taken from http://www.energyinst.org.uk/education/coryton/images/column.gif on 8/11/11.
Image taken from http://wps.prenhall.com/wps/media/objects/165/169061/GIFS/AAAUASO0.JPG on 8/11/11.
Three Ways Compounds Differ from
Mixtures
1. Compounds are chemically combined
elements. Mixtures are physically combined
substances.
2. Compounds are formed from a definite
proportion. Mixtures can have varying
proportions. (Compounds have a definite
formula or “recipe”.
3. Compounds have different properties than
ingredients. Mixtures retain the same
properties of the ingredients.
NaCl (s)
NaCl (aq)
Image taken from http://www.personal.kent.edu/~cearley/ChemWrld/Reaction/H2_O2.gif on 8/11/11.
Molecular Models of Matter
•Can you identify the following pics as …
•element, compound or mixture ???
•solid, liquid or gas???
Online practice
More visuals
Image taken from http://www.yenka.com/activities/Substances_and_Mixtures/attachments/Substances%20and%20Mixtures%20-%20Q2.gif on 8/11/11.
Properties of Gases
•
•
•
•
Fluids
Low Density
Highly Compressible
Completely Fill a Container
Propane gas can
be compressed
in tanks for home
heating and gas
barbeques. It
can be so highly
compressed it
becomes a liquid.
• Pressure
Pressure of Gases
• Amount of force exerted per unit area of surface.
• Measured with barometer or manometer.
• ex: atmospheric pressure
• Units of pressure
– Atmospheres
– Pascals
– mm of Hg
How Std. Atm.
– Torr
pressure is
Evangelista
Torricelli
1606-1647
determined
How a barometer works
How a manometer works
Demo: pressure breaking stick
Demo: Can Crush
Images taken from http://ths.talawanda.net/~BrambleN/classroom/Chemistry/Notes/Section%204A/PressureandTemperature.htm on 8/11/11.
STP
Standard Temperature and Pressure
• Use Reference Table A
• For Gases,
• 273K = 0oC
• 1atm = 29.92 inHg =
760mmHg = 760 torr =
101.3kPa
• For liquids and solids,
• 25oC = ?K
• Same pressure
Image taken from http://www.free-online-private-pilot-ground-school.com/images/standard_sealevel_pressure.gif on 8/11/11.
Graham’s Law of Effusion (Diffusion)
• Diffusion- spreading out from area of high to low
density.
• Effusion-movement of gas through a small
opening into an evacuated chamber.
• The rate of diffusion of a gas is inversely
proportional to the square root of the gas’s
density.
Video
Image taken from http://images.tutorvista.com/content/matter-states/diffusion-effusion-process.gif on 8/11/11.
Kinetic Theory of Gases
or
Kinetic Molecular Theory (KMT)
1. Gas-composed of individual particles which are
in continuous, random straight line motion
2. Not all particles have same KE, avg KE of
particles=temp of gas
3. Elastic collisions between particlestransfer of
energy w/ no loss(Total energy stays the same.)
4. Volume of gas particles ignored compared to
volume of space in which they contain.
5. Gas particlesno attraction to each other
Image taken from
http://www.ucolick.org/~bolte/AY4_00/we
ek6/gas_pressure.gif on 8/11/11.
Ideal Gases
• Gases that follow the 5
points of KMT.
• Best examples are gases
with small molecular
masses like H2 and He.
• Low pressure and high
temperature conditions are
the best for ideal gases.
Image taken from www.wix.com on 8/11/11.
Real Gases deviate from KMT.
• Especially under High pressure and Low
temperatures.
• Can you think of ways gases would
deviate (not follow) from KMT?
KMT
Image taken from http://library.thinkquest.org/C006669/media/Chem/img/PV.gif on 8/11/11.
Gas Laws
•
•
•
•
•
Boyle’s
Charles’
Gay-Lussac
Combined
Ideal
Boyles’ Law
• At constant temp., volume of a
given mass of gas varies
inversely with pressure
• PV=K or V1/V2 = P2/P1
• Example:
Robert Boyle (1627-91)
Image taken from http://en.wikipedia.org/wiki/Robert_Boyle on 8/11/11.
Animation
Animation 2
w/ graphing
Charles’ Law
• At constant pressure, the volume
of a given mass of gas varies
directly with Kelvin temperature.
• V1/V2=T1/T2 or V/T=k
• Example:
V
Animation
Balloon Demo
Jacques Charles
(1746-1823)
Image taken from
http://www.scientificamerican.com/article.cf
m?id=what-is-charles-lawon 8/11/11.
Gay-Lussac
• At constant volume, the Kelvin
temperature of a gas is directly
related to the pressure.
• P1/T1 = P2/T2
• Example:
Joseph Gay-Lussac
(1778-1850)
Image taken from http://www.greatscientists.net/cms/wpcontent/uploads/joseph-louis-gay-lussac.jpg on 8/11/11.
Pressure Cooker
Animation
Image taken from toolskitchen.net on 8/11/11.
Combined Gas Law
• Changes in volume, pressure and
temperature of a gas often occur
simultaneously.
• Combine Boyle’s, Charles’ & Gay-Lussac’s.
• Formula on Ref Table T, remember K temp.
• Example:
Narrated Animation of all Gas Laws
Examples
a) A sample of 150.0 mL of oxygen gas is under
760.0 mmHg of pressure. What will be the
new volume of O2(g) if the pressure is reduced
to 750.0 mmHg?
b) A 250.0 mL Helium balloon is at a temperature
of -23.0oC. What is the size of the balloon
going to be if the system is warmed to 7.00oC?
c) A 175mL sample of gas is at 20.0oC and 1.00
atm. What will the new volume be if the
temperature is lowered to 10.0oC and the
pressure is raised to 1.50 atm?
Partial Pressures
• Pressure exerted by each of the
gases in a gas mixture.
• Total P = sum of partial pressures
John Dalton
(1766-1844)
solve?
Image taken from
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter4/graphics/parcel2.free.gif on
8/11/11.
Image taken from http://reich-chemistry.wikispaces.com/file/view/P3.JPG on 8/11/11.
Image taken from
http://www.chemistryexplained.com/ima
ges/chfa_02_img0256.jpg on 8/11/11.
Avogadro’s Hypothesis
• Equal volumes of gases under the
same conditions of temp. & pressure
contain equal numbers of particles.
• Avogadro’s #=1 mole=6.02 X1023
Image taken from http://library.thinkquest.org/12596/bonus_avogadro.gif on 8/11/11.
Amedeo Avogadro
(1776-1856)
Image taken from
http://en.wikipedia.org/wiki/Amede
o_Avogadro on 8/11/11.
Ideal Gas Law
• Includes the number of moles of gas
related to P (atm. or kPa), T (K) &V
n= number of moles of gas
(L).
R is the gas constant
• Derived from KMT.
R=0.0821 L atm/mol K
• PV=nRT
R=8.314 L.kPa/mol.K
.
.
• Which variables are directly related? Inversely related?
• Example:
a) At 5.00 atmospheres pressure and
70.0oC, how many moles are
present in 1.50 liters of O2 gas?
b) How many moles of gas are
contained in 22.41 liters at
101.325 kPa and 0.00oC?