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Chemical vs. Physical Properties
University of Lincoln presentation
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The periodic tableH
BeLi
Na
K
Rb
Cs
Fr
Mg
Ca
Sr
Ba
Ra
Sc
Y
La
Ac
Ti V Cr Mn Fe Co Ni Cu Zn
Zr
Hf Ta W Re Os Ir Pt Au Hg Tl
Nb Mo Tc Ru Rh Pd Ag Cd In Sn
Pb Bi Po At Rn
Xe
Kr
Ar
Ne
Sb Te I
Ga
Al
Ge
Si P S Cl
As Se Br
Ce Pr Nd Pm Sm
Eu Gd Tb Dy Ho Er Tm Yb Lu
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr
He
B C N O F
MetalsMetalloidsNonmetals
Increasing metallic character
Incr
easin
g m
etal
lic c
hara
cter
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Properties of Matter
• Types of matter are distinguished by their properties
• There are two categories of properties that concern us:
– Physical properties– Chemical properties
• If two samples of matter have the same properties, they must be the same substance
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Properties of Matter
• Understanding the properties of compounds is important for:
– Identifying an unknown substance– Distinguishing between different substances– Characterising a newly discovered substance– Predicting the usefulness of a substance for a
specific application
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Properties of Matter
• Physical properties –the identifying characteristics of matter– Some properties can be readily measured with our
senses• odour • Colour
– Instruments are needed to measure other properties• electrical resistivity• compressibility• hardness• melting point • radioactivity
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Properties of Matter
• Chemical properties – describe the reactivity of a substance towards other substances
– Ethanol burns in air (reacts with oxygen)– Sodium reacts vigorously with water– Corrosion of metal parts (rust) – Trinitrotoluene (TNT) is explosive– Lysergic acid diethylamide (LSD) is an
hallucinogenic drug
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Physical properties• METALS
– good conductors of electricity
– Ductile– malleable, lustrous– typically: solid– high melting point– good conductors of
heat
• NON METALS– poor conductors
of electricity– not ductile– not malleable– solid, liquid or gas– low melting point– poor conductors
of heat
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Chemical properties
• METALS– react with acids
– form basic oxides• react with acids
– form cations– form ionic halides
• NON METALS– do not react with
acids– form acidic oxides
• react with bases– form anions– form covalent halides
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The Rubber Book
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EthanolStoichiometry = C2H6OMelting Point = -115 ºCBoiling Point = 78 ºCDensity = 0.79 g/cm3
Ethylene GlycolStoichiometry = C2H6O2
Melting Point = -16 ºCBoiling Point = 197 ºCDensity = 1.11 g/cm3
Dimethyl EtherStoichiometry = C2H6OMelting Point = -140 ºCBoiling Point = -24 ºCDensity = Gas
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Mixtures
• Homogeneous Mixture – composition and properties are uniform (sometimes called a solution)
– Air – principal components include O2, N2 & CO2 – Vodka – principal components are EtOH & H2O – Brass – solid solution of Cu and Zn– Ruby – solid solution of Al2O3 and Cr2O3
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Mixtures
• Heterogeneous Mixture – composition and properties are non-uniform
– Chocolate Chip Cookie – chocolate, sugar, dough, etc.
– Concrete – cement, sand, aggregate – Vomit – Depends upon previous intake of food
and drink
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Mixtures, Compounds & Elements
Matter
Is it uniform throughout?
Heterogeneousmixture Homogeneous
Does it have a variable
composition?
Homogeneous mixture (solution)
Pure substance
Can it be separatedInto simplerSubstances?
Element Compound
No
No
No
Yes
Yes
Yes
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Na N2
SO3
Mixtures, Compounds & Elements
Mixture
Atoms of an element
Molecules of an element
Molecules of a compound
Mixture of elements and a compound
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Changes in Matter
• Physical change– Substance changes physical appearance
without altering its identity e.g. changes of state
ice melting to form water
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Changes in Matter
• Chemical changes (or chemical reactions)– Substances transform into chemically
different substances i.e. identity changes
e.g. decomposition of water
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Changes in Matter• Chemical • Physical
FreezingDe
posit
ion
Evaporation
Condensation
MeltingSu
blim
ation
Gas
LiquidSolid
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Solubility• Defined as:
– The quantity of a particular substance that can dissolve in a particular solvent (yielding a saturated solution)
– Can be expressed in g/100g of water, mol dm-3
• Generally refers to the compound’s ability to dissolve in water – the aqueous phase (aq)
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Solubility
• A saturated solution– contains the
maximum amount of solute that can dissolve
– undissolved solute remains
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Solubility
• An unsaturated solution – does not contain
all the solute that could dissolve
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SolubilityRule 1
ALL nitrate (NO3
-)nitrite (NO2
-) chlorate (ClO3
-) and perchlorate (ClO4
-) salts are soluble
Exceptions
Silver nitrite and potassium perchlorate
are considered only slightly soluble
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SolubilityRule 2
ALL alkali metal (Li+, Na+, K+, Rb+, Cs+)
and ammonium (NH4
+)salts are soluble
Exceptions
Some Li+ salts are insoluble
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SolubilityRule 3
MOST halogen (Cl¯, Br¯, I¯)salts are soluble
Exceptions
Ag+, Pb2+, Hg22+,
Cu+, Tl+(Pb2+ halogens are soluble in hot water)
HgBr2 is only slightly soluble
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SolubilityRule 4
MOST acetate (C2H3O2¯) saltsare soluble
Exceptions
Ag+, Hg22+
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SolubilityRule 5
MOST sulphate (SO4
2¯) saltsare soluble
Exceptions
Ca2+, Sr2+, Ba2+, Ra2+, Pb2+, Ag+, Hg2+
(Some sources consider calcium sulphate and silver sulphate to be slightly soluble)
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SolubilityRule 6
MANY sulphides (S2¯) saltsare insoluble
Exceptions
All alkali metal and alkaline earth
(Be2+, Mg2+, Ca2+, Sr2+, Ba2+, Ra2+)sulphides are
soluble
Ammonium sulphide is soluble
(Some sources consider MgS, CaSand BaS to be slightly soluble)
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SolubilityRule 7
MOST borates (BO3
2-), carbonates (CO3
2-), chromates (CrO4
2-), phosphates (PO4
3-), and sulphites (SO3
2-) are slightly soluble
Exceptions
MgCrO4 is soluble,
MgSO3 is slightly soluble
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SolubilityRule 8
MOST hydroxide (OH-) salts are insoluble
Exceptions
Alkali metal hydroxides are soluble
Ba2+, Sr2+, Ca2+, Tl+ are considered slightly soluble
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Solubility Product Ksp
• In general, the solubility product is the equilibrium constant for the solubility equilibrium of a slightly soluble (or nearly insoluble) ionic compound
(Next Semester)
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FACT: The solubility of a gas decreases with an increase in temperature
A. Why might a bottle of carbonated drink burst (explode) when it is left out in the hot sun ?
B. Why do fish die in water that gets too warm?
Based on Daltons Law and Henry’s Law
Temperature & Solubility
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Corrosion
• CorrosionCorrosion is the ‘destructive is the ‘destructive interaction between a interaction between a materialmaterial and and its its operation environmentoperation environment’ ’
It leads to material degradation and It leads to material degradation and contamination of the environmentcontamination of the environment
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Corrosion
• Corrosion is a more general term a more general term than ‘rusting’ – a concept that only than ‘rusting’ – a concept that only relates to a homogeneous type of relates to a homogeneous type of attack attack
often of iron or steel, in natural often of iron or steel, in natural environments.environments.
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Corrosion• Non metals can also corrode
• Chemical corrosion – Removal of atoms from a material by
virtue of the solubility or chemical reaction between the material and the surrounding liquid
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Corrosion by Acid Rain1908 1969
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Biodeterioration
• Can be defined as:
– Any undesirable change in the properties of a material caused by the vital activities of organisms
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Biodeterioration• Types:
– physical or mechanical • material is not a food source
– root damage, gnawing by rodents– fouling or soiling
• material not damaged– fungus on shower curtain, barnacles
– chemical assimilatory• material is used as a carbon and/or energy source
– food spoilage, degradation of fuels, metals– chemical dissimilatory
• substance not used as carbon and energy source– acid waste products, tooth decay
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Flammability• A Flammable substance could be defined
as ‘having the ability to burn’
• A Flammable liquid can be defined as:– any liquid having a flash point below 100 F
(37.8 oC)• except any mixture having components with
flash points of 100F (37.8 oC.) or higher, the total of which make up 99 percent or more of the total volume of the mixture
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• Flash Point– Lowest temperature at which a flammable liquid
exposed to air will burn when exposed to sparks or flame.
• Auto Ignition Temperature– Temperature above which spontaneous
combustion can occur without the use of a spark or flame
• Ignition Energy– Lowest amount of energy required for ignition
• Flammable Liquids – Liquids with a flash point < 100F (38 oC)
• Combustible Liquids– Liquids with a flash point > 100F (38 oC)
Definitions
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The Fire Triangle• Fuels:
– Liquids• gasoline, acetone,
ether, pentane– Solids
• plastics, wood dust, fibers, metal particles
– Gases• acetylene,
propane, carbon monoxide, hydrogen
• Oxidizers– Gases
• Oxygen, fluorine, chlorine
hydrogen peroxide,nitricacid, perchloric acid
– Solids• Metal peroxides, ammoniumNitrate
– Liquids• Ignition sources
• Sparks, flames, static electricity, heat
Air (
Oxyg
en)
Fuel
Ignition source
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Fire and Forensics• Accelerant and fire debris analysis• Fire Modelling• Smoke Analysis
– Current work at Lincoln– Characterisation of smoke
• Much, much, more on Fire and Explosion Investigation in Level 3 !
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Acknowledgements• JISC• HEA• Centre for Educational Research and
Development• School of natural and applied sciences• School of Journalism• SirenFM• http://tango.freedesktop.org