Chemical and Physical Properties: Chemical vs. Physical Properties

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Chemical vs. Physical Properties

University of Lincoln presentation

http://creativecommons.org/licenses/by-nc-sa/2.0/uk/

http://chemistryfm.blogs.lincoln.ac.uk/


The periodic table

H

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

easi

ng m

eta

llic

chara

cter



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




• 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




• 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




• 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



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



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



The Rubber Book


http://www.samfundslitteratur.dk/resources/images/items/0849304849_MEDIUM.jpg

http://www.samfundslitteratur.dk/resources/images/items/0849304865_MEDIUM.jpg


EthanolStoichiometry = C2H6O

Melting 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 = C2H6O

Melting Point = -140 ºCBoiling Point = -24 ºCDensity = Gas



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



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



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



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



Changes in Matter

• Physical change– Substance changes physical appearance

without altering its identity e.g. changes of state

ice melting to form water



Changes in Matter

• Chemical changes (or chemical reactions)– Substances transform into chemically

different substances i.e. identity changes

e.g. decomposition of water



Changes in Matter

• Chemical • Physical

FreezingD

epos

itio

n

Evaporation

Condensation

MeltingSu

blim

atio

n

Gas

LiquidSolid



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)



Solubility

• A saturated solution– contains the

maximum amount of solute that can dissolve

– undissolved solute remains



Solubility

• An unsaturated solution – does not contain

all the solute that could dissolve



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



Solubility

Rule 2

ALL alkali metal (Li+, Na+, K+, Rb+, Cs+)

and ammonium (NH4

+)

salts are soluble

Exceptions

Some Li+ salts are insoluble



Solubility

Rule 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



Solubility

Rule 4

MOST acetate (C2H3O2¯) saltsare soluble

Exceptions

Ag+, Hg22+



Solubility

Rule 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)



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)



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



Solubility

Rule 8

MOST hydroxide (OH-) salts are insoluble

Exceptions

Alkali metal hydroxides are soluble

Ba2+, Sr2+, Ca2+, Tl+ are considered slightly soluble



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)



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



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



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.



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



Corrosion by Acid Rain1908 1969



Biodeterioration

• Can be defined as:

– Any undesirable change in the properties of a material caused by the vital activities of organisms



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



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

http://www.ilpi.com/msds/ref/mixture.html

http://www.ilpi.com/msds/ref/flashpoint.html



• 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



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 (O

xyge

n)Fuel

Ignition source



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 !



Acknowledgements

• JISC• HEA• Centre for Educational Research and

Development• School of natural and applied sciences• School of Journalism• SirenFM• http://tango.freedesktop.org