Physical chemistry
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Physical Chemistry. Dónal Leech [email protected] Ext 3563 Room C205, Physical Chemistry. Notes for downloading (powerpoint and word) http://www.nuigalway.ie/chem/Donal/Teaching.htm. Chemistry. Physical Sciences Sub-atomic Atoms Materials Atmosphere Stellar.

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Physical Chemistry

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Physical chemistry

Physical Chemistry

Dónal Leech

[email protected]

Ext 3563

Room C205, Physical Chemistry

Notes for downloading (powerpoint and word)

http://www.nuigalway.ie/chem/Donal/Teaching.htm


Chemistry

Chemistry

  • Physical Sciences

  • Sub-atomic

  • Atoms

  • Materials

  • Atmosphere

  • Stellar

  • Biological Sciences

  • Organisms

  • Organs

  • Tissues

  • Cells

  • DNA

Chemistry

  • Molecules

  • Bonds

  • Forces

Molecular Sciences


Physical chemistry1

Physical Chemistry

Establishes and develops the principles that are used to explain and interpret the observations made in chemistry

Bulk  Individual  Rates

Thermodynamics   Chemical reactions

Quantum mechanics & spectroscopy

Equilibrium  Structure  Change

ENERGY


Textbook

Textbook

  • Brown, LeMay, Bursten

  • Chemistry: The Central Science, 9th Edition

    Companion Web-site

    http://www.prenhall.com/brown


Dynamic equilibrium chapter 15

Dynamic EquilibriumChapter 15

Example

liquid + heat vapour

an endothermic physical change


Le chatelier s principle

Le Chatelier’s Principle

  • When a dynamic equilibrium is upset by a disturbance, the system responds in a direction that tends to counteract the disturbance and, if possible, restore equilibrium

liquid + heat

vapour

Increase the temperature (add heat)


Le chatelier s principle1

Le Chatelier’s Principle

  • When a dynamic equilibrium is upset by a disturbance, the system responds in a direction that tends to counteract the disturbance and, if possible, restore equilibrium

vapour

liquid + heat 

Liquid evapourates to absorb the added heat and the position of the equilibrium shifts to the right


Solution of a weak acid

Solution of a Weak Acid

CH3COOH + H2O H3O++CH3COO-

For a given composition of a system, equilibrium is independent of which side you approach it from…..reactions are REVERSIBLE

N2O4(g)2NO2(g)

Cinit0.0350 mol0

or00.0700 mol

Cequil0.0292 mol0.0116 mol


Physical chemistry

Equilibrium Lawsimple relationship between molar concentrations (or pressures) of reactants and products at equilibrium

H2(g)+I2(g)2HI(g) (at 440C)

Mass action expression:

Where Q is the reaction quotient

LAW:at equilibrium the reaction quotient is equal to the equilibrium constant, K.

In general for

dD + eE  gG + hH


Heterogeneous equilibria involving more than one phase

Heterogeneous Equilibria(involving more than one phase)


Equilibrium law for gaseous reactions

Equilibrium Law for Gaseous Reactions

For gaseous reactions use partial pressures, P, to give an equilibrium constant (Kp)


Predicting direction of equilibrium changes le chatelier redux

Predicting direction of equilibrium changes(Le Chatelier redux)

Adding or removing reactant or product

Cu(H2O) 42+(aq.) + 4Cl-(aq.) CuCl 42-(aq.) + 4H2O

Changing volume (or pressure)-gases only

as liquids and solids are incompressible

Decrease V=>increase P

System opposes this by reducing the number of molecules


Physical chemistry

Predicting direction of equilibrium changes(Le Chatelier redux)

Changing temperature (heat)

System opposes this by trying to absorb the added heat

ONLY factor that actually changes the value of K

Effect of catalyst

Speeds up approach to equilibrium, but does not

alter K or the system (kinetics)


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