Donnerstag, 3. Mai 2012

Rates of Reaction

You've seen how concentration and surface area affect the rate of a reaction. let's now look at the effect of catalysts and how heterogeneous and homogeneous catalysts can work;

The following is a good chem guide link:

Chem guide rates

Chem guide Catalysts

Maxwell Boltsmann distribution curve
temperature and the Maxwell Boltsmann curve

Measuring the rate of a reaction

Some useful notes on rates

IB Syllabus link to rate expression

VIRTUAL EXPERIMENT

Virtual exp results

Another virtual experiment

Chem Wiki

Dienstag, 27. März 2012

Energetics definitions

This is from the interactive syllabus. Remember for standard values you must state under standard conditions i.e. 25 0C 1 atm and any solutions 1 mol/dm3.

Energy Definitions

It should be noted that many of the energy definitions can be considered in the reverse direction with a corresponding change of sign for the energy. Bond formation = exothermic ΔH negative, bond cleavage = endothermic ΔH positive

Enthalpy of vaporisation

The energy required to vaporise one mole of a liquid

Enthalpy of atomisation

The energy required to produce one mole of gaseous atoms from an element in its standard state

Bond dissociation enthalpy

The energy change when one mole of a specific bond is broken or created

Bond enthalpy

The average energy change when one mole of a specific type of bond is broken or created.

Enthalpy of Combustion

The energy released when one mole of a compound is burned in excess oxygen

Enthalpy of formation

The energy change when one mole of a compound is formed from its constituent elements in their standard states

Enthalpy of solution

The energy change when one mole of a substance is dissolved in an infinite amount of water

Hydration enthalpy

The energy change when a particle is taken from infinite separation in the gaseous state to its position in an aqueous lattice

1st Ionisation energy

The energy required to produce one mole of gaseous ions from one mole of gaseous atoms by removal of one mole of electrons

Lattice enthalpy

The energy change when one mole of an ionic substance is broken into its constituent atoms at infinite separation.

Freitag, 24. Februar 2012

Homework- using Bond energies

Please finish the sheet on bond energies. Also read the next part in your book so that you are ready for the lessons after academic travel. Hess's law and Born Haber cycles.

Have a good week.

Montag, 20. Februar 2012

Allotropes of carbon

The following video is interesting about the possible future of graphene:


Donnerstag, 9. Februar 2012

Bonding test

We have just about finished the topic on bonding so please start revising for a test next week. Your notes, experiments and textbook should be used. In addition the IB website is useful too. Here are the following links:

IBbonding standard level

IB bonding higher level