Heat of Precipitation

Heat of precipitation from sweemoi khor

Heat of Displacement

Heat of displacement from sweemoi khor

Heat of Neutralization and the Strength of Acids and Alkalis

1. Heat of neutralization between a strong acid and a strong alkali is always -57.3 kJ mol^-1.  Why?

Heat of neutralisation is the sum of of energy absorbed during bond breaking in the acid and alkali and energy released during bond formation of water molecule from H⁺ ion and OH^- ion.  All the reactions form 1 mole of water. 


2.  Heat of neutralization for neutralization involving weak acid or weak alkali is less than -57.3 kJ mol^-1.  Why?
Weak acid/akali does not ionises completely in water. Some energy released during formation of water is used to ionises the weak alkali/acid.

Heat of Neutralisation

Definition :

Energy change when one mole of water is formed from the neutralization between one mole of hydrogen ion from an acid and one mole of hydroxide ions from an alkali.
  

5H students are carrying out experiment to determine heat of neutralisation between an acid with an alkali.

Pocket Warmer

This pocket warmer use chemicals that react to release heat.  The heat given off through exothermic reaction can be used to warm up body.  Mountain climbers bring pocket warmer  when they are high in the mountain. It can be used to lessen the pain of aching muscles.

Heat of Combustion of Various Alcohols

Heat of combustion of Various Alcohols from sweemoi khor

Interpreting Energy Level Diagram

Interpreting energy level diagram from sweemoi khor

Exothermic Reaction vs Endothermic Reaction

Thermochemistry from sweemoi khor