Entropy A2 Chemistry

Entropy 

this is the amount of disorder in a system( reaction vessel such as a test tube) , it is normlly favourable to increase the amount of entropy. Entropy measures the amount of energy quanta and microstates that are available in system.

Entropy is increased by 3 factors the weight of their effects are the order in which they are stated

State> Moles>Complexity

gases>liquids>solids

So how do we work out the value of entropy?

This is done using three equations 

S system= S Products -S Reactants

S surrounding= -delta H/Tempurature in Kelivn 

S total =  S Surrounding+S System

temp = delta H/ S system

In the exam ( for edexcel anyway) you will be given  a data book , the entropy data will be in this book be sure that you are familiar with it! and that you read it correctly!

lets practice this 

CaO(s) + H2O(l) = Ca(OH)2 (s)

to work out we look in the data book 

Ca(OH)2 = 83.4 

H2O = 69.9

CaO= 39.7

83.4- 69.9-39.7 =…