Introduction to entropy

Question 1

entropy is

Answer 1

a property of matter that is associated with the degree of disorder, or degree of randomness, of the particles

Question 2

a spontaneous process is one that

Answer 2

takes place without continuous intervention from us

Question 3

two examples of spontaneous processes are

Answer 3

• reaction between ammonia and hydrogen chloride to form ammonium chloride a white solid
• oxidation of magnesium when burnt in oxygen

Question 4

two examples of reactions which reach an equilibrium where a mixture of reactants and products is formed

Answer 4

• dissociation of ethanoic acid in water to form CH3COO- ions and H+ ions (only 1% of the mixture is CH3COO-)
• dimerisation of nitrogen dioxide in the gas phase where N2O4 makes up 70% of the mixture

Question 5

two reactions which do not occur at all without help are

Answer 5

• decomposition of ammonium chloride

- decomposition of magnesium oxide

Question 6

the question is not
‘will a chemical reaction occur?’
but rather

Answer 6

‘what will be the position of equilibrium?’

Question 7

the reaction between magnesium and oxygen is exo or endo?

Answer 7

exothermic

Question 8

if the products have less energy than the reactants, then we say they are more……….than the reactants

Answer 8

more energetically stable

Question 9

the second law of thermodynamics is

Answer 9

entropy

Question 10

the equilibrium position determines how much

Answer 10

product is formed
if a very high proportion of product is formed, then we say the reaction goes to completion, but if almost non is formed, then it looks like it may not start at all