Chapter 5 - analysing oxidants and reductants

Page 1

CHAPTER 5 - ANALYSING OXIDANTS AND REDUCTANTS

oxidation involves a loss of electrons

reduction involves a gain of electrons

oxidation and reduction reactions occur simultaneously

an oxidant causes oxidation and is itself reduced

a reductant causes reduction and is itself oxidised

oxidation numbers can be used to identify species that have been oxidised or reduced

oxidation numbers have no physical meaning

an element has been oxidised if its oxidation number has increased

an element has been reduced if its oxidation number has decreased

an oxidation or a reduction reaction can be represented by a half equation

an oxidation half equation and a reduction half equation can be combined by multiplying the half equations so that there is an equal number of electrons in each half equation. The half equations can hen be added.

volumetric analysis can be used to determine the concentration or mass of substances that undergo redox reactions

BALANCING HALF EQUATIONS

1. write the formula of the species being oxidised/reduced and its conjugate pair

2.balance the number of atoms of the species being oxidised/reduced

3.balance the number of oxygen atoms by adding H2O to the equation

4.balance the number of hydrogen atoms by adding H+ to the equation (H+ comes from the acidified solution)

5.balance the charges by adding electrons

6.add states for all species

increase in oxidation number=oxidised=reductant

decrease in oxidation number=reduced=oxidant

OIL RIG

REDOX REACTION: a reaction that involves the transfer of electrons from chemical to another.

New Page