📦 haribo's box

3.2.3 trends in ease of oxidation and reduction of elements

3 min read

chem whatarethemechanismsofchemicalchange

Reactivity 3.2.3 - the relative ease of oxidation and reduction of an element in a group can be predicted from its position in the periodic table.

the reactions between metals and aqueous metal ions demonstrate the relative ease of oxidation of different metals

more reactive non-metals are stronger oxidising agents

most non-metals react by gaining electrons and forming negative ions, acting as oxidising agents.

the stronger the electronegativity, the stronger the oxidising agent

adding a stronger oxidising agent to a solution containing the ions of a weaker oxidising agent leads to a reaction. for example:

a reaction occurs because atoms attract electrons more strongly than atoms, so in the competition for electrons, the stronger oxidising agent wins.

adding a less reactive halogen to the ions of a more reactive halogen results in no reaction

more reactive metals are stronger reducing agents

metals tend to lose electrons and form positive ions in reactions. they act as reducing agents.

the more readily the metal loses their electrons, the stronger it is as a reducing agent.

adding a stronger reducing agent to a solution containing the ions of a weaker reducing agent leads to a reaction. for example:

it is said that the ions are displaced from solution
the brown solid ( is precipitated)

Zinc is acting as the reducing agent. it can be thought of as forcing ions to accept the electrons.

this can be confirmed by trying the reaction with copper metals and a solution of zinc ions.

an activity series is a list of relative strengths of metals as reducing agents, and allows us to predict whether a particular redox reaction between a metal and the ions of another metal will be feasible

challenge questions
  1. carbon can be used as the reducing agent in the extraction of iron and zinc. lead salts are produced when lead is added to dilute acids. suggest where you place the non-metals carbon and hydrogen in the activity series on page 757.

carbon is more reactive than zinc and iron.
carbon is less reactive than aluminium as electricity is needed for the extraction of aluminium.
hydrogen is more reactive than copper, as copper metal does not react with dilute acids, but less reactive than lead