Oxidation of Metals

Review!

What we’ve learned about metal so far:◦Reacts with acid to create hydrogen gas◦Hydrogen is explosive◦Acid will cause metal to disintegrate/erode

What is Oxidation?

Process that is a reaction between a substance and oxygen

Most common type of oxidation is rust

The Reaction

All starts with the atomAtoms are made up of 3 parts:

◦Protons◦Electrons◦Neutrons

For our reactions we will only care about the electrons

Subatomic particles

Once an electron is lost, the atom is known as an ion.

If electron is lost, it is a positive ion

Once an electron is gained, it is also called an ion.

A gained electron makes a negative ion

Where do we find ions?

Ions commonly appear when certain compounds are dissolved in water◦Dissolving salt in water will produce both

sodium and chlorine ions:Na+ and Cl-

Why does this matter?

When a car rusts, the iron in the steel reacts with oxygen in the atmosphere

The iron loses an electron where the oxygen gains one

The reaction simply transfers electrons:

Iron + Oxygen Iron oxide

Description of Reaction

Any time a substance loses one or more electrons, it is called oxidation

Any time a substance gains electrons, it is called reduction

Together the reaction is called a redox reaction

Examples of common oxidation

Rust

Copper

Silver

Aluminum

Issues with Oxidation

Energetic reactions = lots of heat potentially

Can cause fires if reaction happens quickly

Can cause fires to burn more intensely

Predicting Reactions

To predict if a reaction is going to occur we use a chart that ranks the hold on electrons by certain metals

Chart is called the activity series

Activity Series

Any metal found higher in the series has a weak hold on electrons and will react with anything below it

Applications

Protection from corrosion is widely used◦Corrosion = when the surface of a metal is

eaten away chemicallyProtection from corrosion uses the activity

series in 3 ways:1. Painting surface2. Metal coatings – ie galvanizing3. Placing more reactive material close by –

ie zinc pieces on boat motor

Time to answer some questions!