Metals Reacting with Water and Acids

Metals Reacting with Water and Acids

• Metals react with water and acids, and this reactivity is used to create a reactivity series.

• The series orders metals based on their reaction with water and acids.

• Potassium and sodium react violently with water.

• Calcium reacts less violently with water.

• Magnesium, iron, and zinc react slowly with cold water.

• Metals above hydrogen in the reactivity series react with dilute acids.

• More reactive metals produce more vigorous reactions with dilute acids.

• The general equation for a metal reacting with an acid is: Metal + Acid → Salt + Hydrogen

• Example: Ca + 2H₂O → Ca(OH)₂ + H₂

Metal Displacement Reactions

• The reactivity of metals determines if displacement reactions will occur.
• More reactive metals displace less reactive metals from their compounds.
• Example: Iron displacing copper from copper(II) chloride.
• Example: Zinc reducing copper(II) oxide.

Displacement Reactions in Aqueous Solutions

• Reactive metals can displace less reactive metals from aqueous metal salt solutions.
• This reaction involves a change in the colour of the solution and the formation of a new metal.
• Example: Magnesium displacing copper from copper(II) sulfate solution.

Order of Metal Reactivity

• A mnemonic device (P-Please, S-Send, L-Lions, etc.) can help remember the order of reactivity.
• Reactivity decreases as you move down the list.

Rusting of Iron

• Rusting is iron's corrosion in the presence of water and oxygen.
• Water and oxygen are needed for rust to form.
• Rust is hydrated iron(III) oxide.
• Barrier methods (e.g., paint, oil) prevent rust formation by creating a barrier.
• Sacrificial protection involves using a more reactive metal to protect iron.
• Galvanizing is a common method for sacrificial protection, using zinc to coat iron.

Oxidation and Reduction

• Oxidation is a loss of electrons or a gain of oxygen.
• Reduction is a gain of electrons or a loss of oxygen.
• Redox reactions involve both oxidation and reduction occurring simultaneously.
• Examples of redox reactions are seen in rusting and displacement reactions.
• Oxidising agents gain electrons.
• Reducing agents lose electrons.