Reactivity of Metals
This page provides a comprehensive overview of the reactivity of metals with water and acids, as well as methods to prevent rusting. It is organized into several key sections, each focusing on different aspects of metal reactivity and corrosion prevention.
Reactivity Series
The page begins by presenting the reactivity series of metals, arranged from most reactive to least reactive. This series is crucial for understanding the behavior of different metals in various chemical reactions.
Highlight: The reactivity series ranges from potassium (most reactive) to platinum (least reactive), with hydrogen included as a reference point.
Reactions with Water
The document explains the reactions of metals with water, focusing on the most reactive metals.
Example: The reaction of potassium with water is represented as: 2K + 2H₂O → 2KOH + H₂
Vocabulary: Hydroxide - A compound containing the OH⁻ ion, formed when a metal reacts with water.
The reactions of other reactive metals like sodium, lithium, and calcium with water are also described, all producing metal hydroxides and hydrogen gas.
Reactions with Steam
For less reactive metals, reactions with steam are discussed.
Example: Magnesium reacts with steam: Mg(s) + H₂O(g) → MgO(s) + H₂(g)
The document notes that zinc and iron also react with steam, producing metal oxides and hydrogen.
Reactions with Dilute Acids
The page covers metal reactions with dilute acids, explaining the general equation:
Definition: METAL + ACID → SALT + HYDROGEN
Example: Magnesium + hydrochloric acid → Magnesium chloride + hydrogen
Mg + 2HCl → MgCl₂ + H₂
The document emphasizes that metals below hydrogen in the reactivity series do not react with acids.
Preventing Rust
The final section discusses methods for preventing rust, including:
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Barrier Methods: Coating iron with paint, plastic, oil, or grease to prevent contact with water or oxygen.
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Galvanising: Coating iron with a more reactive metal, usually zinc, which acts as both a barrier and a sacrificial metal.
Highlight: In galvanising, zinc is oxidized instead of iron, protecting the iron from corrosion.
The page concludes with a brief explanation of rust formation, describing it as an oxidation reaction where iron reacts with oxygen and water to form hydrated iron(III) oxide.
