Reactions Of Metals With Oxygen Flashcards
Metal oxides are usually
Solids
Formula for metal oxides
Metal + Oxygen ➡️ Metal Oxide
Not all metals…
React with oxygen in the air to form metal oxides: some metals are too unreactive e.g. gold
Exothermic reactions release
Light and heat energy
When exposed to air:
Many metals rust - air contains moisture and some of the oxygen dissolves in the moisture
Rust
- Contains iron oxide
- Orange-brown solid that easily flakes off, leaving the underlying metal exposed to air (this metal then also starts to rust)
- Type of corrosion: that results weakness in the metal and literally “eats” it away
What can rust
Iron and alloys (containing iron) can rust
Rusting process
Is very slow, over long periods of time can cause very serious problems
Methods used to prevent formation of rust involve
The exclusion of air (oxygen)
Prevention of rust …
Adds cost to an item, corroded components weaken structures and adds cost for parts to be replaced
Ways to prevent rust
- Painting
- Oil/grease
- Galvanising
- Electroplating
- Sacrificial anode
Oil/grease involves
Lubricating
Galvanising
- Zinc layer quickly reacts with oxygen to become zinc oxide
- This layer protects the zinc underneath it from being further oxidised
- Also protects the iron underneath the zinc from contact with oxygen
Electroplating
Chromium is a metal highly resistant to corrosion
Non-metals can also
Combust
Phosphorous
- Non-metal that burns more easily than others in oxygen
- Relatively pure sample of phosphorous comes into contact with air, will ignite spontaneously & burn with an orange flame
Different forms of phosphorous
- White phosphorous
- Red phosphorus
Both forms of phosphorous (red and white) are…
Stored under water: so that they don’t/can’t come into contact with the oxygen in the air
Application of combustion
- Striking surface of matchbox: mixture of substances e.g. red phosphorous
- Matchs head: dipped in mixture that contains potassium chlorate and sulphur
- When match is striked, friction causes red phosphorous to react vigorously with potassium chlorite in presence of oxygen. Match ignites
Acid rain:
- Vehicles, diesel fumes, burning of coal & oil emits nitrogen oxide, sulphur dioxide, carbon dioxide, carbon monoxide and water in atmosphere
- When non-metal oxides dissolve in water, they are acidic, results in “acid rain”
- Can have harmful effects on plants, animals and buildings
For combustion
- Fuel
- Oxygen
- Heat
