Combination Reactions

In a combination reaction, two or more substances combine to form a single product. These are also called synthesis reactions. 

Example: Hydrogen and Oxygen

• The reaction between non-metal hydrogen gas (H) and non-metal oxygen gas (O₂) is a combination reaction because non-metal + non-metal → covalent compound. 

CHECKPOINT ACTIVITY:

Write the word equation and balanced symbol equation for the following combination reaction. Note: You don't have to use all of the words / numbers provided. 

• Charcoal (carbon) burns on a barbecue and produces carbon dioxide gas. 

Example: Sodium and Chlorine

The reaction between sodium metal (Na) and non-metal chlorine gas (Cl) is a combination reaction because metal + non-metal → ionic compound. 

Example: Magnesium and Oxygen

The reaction between magnesium metal (Mg) and non-metal oxygen gas (O₂) is a combination reaction because metal + non-metal → ionic compound. 

Example: Copper and Oxygen

The reaction between copper metal (Cu) and non-metal oxygen gas (O₂) is a combination reaction because metal + non-metal → ionic compound. 

Example: Iron and Sulfur

The reaction between iron metal (Fe) and non-metal sulfur solid (S) is a combination reaction because metal + non-metal → ionic compound. 

CHECKPOINT ACTIVITY:

Write the word equation and balanced symbol equation for the following combination reaction. Note: You don't have to use all of the words / numbers provided. 

• Iron powder reacts with chlorine gas to produce iron chloride (FeCl₂). 

Rust is an example of  an oxidation reaction. This is the slow reaction of a substance with oxygen (combustion is rapid oxidation). In the presence of water (e.g. damp air or rain), iron and steel combine with oxygen in the air to form reddish-brown rust (hydrated iron oxide - Fe₂O₃.H₂O)

Rust not only corrodes the surface of metal, but over time it weakens the metal and can make holes through it.