Chemical reaction facts for kids

Rusting iron

A bonfire is an example for redox

A chemical reaction happens when one or more chemicals are changed into one or more other chemicals. Examples:

• iron and oxygen combining to make rust;
• vinegar and baking soda combining to make sodium acetate, carbon dioxide, and water;
• things burning or exploding;
• many reactions that happen inside living things;
• electrochemical reactions when discharging or recharging batteries.

Some reactions are fast, and others are slow. Some happen at different speeds, depending on temperature, or other things. For example, wood does not react with air when it is cold, but if it is made hot enough, it will start to burn. Some reactions give out energy. These are exothermic reactions. In other reactions, energy is taken in. These are endothermic reactions.

Nuclear reactions are not chemical reactions. Chemical reactions involve only the electrons of atoms; nuclear reactions involve the protons and neutrons in the atomic nuclei.

Four basic types

The four basic chemical reactions types: synthesis, decomposition, single replacement and double replacement

Synthesis

In a synthesis reaction, two or more simple substances combine to form a more complex substance.

"Two or more reactants giving one product" is another way to identify a synthesis reaction. One example of a synthesis reaction is the combination of iron and sulfur to form iron(II) sulfide:

Another example is simple hydrogen gas combined with simple oxygen gas to produce a more complex substance, such as water.

Decomposition

A decomposition reaction is when a more complex substance breaks down into its more simple parts. It is thus the opposite of a synthesis reaction, and can be written as:

One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:

Single replacement

In a single replacement reaction, a single uncombined element replaces another in a compound; in other words, one element trades places with another element in a compound These reactions come in the general form of:

One example of a single displacement reaction is when magnesium replaces hydrogen in water to make magnesium hydroxide and hydrogen gas:

Double replacement

In a double replacement reaction, the anions and cations of two compounds switch places and form two entirely different compounds. These reactions are in the general form:

For example, when barium chloride (BaCl₂) and magnesium sulfate (MgSO₄) react, the SO₄²⁻ anion switches places with the 2Cl⁻ anion, giving the compounds BaSO₄ and MgCl₂.

Another example of a double displacement reaction is the reaction of lead(II) nitrate with potassium iodide to form lead(II) iodide and potassium nitrate:

Related pages

• Organic reaction
• Redox

Images for kids

• 

  A thermite reaction using iron(III) oxide. The sparks flying outwards are globules of molten iron trailing smoke in their wake.

• 

  Antoine Lavoisier developed the theory of combustion as a chemical reaction with oxygen.

• 

  As seen from the equation CH
  4 + 2O
  2 → CO
  2 + 2 H
  2O, a coefficient of 2 must be placed before the oxygen gas on the reactants side and before the water on the products side in order for, as per the law of conservation of mass, the quantity of each element does not change during the reaction

• 

  Illustration of a redox reaction

• 

  Sodium chloride is formed through the redox reaction of sodium metal and chlorine gas

• 

  Ferrocene – an iron atom sandwiched between two C5H5 ligands

• 

  Solid heterogeneous catalysts are plated on meshes in ceramic catalytic converters in order to maximize their surface area. This exhaust converter is from a Peugeot 106 S2 1100

• 

  Acid-catalyzed addition-elimination mechanism

• 

  The Cope rearrangement of 3-methyl-1,5-hexadiene

• 

  Thermite reaction proceeding in railway welding. Shortly after this, the liquid iron flows into the mould around the rail gap.

See also

In Spanish: Reacción química para niños