User:Naveen Kittup

CHEMICAL EQUATION AND REACTIONS. FOR 10th CLASS FULL CHAPTER ON CHEMICAL EQUATIONS...

About Henry Cavendish ￼(1731-1810). He conducted first experiment on heat, electricity and magnetism. He showed that water is composed of two elements oxygen and hydrogen. Where as he found that two molecules of hydrogen and one molecule of oxygen.

Representation of four basic chemical reactions types: synthesis, decomposition, single replacement and double replacement.

Synthesis
Main article: Synthesis reaction

In a synthesis reaction, two or more simple substances combine to form a more complex substance. These reactions are in the general form:



Two or more reactants yielding 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
Main article: Decomposition reaction

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: