What is a precipitate?
An insoluble solid formed by the reaction between two soluble substances is called a precipitate
The process is called precipitation.
The reactions in which precipitate formed is called precipitation reactions.
Experiment to show the precipitation reactions
Take a test tube and mix 1 ml. of aqueous solution of silver nitrate and 1 ml. of aqueous solution of sodium chloride .A milky white precipitate is formed.
How can we prove that it is a precipitate:
- Look at the product and see if it is opaque or not clear
- Try another reaction
Mix 1 ml. of lead nitrate and 1 ml. of potassium iodide, a yellow precipitate is formed.
- Look in the Data Book
Look colour of lead iodide and silver chloride. Then look for their solubility
Na Cl + AgNO3 NaNO3+Ag Cl
Ag + + Cl – AgCl these are the reacting ions
Na+ + and NO3– ions do not react so they are spectator ions
This equation is called the ionic equation for the reaction.