Preparing Soluble Salts

Copper Sulfate is a soluble salt

Made by reacting sulfuric acid and copper oxide together

• Copper oxide reacts with sulfuric acid but doesn't dissolve in water.
• Added a little at a time to warm sulfuric acid, the copper oxide forms a blue solution of copper sulfate
• When all the sulfuric acid had reacted, the copper oxide remains as a solide and makes a cloudy mixture, it is now in excess (this assures all the acid has been used up).
• The solution is then filtered, leaving a clear blue liquid.
• Excess copper oxide is washed, dried and reused
• Copper sulfate will start to crystallise as the water in the solution evaporates 
• Evaporating slowly causes bigger crystals

To prepare soluble salts using a soluble base, an indicator must be used. 

• Acid is added to the base
• Inidicator changes color as it neutralises
• Burrette is used to add small amounts of acid at a time
• This is repeated till we have concordant results
• The method is then repeated without indicator and with the mean volume of acid recorded to produce a pure solution of the salt
• It is then left to evaporate and crystalise