- Messages
- 106
- Reaction score
- 11
- Points
- 28
There are two types of salts that can be prepared ... Insoluble and the other ones are soluble .
There are different methods such as .. For preparing soluble salts -
- Titration method
1. Put 25cm cube of base eg NaOH soln into a flask using a pipette an then add 2 drops of phenolphthalein indicator which turns pink when added .
2. Add an acid eg HCl from a burette little at a time ( Mark the starting point ) .. And mix it carefully by swirling the flask which helps in mixing of acid and the base .
3. By adding the acid more dr by drop would result in to the solution getting colourless which means that all the acid is used up and the solution is neutral ( Mark the ending point ) . By this you can say that how much acid is needed to neutralise 25cm cube of base .
4. Then , again .. Carry out this reaction WITHOUT the indicator ( this is because the indicator would make the salt impure ) . Put 25 cm cube of base into a flask and burette the same amount of acid into it .
5. Then .. Heat the solution from the flask and evaporate the water .. You'll notice that White crystals of NaCl will be left behind !
Making insoluble salts with metals which depends upon the metals like eg mg al zn and fe can react properly with the acid .. Na K and Ca won't react bcz they are too violent .. Lead reacts slowly whereas cu ag au do not react with the acid !
In this reaction let's use dilute h2so4 as an acid and zn in solid form to form znso4 as an soluble salt .
1. Add zn to the acid in a beaker . As it starts to dissolve in the acid .. It releases hydrogen bubbles . This bubbling stops when the acid is used up .
2. Some zinc is still left as the metal was in excess .. So .. Remove it by filtering which leaves an aqueous solution of zinc sulphate .
3. Heat the solution to evaporate some of the water and then leave it to get cool .. The crystals on znso4 soon start to form !
Soluble salts from insoluble base and an acid ( neutralisation ) -
Copper will not react with dilute h2so4 .. So to make a copper salt , you must start with a base like copper(2)oxide which is insoluble and .. Blue cuso4 forms with h2o .
1. Add copper(2)oxide to dilute h2so4 . It dissolves on heating and turn the solution to blue . Keep it excess until no more of it is dissolved .. Which will mean that no more acid is left to be used up !
2. Remove the excess solid by filtering which leaves up a blue solution of copper(2)sulphate in aqueous state .
3. Heat the solution to evaporate some of the water .. And then leave it to be get cooled . blue crystals of copper (2) sulphate start to form !
And you're done with the preparation of soluble salts . And here's the turn of the preparation of insoluble salts .
Theres only one way given in our syllabus to prepare them . Which is by precipitation .
Eg barium sulphate is an insoluble salt which can be prepared by adding barium chloride and magnesium sulphate .
1. Make up solutions of barium chloride and magnesium sulphate .
2. Mix them . A White precipitate of barium sulphate forms at once .
3. Filter the mixture .the precipitate is trapped in the filter paper .
4. Rinse the precipitate by running distiller water through it .
5. Then place it in a warm oven to dry .
Keep in mind that - to precipitate an insoluble salt , you must mix a solution that contains it's positive ions with the one that contains it's negative ions
Like in this experiment ..
BaCl2 - Ba2+ and Cl-
MgSO4 - Mg2+ and SO4 2-
I hope you understood the. Concept .. If more doubts .. I am here !
Best of luck !
There are different methods such as .. For preparing soluble salts -
- Titration method
1. Put 25cm cube of base eg NaOH soln into a flask using a pipette an then add 2 drops of phenolphthalein indicator which turns pink when added .
2. Add an acid eg HCl from a burette little at a time ( Mark the starting point ) .. And mix it carefully by swirling the flask which helps in mixing of acid and the base .
3. By adding the acid more dr by drop would result in to the solution getting colourless which means that all the acid is used up and the solution is neutral ( Mark the ending point ) . By this you can say that how much acid is needed to neutralise 25cm cube of base .
4. Then , again .. Carry out this reaction WITHOUT the indicator ( this is because the indicator would make the salt impure ) . Put 25 cm cube of base into a flask and burette the same amount of acid into it .
5. Then .. Heat the solution from the flask and evaporate the water .. You'll notice that White crystals of NaCl will be left behind !
Making insoluble salts with metals which depends upon the metals like eg mg al zn and fe can react properly with the acid .. Na K and Ca won't react bcz they are too violent .. Lead reacts slowly whereas cu ag au do not react with the acid !
In this reaction let's use dilute h2so4 as an acid and zn in solid form to form znso4 as an soluble salt .
1. Add zn to the acid in a beaker . As it starts to dissolve in the acid .. It releases hydrogen bubbles . This bubbling stops when the acid is used up .
2. Some zinc is still left as the metal was in excess .. So .. Remove it by filtering which leaves an aqueous solution of zinc sulphate .
3. Heat the solution to evaporate some of the water and then leave it to get cool .. The crystals on znso4 soon start to form !
Soluble salts from insoluble base and an acid ( neutralisation ) -
Copper will not react with dilute h2so4 .. So to make a copper salt , you must start with a base like copper(2)oxide which is insoluble and .. Blue cuso4 forms with h2o .
1. Add copper(2)oxide to dilute h2so4 . It dissolves on heating and turn the solution to blue . Keep it excess until no more of it is dissolved .. Which will mean that no more acid is left to be used up !
2. Remove the excess solid by filtering which leaves up a blue solution of copper(2)sulphate in aqueous state .
3. Heat the solution to evaporate some of the water .. And then leave it to be get cooled . blue crystals of copper (2) sulphate start to form !
And you're done with the preparation of soluble salts . And here's the turn of the preparation of insoluble salts .
Theres only one way given in our syllabus to prepare them . Which is by precipitation .
Eg barium sulphate is an insoluble salt which can be prepared by adding barium chloride and magnesium sulphate .
1. Make up solutions of barium chloride and magnesium sulphate .
2. Mix them . A White precipitate of barium sulphate forms at once .
3. Filter the mixture .the precipitate is trapped in the filter paper .
4. Rinse the precipitate by running distiller water through it .
5. Then place it in a warm oven to dry .
Keep in mind that - to precipitate an insoluble salt , you must mix a solution that contains it's positive ions with the one that contains it's negative ions
Like in this experiment ..
BaCl2 - Ba2+ and Cl-
MgSO4 - Mg2+ and SO4 2-
I hope you understood the. Concept .. If more doubts .. I am here !
Best of luck !
