Topic 5b- Practicals involving acids (paper 1) Flashcards
What is the excess base method?
The base is insoluble and the salt made is soluable.
In the excess base method, how do we separate the undissolved solid from the solution?
Filtration.
What must be done in order to get a solid substance in the excess base method?
You must first evaporate some of the water away using a Bunsen Burner before leaving the solution crystallise in a warm place.
How do we know that the solution from the excess base method has lost enough water to crystallise?
By dipping a glass rod into the solution and blowing on it in order to see if crystals form.
What is meant by anhydrous?
There is no water remaining in the substance.
What is the titration method used for?
When the base is soluble (for example sodium, potassium and ammonium salts.)
What can only measure a single volume of liquid?
A pipette.
What item do we use to control the amount of acid entering the alkali in the titration method?
A burette.
What do you do in order to create the crystals in titration?
Heat the solution, leave to cool and crystalize, filter the crystals from the solution and leave to dry in a cool place.
How many times do you do the titration and what do you call each one?
1 rough because you do not know how much acid you will need.
At least 2 accurate ones.
What is the precipitation method used for?
To make insoluble salts.
What substances must be used in the precipitation method?
Two solutions, one containing the positive ion in the salt wanted and one containing the negative ion.
What happens after mixing the two solutions together in the precipitation method?
A precipitate forms, you filter the solution (the residue is the insoluble solution.) This residue will have impurities so it must be washed with distilled water before being left in a warm, dry place.
