Filtration And Crystallisation Flashcards
(15 cards)
What is filtration and crystallisation?
Methods of separating mixtures. It’s used all the time to separate solids from liquids
What does filtration do?
Filtration separates insoluble solids from liquids
When can filtration be used?
Filtration can be used if your product is an insoluble solid that needs to be separated from a liquid reaction mixture. It can also be used in purification as well, for example solid impurities in the reaction mixture can’t be separated out using filtration.
What is rock salt?
A mixture of sand and salt
What does insoluble mean?
A substance unable to dissolve
What are the 2 ways to separate soluble solids from solutions?
Evaporation and crystallisation
When using evaporation to separate soluble solids from solutions, what steps do you have to do for this experiment?
-Pour the solution into an evaporating dish.
-Slowly heat the solution under a small flame. The solvent will evaporate and the solution will get more concentrated. Eventually crystals will start to form.
-Keep heating the evaporating dish until all you have left are dry crystals.
When can you use evaporation?
When the salt doesn’t decompose when it’s heated, otherwise you’ll have to use crystallisation
What are the steps of doing crystallisation?
Pour the solution into an evaporating dish and gently heat the solution under a small flame. Some of the solvent will evaporate and the solution will get more concentrated.
Once some of the solvent has evaporated or when you see crystal start to form remove the dish from the heat and leave the solution to cool
The salt should start to form crystals as it becomes insoluble in the cold highly concentrated solution
Filter the crystals out the solution and leave them in a warm place to dry. You could also use a drying oven or a dessicator.
What is rock salt?
A mixture of salt and sand
What 2 ways can be used to separate rock salt?
Filtration and crystallisation
What are the differences between the 2 compounds in rock salt?
Salt dissolves in water and sand does not
What four things can you do to rock salt to separate the two compounds?
Grinding, dissolving, filtering, and evaporation
Why do you grind rock salt?
Grinding the mixture makes sure the salt crystals are small so they will dissolve easily
What are the steps of separating rock salt?
-First you grind the mixture to make sure the salt crystals are small so they will dissolve easily
-Then you dissolve the mixture. You put it in water and stir. The salt will dissolve but the sand will not.
-Then you filter the mixture. The grains of sand won’t fit through the filter paper hole, so they stay on the paper.
-The salt passes through the filter paper as it’s part the solution.
-Evaporate the water from the salt so that it forms dry crystals. You could also use crystallisation to make big crystals.
