By: 3A Julia Chan (1) Vivian Chan (4) Vivian Chan (2) Melody Chan (5) Haily Chan (3)

In chemistry, filtration is the process of using a filter to mechanically separate a mixture, to remove microorganisms from liquid. - There are many different methods of filtration, but all aim to attain the separation of two or more substances. - This is achieved by some form of interaction between the substance or objects to be removed and the filter. - The substance that is to pass through the filter must be a fluid, i.e. a liquid or gas. The simplest method of filtration is to pass a solution of a solid and fluid through a porous interface so that the solid is trapped, while the fluid passes through. This principle relies upon the size difference between the particles making up the fluid, and the particles making up the solid.

The filtration we do in the laboratory is called gravity filtration. - It relies simply on gravity to effect the filtration. - It is most useful when removing reasonably large solid particles from a solution. - The “impurity” can be a drying agent or an undesired side product or leftover reactant

Fold the round piece of filter paper in half Folded it again and crease to produce a quarter circle Make a crease so it becomes a half circle Make one outer layer of the paper be separated from the other three Make the opening wider by squeezing slightly together at the creases Place the conical shaped piece of filter paper into a glass or plastic funnel

1) Support the filter funnel by a clamp.  this helps to avoid having the apparatus tip over 2) Select the suitable size of filter paper. Fold it and put it in the funnel. 3) Carefully pour the solution into the funnel (be careful not to overfill the funnel, but you can keep topping up the funnel) 4) Prepare a beaker or container to collect the filtrate Procedure for the gravity filtration:

We can see the result of the filtration: - a clear, colourless solution is collected in the beaker -the black residue (charcoal) is trapped on the fluted filter paper in the funnel. *Note* Folding the filter paper this way can provide more surface area for the solution to be filtered. filter paper residue filtrate

-It is used to collect a desired solid -It is faster than gravity filtration,  the solution and air is forced through the filter paper by the application of reduced pressure

Procedure for vacuum filtration: 1)Set up an apparatus with a side arm flask, a filter paper, an adaptor, a Buchner funnel 2)Connect the side arm flask to a vacuum source with a thick-walled tubing tubing Buchner funnel

3) Wet the paper with a small amount of the solvent to be used in the filtration.  this keeps the paper to stick to the plate Turn on the water aspirator. 4) Filter the solution Pour the mixture to be filtered onto the filter paper. The vacuum pull the liquid rapidly through the filter into flask. mixture

5) Rinse the cake with a small amount of fresh, cold solvent  To help remove impurities that were dissolved in the filtrate 6) Carefully remove the filter paper and solid from the funnel. Set the filter cake onto a watch glass to air dry. solvent filter cake