Filtration

Simple crucible

Gooch filter crucible : fritted glass(= sintered glass) funnel

porosity : f (=fine), m (=medium), c (=coarse)

Aspirator or vacuum pump

Trap

Mother liquor

Filtrate

Decantation is the process of pouring a liquid gently so as to not disturb a solid in the bottom of the container.

Rubber policeman

Squirt bottle

Gooch crucible

Filtering crucible

Separating funnel

Crucibles

Train for vacuum filtration

Vacuum filtration with a Gooch crucible that has a porous (fritted) glass disk through which liquid can pass. Suction can be applied by the vacuum system or by an aspirator that uses flowing water to create vacuum. The trap prevents backup of tap water from the aspirator into the suction flask. Alternatively, the trap prevents liquid in your suction flask from being accidentally sucked into the vacuum system.

Ashless filter-paper :

Specially treated filter-paper (pulps treated by using 6M HCl, HF) that leaves a negligible residue(=incombustible matter) after ignition. Ash 0.2mg when a filter-paper(I.D. 11cm) has been incinerated.

(Left) Filtering a precipitate. The conical funnel is supported by a metal or wood ring attached to a ring stand. (Center) Washing by decantation. (Right) Transferring the precipitate.

Creeping is a process in which a solid moves up the side of a wetted container or filter paper.

Folding filter paper for a conical funnel.

(a) Fold the paper in half.

(b) Then fold it in half again.

(c) Tear off a corner to allow better seating of the paper in the funnel.

(d) Open the side that was not torn when fitting the paper in the funnel.

Method for folding and seating a filter paper

The filtering operation.

Washing by decantation and transferring the precipitate

Ignition of precipitate

Pipets and sylinder.

Pipets and syringes

TC 20oC = calibrated to contain the indicated volume at 20oC (ambient temperature)

  E : eingu

TD 20oC = calibrated to deliver the indicated volume at 20oC

  A : ausgu

The coefficient of expansion for dilute aqueous solution: 0.025%/oC

VT1 = VT2 + 0.00025(T1-T2)VT2

where T1 > T2

Transfer pipet

Don’t blow out the last drop

Measuring (Mohr) pipet

Microliter pipet (Eppendorf)

Examples of pipets

a. Volumetric (TD)

b. Mohr : Measuring (TD)

c. Serological : Measuring (TD)

d. Eppendorf micropipet (TD)

e. Ostwald-Folin (TD)

f. Lambda (TC)

Pipet fillers and pipets

1. Latex bulb

2. Pipet filler

3. Mechanical pipet filler

4. Pipettor pump

5. Pasteur pipet

6. Volumetric pipet

7. Mohr pipet

8. Serological pipet

Safety rubber bulb filler and auto-filler

Safety rubber bulb filler

A : press on valve A and squeeze bulb

S : Insert pipet into liquid sample. Press on valve S. Suction draws liquid to desired level.

E : Press on valve E to expel liquid sample.

To deliver the last drop, maintain pressure on valve E, cover E inlet with middle finger, and squeeze the small bulb.

E

A

S

1 2 3 4

Transfer pipet.

Measuring (Mohr) pipet.

Microliter pipet with disposable plastic tip.

Volume selection dial of microliter pipet.

Repeater pipet, which can deliver preset volumes between 10 L and 5 mL to 48 times at 1-s intervals without refilling.

Hamilton syringe

Digital dispenser for syringes with volumes of 0.5 to 500 microliter provides accuracy and precision of 0.5%

Micropipet (lambda pipet) : 1 l ( 10–6 l)

Eppendorf

Disposable plastic(polypropylene) tip

Hamilton syringe

needle(gauge no)

barrel

plunger

Syringe pump

Loop injector : Rheodyne injectorHamilton syringe

Rheodyne loop injector.

Syringe pump