laboratory apparatus and their definition

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From Wikipedia

Laboratory equipment

Laboratory equipment refers to the various tools and equipment used by scientists working in a laboratory. These include tools such as Bunsen burners, and microscopes as well as specialty equipment such as operant conditioning chambers, spectrophotometers and calorimeters. Another important type of laboratory equipment is Laboratory glassware such as the beaker or reagent bottle.

Laboratory equipment is generally used to either perform an experiment or to take measurements and gather data. Larger or more sophisticated equipment is generally called a scientific instrument.


Dean-Stark apparatus

For the video game character, seeWild Arms 5

The Dean-Stark apparatus or Dean-Stark receiver or distilling trap is a piece of laboratory glassware used in synthetic chemistry to collect water (or occasionally other liquid) from a reactor. It is used in combination with a reflux condenser and a batch reactor for continuous removal of the water that is produced during a chemical reaction performed at refluxtemperature. It was invented by E. W. Dean and D. D. Stark in 1920 for determination of the water content in petroleum.

Function

Two types of Dean-Stark traps exist – one for use with solvents with a density less than water (shown in the figure on the left) and one for use with solvents with a density greater than water.

The Dean-Stark apparatus in the laboratory typically consists of vertical cylindrical piece of glass (the trap, above part 9), often with a volumetric graduation on its full length and a precision tap on the bottom very much like a burette. The top of the cylinder is a fit with the bottom of the reflux condenser (5). Protruding from the top the cylinder has a side-arm sloping toward the reaction flask (2). At the end the side-arm makes a sharp turn so that the end of the side arm (3) is vertical as well. This end connects with the reactor.

During the reaction in (2), vapors containing the reaction solvent and the component to be removed travel out of reaction flask up into the condenser (5), and then drip into the distilling trap (above 9). Here, immiscible liquids separate into layers. When the top (less dense) layer reaches the level of the side-arm it can flow back to the reactor, while the bottom layer remains in the trap. The trap is at full capacity when the lower level reaches the level of the side-arm--beyond this point, the lower layer would start to flow back into the reactor as well. It is therefore important to syphon or drain the lower layer from the Dean-Stark apparatus as much as needed.

More rarely encountered is the model for solvents with a density greater than water. This type has a tube at the bottom of the side-arm to allow the organic solvent at the bottom to flow back into the reaction vessel. The water generated during the reaction floats on top of the organic phase.

This piece of equipment is usually used in azeotropic distillations. A common example is the removal of water generated during a reaction in boiling toluene. An azeotropic mixture of toluene and water distills out of the reaction, but only the toluene (density=0.865 g/ml) returns, since it floats on top of the water (density=0.998 g/cm3), which collects in the trap. The Dean-Stark method is commonly used to measure moisture content of items such as bread in the food industry.

This equipment can be used in cases other than simple removal of water. One example is the esterification of butanol with acetic acid catalyzed by sulfuric acid. The vapor contains 63% ester, 24% water and 8% alcohol at reflux temperature and the organic layer in the trap contains 86% ester, 11% alcohol and 3% water which is reintroduced. The water layer is 97% pure.

Another example is the esterification of benzoic acid and n-butanol where the ester product is trapped and the butanol, immiscible with the ester flows back into the reactor. Removing water in the course of these esterifications shifts the chemical equilibrium in favour of ester formation.


Cavendish experiment

The Cavendish experiment, performed in 1797ndash;98 by British scientist Henry Cavendish and inspired in part by observation of systematic surveying errors in the Mason Dixon line survey, was the first experiment to measure the force of gravity between masses in the laboratory, and the first


From Yahoo Answers

Question:what are the 20 laboratory apparatus

Answers:Common Laboratory Apparatus Test Tube test Tube Rack Test Tube Holder Reagent Bottle Beaker Bunsen Burner Stand and Clamp Crucible Measuring Cylinder Dropper Electronic Balance Evaporating Dish Filter Funnel Flask Safety Glasses Mortar and Pestle Round Bottomed Flask Spatula Tripod Plastic Wash Bottle Wire Gauze Triple Beam

Question:from the common laboratory apparatus shown below, select the best apparatus to perform each of the following tasks. ( you may use any of the apparatus once, more than once or not at all) apparatus: 100 cm3 measuring cylinder 100 cm3 beaker watch glass 20 cm3 pipette test tube 50 cm3 burette 50 cm3 gas syringe (a) measuring 80 cm3 of alcohol : ____________________ (b) measuring 35 cm3 of hydrogen: __________________ (c) measuring 21.1 cm3 of vinegar: _________________ (d) boiling 40 cm3 of a non-flammable liquid: ___________________ (e) holding 2 g of a solid for weighing: _____________ (f) holding 5 cm3 of water for heating: __________________ what would a chemist use to measure exactly 25.5 cm3 of dilute hydrochloric acid? A burette B beaker C measuring cylinder D pipette

Answers:I will answer because I know, but you should submit your attempt for correction,if you really want to learn. a) 100 cm3 measuring cylinder, or for better accuracy 4 x 20 cm3 pipette. b) A gas syringe c) Burette d) test tube e) watch glass f) test tube. or watch glass depending on it's size. A pipette would be most accurate, however 25.5 cm3 is an unlikely number for a pipette So the next best alternative is the burette. Not available in your list is a gravimetric option, the most accurate.

Question:... clay triangle ... iron clamp ... difference of hard glass test tube and ordinary test tube ... crucible tongs ... water trough ... water bath ... crucible and cover ... mortar and pestle i need answers in 20 minutes haha

Answers:Clay triangle- It is used as a base to keep some apperatus(e.g. beaker,flask, etc.) on it while heating them. IF we keep apparatus directly on sand bath then the tem. will not uniform & also the apparatus will get break. due to the clay tringle. apparatus will get uniform heating surface as well as remain protected as it is not in direct contact with sand. Diff in Hrad & ordinary Tubes? The material of which it is made of create a difference in their properties.The so called hard contain greater % of silica so that it remain intact even on heating to a higher temp.as it has high resistance.On the contarary the ordinary test tubes are not meant to be heat at higher temp.(above 70 C) as they may get broken up. They are only for pbserving the reactions. a so the hard one also called as Borosil test tubes ar costlier. Water Bath- It serves the simple purpose of not to heat the substance above !00 C i.e. the boiling point of Water. It is use for control temp. reactions.(practically it gives temp. of upto 90 c only) Crucible & cover- It has the many uses. Basically it is used for heating the substances at very higher temp. & cover is simply to avoid any loss of material as well as to prevent external material to enter in.(for quantitative measurments) Mortar & pestle- It is same as the crusher which we use at home to prepare chutny and spices .it has the basic purpose of grinding or mixing the substances very finely,

Question:1) glass tubing 2) fish tail or wing top 3) pneumatic trough 4) triangular file 5) utility clamp 6) water bath 7) spot plate 8) cork stopper 9) rubber stopper 10) rubber tubing

Answers:Sounds like you're trying to make a still. : )

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