examples of laboratory apparatus and their uses
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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.
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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.
Two types of Dean-Stark traps exist â€“ 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.
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Answers:The ones we use most often in our lab: Dissecting microscope Compound microscope Electronic balance Soft forceps Fine forceps Rearing jar Sample jar Hot plate Beaker Petri dish Masking tape Permanent marker Rearing cage Aquarium tank Pyrex tray Bussing tray Air pump Mechanical pencil Dissecting probe
Answers:You need to learn to do a simple web search as it is so easily answered yourself! Open Google .... type' lab apparatus' in the seach box .... press enter ... select answer I found http://wiki.answers.com/Q/What_are_the_names_and_uses_of_the_various_laboratory_tools has a list of no less than 27 bits of apparatus and their uses .. and is an old 'Answers' response from only a few days ago. For biological science I'd add a microscope and magnifying hand lens for looking at things .. but I expect you know that. Source(s): rtc
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.
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,