Names, main uses and precautions of commonly used chemical experimental instruments

Main uses:

A thermometer is an instrument for measuring temperature. There are many kinds, such as digital thermometer, thermal thermometer and so on. Glass liquid thermometers are often used in laboratories.

Thermometers can be divided into standard thermometers and practical thermometers according to their purposes and measurement accuracy. The standard thermometer has high accuracy and is mainly used to calibrate other thermometers. Practical thermometers refer to thermometers used for actual temperature measurement, mainly including experimental thermometers, industrial thermometers, meteorological thermometers, medical thermometers, etc. Rod industrial thermometer is commonly used in middle schools.

Precautions for use:

1, a thermometer suitable for the measuring range should be selected. It is forbidden to use thermometers beyond the scope.

2. When measuring the liquid temperature, the glass bulb of the thermometer should be completely immersed in the liquid, but it should not touch the container wall. When measuring the steam temperature, the glass bubble should be higher than the liquid level, and when measuring the distillate temperature, the glass bubble should be slightly lower than the distillation bottle branch pipe.

3. When reading, the line of sight should be flush with the highest point (mercury thermometer) or lowest point (alcohol thermometer) of the liquid meniscus.

4, it is forbidden to use thermometer instead of glass rod for mixing. Wipe it clean after use, put it in a paper sleeve and store it away from heat sources.

Second, the tray balance

Main uses:

Pallet balance is an instrument used to roughly weigh the mass of substances, and each balance is equipped with a box of weights.

The commonly used loads in middle school laboratories are 100g and 200g2. Load, also called loading capacity, refers to the maximum weight that can be weighed. Sensitivity refers to the balance error (+/-). For example, a pallet balance has a sensitivity of 0. 1 g, which means that the error is 0. 1 g, so it cannot be used to weigh items with a mass less than 0.1g..

Precautions for use:

1. Before weighing, place the balance smoothly, move the traveling code to the zero point of the balance, and check whether the balance swings smoothly. If the balance has been reached, the number of squares on the left and right sides of the ruler indicated by the pointer swing is nearly equal. When the pointer is at rest, it should point to the center of the ruler. If the balance swings unevenly, you can adjust the left and right balance nuts to balance the swing.

2. The weighed objects cannot be directly placed on the tray. Put a piece of paper with the same size on two trays respectively, and then weigh the reagent to be weighed on the paper. Wet or corrosive reagents must be weighed in glass containers.

3. Put the weights on the left board and the weights on the right board, and weigh them with tweezers. First add the weight with large mass, then add the weight with small mass, and finally move the code until the pointer swings to balance.

4. After weighing, put the weights back in the weight box in turn. Move the roaming code back to zero.

Third, the beaker

Main uses:

When the amount of reactants is large, beakers are usually used as reaction containers. In addition, it is also used to prepare solutions, accelerate the dissolution of substances and promote the evaporation of solvents. There are many kinds and specifications of beakers, and low-type beakers are commonly used in middle schools.

Precautions for use:

1, the beaker should not contain too much solution, which is about the volume of 1/2, but when heated, the solution should not exceed the volume of 1/3.

2. The beaker can't be dry-burned, and it can be heated for a long time when it is filled with liquid, but it must be padded with asbestos net.

3. When holding the beaker, hold the outer wall and don't touch the inner wall with your fingers. Take out the beaker after heating and use the beaker clamp.

4. When the solution in the beaker needs to be stirred with a glass rod, the glass rod should rotate evenly along the cup wall, and it is forbidden to hit the cup wall and bottom.

Beakers should not be stored for a long time. Immediately after use, it should be cleaned, dried and stored upside down.

Fourth, the flask

Main uses:

As a container, the flask has more reactants and longer heating time, and the liquid participates in the reaction. Its bottleneck is small in diameter, and it is often used to generate steam or as a gas generator after being fitted with plugs and necessary accessories.

A round-bottomed flask is usually used as a reaction vessel under heating conditions. Flat-bottomed flask is used for unheated gas generator, and is also commonly used for assembling and washing bottles. Because the bottom plane of the flat-bottomed flask is small, the edge is angular, and the force is large, it is easy to burst when heated. Therefore, it is generally not used in reaction vessels under heating conditions.

Precautions for use:

1. The bottom of the round bottom flask is even in thickness and has no edge, which can be used for long-term intense heating.

2. When heating, the flask should be placed on an asbestos net and cannot be directly heated by flame.

3. After the experiment, the heat source should be removed, and after standing and cooling, the waste liquid should be treated and washed.

Verb (abbreviation for verb) conical flask

Main uses:

This conical bottle has a big bottom and a small mouth. After the solution is filled, the center of gravity is low, which is very convenient for hand-held oscillation, so it is often used as a titration container in volumetric analysis. Laboratories also use it to assemble gas generators or wash bottles.

Precautions for use:

1. When vibrating, hold the bottleneck with your right thumb, forefinger and middle finger, gently hold the lower part of the bottleneck with your ring finger, relax your wrist, and use your palm to drive your fingers to do circular vibration.

2. When the conical flask needs to oscillate, the solution in the flask shall not exceed 1/2 by volume.

3. If you need to heat the liquid in the conical flask, you must pad it with asbestos mesh.

Baidu encyclopedia-chemical instrument