Distracted by these “little troubles” in the laboratory? Look here, there are good ideas!

Distracted by these “little troubles” in the laboratory? Look here, there are good ideas!

In the laboratory, in addition to the first problem “washing the bottle”, everyone often encounters some large and small problems, such as the bottle stopper sticking and not opening, emulsification during liquid separation, and the inner lining of the reactor. Difficult to clean and so on. If appropriate methods or techniques are adopted to deal with these problems, these troubles will be easily solved.

1. Open the cemented glass grinding mouth

When the grinding part of the glass instrument cannot be opened due to adhesion, the following methods can be used to deal with it.

(1) Knock Use a wooden tool to lightly hit one side of the grinding mouth, so that it will gradually loosen due to vibration. For cemented reagent bottles, ground stoppers of separatory funnels, etc., the stopper and bottle mouth of the instrument can be stuck at the corners of the experimental table or wooden table, and then the wooden utensils can be lighted along the direction of about 70° with the axis of the instrument. Tap lightly while rotating the instrument intermittently. Repeated operations like this several times can generally open the grinding mouth that is not severely cemented.

(2) Heating some cemented grinding mouths, which is inconvenient to knock or knocking invalid. The outer layer of the cemented part can be heated to make it expand and separate from the inner layer. For example, use a hot damp cloth to “hot compress” the cemented part, use an electric hair dryer or a moving flame to bake the grinding mouth, and so on.

(3) Infiltration. Some grinding mouths are relatively firm due to chemical erosion, or are expensive instruments with complex structures. They are not suitable for knocking and heating. They can be opened after being soaked in water or dilute hydrochloric acid for several hours. If the instrument is used urgently, organic solvents with strong penetrating power (such as benzene, ethyl acetate, petroleum ether and dioctyl sodium sulfosuccinate, etc.) can also be added dropwise to the gap between the grinding mouths, so that they can penetrate and infiltrate. The fixed parts are thus separated from each other.

2. Open the fastened screw cap

When the screw cap cannot be unscrewed, you can use an electric hair dryer or a small flame to bake around the cap to make it expand by heat, and then use a cloth to wrap the cap to unscrew it forcefully.

If the bottle contains non-heatable or flammable substances, you can take a strong rope and tie one end to a fixed object (such as door and window handles), and then loop the rope clockwise around the bottle cap, and then tighten it with one hand On the other end of the rope, hold the bottle with one hand and push it forward to open the bottle cap.

3. Take out the thermometer bonded by the rubber plug

When the thermometer or glass tube is stuck together with the rubber plug or hose and it is difficult to remove, insert the tip of a small screwdriver or knife file between the thermometer (or glass tube) and the rubber plug (or hose) to form a gap, and then Add a few drops of water, do so and expand around the thermometer (or glass tube), while gradually deepening, and it will be taken out soon. You can also use a drill that fits into the thermometer (or glass tube), dipped in a little glycerin or water, and insert from one end of the thermometer. Use gentle force to push while rotating. When it is difficult to rotate, pull out and then dip it in. Lubricant, continue to rotate, after repeating several times, the thermometer (or glass tube) can be taken out.

4. Remove special dirt on the instrument

When special dirt is attached to the glass instrument and it is difficult to remove it with general washing methods, the nature of the dirt should be distinguished first, and then targeted treatment.

For acidic dirt that is insoluble in water, such as organic acids, phenolic deposits, etc., it can be cleaned after soaking in alkaline solution; for alkaline dirt that is insoluble in water, such as metal oxides, scale, etc., it can be cleaned after soaking in hydrochloric acid; if it is Potassium permanganate deposits can be cleaned with sodium sulfite or oxalic acid solution; manganese dioxide deposits can be dissolved with concentrated hydrochloric acid; when iodine is stained, they can be soaked with potassium iodide solution; silver nitrate stains can be soaked with sodium thiosulfate solution and cleaned; The silver (or copper) adhering to the silver mirror (or copper mirror) after reaction can be dissolved by adding dilute nitric acid with slight heat; tar or resin-like dirt can be soaked in organic solvents such as benzene and esters and then cleaned by ordinary methods . For glass instruments that cannot be cleaned by the above methods, dilute hydrofluoric acid can be used to soak the edges of the dirt, the dirt will fall off with the etched glass thin layer, and then clean with water. Although the glass is corroded, the damage is small and generally does not affect the continued use.

5. Dissolve the crystals precipitated on the inner wall of the flask

During the reflux operation or concentration of the solution, crystals often precipitate on the inner wall of the flask above the liquid surface, and the adhesion is firm, not only cannot continue to participate in the reaction, but sometimes gradually decomposes and discolors due to poor thermal stability. In this case, shake the flask gently to infiltrate the crystal with the internal solution to dissolve it. If the activity of the device is restricted and the flask cannot be shaken, a cold wet cloth can be used to cover the upper part of the flask, so that when the solvent is condensed and flows down the wall, the crystals will be dissolved.

6. Eliminate emulsification

When using a separatory funnel for extraction and washing operations, especially when washing organic substances with alkaline solution, after vigorous shaking, it is often difficult to separate due to emulsification and no stratification. If the degree of emulsification is not serious, you can rotate the separatory funnel slowly in the horizontal direction and then let it stand for a while to eliminate the foam at the interface and promote delamination. If there is still no layering, you can add a proper amount of water and then rotate it horizontally or leave it overnight to separate a clear interface. If the density of the solvent is close to that of water, it will easily emulsify with water during extraction or washing. At this time, an appropriate amount of ether can be added to reduce the density of the organic phase, thereby facilitating separation.

For the emulsified liquid formed by slightly soluble lower esters and water, the layering can be promoted by adding a small amount of inorganic salts such as sodium chloride and ammonium sulfate.

7. Quickly dry the instrument

When a dry instrument is urgently needed in the experiment and it is too late to dry it by conventional methods, first rinse the inner wall of the instrument twice with a small amount of absolute ethanol, and then rinse once with a small amount of acetone to remove the residual ethanol, and then use a hair dryer to blow for a while. , You can achieve the drying effect.

8. Stabilize the flask in the water bath

When cold water or ice bath is used to cool the materials in the Erlenmeyer flask, the flask will float up due to the small amount of materials and the high buoyancy of the bath liquid, which will affect the cooling effect. Sometimes the accident of the flask being poured into the bath liquid at an angle may occur. If a lead strip of moderate length is used to make a circle smaller than the bottom diameter of the Erlenmeyer flask and put it on the flask, the flask will be immersed in the bath. If the container used is a beaker, you can wrap the circle around the beaker and hang on the mouth of the beaker with iron wire to make it stable and achieve sufficient cooling.

9. Make a simple constant temperature cooling tank

When some experiments require the temperature of a constant temperature bath to be kept below room temperature for a long time, cooling with cold water or ice bath often fails to achieve satisfactory results. At this time, you can make a simple constant temperature cooling tank: use a larger carton (reagent or instrument packaging box) as the outer tank, put the constant temperature tank in the carton as the inner tank, and put an appropriate amount of dry ice between the inner and outer tanks , And then use foamed plastic as insulation material to fill the gaps and cover the upper part. The amount of dry ice can be adjusted according to the temperature and time required for the experiment. The cooling tank is easy to manufacture and has good heat preservation effect.

For the emergence of the problem, first make a preliminary judgment to see if the problem is recommended to be easy to deal with by yourself, and if it is, then solve it by yourself. If you are not sure, first consult your superiors or brothers to find out the reason. If you can’t find the reason, then go to the manufacturer and ask for guidance. If you can solve it yourself after getting advice, do it yourself; otherwise, ask someone to do it. In this way, you can gradually cultivate your own abilities and make yourself grow gradually.

10. Clean the inner lining of the reactor

When dealing with the reactor every day when making materials, cleaning the inner lining is the most troublesome. In addition to brushing hard, the following tips are summarized by the editor:

①The synthetic materials of the hydrothermal reactor are different, and the cleaning methods are also different. If it is a silicon system, you can add a little alkali to heat and wash it after use; if it is a silicon metal system, it depends on what acid it is dissolved in.

②Boil with oxalic acid solution for 6 hours, and the temperature of about 160 degrees depends on the experimental situation.

③Use ethanol for heating reaction cleaning, or other strong acids!

④ Dissolve potassium permanganate in water, then add 3-5 mL of concentrated hydrochloric acid, put it in the reactor and seal it, and react at 180 degrees hydrothermally for 5-10 hours, and the washing is very clean~

⑤It can be washed very clean with repeated soaking with aqua regia.

⑥ Add decontamination powder to clean in the ultrasonic cleaner