How To Clean Glassware And Test Tube Commonly Used in Laboratory

General washing procedures for glassware

Various glassware should be used in the experiment. Whether these glassware are clean or not will directly affect the accuracy of the experimental results. Therefore, the glassware must be cleaned before the experiment.

General glassware, such as beakers, flasks, conical flasks, test tubes and measuring cylinders, can be brushed with water from outside to inside with a brush, so as to wash away water-soluble substances, some insoluble substances and dust; If there is organic matter such as oil stain, it can be washed with decontamination powder, soap powder or detergent. Scrub with a brush dipped with decontamination powder or detergent, then rinse with tap water, and finally moisten the inner wall with distilled water or deionized water for 2 ~ 3 times. The inner wall of cleaned glassware shall be able to be evenly wetted by water without water stripes, and there shall be no water droplets. In organic experiments, glass instruments with grinding mouth are often used. When washing, attention should be paid to protecting the grinding mouth. Detergent should not be used instead of detergent.

For glass instruments that are not easy to brush with a brush or are not clean with a brush, such as burette, volumetric flask, pipette, etc., usually pour the detergent into or suck it into the container for soaking for a period of time, pour the detergent in the container into the storage bottle for standby, and then rinse with tap water and deionized water.

The sand core glass filter must be cleaned immediately after use. For the different precipitates remaining in the sand core of the filter, use appropriate detergent to dissolve the solid precipitated on the surface of the sand core first, and then use the decompression pumping method to repeatedly pump and wash all the precipitates remaining in the sand core with detergent, then wash them with distilled water, dry them at 110 ℃ and store them in a dust-proof cabinet.

Washing method of difficult to wash dirt

Washing of crystals and precipitates

For example, when sodium hydroxide or potassium hydroxide absorbs carbon dioxide in the air to form carbonate and there is precipitation of copper hydroxide or iron hydroxide, it can be soaked in water for several days, then washed with dilute acid to form substances soluble in water, and then washed with water. If there is organic precipitation, it can be washed with boiling organic solvent or sodium hydroxide solution.

Washing of residual amalgam

Mercury forms a metal alloy (amalgam) with some metals and adheres to the glass wall to form dark spots. The amalgam can be dissolved with 10% nitric acid solution, and then washed with water.

Washing of dry oil, grease and paint

It can be washed with ammonia or chloroform, and the oil that has not hardened can be washed with organic solvent; Kerosene can be washed with hot soapy water; Viscous oil can be soaked and washed with hot sodium hydroxide solution.

Stain washing

The white stain on the glass is formed by alkali corrosion due to long-term alkali storage; The yellowish brown rust spots attached to the glass can be washed with hydrochloric acid solution; The turbidity generated during electrolysis of lead acetate can be washed with acetic acid; Brown manganese dioxide spots can be washed with ferrous sulfate, hydrochloric acid or oxalic acid solution; Ink stains on the glass can be washed with soda or sodium hydroxide solution.

Washing of silver salt stains

The stains of silver chloride and silver bromide can be washed with sodium thiosulfate solution, and the silver mirror can be washed with hot dilute nitric acid solution to produce silver nitrate that is easily soluble in water.

Common detergent

According to the different dirt on the glass, the corresponding detergent is used for washing, and the glass instrument can be effectively cleaned by chemical or physical methods. See Table 2 for several commonly used detergents at present. It should be noted that when using various detergents with different properties, it is necessary to remove the former detergent and then use another detergent, so as to avoid the interaction between them and produce products that are more difficult to remove.