Glassware(Incubator) for chemical analysis should be cleaned and dried after each test.Different instruments for different experiments have different requirements for drying. In general quantitative analysis, beakers, conical bottles and other instruments can be used after being cleaned. However, many instruments for organic chemistry experiments or organic analysis require drying.

Cleanliness standards for glassware:

In chemical experiments, clean glass instruments must be used to avoid impurities entering the reaction system and affecting the reaction conditions and observation of experimental phenomena.Instrument cleaning should be done immediately after each test.This is because, on the one hand, it is clear about the nature of the dirt at that time so that it can be removed in an appropriate way;And on the other hand, get ready for the next experiment.

The general cleaning method of glassware is:

Select the appropriate brush, the brush and the instrument with water after wet, brush with detergent brush on the inside and outside of the instrument (grinding bottle should not use detergent, so as not to damage the grinding mouth), when the dirt on the glass instrument removed, then rinse with tap water.

If a high degree of cleanliness is required, a small amount of distilled water should be rinsed for two to three times.A clean glass instrument should have no beads of water on the bottle wall. If there are beads of water, it should be washed again.It should be noted that after washing the instrument should not be dried with cloth, filter paper, etc.

Some reaction with household cleanser residue is not easy to wash, can be adopted according to the specific situation of sewage with low prices or soaking in the recovery of organic solvent or with dilute acid, lye, but cannot be used blindly, lest cause waste and accidents (residual bromine instruments, for example, if wash will produce a strong tear agent with acetone - bromide acetone).The traces on the wall of the instrument can be soaked with lotion and then cleaned and removed.

Taboos on Washing

1. Regular washing instrument

When washing the instrument, the hand should be first washed with soap, lest hand oil stains attached to the instrument, increase the difficulty of washing.If the instrument is stored for a long time with dust, flush it with clean water first, and then choose a cleaner to wash or wash as required.When rinsing with distilled water, rinse along the wall and shake thoroughly. After rinsing with distilled water, the instrument should be checked as neutral with indicator.

2. Glassware for trace metal analysis is soaked in 1:1 ~ 1:9 HNO3 solution and then washed normally.

3. When conducting fluorescence analysis, the glassware should be cleaned with washing powder (because washing powder contains fluorescent whitening agent, which will bring errors to the analysis results).

4. When analyzing carcinogenic substances, appropriate washing and elimination should be selected to soak at night, and then washing according to the normal method.

Common drying method

Instruments used in chemical experiments often need to be dried as well as cleaned.The presence of water can sometimes affect the rate or yield of a chemical reaction or even make it impossible to proceed.For experiments requiring no water in general, the instrument can be used simply by turning it upside down and drying it.For absolutely no water experiment, the instrument should be placed in the oven or on the hot gas flow dryer drying.If necessary, the cleaned instrument can be swabbed with a small amount of ethanol or acetone and then blow-dried with a hair dryer.It must be noted in particular that whatever method of drying the apparatus is used, it must be cooled to room temperature before it can be taken out; otherwise, when the hot apparatus is quenched, water vapour will condense on the walls.

As long as it is not a volume instrument (measuring cylinder, burette, pipette, etc.) can be dried.

Dry in 1.

It is not urgent, generally dry, can be rinsed in pure water, inverted in a dust-free place to dry water, and then natural dry.The equipment can be placed on shelves with inclined wooden pegs and in glass cabinets with air holes.

2. The drying

The cleaned instrument is controlled to remove water and dried in an electric oven at a temperature of 105 ~ 120℃ for 1h.Can also be put in the red lamp drying box.This method is applicable to general instruments.The weighing bottle should be cooled and preserved in a dryer after drying.When drying the instrument with solid glass plug and thick wall, it is necessary to raise the temperature slowly and the temperature should not be too high to avoid cracking. The measuring device should not be put in the oven for drying.

Hard test tube can be used alcohol lamp drying, from the bottom to bake, the tube mouth down, so as not to reverse the water droplets burst the test tube, bake to no water droplets, the tube mouth up to catch water vapor.

3. Dry by hot (cold) wind

Element analyzer for eager to dry the instrument or not suitable for larger instruments available is put in the oven dry method, usually with a small amount of ethanol, acetone (or final reoccupy ether) has been introduced into the control to water wave washed in instrument control net solvent (solvent to recycle), and then use hair dryer, start with the cold wind blow 1 ~ 2 min, when most of the solvent evaporation blowing hot air to dry completely, after reoccupy cold wind blow the residual steam, so that it is no longer condensation in the container.This method requires good ventilation, prevent poisoning, do not contact open flame, in order to prevent the explosion of organic solvents.

What should be paid attention to in drying oven?

To be precise, glassware should not be placed in the oven for drying. Glassware that can be placed is used for storage, not for measuring.For example, beakers, flutes, and flutes with round bottoms are suitable for drying, while burette, pipette, and measuring cylinder of glass products (with scale) are not suitable for drying.

The temperature of glass is easy to be dried should not be too high, and it should be below 100 degrees. When taking out, please pay attention to wear heat-resistant gloves to prevent burns. In addition, it is better to take out the instrument after the oven temperature reaches below 45 degrees (or normal temperature).

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