In the last article, Lebes mentioned five of the common troubleshooting methods for laboratory instruments . In this article, Lebe will continue to talk about the latter methods.
6 . How to clean up the spilled mercury?
In the laboratory we often use mercury-filled pressure gauges and mercury thermometers. If the operation is improper or the thermometer is damaged, a “spraying accident†will occur. Mercury vapour is extremely harmful to the human body, so it is necessary to clean up the spilled mercury in a timely and thorough manner and not allow it to be lost. There are many specific cleaning methods, and we can choose to use according to different situations.
1) If it is absorbed by a small amount of mercury, you can use a common dropper to suck up the mercury beads one by one and collect them in a container. If the amount of mercury is large or spilled in the gap of the groove, the suction filter bottle can be connected with a 75° glass elbow through the rubber plug, and a “decompression aspirator†can be made by itself, using negative pressure. Mercury particles are sucked into the filter bottle through a glass tube. The connection between the suction filter bottle and the pressure reducing pump can be suitably longer to avoid drawing mercury into the pump.
2) Adhesion of mercury spilling on the table or the ground. If the mercury has been dispersed into fine particles, then we can stick it with tape paper, then immerse it in water and brush it into the container with a brush. This method is simple and easy, and the effect is good.
3) Since the melting point of frozen mercury is -38.87 °C. Therefore, if the sprinkled mercury is covered with an appropriate amount of dry ice-acetone mixture, the mercury will be frozen into a solid state and lose its fluidity within a few seconds, which can be easily cleaned up at this time.
4) Conversion For the presence of trace amounts of mercury that are scattered in the corners and difficult to retract by the above three methods, we can use sulfur powder to cover the areas where the mercury particles are lost, so that mercury and sulfur are combined to form less toxic mercury sulfide, and then Clear it again.
7 . How to eliminate emulsification?
When the extraction and washing operation is carried out using a separatory funnel, in particular, the organic matter is washed with an alkali solution, and after vigorous shaking, it tends to be difficult to separate due to the occurrence of emulsification without delamination. If the degree of emulsification is not serious, the separatory funnel can be slowly rotated and shaken in the horizontal direction, and then left to stand for a while, thereby eliminating the foam at the interface and promoting delamination. However, if you still do not stratify after this operation, you can separate the clear interface after adding a proper amount of water and then shaking it horizontally or standing overnight.
If the density of the solvent is close to that of water, it is easy to emulsify with water during extraction or washing. In this case, we can add an appropriate amount of B to reduce the organic phase density to facilitate stratification.
For an emulsion formed by a slightly soluble ester of water and water, it can be stratified by adding a small amount of an inorganic salt such as sodium chloride or ammonium sulfate.
　 8 . How to dry the instrument quickly ?
When we urgently need to use a dry instrument during the experiment, but it is too late to dry the instrument by conventional methods, we can first rinse the inner wall of the instrument twice with a small amount of absolute ethanol, and then rinse it with a small amount of acetone to remove residual ethanol. Then use a hair dryer to blow for a while, you can achieve the drying effect.
9 . How to stabilize the flask in the water bath?
When the material in the conical flask is cooled by cold water or ice bath, the flask is often floated due to the small amount of material and the buoyancy of the bath, which affects the cooling effect, and sometimes the accident that the flask is tilted into the bath may occur. If a circle of moderate length is used to make a circle smaller than the bottom diameter of the conical flask, the flask is placed in the flask and the flask is immersed in the bath. If the container used is a beaker, the circle can be placed over the beaker and hung on the beaker mouth with a wire to stabilize it and achieve adequate cooling.
10 . How to make a simple constant temperature cooling tank?
When some experiments require the temperature of the bath to remain below room temperature for a long time, cooling with cold water or ice bath often does not achieve satisfactory results. At this time, we can make a simple constant temperature cooling tank. The specific method is as follows: First, use a larger carton reagent or instrument packaging box as the outer tank, put the thermostatic bath into the carton as the inner tank, and then the inner and outer tanks. Put a proper amount of dry ice between them, and then use foam as a heat insulating material to fill the gap and cover the upper part. The amount of dry ice can be adjusted according to the temperature and time required for the experiment. This cooling tank is easy to manufacture and has a good heat preservation effect.
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