Broken glass thermometers

Digital thermometers are safer to use in children than glass thermometers as there is no risk of the glass being broken. Digital thermometers tend to be more expensive. 

Metallic mercury is used in a variety of household products and industrial items, including thermostats, fluorescent light bulbs, barometers, glass thermometers, and some blood pressure devices. The mercury in these devices is contained in glass or metal, and generally does not pose a risk unless the item is damaged or broken, and mercury vapors are released. Spills of metallic mercury from broken thermometers or damaged electrical switches in the home may result in exposure to mercury vapors in indoor air. You must be careful when you handle and dispose of all items in the home that contain metallic mercury. 

Add a broken glass boiling chip, 25 ml of concentrated sulfuric acid and 10 ml of concentrated nitric acid. Insert a 500°C thermometer and cover the beaker with a watch glass. Place on a room temperature hot plate and slowly increase the temperature until fumes of nitrogen dioxide appear. Maintain the temperature at about 200°C and add 5-ml increments of concentrated nitric acid with sufficient frequency to produce nitrogen dioxide fumes at a steady rate. 

A glass thermometer that was also used to indicate the bath temperature was broken and about one fifth of the lower part was molten and misshapen. The plastic of the clamp used to hold it was charred. 

Very few modem calorimeters employ mercury-in-glass thermometers. The limit of accuracy of the most accurate instrument of this type, the Beckmann thermometer, is about 0.001 K it is easily broken, and subject to errors caused by exposed stem, pressure, sticking of the mercury column, and drift in calibration. 

Mercury-in-glass laboratory thermometers are convenient for many applications and are still frequently used. The only safety concern is the possibility of a broken thermometer bulb. If breakage occurs, the thermometer must be given to the laboratory staff for disposal and any mercury spillage must be promptly cleaned up. Safety concerns about mercury should be kept in perspective. There is no appreciable danger from the normal use of mercury thermometers or other laboratory devices containing mercury (such as manometers or barometers) if they are used properly. 

These thermometers contain either mercury, alcohol, etc., as liquids. The thermal expansion of these liquids is greater than the glass, so the height of liquid in the glass capillary rises as the temperature increases. A major problem is that the glass can be easily broken. Furthermore, mercury causes toxicity problems if the thermometer breaks. Visual observations are usually required to read the thermometers. Often these instruments are restricted to temperatures from about 0°C to 400°C. Their advantages are low costs, long life if properly protected, and reasonable accuracy. They still are widely used in experimental setups and for various home uses. 

Catalyst samples were ground into fine powder, freed of moisture, and sealed in glass bulbs, which were ultimately broken within a Dewar-flask calorimeter. A heater, Beckmann thermometer, sample holder, and stirrer were introduced into the calorimeter through an evacuated lid. The dissolutions were carried out at 160° in equivolume mixtures of H2SO4 and H3PO4. The calorimeter constant was reproducible within 0.05% the over-all precision of the determinations is estimated to be within 1 cal./g. 

Broken thermometers. Collect spilled mercury and glass and place in a screw-capped, wide-mouth bottle or jar. Securely close the container and label it BROKEN THERMOMETER AND ELEMENTAL MERCURY. For spills of mercury, also see Appendix 1. 

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