Difference Between Alcohol Thermometer and Mercury Thermometer
Table of Contents
Main Difference
The main difference between Alcohol Thermometer and Mercury Thermometer is that Alcohol Thermometer is a temperature measuring device in which alcohol is enclosed in the bulb, whereas Mercury Thermometer is a temperature measuring device in which mercury is enclosed in the bulb.
Alcohol Thermometer vs. Mercury Thermometer
Alcohol thermometers are one of the types of the thermometer with alcohol enclosed or filled in the bulb of the thermometer and the alcohol acts as the sensor to measure temperature; whereas mercury thermometer is one of the types of the thermometer with mercury enclosed or filled in the bulb of thermometer in which mercury acts as the sensor to measure temperature. The alcohol present in the alcohol thermometers is colored using a dye, usually containing blue or red color; however, the mercury present in the mercury thermometers already has a natural silver color, so it does not need any dye to color.
As alcohol has a low boiling point, it wets the wall of alcohol thermometer of its place, while the mercury in the mercury thermometer does not wet the walls of the thermometer glass. The endurability of alcohol thermometers is relatively less because it is susceptible to evaporation, but the endurability of mercury thermometers is high as mercury is resistant to evaporation. Liquids such as pure alcohol, kerosene, and toluene can be present interior to the bulb of alcohol thermometer, but mercury is the only liquid that can be present inside the bulb of a mercury thermometer.
Alcohol thermometers can measure comparatively low temperatures that range from -115-78.5°C (-117 to 173.3°F), while mercury thermometers can measure relatively high temperatures ranging from −37 to 356 °C (-34.6 to 672.8°F). Toxicity of alcohol is less; thus, alcohol thermometers have a secure use; however, the toxicity of mercury is higher; therefore, mercury thermometer is less safe for use. Using an alcohol thermometer is appropriate for measuring Low-temperatures, but for measuring high temperatures, mercury thermometers are suitable.
The accuracy of alcohol thermometers is less than mercury thermometers as alcohols are more prone towards evaporation, capillary separation and, polymerization potential, whereas the measurement of mercury thermometer is more accurate as mercury is susceptible to sufficient expansion to observation regarding temperature changes from 0.1° which helps graduate the thermometer.
Alcohol thermometers are advantageous as they ensure that they are safe and secure for humans, and the environment, whereas the mercury in mercury thermometers is an environmental hazard as its introduction in the environment can affect the marine life where it is broken down into methylmercury compounds that are consumed by sea life and ultimately all the mammals and birds life is threatened by eating contaminated seafood.
Disposing of broken alcohol thermometers is always carried out in a usual way despite the broken glass pieces which should be carefully handled, while immediate action should be taken in response to a broken mercury thermometer as it is an alarming situation; one should keep the mercury thermometers out of the reach of children.
Comparison Chart
| Alcohol Thermometer | Mercury Thermometer |
| It is a thermometer with alcohol enclosed in the bulb of the glass tube, which acts as a temperature detector. | It is a kind of thermometer with mercury enclosed in the bulb of the glass tube, which acts as a temperature detector. |
| Toxicity | |
| Less toxic | Highly toxic |
| Liquid Inside Bulb | |
| Alcohol, toluene, kerosene | Mercury |
| Temperature Range | |
| -115°C to78.5°C | −37 to 356 °C |
| Use of Dye | |
| Uses colored alcohols with a dye | Uses mercury with its natural silver color without a dye |
| Durability | |
| Less durable | Highly durable |
| Wetting the Wall | |
| Alcohol causes the wall wet of a thermometer. | Mercury does not cause the wall wet of a thermometer. |
| Measurement | |
| Suitable for measuring low temperatures | Suitable for measuring high temperatures |
| Effects on the Environment | |
| Environmental friendly | Environmental hazard |
| Disposing | |
| Normal manner | Careful manner |
What is Alcohol Thermometer?
It is a kind of thermometer with alcohol inside the bulb of the glass tube, which acts as a temperature detector. Suitable organic components, mainly ethanol, toluene, kerosene, are present in the bulb of alcohol thermometer according to its application. The components used in the alcohol thermometers are colorless or transparent hence uses dyes for the liquid such as blue or red dye to make it more visible. Capillary present at halfway of the thermometer glass is enameled in yellow or white color to provide a base to the marked scale.
The measurement range of alcohol thermometer depends on the boiling point of the liquid present in it. The maximum measuring range ethanol-enclosed thermometer is 78 °C (172.4 °F) that is suitable for measurements such as body, daytime, nighttime temperatures limiting the measurement of much heat. The toxicity of liquids present in alcohol thermometers is less toxic because they are susceptible to evaporation. Due to the low price and less endangerment of ethanol composed thermometer, it is more useful.
Alcohol thermometer consists of an organic liquid, enclosed inside the bulb of glass and connected to the capillary of the glass while the expansion valve seals the ending point of the glass tube; a combination of liquid fumes and nitrogen is present at the cavity above the liquid. The meniscus is present in the liquid inside the capillary, which allows the operating of the temperature range. The meniscus moves along the capillary as the temperature rises because it causes the spreading of the meniscus along the capillary tube; the position of the meniscus, identified by the marked scale on the thermometer measures the temperature.
Alcohol thermometers can measure temperatures ranging from -115°C to78.5°C. The maximum temperature that can be measured depends on the boiling point of the liquid inside the bulb. The magnitude of the liquid (alcohol) extends while the bulb of the alcohol is exposed to the sample which needs to measure. The preference of alcohol thermometers as compared to the mercury thermometers is due to their secure and safe chemical compound.
What is Mercury Thermometer?
It is a kind of thermometer with mercury inside the bulb of the glass tube, which acts as a temperature detector and also referred to as a mercury-in-glass thermometer. In 1714 invention of the mercury thermometer took place by a scientist named Daniel Gabriel Fahrenheit. The bulb inside a thermometer has mercury inside it that connects with a glass tube, consist of a tube called capillary tube interiorly. The marked plane of the glass tube allows to measure a certain temperature and space is present above the mercury of the capillary tube that encloses nitrogen gas.
The accuracy and durability of mercury thermometers are high as they are useful for almost every measurement of temperature, having a low cost. Even though its scientific and industrial use is getting restricted because of the environmental hazards and safety problems are taking actions against mercury products disposal. Traditional use of mercury in liquid form is useful due to its adherence and separating properties of fluid properties during maximum temperatures. The mercury liquid does not require a dye and recognized by its natural metallic silver color.
However, they can present environmental dangers, whereas mercury in the form of the metallic liquid is comparatively harmless when limited. But it becomes lethal in a gaseous state like inorganic salts and organomercuric compounds, and it has considerable toxic effects on fetuses, infants, and children. The magnitude of the liquid mercury extends while the bulb of the alcohol is exposed to the sample which needs to measure; the position of the meniscus, identified by the marked scale on the thermometer measures the temperature.
Mercury thermometers can measure the temperatures ranging from −37 to 356 °C. But if the capillary tube has nitrogen gas, then it increases the temperature range because nitrogen gas has the property of being inert, so it applies pressure on the mercury, which results in the rising of the boiling point of mercury. Mercury thermometer has mercury-filled in a bulb, connected by the narrow width glass tube.
It consists of a bulb containing mercury connected to a glass tube of narrow diameter; the proportion of mercury inside the bulb is greater than the proportion inside the tube. The temperature changes cause a change in the volume of mercury; the mercury expands far along the narrow tube by the small change in volume.
Key Differences
Conclusion
Both alcohol thermometer and mercury thermometer are different kinds of thermometers that have a bulb containing a liquid and capillary tube. However, they have differentiated as; the bulb of alcohol thermometer contains alcohol inside it, which is less toxic, whereas the bulb of mercury thermometer has mercury inside, which is highly toxic.
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