Why don t you use water for thermometer?

1 Due to melting point and boiling point.

In the standard state, the melting point (freezing point) of water is 0 and the boiling point of water is 100. The melting point (freezing point) of mercury is 38 5 and the boiling point is 357; The melting point (freezing point) of alcohol is 114 and the boiling point is 78; A good kerosene melting point (freezing point) is 30 and the boiling point is 325.

If you measure the air temperature with a thermometer filled with water, it is below 0 in winter, and the water solidifies into ice, which cannot be measured; When the temperature reaches 100, the water boils Although the boiling point of water increases with the increase of water vapor pressure in the tube, the proportional relationship between the volume expansion of water and the increase of vapor pressure is very complex and not proportional, so it cannot be used to measure the temperature above 100. Mercury is different, it can be used to measure the temperature between 38 5 357; Although the boiling point of alcohol is not high, its melting point (freezing point) is 114, that is, it will not freeze above minus 114; With kerosene, the temperature between 30 and 325 can be measured.

2 Due to the coefficient of thermal expansion.

The coefficient of thermal expansion of water is 2 110 4, and the coefficient of thermal expansion of mercury, alcohol, and kerosene is 010 3, respectively. The same volume of liquid is increased1, and the volume of alcohol and kerosene expansion is about 5 times that of water, so in terms of using the scale of volume change, the scale distance of water is small, the scale distance of alcohol and kerosene is large, and the same temperature interval distance is large, which not only brings convenience for measurement and reading, but also can measure small temperature change values.

3 Due to specific heat capacity.

The specific heat capacity of water is 4 2103 J kg, and the specific heat capacity of mercury, alcohol and kerosene is 0 14103 J kg 4103 J kg and 1103 J kg respectively. Water.

The specific heat capacity is 30 times that of mercury, and if water and mercury of the same mass absorb the same amount of heat, mercury rises to a temperature 30 times that of water. It can be seen that the thermometer filled with water has a great influence on the temperature of the measured object, and the time to reach thermal equilibrium is long; The mercury thermometer has little influence on the temperature of the measured object, and the time to reach thermal equilibrium is short. In particular, if the thermometer has an effect on the measurement of a relatively small object, the measurement of its temperature will not be accurate.

1.Water has a very low boiling point and can easily vaporize to blow up the thermometer;

2.After water solidification, the volume change with temperature is small, and it is not easy to observe.

3.When the volume of water is from minus 4 degrees to 0 degrees, the volume will decrease with the increase of temperature, and the decrease will increase.

Because water is used to measure temperature, there is no standard for measuring mercury temperature.

Because water is easy to expand when heated, the measurement is inaccurate.

Water expands when heated, which affects accuracy.

Water has a lower boiling point than mercury and is prone to exploding thermometers.

Water evaporates easily and consumes a lot during the manufacturing process.

The boiling point of water is too low, and the test questions are difficult to operate

The idea that you want to measure the temperature of a liquid with water is wrong, water has a low boiling and melting point.

The volume of water will change, and there will be errors when measuring.

The volume of water changes with temperature.

Such as water resistance can not be used as a thermometer reasons:

1. The boiling point of water is very low, and it is easy to vaporize and make the thermometer burst slag Zhenchun;

2. After water solidification, the change amplitude of volume with temperature is small, and it is not easy to observe;

3. When the volume of water is from minus 4 degrees to 0 degrees, the volume will decrease with the increase of temperature, and the decrease will increase.

Electronic thermometers can measure the temperature of water, which traditional mercury thermometers really cannot. A mercury thermometer is made by placing a small amount of mercury in a glass tube, most of the mercury is stored in a bubble in the head, and as the temperature rises, the mercury expands and the length of the mercury column becomes longer, thus indicating the temperature. If you measure a temperature above 42 with a mercury thermometer, the temperature will rise in a straight line and the bottom of the thermometer will burst.

The electronic thermometer can measure the temperature of water, because it uses the temperature sensor to output an electrical signal, directly output a digital signal or convert the current signal (analog signal) into a digital signal that can be recognized by the internal integrated circuit, and then display the temperature in digital form through a display (such as liquid crystal, digital tube, LED matrix, etc.), which can record and read the highest value of the measured temperature.

A thermometer is a kind of instrument commonly used by Zheng manuscript to measure temperature. Placing a thermometer in water to measure the temperature of the water is a specific application. To be sure, the thermometer that Brother Tan puts in the water to measure the temperature of the water will reflect the actual temperature of the water, but it is important to note that the values obtained by this method may be biased due to external factors.

In practice, the temperature of water plays a very important role in many industries, such as water treatment, hydrology and hydraulic engineering. Therefore, it is particularly important to put a thermometer in the water to measure the water temperature. However, it should be noted that the density of water has a great relationship with temperature, so the measurement of water temperature needs to pay special attention to the density change of water to ensure accuracy and precision.

In addition to influencing factors, the type of thermometer can also have an impact on the measurement results. For example, commonly used glass expansion thermometers are usually only suitable for liquid measurements, but can also be used to measure water temperatures. In addition, digital thermometers and infrared thermometers are another common way to measure water temperature.

For thermometer applications that are placed in water to measure water temperature, it is important to note that the ambient temperature and water quality will have an impact on it, which can lead to errors. At the same time, different types of thermometers also need to pay attention to sample and uniformity when using to ensure the accuracy and reliability of the measurement.

In general, thermometers that measure water temperature in water have a wide range of applications and importance, and to ensure accuracy and reliability, you need to pay attention to the influencing factors and the type of thermometer. <>

Categories: Education Science.

Analysis: People often judge the degree of heat and cold of an object based on their own feelings, but such judgments are usually inaccurate due to the clarity of many factors. To know exactly the temperature of an object, you need to use a thermometer.

The first to invent the thermometer was the Italian scientist Galileo Galilei. Galileo designed a glass tube with a spherical end and an air filling center, with the other end open facing down in the liquid. When the temperature rises, the air inside the tube expands by heat.

Under the same conditions, the thermal expansion of the liquid is not as large as that of the gas, so the height of the liquid level in the tube will be reduced. In the same way, when the temperature decreases, the liquid level in the tube will rise, but such a thermometer is not very accurate due to the influence of atmospheric pressure changes.

The thermometer we use now is completely made by using the principle of thermal expansion and cold contraction of liquid: because under the same conditions, the thermal expansion of liquid is greater than that of solid, so when the temperature changes, the liquid level in the glass tube will rise or fall; And because the inner diameter of the glass tube of the thermometer is very thin, the change in the volume of the liquid shows a more obvious height change in the tube, so the specific value of temperature can be read from the scale on the glass tube. The liquids in the thermometer are generally mercury, kerosene, and alcohol.

Hello dear <>, happy to answer for you. The thermometer that measures the temperature of the water can measure the human body. No!

There is a difference between an aquarium thermometer and a human body thermometer. The aquarium thermometer is used to measure the temperature of the water body, and its range is generally between 0-50 °C, and the aquarium thermometer adopts constant current technology, and the current value can be very high to ensure the measurement accuracy; The human body thermometer is used to measure the body temperature of the human body, and the range is generally between 35-42 °C. Even after leaving the human body, the temperature indicator will drop immediately, which leads to the problem that Shizheng cannot read the body temperature reading even if he measures it alone.

Summary. Mercury thermometers can measure the temperature of water or boiling water with or without a thermometer.

Because, the minimum temperature of water is 0°C, and boiling water is 100°C. The freezing point of mercury is -39, and the boiling point is 357; The freezing point of kerosene is generally lower than -30, and the boiling point is generally higher than 150. Therefore, it is appropriate to use these two liquid ranges.

Kerosene thermometers are more practical, and the range is generally greater than 100 degrees Celsius.

Mercury thermometers are generally used as thermometers, and it is not recommended to use them (it is not easy to find a large range) Alcohol thermometers are absolutely not good, and the boiling point of alcohol is Celsius at standard atmospheric pressure.

Can an ordinary thermometer measure 100 degrees of water?

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Hello, can an ordinary thermometer measure 100 degrees of water thermometer is not energy water temperature, the highest energy of the body branch sail thermometer is 42 degrees Celsius, and the water temperature can reach 100 degrees, so it is suitable to use a thermometer to measure the water temperature in the event of a hailstorm.

Both mercury thermometers and non-dairy thermometers can measure the temperature of water or boiling water. Because, the minimum temperature of water is 0°C, and boiling water is 100°C. The freezing point of mercury is -39, and the boiling point is 357; The freezing point of coal is generally lower than -30, and the boiling point is generally higher than 150.

Therefore, it is appropriate to use these two liquid ranges. Kerosene thermometers are more practical, and the range is generally greater than 100 degrees Celsius. Mercury thermometers are generally used as thermometers, and it is not recommended to use them (it is not easy to find a large range) Alcohol thermometers are absolutely not good, and the boiling point of alcohol is Celsius at standard atmospheric pressure.