Thermometer Centigrade

Any instrument which can be used for measuring temperatures is called a thermometer. Thermometers may be, and are, constructed which utilise any property of a body such as those mentioned above. To evade the difficulty of comparison of scales, they are usually all referred to a gas thermometer, with Centigrade scale as standard. The ice and steam-points on the latter are taken as 0° and 100° respectively. 

The intensity of heat, or temperature, is measured in Celsius (centigrade) or Fahrenheit scales, and expressed in degrees (°). The instrument that measures the temperature is called thermometer. Most thermometers in the United States use the Fahrenheit scale. 

Thermometers. A high quality thermometer is only about 8. It is best to purchase two — one for high temps and the other for low temps. Make certain it is for measuring degrees in centigrade as this is what all formulas require, unless specified differently. Candy, meat and other types of thermometers will not fit your apparatus, are not accurate enough for most reactions and are unacceptable. 

A. Apparatus. Set up a melting point bath equipped with a mechanical stirrer and a source of heat that can be easily regulated. A beaker of 1 to 2 liters capacity about % full of clear peanut oil is recommended. Suspend an accurately standardized total immersion Centigrade thermometer in the bath so that the bulb is not less than 1.5 inches from die bottom of the bath. If the mercury column... 

Thermometer shall be an ASTM Open Flash-Type, graduated in either centigrade (—6° to +400°C) or Fahrenheit (+20° to +760°F) degrees and conforming to the requirements for thermometer 11C or 11F, respectively, as prescribed in ASTM El Procedure... 

Temperature is measured by such instruments as thermometers, pyrometers, thermocouples, etc., and by scales such as centigrade (Celsius), Fahrenheit, Rankine, Reaumur, and absolute (Kelvin). 

Different empirical temperature scales will naturally differ from each other except at the respective fixed thermometnc points, Even different scales of the same type (say different Centigrade scales) will differ at all temperatures, except the steam point and ice point, depending on the fortuitous properties of the system chosen as a thermometer. It is, therefore, necessary to remove these differences and to obtain a more universal scale. This has been achieved in two ways. The practical way of achieving uniformity is to lay down detailed rules concerning the thermometer (actually different thermometers depending on the range of temperatures to be measured). Such rules have been agreed on internationally and... 

Celsius, Anders(l701-1744). Swedish astronomer, known for invention of "centigrade thermometer, also known as "Celsius thermometer Ref EncyclBritannica 5(1952), 101... 

It is important to consider what happens when the substance or property employed is changed. For example, for a liquid in glass thermometer (using the Centigrade scale) ... 

We will assume that Charles measured temperature with a mercury thermometer calibrated for the centigrade (Celsius) scale. 

In 1742 Anders Celsius, a Swedish astronomer, developed the mercury centigrade thermometer. He chose the boiling and freezing points of water as calibration points. Curiously, he chose 0° for the high temperature and 100° for the low temperature. His choices were reversed in 1850 by Marten Stromer, also a Swedish astronomer. In 1948 the centigrade scale was officially renamed the Celsius scale. 

There are many specialized thermometers available. Some are used to obtain maximum and minimum temperatures, while others are used for specific tests. The ASTM has defined a series of special partial-immersion thermometers for specific tests. These thermometers are identified as ASTM thermometers and are marked with a number followed by a C (for centigrade) or an F (for Fahrenheit). The number is strictly an identifying number with no relation to the temper-... 

K = 0.00016 for centigrade mercurial thermometers and K = 0.001 for centigrade organic liquid thermometers To better understand stem corrections, consider the following example ... 

Platinum Resistance Thermometer. Platinum resistance thermometers are based on the electrical resistance of Pt. This resistance for Pt wires wound on a mica support and enclosed in a glass or silica vessel can be manufactured to be either 25.5 Q at 0°C or 2.5 Q at 0°C. The electrical resistance, typically measured in a Wheatstone or Mueller bridge, increases by about 0.1 Q or 0.01 Q, respectively, per degree centigrade (0.4%/°C). Empirical equations convert Pt resistance and its small nonlinearities to temperature ... 

Quartz Crystal Thermometer. The temperature coefficient of the resonant frequency of quartz (14-20 MHz), using the piezoelectric effect, is a function of temperature (1 kHz per degree). In the temperature range -80°C to 230°C, an electronically controlled quartz crystal thermometer can be accurate to 0.02°C and has a sensitivity of 10 microdegrees centigrade in temperature difference measurements. 

A quartz crystal thermometer sustains a capacitance if the frequency of the RLC circuit is precisely tuned to 14 or 20 MHz (depending on the exposed crystal faces). The quartz crystal will then transmit a very precise frequency, which has a temperature coefficient (typically 1 kHz per degree centigrade). If the temperature fluctuations are precisely compensated by a feedback heater circuit, then a quartz crystal oscillator is precise to about 1 part in 1.4 x 108. 

For quantitative measurements, it is necessary to set up some kind of a scale on which numerical values can be assigned to r. Many such scales are in use one which is particularly convenient is the so-called Celsius or centigrade scale, for which r - 0 when ice at atmospheric pressure is equilibrated with water, and for which r - 100 when water is in equilibrium with steam under a total pressure of one atmosphere. The unit interval in r is termed the degree Celsius (°C). If now V0, V100, and V represent the volume of the gas thermometer in equilibrium with a system at r - 0, r - 100, and r, respectively (when the pressure of the gas thermometer is fixed at some arbitrary, low value), then r is measured by... 

Temperature is the measure of thermal energy (the total energy of all the atoms and molecules) of a system. The SI unit for temperature is Kelvin, but most scientific thermometers use the centigrade (Celsius) scale. However, most are more familiar with the Fahrenheit scale. Because many chemical calculations require Kelvin temperature, scientists frequently convert from degrees Celsius to Kelvin and from Kelvin to degrees Celsius. 

The fluid bed distributor was an aluminium perforated disc whose holes were 0.5 mm. in diameter arranged in one centimeter square pitch. A stainless steel 325 mesh screen was fixed at the entrance side of the perforated disc. The thermometers used for temperature measuring had 0.1 degree centigrade divisions.In order... 

A Thermometer (Fig. 113) is an instrument for measuring temperatures. There are two kinds in use the one in scientific use is the Centigrade, the one in general use in this country is the Fahrenheit. The change in temperature is measured by expansion and contraction of the mercury, or popularly speaking, by rise and fall of the thermometer. The abbreviation for centigrade is C. and for Fahrenheit is F. 

We have seen (Chap. II, Art. 24) that when a centigrade-scale thermometer constructed with a perfect gas indicated the temperature t, the absolute temperature had the value T= +t, a... 

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