Millimeter of mercury mmHg

The unit millimeter of mercury (mmHg) is defined in terms of the pressure exerted by a column of mercury under certain conditions (15°C and in a standard gravitational field), bur it has now been largely displaced by a unit of similar magnitude, the torr (Torr). This unit is defined by the exact relation... 

Boiling Point. Such points/ranges are distinguished from melting points and ranges by the presence of a pressure in millimeters of mercury (mmHg) after the temperature for example, 97-98/0.5. 

VP Vapor pressure of the material in millimeters of mercury (mmHg) at 68°F. If another temperature is used, it is indicated in parentheses following the vapor pressure. 

The pascal represents a very small pressure, and therefore the most common applications, such as tire pressure, will use kilopascals (kPa) instead of Pa. Other units of pressure include the torr (or millimeter of mercury, mmHg), inches of mercury, the atmosphere (atm), and the bar. A torr is an amount of pressure necessary to support a column of mercury 1 mm in height. One atmosphere of pressure is loosely defined by the atmospheric pressure at sea level, but is more precisely defined as the pressure necessary to support a column of mercury 760 mm in height. One bar of pressure is equal to 100 kPa. The relationships between the various units of pressure are given below ... 

Blood pressure is a measure of the force of blood rushing through and pushing against arteries. Measured in millimeters of mercury (mmHg), systolic blood pressure, the top number in, say, the reading 120/80, indicates arterial pressure as the heart beats, while the diastolic, the lower number, is the pressure between beats, while the heart rests. 

The measurement of blood pressure usually involves the joint measurement of two aspects of arterial blood pressure, systolic blood pressure (SBP) and diastolic blood pressure (DBP). The SBP provides a representation of the pressure of blood as it is ejected from the heart into the body s arteries at each heart beat. The DBP provides a representation of the blood pressure in the arteries in between each heart beat. A healthy blood pressure for a young adult is often represented as "120/80." This is pronounced "one twenty over eighty." In this case, the I" symbol does not represent the division of 120 by 80 to get a value of 1.5 It is simply used to separate the two blood pressure readings. The units of blood pressure are millimeters of mercury (mmHg), so... 

Air has weight and therefore exerts a pressure. The atmospheric pressure is due to the weight of the overlying air. A standard atmosphere (1 atm) is defined as exactly 101 325 Pa. It is approximately equal to the average pressure of the atmosphere at sea level. The standard atmosphere also is approximately equal (within several parts in 10 ) to the pressure exerted by a column of mercury 760 mm high, at 0 °C and at sea level. The torr is defined by 760 torr = 1 atm. For problems in this book, the torr and the millimeter of mercury (mmHg) will be taken to be the same. The bar is defined by 1 bar = exactly 10 Pa. One bar has recently replaced 1 atm as the standard pressure for reporting thermodynamic data. 

Convert between the names and abbreviations for the following pressure units pascal (Pa), atmosphere (atm), millimeter of mercury (mmHg), and torr. 

Convert a gas pressure described in pascals (Pa), atmospheres (atm), millimeters of mercury (mmHg), or torr to any of the other units. 

Gases exert pressure because their molecules move freely and collide with any surface with which they make contact. Units of gas pressure include millimeters of mercury (mmHg), torr, pascals, and atmospheres. One atmosphere equals 760 mmHg, or 760 torr. 

Another common unit is the millimeter of mercury (mmHg), mentioned above, which is based on measurement with a barometer. In honor of Torricelli, this unit has been named the torr ... 

How can a unit of length such as millimeter of mercury (mmHg) be used as a unit of pressure, which has the dimensions of force per unit area ... 

Millimeter of mercury (mmHg) - A non-SI unit of pressure, equal to 133.322 Pa. The name is generally considered interchangeable with torn... 

It is veiy important to understand the general aspects of gas pressure, its measurements, and calibrations. Pressure is force exerted over imit area. The unit of pressure is pascal (Pa) which is equivalent to kg/(m.s ). In chemistry, we usually use a mercury-based barometer to measure the pressure. The unit is millimeter of mercury (mmHg). This is the same as the unit torr. Another unit commonly used to denote pressure is atmosphere (atm). You should be able to convert these units back and forth as required. 

Despite attempts to standardize measurement units, you will probably encounter a number of different units of pressure in your future studies and employment. Some of the more common are standard atmosphere (atm), torr, millimeters of mercury (mmHg), inches of mercury (in. Hg), pounds per square inch (psi), bar, and kilopascals (kPa). One standard atmosphere is the pressure needed to support a 760-mm column of mercury in a barometer tube, and 1 torr (named in honor of Torricelli) is the pressure needed to support a 1-mm column of mercury in a barometer tube. The relationships of the various units to the standard atmosphere are given in I Table 6.3. Note that the values of 1 atm and 760 torr (or 760 mmHg) are exact numbers based on definitions and do not limit the number of significant flgures in calculated numbers. 

Because the pressure of the mercury column is directly proportional to its height, a unit commonly used for pressure is millimeters of mercury (mmHg). We discuss other units of pressure shortly. At sea level and (fC, normal atmospheric pressure is 760 mmHg at the top of Mt. Everest (elevation 29,028 ft, or 8848 m), the atmospheric pressure is only about 270 mmHg. Thus, pressure decreases with altitude the column of air above the sea is taller, so it weighs more than the column of air above Mt. Everest. 

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