Pressure Units and Conversion Factors

Pressure is force per unit area. Pressure may be expressed in many different units.
Units like pounds per square inch give the units used for force and area. Units that include length, like millimeters of mercury refer to the pressure exerted by a column of the liquid of that height. The unit atmosphere refers to the pressure exerted by the gases in our atmosphere on all objects open to it. Since this varies with height above sea level, an average value at sea level is used and expressed in terms of millimeters of mercury. The Pascal is the name for the SI unit of pressure.
The following abbreviations are used:

atmospheres	=	atm
millimeters of mercury	=	mm Hg
Pascal	=	Pa
inches of mercury	=	in Hg
pounds per square inch	=	psi

The following equivalences provide conversion factors between pressure units.

1 atm	=	760 mm Hg	=	760 torr
1 atm	=	1.013 x 105 Pa	=	101.3 kPa
1 atm	=	29.92 in Hg	=	14.69 psi

Questions Recieved:
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Question 1:

An automobile tire is inflated to a pressure of 31.3 psi. Express this pressure in atmospheres, kilopascals, inches Hg, millimeters Hg and torr.

Hint:   1 atm   =   101.3 kPa   =   29.92 in Hg   =  760 mm Hg   =   14.69 psi   =   760 torr


Solutions:



Convert 31.3 psi

To atm:	31.3 psi	1 atm	=     2.13 atm
		14.69 psi

To kPa:	31.3 psi	101.3 kPa	=     216 kPa
		14.69 psi

To in Hg:	31.3 psi	29.92 in Hg	=     63.8 in Hg
		14.69 psi

To mm Hg:	31.3 psi	760 mm Hg	=     1.62E+3 mm Hg
		14.69 psi

To torr:	31.3 psi	760 torr	=     1.62E+3 torr
		14.69 psi

Question 2:

A student reads a barometer in the laboratory and finds the prevailing atmospheric pressure to be 687 mm Hg. Express this pressure in atmospheres, kilopascals, torrs, pounds per square inch, and pascals.

Hint:   1 atm   =  101.3 kPa   =  760 torr   =  760 mm Hg   =  14.69 psi   =   1.013 x 10⁵ Pa
Solutions:

Conversion factors:   1 atm   =  101.3 kPa   =  760 torr   =  760 mm Hg   =  14.69 psi   =   1.013 x 10⁵ Pa

Convert 687 mm Hg

To atm:	687 mm Hg	1 atm	=     0.904 atm
		760 mm Hg

To kPa:	687 mm Hg	101.3 kPa	=     91.6 kPa
		760 mm Hg

To torr:	687 mm Hg	760 torr	=     687 torr
		760 mm Hg

To psi:	687 mm Hg	14.69 psi	=     13.3 psi
		760 mm Hg

To Pa:	687 mm Hg	1.013 x 105 Pa	=     9.16E+4 Pa
		760 mm Hg

Question 3:

The prevailing atomospheric pressure on a plateau in Colorado is 0.795 atm. Express this pressure in pounds per square inch, kilopascals, pascals, millimeters Hg, and inches Hg.

Hint:   1 atm   =   101.3 kPa   =  1.013x10⁵ Pa   =  760 mm Hg   =   14.69 psi   =   29.92 in Hg
Solutions:

Conversion factors:   1 atm   =  101.3 kPa   =  1.013 x 10⁵ Pa   =  760 mm Hg   =  14.69 psi   =   29.92 in Hg

Convert 0.795 atm

To psi:	0.795 atm	14.69 psi	=     11.7 psi
		atm

To kPa:	0.795 atm	101.3 kPa	=     80.5 kPa
		atm

To Pa:	0.795 atm	1.013 x 105 Pa	=     8.05E+4 Pa
		atm

To mm Hg:	0.795 atm	760 mm Hg	=     604 mm Hg
		atm

To in Hg:	0.795 atm	29.92 in Hg	=     23.8 in Hg
		atm