Chemistry / Unit 7 Chem 1206 worked example, 60 to 90 seconds
Converting Among Pressure Units
The idea
Converting a pressure into other units means applying the fixed relationships among pascals, atmospheres, torr, millimeters of mercury, bar, and psi as a chain of conversion factors, one unit pair at a time.
In practice
A weather-station reading of 29.2 inches of mercury converts first to torr, using 1 in. Hg = 25.4 mm Hg together with 1 mm Hg ≈ 1 torr, giving about 742 torr. The same pressure converts to atmospheres by dividing by 760 torr per atmosphere, giving about 0.976 atm, and to kilopascals by multiplying atmospheres by 101.325 kPa per atmosphere, giving about 98.9 kPa. Each step uses exactly one defined relationship from Chem 1203's table, chained rather than combined into a single memorized formula.
Where people slip
Applying a conversion factor upside down, or reaching for a relationship two units don't share directly, is the most common error — check that each factor's units cancel the ones it should before multiplying.
Your place on the trail
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