CHEM 1A Chapter 5: Chapter 5 Book Notes
94
CHEM 1A Full Course Notes
Verified Note
94 documents
Document Summary
The first person to attempt a scientific study of the vapors produced in chemical reactions was the flemish physician jan baptista van helmont (1577-1644). In 1643 the italian physicist evangelista torricelli (1608-1647) performed experiments that show that the air in the atmosphere exerts pressure. He designed the first barometer by filling a tube that was closed at one end with mercury and then inverting it in a dish of mercury. The instruments used for measuring pressure, such as the manometer, often use columns of mercury because of its high density. The most commonly used units for pressure are determined by the height of the mercury column (mm) the gas pressure can support. The unit millimeters of mercury (mm hg) is called the torr. 1 standard atmosphere = 1 atm = 760 mmhg = 760 torr. The unit of pressure in the si system is newtons per meter squared (n / m2) called the pascal (pa).
